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Angela Dewhirst NZATS

The Evolution of Cardiopulmonary Resuscitation

– An Historical Perspective

Angela Dewhirst

September 2010

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Evolution of Cardiopulmonary Resuscitation – An Historical Perspective

The first Cardiopulmonary Resuscitation (CPR) course that I attended was as a young and keen “Zambuk” with the St John Ambulance Brigade in 1979. The most recent was last week in my

capacity as a Level 6 Instructor for the New Zealand Resuscitation Council (NZRC). The changes in this 30 (plus) year period have been immense. The techniques used today are the result of the latest research findings and what we currently believe to be the most effective means of revival. But this has always been the case. As health professionals we strive to stay up to date with the latest findings in our field as our predecessors did centuries ago. CPR is practiced throughout the world as a life saving skill. It is still the only known effective method of keeping someone who has suffered cardiac arrest alive long enough for definitive treatment to be delivered (usually defibrillation and intravenous cardiac drugs).As this year marks the 50th anniversary of modern resuscitation I thought it timely to reflect on where we have come from and where we are going in the field of

Cardiopulmonary Resuscitation. The following is my interpretation of this evolution and the information I have managed to gather on this extensive subject.

Throughout history it was long considered impossible, even blasphemous, to attempt to reverse ‘death’. Reversal of death was considered the province of God and not something mere mortals should undertake. Yet ancient writings by the Egyptians and Greeks (around 3000 BC) described theories of respiration and revival techniques such as inversion or rectal fumigation! So it would seem that despite religious beliefs or popular superstitions man has always wanted to prevent the loss of loved ones, as this quote from the William Shakespeare play King Henry VI, suggests: “O, that I could call these dead to life!” In the old testament of the Bible (around 800 BC) there is mention of the Prophet Elisha inducing pressure breathing from his mouth into the mouth of a child who was dying; “And when Elisha was come into the house, behold, the child was dead, and laid upon his bed… He went up, and lay upon the child, and put his mouth upon his mouth … and the flesh of the child waxed warm… and the child opened his eyes.”(Kings 4:34-35)

Other ancient records include Hippocrates (460-375 BC) who wrote the first description of endotracheal intubation in his book –‘Treatise on Air’ “One should introduce a cannula into the trachea along the jaw bone so that air can be drawn into the lungs.” Also Galen of Pergamum (129-200AD) who inflated the lungs of dead animals via the trachea with a bellows and concluded that air movement caused chest “arises”. Galen believed that the ‘innate heat of life’ was produced in the ‘furnace of the heart’; being turned on at birth and extinguished at death, never to be lit again. This strongly held belief, that ‘death’ was irreversible was maintained for centuries.

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In the Early Ages (around 500 AD) people realized that the body became cold when lifeless and connected heat with life. Therefore, in order to prevent death from taking the person, the body was warmed. The uses of warm ashes, burning excrement, or hot water

placed directly on the body were all employed in an attempt to restore life.Around this same time would-be rescuers would actually whip the victim (flagellation) in an attempt to stimulate some type of response. In the region of 1000 AD an experimental intubation of the trachea by Muslim philosopher and physician Avicenna was reported; “When necessary, a cannula of gold, silver or another suitable material is advanced down the throat to support inspiration.”

Philippus Paracelsus (1493-1541), a Swiss doctor and alchemist, used ‘Fire Bellows’ connected to a tube inserted into patient’s mouth as a device for assisted ventilation. He was known for opposing Galen’s medical theories. A study in 1550, after his death, credited him with the first form of mechanical ventilation.

It was not until around the Renaissance that Galen’s work was further challenged by anatomist Anreas Versalius. Versalius published “De humani corporis fabrica” (On the Workings of the Human Body) in 1543, which described blowing into a tube to resuscitate an animal. He performed this ventilation via a tracheostomy in a pregnant sow.

In 1628 William Harvey an English Physician, published “De Motu Cordis” (On the Motion of the Heart and Blood). The prevailing attitude of the time was that the wisdom of the Lord should be accepted in all things. This was a concept that Harvey struggled with when doing his research. “...I found the task so truly arduous... that I was almost tempted to think... that the movement of the heart was only to be comprehended by God. For I could neither rightly perceive at first when the systole and when the diastole took place by reason of the rapidity of the movement...”

In 1667 English scientist Robert Hook kept a dog alive for over an hour using fireside bellows via a tracheostomy in the dog. From the late 1500’s it was not uncommon to use a bellow from a fireplace to blow hot air and smoke into the victim's mouth, this method was used for almost 300 years. Unfortunately, not many people carried fireplace bellows with them, but the success of this procedure motivated various manufacturers to design and manufacture early versions of bag mask valve resuscitators. However, in those days, the medical authorities were not aware of the anatomy of the respiratory system and did not appreciate the need to extend the victim's neck and lift the jaw in order to obtain a clear airway.

A method of fumigation was explored in the 1700’s. This involved blowing tobacco smoke into the victim’s rectum. It seemed logical to stimulate the body to restart breathing. The method was thought to have had some success by the North American Indians and so American Colonists introduced it in England in 1767. This practice was abandoned in 1811 after research by Benjamin Brodie found that

small amounts of tobacco could kill a cat (1 oz) or a dog (4 oz).3


A presentation in 1744 to the Royal Society of London (Founded in 1660 as the Royal Society of London for the Improvement of Natural Knowledge) was made by surgeon William Tossach which aroused interest. He reported the successful revival of James Blair (twelve years earlier in 1732), a coal miner overcome by smoke, using mouth to mouth resuscitation (he knew of it as a technique used at that time by midwives to revive stillborn infants). Tossach’s account is thought to be the first clinical description of the procedure in the medical literature. “The colour was natural, except where it was covered with Coal-dust; his eyes were staring open, and his Mouth was gaping wide; his Skin was cold; there was not the least pulse in either Heart or Arteries, and not the least Breathing could be observed; So that he was in all appearance dead. I applied my Mouth close to his, and blowed my breathe as strong as I could; but having neglected to stop his Nostrils all the Air came out at them; Wherefore taking hold of them with one hand and holding my other on his Breast at the left Pap I blew again my breath as strong as I could. Raising his Chest fully with it: and immediately I felt six or seven very Quick Beats of the heart: his Thorax continued to play and the Pulse was felt soon after in the Arteries. I then opened a Vein in his Arm; which, after giving a small Jet, sent out the Blood in Drops only, for a Quarter of an Hour … And then he bled freely. Tho’ the lungs continued to play, after I had first set them in Motion; yet for more than half an Hour, it was only as a pair of bellows would have done, that is, he did not so much as grone, and his Eyes and Mouth remained both open. After about an Hour he began to yawn, and to move his Eyelids, Hands, and Feet. In an Hour more he came pretty well to his Senses, and could take Drink; but knew nothing at all that had happened after his lying down at the Foot of the Ladders, till his waking”Sadly however, The Royal Society was not impressed, maintaining that “life ends when breathing ceases”. While mouth to mouth was already known at this time it was not favoured, and instead the use of bellows were advocated. This was because scientists of the time had established that exhaled air contained a poisonous gas (CO2) that they referred to as ‘fixed air’. There was a strongly held belief that expired air did not contain enough oxygen to sustain life.

Other methods were developed in the 1700’s in response to the leading cause of sudden death of that time, drowning. Inversion was originally practiced in ancient Egypt and it again became popular in Europe around 1770. This method involved hanging the victim by his feet, with chest pressure to aid in expiration and pressure release to aid inspiration. These and other methods had been applied for years as documented in the report of Anne Green’s hanging, resuscitation and recovery in 1650 by English anatomist and physician Thomas Willis. Other methods of revival included physical and tactile stimulation in an attempt to ‘wake up’ the victim. That is yelling and slapping was used in the hope of reviving the casualty.

It was during the Age of Enlightenment, starting around 1750, that there was a rapid increase in scientific discovery. Scientists and philosophers questioned the dogma of the past and came to believe that humans could understand and control their own destinies. There was a growing belief that people could unravel the mysteries of the universe and with good evidence it became seen as a doctor’s duty to ‘prolong life’. This finally set the stage for progress in the area of resuscitation.

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Mouth to mouth resuscitation had been used to revive ‘stillborn’ infants intermittently throughout history. It was only in 1740 that the Paris Academy of Sciences officially recommended mouth to mouth resuscitation for drowning victims.

The first city to teach and promote resuscitation was Amsterdam, located in the heart of the European Enlightenment and also a city of canals, therefore a city with many drownings, as many as 400 per year. Death from cardiac disease was still not prevalent and sudden deaths were mostly from accidents. In August 1767 a few wealthy and civic minded citizens in Amsterdam gathered to form the Dutch Society for Recovery of Drowned Persons later to be known as the Dutch Humane Society. This society was the first organized effort to respond to

sudden and unexpected death. Within 4 years of its founding, the society in Amsterdam claimed that 150 persons were saved by their recommendations. Their techniques involved a range of methods to stimulate the body. They published guidelines for resuscitation of victims of drowning. The members of the society recommended:1. Warming the victim (which sometimes required transporting the body to a different location) by lighting a fire near the victim, burying him in warm sand, placing the body in a warm bath, or placing in a bed with one or two volunteers2. Removing swallowed or aspirated water by positioning the victim's head lower than feet 3. Applying manual pressure to the abdomen 4. Respirations in to the victim's mouth, either using a bellows or with a mouth to mouth method (mouth to mouth or mouth to nostril respiration is described including the advice that “a cloth or handkerchief may be used to render the operation less indelicate”) 5. Tickling the victim's throat with a feather to induce vomiting6. ‘Stimulating’ the victim by such means as rectal and oral fumigation with tobacco smoke. This may seem very unusual in modern times; however it may have been that the nicotine was enough of a stimulant to engender a response in the “almost” dead 7. Bloodletting The first four of these techniques (or variations of them) are still in use today, whereas the last three are now out of line with modern medical thinking. However, regardless of the scientific merit of these techniques, it started a collective belief that resuscitation was possible, and the ‘suddenly dead’ could be revived.

In Hamburg, Germany an ordinance was passed in 1769 providing notices to be read in churches describing assistance for drowned, strangled, and frozen persons and those overcome by noxious gases. This is probably the first example of mass medical training.

In response to the increasing numbers of drownings during this time period, societies were formed to organize efforts in resuscitation. England’s Royal Humane Society was founded in 1774. It was originally known as the ‘Institution for affording immediate Relief to Persons apparently dead, from drowning’. Founded by two doctors, William Hawes (1736-1808) and Thomas Cogan (1736-1818) who wanted to promote the new, but controversial, medical

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technique of resuscitation. In 1776 it became known as the Humane Society. In 1787 it became the Royal Humane Society of London. The Society’s emblem shows an angel blowing on an ember with a Latin Inscription that translates ‘A little spark may yet lie hid.’ This emblem reflected the belief of the time that as long as there was warmth in the body, life could be reignited. John Fathergill reported a successful case of mouth to mouth resuscitation in 1744 of a drowning victim. The Royal Humane Society in London advocated mouth to mouth resuscitation of stillborn infants in 1775 following reports from Obstetrician Benjamin Pugh in 1754 of successes using mouth to mouth and an endotracheal tube. William Hunter (1718 – 1783) a Scottish Obstetrician, referred to this as “the method practiced by the vulgar to restore stillborn children.” He and his Surgeon brother John Hunter developed double bellows for resuscitation in 1775 - one for blowing air in and the other for drawing bad air out. By 1776 the Royal Humane Society recommended the use of bellows rather than mouth to mouth. Much like the Royal Societies concern that exhaled air contained a poisonous gas (CO2) this limited understanding of oxygen concentrations made the widespread introduction of ‘mouth to mouth’ problematic.

Hippocrates (460–375BC) had previously proposed a life giving constituent of air, and Robert Boyle (1627–1691) had demonstrated that larks, sparrows, and mice died if placed in vacuum chambers. Joseph Priestly (1733–1804), an English chemist, however, first isolated “dephlogisticated air” in 1774. He noted that it kept mice alive and caused candle flames to burn brighter. Antoine-Laurent Lavoisier (1743–1794) termed the gas “the acid producer” or “oxygine” with Pierre-Simon de Laplace (1749–1827), he showed that respiration was an oxidative process in which water and carbon dioxide were formed as byproducts and showed that the lungs take in oxygen and excrete carbon dioxide. There are accounts of François Chaussier (1746–1828) giving oxygen to newborns in 1780.

Around 1773 the Barrel Method was employed. In an effort to force air in and out of the victim's chest cavity, the rescuer would hoist the Victim onto a large wine barrel and alternately roll him back and forth. This action would result in a compression of the victim's chest cavity, forcing air out, and then a release of pressure which would allow the chest to expand resulting in air being drawn in. This technique was in many ways a precursor to modern CPR techniques as it attempted to force air in and out of the lungs.

In 1778 defibrillation was first suggested. Goodwin and Kite deduced that asphyxia caused the heart to stop. Kite suggested electric shock treatment (defibrillation). However airway problems produced by the tongue were not appreciated at the time. Early descriptions of possible defibrillation include one in 1780, a report of “Sophia Greenhill who fell from a window and was taken up, by all appearances, dead.” The report goes on to say that “Mr Squires tried the effects of electricity, and upon transmitting a few shocks to the thorax, perceived small pulsatations.”

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In 1803 Russian Scientists devised a concept which involved reducing the body’s metabolism by freezing the body under a layer of snow and ice. Unfortunately, what the medical authorities did not realize at the time was that the most critical organ which needed to be frozen in order to accomplish a reduction of the body's metabolism was the brain, sadly the head being the only part of the body they didn’t chill!

In 1812 Lifeguards were equipped with a horse which was tied to the Lifeguard station. When a victim was rescued and removed from the water, the Lifeguard would hoist the victim onto his horse and run the horse up and down the beach. This resulted in an alternate compression and relaxation of the chest cavity as a result of the bouncing of the body on the horse. This procedure was banned across the United States in 1815 as a result of complaints by ‘Citizens for Clean

Beaches’

In 1829, Leroy d’Etiolles demonstrated that over distension of the lungs by bellows could kill an animal (pneumothoraces) in a lecture in Paris. Subsequently, both mouth to mouth and bellows inflation fell out of favour and remained so for many years.However, by 1850 mouth to mouth, as seen for babies resuscitated by midwives, was gaining momentum to replace chest pressure. This was timely as Anaesthetics were also gaining momentum around this time (first inhaled ether anaesthetic public demonstration - 1846 William Morton), resulting in an increase in respiratory arrest in people under medical supervision.

As late as 1856, manual ventilation was still being given a low priority. Concentration was on maintaining body heat. These were the same recommendations as provided by the Dutch nearly 100 years earlier. A significant change in priorities occurred when Marshall Hall challenged the conventional wisdom of the era. His contentions were that time was lost transporting the victim; that the restoration of warmth without some type of ventilation was detrimental; that fresh air was beneficial; and that if left in the supine position, the victim's tongue would fallback and occlude the airway. Because the bellows were no longer an option, Marshall Hall developed a manual method in which the victim was rolled from stomach to side 16 times a minute. In addition, pressure was applied to

the victim's back while the victim was prone (expiratory phase). Tidal volumes of 300 ml to 500 ml were achieved and soon became adopted by the Royal Humane Society. Instructions for the Marshall Hall method were; “Chest elevated, victim pulled up on side momentarily, and then rolled back, Pressure on back expelled air. Pressure released when victim on side for inspiration.”

In 1858 Dr H. R. Silvester introduced a method of artificially resuscitating a still born child and for ‘restoring persons apparently drowned or dead.’ The patient would be on his or her back, with arms raised to the sides of the head, held there temporarily, then brought down and pressed against the chest. This movement was repeated 16 times per minute. This chest pressure arm lift method, coined the phrase; ‘out goes the bad air, in goes the good air’.

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The 1911 Boy Scout handbook promoted the Silvester method of resuscitation and continued to do so well into the 1950’s. It was taught to thousands of Boy Scouts and may have saved an occasional drowning victim who was merely apnoeic. It was seen to be used in episodes of ‘Lassie’ and ‘Tom and Jerry’ around this time. In 1950, Archer Gordon evaluated this most popular method of respiratory support (chest pressure arm lift) and concluded it was of marginal benefit.

As we have seen from 1700 to 1950 there were many techniques and procedures recommended for artificial ventilation. Most relied on direct pressure to the abdomen, chest, or back. The inventors of these techniques thought, wrongly, that passive entrainment of air into the lungs was sufficient to maintain adequate oxygenation.

Although the first record of external chest compression was written about by John Howard in the 18th Century it was not until 1878 that one of the first successful attempts to achieve artificial circulation via external chest compression was reported in animals by Dr Boehm, and not until 1891 that Friedrich Maass performed the first equivocally documented use of external chest compression on humans. In 1885 Dr Koenig described survival after closed chest massage in a human. Despite the fact that external chest compression had been well described in several case reports, and that a form of it was already in use as part of the manual ventilation methods for artificial respiration mentioned above, external chest compression did not catch on as a means of artificial circulation. It is thought the reason for this may have been people at the time could accept external chest compression as a means of aiding ventilation, but they found it difficult to envisage an artificial circulation role for chest compression. Indeed, many at the time did not even believe artificial circulation was possible. As a doctor in 1890 wrote, “we are powerless against paralysis of the circulation, while asphyxia can be treated through artificial respiration as long as the heart keeps beating”.Unlike cessation of respiration, an obvious sign of sudden death, the cessation of circulation, and particularly the rhythm of the heart, was invisible to an observer. Perhaps as a result, the appreciation of artificial circulation lagged behind the more obvious need for artificial respiration.

John McWilliam made the first detailed descriptions of ventricular fibrillation (VF) in animals and he was the first to postulate an importance for humans in a series of articles from 1887 to 1889 published in the British Medical Journal (BMJ). In McWilliams day it was assumed that sudden cardiac collapse took the form of a sudden standstill – in other words, no electrical activity. Experiments by McWilliams performed on a range of animal hearts disproved this. In 1889 McWilliam wrote “The normal beat is at once abolished, and the ventricles are thrown into a tumultuous state of quick, irregular, twitching action…The cardiac pump is thrown out of gear, and the last of its vital energy is dissipated in a violent and prolonged turmoil of fruitless activity in the ventricular walls….It seems to me in the highest degree probable that a similar phenomenon occurs in the human heart, and is the direct and immediate cause of death in many cases of sudden dissolution.” Although McWilliam used an electrical current to induce the fibrillation, he never tried electricity to stop the fibrillation of a heart muscle. These research findings were conducted prior to the invention of the Electrocardiograph (ECG).

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This image (below) is of Dr Bernhard Schultze demonstrating the Schultze method of neonatal resuscitation in 1871. This method involved swinging the infant upside down in the hope that this would stimulate breathing.

In 1892 the seemingly ludicrous suggestions continued when a French physician Dr Laborde recommended tongue stretching. This procedure was described as holding the victim's mouth open while pulling the tongue forcefully and rhythmically. Other methods still used included stretching the rectum, rubbing the body, tickling the throat with a feather and waving strong salts, such as ammonia, under the victim’s nose.

In 1898 the first documented attempt at open chest cardiac massage was performed by Tuffier and Hallion.

In 1899 Jean Louis Prevost and Frederic Batelli, two physiologists from the University of Geneva, Switzerland reported termination of VF in the open chested dog using alternating current. Prevost and Battelli established that a weak electric current passed through the heart, directly would fibrillate the heart, and that a stronger electric current was capable of terminating fibrillation. It was considered a medical curiosity with no relevance for humans.

The first successful open chest compression on a human was demonstrated by Dr George Crile in 1903. In 1904 Crile described an experimental method in animals combining chest compression, artificial respiration, and intravenous adrenaline. Crile recognized the importance of achieving adequate coronary perfusion pressure and the value of Adrenaline.

In 1911 Draeger Medical designed an artificial breathing device, which was oxygen powered, the “Draeger Pulmoter” (seen here at right) was used by fire and police units.

Dr Shafer recommended the prone-pressure method (as seen below) in 1909:

Interest in VF grew during the first half of the twentieth century because of increasing use of electricity. In 1926, the Edison Electric Institute, concerned about fatal electric shocks suffered by its utility workers, funded research to prevent fatalities. Researchers Donald Hooker, William Kouwenhoven, and Orthello Langworthy began to study the effects of electricity directly on the heart, in 1930. The findings from their research, conducted on animals, backed up the earlier work of Prevost and Battelli. Hooker et al showed that even small electric shocks could induce VF in the heart and that more powerful shocks could erase the fibrillation. These investigators induced VF in dogs and then were able to defibrillate the heart without opening the chest. The term ‘countershock’ was derived from their research and became synonymous with the meaning defibrillation for many years. They found their closed chest defibrillation

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was successful only if the fibrillatory contractions were vigorous and the period of no circulation or breathing did not exceed several minutes. These findings were aided by the invention of the Electrocardiograph in 1903 by Willem Einthoven.

In 1932 the Holger-Neilson method was promoted. This involved the patient in a prone position with hands under their head. Expiration was ‘achieved’ by pressing on chest and inspiration by lifting the elbows.

This is also known as the ‘back-pressure arm lift artificial respiration method’. This method was later shown by Safar and Elam to be ineffective.

During World War II, mouth to mouth resuscitation was reported to have been used. While the Second World War prevented Hooker, Kouwenhoven, and Langworthy from developing the ability to defibrillate human hearts, it was on the basis of their work that Claude Beck constructed the first defibrillator; an alternating current (AC) manual internal defibrillator which was applied directly to the heart.

Beck witnessed his first cardiac arrest during his internship in 1922 while on the surgery service. During a urologic operation, the anaesthetist announced that the patient’s heart had stopped. To the amazement of Beck, the surgical resident removed his gloves and went to a telephone in a corner of the room and called the fire department. Beck remained in total bewilderment as the fire department rescue squad rushed into the operating room 15 minutes later and applied an oxygen powered respirator, such as the Draeger Pulmoter, to the patient’s face. The patient died, but the episode reportedly left an indelible impression on him. Twenty years later, Beck wrote, “Surgeons should not turn these emergencies over to the care of the fire department” Recalling the same event, he remarked to medical students, “The experience left me with a conviction that we were not doing our best for the patient.”

Beck realized that ventricular fibrillation often occurred in hearts that were basically sound and he coined the phrase “Hearts too good to die.” In 1947, Beck accomplished his first successful defibrillation of a 14-year-old boy using open chest massage and internal defibrillation with

alternating current. The boy was being operated on for a severe congenital caved in chest (pectus excavatum). In all other respects the boy was normal. During the closure of the chest, the pulse suddenly stopped and the blood pressure fell to zero. The boy was in cardiac arrest. Dr. Beck immediately reopened the chest and began manual heart massage to restore blood circulation. As he looked at and felt the heart, he realized that ventricular fibrillation was present. Massage was continued for 35 minutes at which time an electrocardiograph was taken that confirmed the presence of ventricular fibrillation. Another 10 minutes passed before the defibrillator was brought to the operating room. The first shock using electrode paddles placed directly on the sides of the heart was unsuccessful. Beck administered procaine

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amide, a drug to stabilize the heart’s rhythm. He gave a second shock that wiped out the fibrillation. In a very few seconds a feeble, regular, and fast contraction of the heart occurred. The blood pressure rose from 0 – 50 mmHg. Beck noted that the heartbeat remained regular and saw that the pressure slowly began to rise. Twenty minutes after the successful defibrillation, the chest wound was closed. By three hours, the blood pressure rose to a normal level, and the child awoke and was able to answer questions. The boy made a full recovery, with no neurological damage.

As Beck made his defibrillators individually he was known to experiment with their design. They were all intended for open heart defibrillation. Beck designed a model that would both shock and perform heart massage. Suction cups were attached to the walls of the heart and alternating suction would expand and allow the heart to relax. These suction cups doubled as defibrillator electrodes. However, the medical profession still lacked the ability to defibrillate the human heart without having the victim’s chest open.

All this changed when Paul Zoll developed external defibrillation in 1955. This work was a natural extension of his earlier work with external cardiac pacemakers. Zoll reported successful closed chest defibrillation using alternating current. Over a period of four months, Zoll had used an external defibrillator to successfully stop ventricular fibrillation eleven times in four different patients. The energy required for defibrillation ranged from 240 to 720 volts. Zoll’s findings were published in the New England Journal of medicine in 1956.

The defibrillator that Zoll designed (just like the earlier internal defibrillator developed by Beck) utilised alternating current (AC). Because of this, these defibrillators were very large and heavy. While some manoeuvrability could be attained by storing the defibrillator in a large cabinet with wheels attached to the bottom, it was essentially not practical to bring the defibrillator to the patient. This lack of portability was a serious limitation of the AC defibrillators, and meant that not many lives would be able to be saved until this portability issue was resolved.

Bernard Lown addressed the portability issue in the early 1960s when he developed a defibrillator that used direct current (DC) instead of AC. With DC it was possible to use power, supplied by a battery, to charge a capacitor over a few seconds. The capacitor stored the energy until it was released in one massive jolt to the chest wall. This monophasic energy pulse became known as the ‘Lown waveform’. The availability of new, small capacitors considerably reduced the size and weight of the device. This eliminated the need for a heavy transformer, thus allowing the defibrillator to be battery operated. With this came portability, and meant that the defibrillator could now travel to the patient.

Animal experiments on dogs in 1960 and in 1961 showed that DC shocks were extremely effective and many times safer than AC when applied through the chest wall. Lown submitted an article to the American Journal of Cardiology in 1962 that showed the incidence of VF was 10 times more frequent after AC than DC Cardioversion. The development of portable defibrillation was particularly significant as it coincided with the emergence of modern CPR.

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Danish anaesthetist Henning Ruben invented a self inflating resuscitation bag in 1954. His original device consisted of bicycle spokes welded together and fitted inside an anaesthesia bag. He later modified and described it in 1957.

In 1949, during the middle of a polio outbreak, anaesthetist James Elam applied mouth to mouth to an older child in an emergency situation. Elam described the event in his own words as “I was browsing around to get acquainted with the ward when along the corridor came a gurney racing - a nurse pulling it and two orderlies pushing it, and the kid on it was blue. I went into total reflex behaviour. I stepped out in the middle of the corridor, stopped the gurney, grabbed the sheet, wiped the copious mucous off his mouth and face, sealed my lips around his nose and inflated his lungs. In four breaths he was pink.” On the evening before this rediscovery, Elam read a chapter on the history of resuscitation in which mouth-to-mouth ventilation for newborns was described. He credits this chapter for his “reflex behaviour.” Elam’s experience led to his extolling the merits of mouth to nose ventilation. He set out to prove that exhaled air was adequate to oxygenate non breathing persons. Elam moved to Buffalo’s Roswell Park Memorial Institute along with his top two collaborators, Dr Elwyn Brown, and Dr Raymond Ten Pas. He obtained permission from his chief of surgery to do studies on postoperative patients before the ether anaesthesia wore off. In this 1954 study, he demonstrated that expired air blown into the endotracheal tube maintained normal oxygen saturation. Even after he had established this, manual ventilation methods were still preferred by the unconvinced physicians of the time.

A few years later James Elam met Peter Safar, an Austrian anaesthetist, and convinced him to join the effort to show the world that expired air ventilation was effective. Safar set out on a

series of experiments using paralyzed individuals to show that the technique could maintain adequate oxygenation. Peter Safar describes the experiments: “Thirty-one physicians and medical students, and one nurse volunteered . . . Consent was very informed. All volunteers had to observe me ventilate anaesthetised and curarized patients without a tracheal tube. I sedated the volunteers and paralyzed them for several hours each. Blood O2 and CO2 were analyzed. I demonstrated the method to over 100 lay persons who were then asked to perform the method on the curarized volunteers.” These experiments provided compelling data to switch from manual to mouth to mouth ventilation.

The United States military accepted and endorsed the method in 1957 and the American Medical Association followed suit in 1958. The May 1958 issue of Journal of the American Medical Association (JAMA) contains the following endorsement: “Skillful performance of expired air breathing is an easily learned, lifesaving procedure. It has revived many victims unresponsive to other methods and has been proved in real emergencies under field conditions. Information about expired air breathing should be disseminated as widely as possible.”

In 1956 Peter Safar and James Elam demonstrated that mouth to mouth rescue breathing was superior to mechanical techniques, such as the Shafer prone-pressure method. By 1957 Safar was able to establish conclusively three important points:

First, simply tilting the person’s head backward would usually open the airway

Second, most of the manual ventilation methods provided little air, whereas mouth to mouth ventilation provided excellent artificial respiration

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Third, anyone could perform mouth to mouth ventilation easily and effectively

These findings were published in his 1957 book ‘ABC of resuscitation’ and were considered substantial enough to convince the world to change from manual ventilation to mouth to mouth ventilation.

In 1959 the New York State Health Commissioner, Herman Hilliboe, commissioned James Elam to write an instructional booklet titled ‘Rescue Breathing’. This success of this booklet encouraged Elam into producing a film which demonstrated this new life saving technique.

In 1960, rescue breathing was adopted by the National Academy of Science, American Society of Anaesthesiologists, Medical Society of the State of New York and the American Red Cross as the preferred method of resuscitation. The American Red Cross began an aggressive education campaign in order to educate the American public. An American Red Cross volunteer trainer called Roger Mehalek introduced a breathing trainer called ‘Miss Sweet Breath’ which was a plaster and plastic training mannequin he created. In the 1960’s this training was expanded and Lifeguard Personnel were instructed in this procedure by performing mouth to mouth resuscitation in the water using rescue buoys, paddleboards, boats and canoes as flotation supports. In 1960 Elam and Safar collaborated with Norwegian toy maker Asmund Laerdal to create ‘Resusci Anne’, the CPR training mannequin which allowed the public to learn the technique in a safe manner. Laerdal is now is a medical equipment manufacturer.

The formalized system of chest compression was really an accidental discovery made by William Bennett Kouwenhoven, Guy Knickerbocker, and James Jude. Their 1960 animal research involved studying defibrillation. They noticed that by forcefully applying the paddles to the chest of the dog, they could achieve a pulse in the femoral artery. Further meticulous experimentation, answered such basic questions as how fast to press, where to press, and how deep to press. They had accidentally discovered that they could achieve adequate artificial circulation by applying pressure to the chest with their hands. This finding was the key observation that led them to try chest compressions on humans.

The first person saved with this technique was recalled by Jude: “She was rather an obese female who … went into cardiac arrest as a result of flurothane anesthetic. This woman had no blood pressure, no pulse, and ordinarily we would have opened up her chest. Instead, since we weren’t in the operating room, we applied external cardiac massage. Her blood pressure and pulse came back at once. We didn’t have to open her chest. They went ahead and did the operation on her, and she recovered completely.” They published their findings that year on twenty cases of in-hospital cardiac arrest in the Journal of the American Medical Association (JAMA). Fourteen of the twenty patients (70%) survived and were discharged from the hospital. Many of the patients were in cardiac arrest as a result of anaesthesia. Three patients were documented to be in ventricular fibrillation. The duration of chest compression varied from less than one minute to sixty-five minutes. The JAMA article was very straightforward: chest compression buys time until the external defibrillator arrives on the scene. As the authors write in the article, “Anyone, anywhere, can now initiate cardiac resuscitative procedures. All that is needed is two hands.”

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The report of closed chest cardiac massage, by Kouwenhoven et al. in 1960, combined with mouth to mouth ventilation marked the beginning of the modern era of CPR. The crucial aspect of this technique is that the patient receives oxygen which is transported to the brain by the development of a minimal blood circulation. On this basis many national and international guidelines to perform CPR came out. Further work by these investigators led to the development of modern closed chest resuscitation. The two techniques of mouth to mouth breathing and closed chest cardiac massage were brought together. This formally took place on 16 September 1960, when Safar, Jude, and Kouwenhoven presented their findings at the Maryland Medical Society. In this presentation, Safar stressed the importance of combining artificial respiration and artificial circulation, stating that the two techniques of mouth to mouth ventilation and external chest compression “cannot be considered any longer as separate units, but as parts of a whole and complete approach to resuscitation”. At this stage the term ‘CPR’ had yet to be coined. Also, there needed to be a way of re-establishing a normal cardiac rhythm. The value of portable DC closed chest defibrillation was tied into the mix very soon after (early 1960’s) thanks to Bernard Lown’s work.

In 1962 Archer Gordon and David Adams, produced a half hour training film called ‘The Pulse of Life.’ The film was used in CPR classes and viewed by millions of students. The film demonstrated the airway, breathing and circulation steps that make up CPR.

In 1963 Cardiologist Leonard Scherlis started the American Heart Association’s CPR Committee, and the same year, the American Heart Association formally endorsed CPR.

In 1966 The American National Research Council of the National Academy of Sciences convened a conference on cardiopulmonary resuscitation. The conference was the direct result of requests from the American National Red Cross and other agencies to establish standardized training and performance standards for CPR.

In 1965 Irish physician Frank Pantridge took the portability of defibrillators to a new level by setting up the world’s first mobile coronary care unit (MCCU). He staffed it with an ambulance driver, a doctor and a nurse. This Belfast based system was set up to reach patients with acute myocardial infarction. The initial results of this program were published in the 5 August 1967 issue of The Lancet; their findings on 312 patients covered a 15 month period. Half the patients had myocardial infarct and there were no deaths

during transportation. Of ground breaking importance was the information on 10 patients who had cardiac arrest. All had ventricular fibrillation; six arrests occurred after the arrival of the MCCU, and four occurred shortly before its arrival. All 10 patients were resuscitated and admitted to the hospital. Five were subsequently discharged alive. The article has historical importance because it served to stimulate pre hospital emergency cardiac care programs throughout the world. As an historical footnote, August 1967 is exactly 200 years to the month from the founding of the Dutch Humane Society. The rescue effort that began in 1767 in Amsterdam as an attempt to resuscitate drowning victims (the sudden death of the 18th century) finally culminated two centuries later in Belfast with a successful way to achieve resuscitation for cardiac arrest (the sudden death of the 20th century).

The extensive international readership of the Lancet helped explain why Pantridge’s idea spread so rapidly to other countries. Within two years, similar physician staffed MCCU

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programs began in the United States, Australia and Europe. The first program in the United States was started in 1968 by William Grace out of St. Vincent’s Hospital in New York City. The program was a clone of the Belfast program and utilized specially equipped ambulances with physicians on board to provide advanced resuscitation care directly at the scene of cardiac emergencies. Calls for medical emergencies in which chest pain was a complaint were passed on from the police operator to the hospital. There an ambulance would fight New York traffic to arrive at the scene. Grace described the rather full ambulance and how it was sent: “The personnel include an attending physician, resident physician, emergency room nurse, ECG technician, as well as a student nurse observer, in addition to the driver and his assistant. This team is summoned from various points in the hospital to the emergency room by a personal paging system which each member of the team carries. This team has four and one half minutes to get to the emergency room, obtain their equipment and board the ambulance. Anyone who is not there within this time is left behind.” Physicians with defibrillators rushing through the city to reach a non breathing, unconscious person whose heart had stopped were quite unusual by 1968 standards.

Eugene Nagel, a Miami physician became aware of Pantridge’s work in 1967. He became convinced it was time to move away from a program using physicians to one staffed by paramedics. Nagel established a radio link and telemetry between the paramedic fire fighters and the hospital. Nagel vividly recalled the first save of the Miami paramedic program. The collapse occurred near Station 1, on the fringe of downtown Miami. He reminisced: “There was a guy named Dan Jones who was then about 60 years old, who was a wino who lived in a fleabag in the bad part of town. Jones was well known to rescue. In June of ‘69 they got a call—man down—it was Jones. They put the paddles on him, he was in VF, started CPR, zapped him, he came back to sinus rhythm, brought him in to ER and three days later he was out and walking around. In gratitude, about a week later, he came down to Station 1, which he had never done before, and he said he would like to talk to the man who saved his life. They told me they had never seen Dan Jones in a clean shirt and sober, both of which he was that day. He would periodically come to the fire house and just say hello and he seemed to be sober. In my talks in those days I said this was the new cure for alcoholism. That was our first true save.”

By 1970 a true tiered response to medical emergencies existed. The beauty of the tiered response system was the efficient use of fire department aid personnel, which allowed reaching the scene quickly to start CPR. Then a few minutes later the paramedics arrived to provide more definitive care such as defibrillation. In this way the brain could be kept alive until the electric shock converted the heart to a normal rhythm. As by this time it was understood that CPR would prolong the time taken for pulseless ventricular Tachycardia (VT) to deteriorate into VF or worse (asystole) and would help to preserve heart and brain function. They were starting to realize that most resuscitation attempts that failed were due to circulatory collapse and myocardial damage due to hypoxaemia. It was well recognized that survival from arrest involves immediate restoration of oxygenated blood by performing CPR. After stabilization the paramedics would transport the patient to the hospital where the cause of arrest (‘H & T’s’) could be found, so definitive treatment could occur. Full understanding of these concepts and the resources to carry this out however, was still evolving at this time.

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Leonard Cobb, a Seattle doctor was also energised by Pantridge’s work. He set up a similar system to Nagel and knew from data the program had collected that the sooner CPR was started, the better the chances of survival. He reasoned that the best way to ensure early initiation of CPR was to train the bystanders. Cobb, with the support of Gordon Vickery (chief of the Seattle fire department), held the world's first mass citizen training in CPR in Seattle, Washington called Medic 2 in 1972. He helped train over 100,000 people the first two years of the programs. Some national medical organisations were initially sceptical of this approach but the alarmists voices were stilled by some fortunate saves.

During the Vietnam War the US army introduced CPR to the people for the first time. Then, in 1973 the American Red Cross and the American Heart Association (AHA) began a big campaign to teach the American population this method.

Dr Henry Heimlich saw the value of airway clearing techniques in a patient with airway obstruction. In 1974 he pioneered a life-saving manoeuvre to prevent food-choking. His findings were published in ‘The Annals of Thoracic Surgery’ in August of 1975. His paper titled “Food choking and drowning deaths prevented by external sub diaphragmatic compression” was well received. He explained that sudden elevation of the diaphragm compresses the lungs, which explosively forces air out through the trachea, ejecting the obstructing object. His abdominal thrust technique is still recommended as part of the airway obstruction algorithm taught today.

Modern American philosopher Daniel Callahan (born 1930) widely recognized for his innovative studies in biomedical ethics, around this time argued that as death became more and more under the control of humans, as it became increasingly possible for medicine to save and prolong life, to manipulate the conditions of dying, the fatalistic view of death was rejected, and morality was called upon to increase its demands to struggle against death. Embedded in this change is what Callahan calls the ‘moral logic’ of medical progress; where the scientific imperative of progress comes to take on the force of a moral imperative: what can be done medically to struggle against death, ought to be done, and what ought to be done, ought to be available to all. If not, then “...we are open to moral blame. People will die who need not die. If we do not use our newly available technologies to save lives, we can be held accountable for the loss of those lives”.

The Lown waveform was the standard for defibrillation until the change to biphasic defibrillation which started in the late 1980s. With the Lown or monophasic waveform current traveled in one direction through the heart. With a biphasic waveform, current is delivered to the heart in two vectors. Because of the two vector approach, the peak current required to convert the arrhythmia is reduced, and the efficacy of the shock is greatly enhanced. For example an adult setting for defibrillation in a monophasic defibrillator would be 360 Joules of energy; a comparable shock can be delivered with a biphasic defibrillator with only 200 Joules. Biphasic defibrillation results in less myocardial damage from the shock itself. Until recently, most external defibrillation shocks

were delivered via paddles placed upon the patient’s chest. Today in developed countries, the majority of defibrillation shocks are delivered through defibrillation electrodes, pads that are placed directly on the patient’s skin. These defibrillation pads are safer for rescuers (less risk of

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electric shock) and safer for the patient (less risk of electrical burns), and because they conform to the chest are generally able to deliver the current more effectively.

In 1981 a program to provide telephone instructions in CPR began in King County, Washington. This program used the emergency dispatchers to give instant directions while the fire department EMT personnel were en route to the scene. This demonstration project increased the rate of bystander provided CPR by 50%. Dispatcher assisted CPR is now standard care for dispatcher centers throughout the United States and in other countries such as Israel, Great Britain, Sweden, Norway, Australia and New Zealand. The dispatcher is trained to recognize early warning signs of cardiac or respiratory arrest. For example if the dispatcher suspects an agonal breathing pattern they will ask the caller to closely observe the breathing and report back. The dispatcher can then assess the situation and give instructions accordingly. This allows even untrained bystanders to be utilized while waiting for the ambulance.

In 1980 the first program to train Emergency Medical Technicians (EMT’s) to perform defibrillation began in Washington. This training required 10 hours, and in the first demonstration project, survival from ventricular fibrillation increased from 7% to 26%.

In 1984 the first program with fire fighter EMT’s using automated external defibrillators (AED’s) also began in Washington. The use of AED’s simplified the training of EMT’s and thus allowed the procedure to spread more rapidly throughout communities. Automated external defibrillators require considerably less training time compared to manual defibrillators since the user does not have to interpret the cardiac rhythm.

The idea for an automated defibrillator was first conceived by Dr. Arch Diack, a surgeon in Portland, Oregon. His prototype, literally assembled in a basement, utilized a unique defibrillatory pathway – tongue to chest. There was a breath detector that was a safeguard to prevent shocking breathing persons. The electrode was essentially a rate counter, far cruder than today’s sophisticated VF detectors. The production model weighed 16 kg and gave verbal instructions. It was an idea ahead of its time. Most people viewed it as a curiosity. By the late 1980’s, however, other manufacturers entered the field leading to the automated external defibrillators we have today.

Current AED’s, like modern manual defibrillators, use electrode pads attached to the chest. AED’s are programmed to guide the operator (with a series of voice prompts) through the procedure. The pads once attached automatically detect the type of heart rhythm and if VF is present the AED instructs the operator to press a button (usually flashing red) to shock the patient. From EMT defibrillation with AED’s, there was a natural and logical progression to first responder defibrillation (AED’s used by police or security personnel), next widespread public access defibrillation (AED’s used by lay persons in public locations such as airports, schools, exercise facilities, etc.) and finally home AED including the opportunity to purchase

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AED’s over the counter. In the United States of America AED’s are promoted as a personal safety device for private citizens homes!

AED’s are improving survival rates due to their accessibility. A New Zealand website is currently under development (www.aedlocations.co.nz) which explains their locations within the community with a view to eventually being able to access this information via the global positioning device in your mobile telephone promoting widespread public access to defibrillation. The website www.firstaidcorps.org is an international equivalent.

In the community, AED studies in Rochester, New York, Chicago airports, and Las Vegas casinos have demonstrated that, where the mean response time is no more than 5.5 minutes, survival rates are over 40%. Fox News, in the United States recently reported that “The best place to have your cardiac arrest is in a casino.”

Recent innovations in technology have provided AED’s that offer immediate feedback on the rate and depth of compressions. Future features will likely include AEDs that can analyse rhythms while chest compressions are ongoing and AED’s which provide feedback on the quality of ventilations. Future AED’s are likely to interact more with the victim of the cardiac arrest and provide support to the rescuer. For example, a device may obtain information from the hearts ECG, or wall motion or internal sound that could be fed back to tell the rescuer to perform CPR prior to defibrillation. In other words, the ECG signal may be a surrogate for downtime that in turn can better advise how to proceed with the resuscitation.

Back in the early 1970’s it was dogma that CPR should precede defibrillation to ‘prime the pump’ and rid the heart of lactic acid. By the 1980’s there was a growing body of information to suggest that time to shock was the best predictor of outcome. Thus, defibrillation became the priority and defibrillatory shocks were given as rapidly as possible. The mantra became ‘CPR until the defibrillator arrives.’ Now with recent studies from Seattle and Oslo, some are once again questioning whether CPR should be given priority to defibrillation. Recent evidence suggests both are correct. That is immediate shock for witnessed VF or pulseless VT of short duration and CPR prior to shock for VF of longer duration. We now appreciate that there is an interaction between CPR and defibrillation. Each procedure is not independent of the other. It is possible to learn much from the fine or course nature of the VF signal this can be used to provide feedback regarding whether CPR or immediate defibrillation is the procedure of choice.

Recent studies coming from the world of engineering demonstrate that the probability of return of spontaneous circulation (PROSC) based on the VF signal can be calculated. This probability is determined from calculations of spectral densities, frequency, amplitude, and other electrical terms. The information is then translated into a probability. And because it can be calculated every second, it will be possible to determine if the PROSC is rising or falling. This in turn can guide the resuscitation. For example, if the PROSC is 20% after attaching the pads, then CPR is indicated and perhaps drugs (Adrenaline, Amioderone). Once the PROSC reaches 60% then, a shock is indicated. Shocking for low PROSC are not indicated because they are likely to damage the heart with low likelihood of success and deprive the heart of CPR during

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http://www.firstaidcorps.org/

http://www.aedlocations.co.nz/


the pause for defibrillatory shock. It is possible to gain the information from the VF signal even in the presence of chest compressions and ventilation.

The International Liaison Committee on Resuscitation (ILCOR) was formed in 1992 to provide a forum for liaison between resuscitation organizations in the developed world and led to publication of consensus international advisory statements on resuscitation in 1997. Member organisations of ILCOR include the American Heart Association (AHA), European Resuscitation Council (ERC), Heart and Stroke Foundation of Canada (HSFC), Resuscitation Council of Southern Africa (RCSA), the Australia and New Zealand Council on Resuscitation (ANZCOR), the New Zealand Resuscitation Council (NZRC) and the Inter-American Heart Foundation (IAHF).

One of the tasks ILCOR has is to analyse the resuscitation literature and issue recommendations for its member organisations. The most recent recommendations were published in 2005, and involved analysis of over 22,000 studies. The recommendations were published simultaneously in Resuscitation, the official journal of the European Resuscitation Council and in Circulation, the journal of the American Heart Foundation. Since then, different countries and organisations have adapted the recommendations to suit their local context.

In 1995, the American Heart Association (AHA) introduced the concept of the chain of survival in cardiac arrests. There are four time-sensitive links that must occur rapidly for the

victim to have a chance at survival: • Early recognition of the emergency and activation of the local emergency response system e.g. 111• Early bystander CPR• Early delivery of a shock with a defibrillator• Early, advanced life support (such as medications, endotracheal intubation) followed by post resuscitation care to restore good quality of life

NZRC also now uses this metaphor to describe the elements of successful resuscitation. This concept is widely taught and is designed to provide CPR, defibrillation, and advanced care quickly enough to resuscitate patients in cardiac arrest.

A 1996 study by the New England Journal of Medicine showed that CPR success rates in television shows were 75%. The real survival rate of an unwitnessed, out of hospital sudden cardiac arrest is in the range of 6 % to admission and even less to hospital discharge.

Drs P Larsen, M Parnell, J Pearson, D Galletly study into the knowledge and attitudes towards cardiopulmonary resuscitation in the community surveyed 400 adults in 2004. The results of this New Zealand study are encouraging: 74% had been taught CPR at some time, 73% wanted to know more, and 63% said they would perform mouth to mouth resuscitation on a stranger. International comparisons suggest that the willingness to do ‘mouth to mouth’ range from 43% in Australia, 15% in the USA, to 3% in Japan. Despite the apparent willingness of New Zealanders to do CPR, their ability to do so has room for improvement the authors of this study found. So concepts such as ‘chain of survival’ are a useful tool for educating the masses.

Now the various international committees, councils, and associations provide consensus guidelines through ILCOR. NZRC is an active participant in this process. In New Zealand, the

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guidelines are published and taught by the NZRC in a multi-tiered fashion, aimed at resuscitators with levels of expertise ranging from lay person to specialist resuscitator. Larson et al point out that if people learn the assessment and management of the airway of a person with impaired consciousness, as well as the control of external bleeding after trauma, then there is potential to save many victims, including in other circumstances apart from cardiac arrest. Sudden cardiac arrest is a disease with an extremely rapid natural history, measured in minutes, with an inexorable outcome. But when treated with CPR the course of death can be extended (CPR will delay the dying process) and if treated with timely defibrillation death can be aborted.

Since CPR was first widely introduced in the 1960’s there has been a number of changes in the ratio and order of chest compressions and breaths. Changes made in the 2005 guidelines were based on a comprehensive, evidence based review of resuscitation science that was undertaken over a two year period by experts from all over the world. The single most important change in these guidelines was an increased emphasis on chest compressions (30 chest compressions to 2 breaths for adult collapse). This change was made to minimize ‘hands off’ time. The rationale behind this thinking is to maintain a good diastolic pressure to preserve coronary perfusion, as the coronaries perfuse during diastole. Further rationale for this change comes from the observation that in over 40 years of resuscitation training, the improvement in outcome from sudden cardiac arrest has been minimal. The apparent lack of success might be due to changes in the typical patient profile. People are living longer than ever before, and have a greater chance of significant comorbidity at arrest compared with previous generations. The most effective and cost efficient way to improve survival rates is to increase effective bystander CPR with timely emergency defibrillation via the first response team.The post intubation ventilation rate in the 2005 guidelines has been reduced from, one ventilation per five chest compressions to 10 ventilations per minute. The reason for this is two-fold: to avoid hyperventilation and to reduce the amount of time there is positive pressure in the chest, as the latter compromises blood flow.

A conceptual framework for the physiology of sudden cardiac arrest has been developed and adopted by NZRC. Different therapies are required depending on the phase of the arrest, as mentioned earlier with PROSC. Defibrillation is most important in the electrical phase of cardiac arrest. The electrical phase lasts 0-4 minutes, and here optimal resuscitation occurs through correction of an electrical problem by defibrillation in the case of VF or pulseless ventricular tachycardia (VT), or pacing in the case of bradycardia.

Understanding the electrical phase comes from extensive experience with the automatic implantable defibrillator (AID), where defibrillation occurring within 15 to 20 seconds after the onset of what would be a lethal VT or VF is almost uniformly life saving. Survival rates from an arrhythmia for those with a permanent defibrillator exceed 95%. At this time point, there is clearly no need for artificial circulation (chest compressions) as there is little or no metabolic embarrassment. Similarly, many working in cardiac care facilities will attest to the effectiveness of prompt defibrillation delivered to monitored patients.

In the next 4 to 10 minutes of the cardiac arrest, the electrical phase gives way to the circulatory phase. In the circulatory phase, optimal results occur with provision of artificial circulation through CPR. Defibrillation is required, but only after circulatory support has been provided. Theoretical considerations for the importance of CPR in the circulatory phase

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include the idea that chest compressions and ventilation maintains oxygen and substrate delivery to the heart and brain. Chest compressions help coarsen fine ventricular fibrillation, thus optimizing the chances of success with defibrillation. In addition, chest compressions reduce dilatation of the right ventricle, which also aids the return of an organized rhythm after defibrillation.

Empirical support for the concept of the circulatory phase comes first from animal studies. Steen et al. reported a study involving 18 pigs subjected to VF arrest for 6½ minutes before any resuscitative measures were undertaken. After 6½ minutes of VF, six pigs received defibrillation alone. None of these pigs survived. A second group of six pigs received mechanical CPR (mCPR) for 3½ minutes, followed by a 40 second hands off time, designed to mimic current AED delays due to rhythm analysis and charging, and then defibrillation. One of the six pigs in this group survived. In a third group of six pigs, mCPR was continuous for 3½ minutes and continued during defibrillation. Five out of these six pigs survived. The explanation provided by Steen for these results related to the delivery of blood from the left ventricle to the venous circulation during the first few minutes of cardiac arrest. This results in the blood pooling in a distended right ventricle, with subsequent under filling of the left ventricle. Chest compressions help to correct this situation by establishing an adequate coronary perfusion pressure, which is quickly lost if chest compressions are interrupted.

The concept of right ventricular dilatation was reiterated by Prof Kern at the “Spark of Life” conference in April of 2007 in Queensland Australia. Here he illustrated with MRI images from the porcine laboratories in Tucson, Arizona dilatation of the right ventricle. Several human studies have now been conducted which also support the notion that, after the first few minutes of cardiac arrest, outcomes are improved by performing chest compressions prior to defibrillation. An early study by Cobb et al. from Seattle demonstrated that, where response times were four minutes or longer, survival was improved significantly by the addition of 90 seconds of CPR prior to the delivery of a shock. Wik and colleagues from Norway also demonstrated a statistically significant (p < 0.006) increase in survival rate in patients receiving CPR prior to defibrillation where the emergency response time was longer than 5 minutes.

The metabolic phase in cardiac arrest occurs after the first 10 minutes. It is the least well understood of the three phases. The patient who reaches the metabolic phase with no return of spontaneous circulation has the lowest chance of survival. Different defibrillation sequences are advised depending on the type of defibrillator and the time during the arrest that the shocks are given.

In addition to preceding defibrillation by CPR in selected groups of sudden cardiac arrest, there is now also an emphasis on commencing CPR immediately after the cessation of defibrillation, without pausing to do a pulse or rhythm check. The argument supporting this is that even though defibrillation may be successful at returning an organized rhythm, this rhythm may not be sustained because of structural abnormalities in the heart, such as right ventricular dilatation. Proponents of chest compressions argue that superimposing chest compressions on slow, isolated sinus beats post defibrillation does no harm, and in fact does good by increasing the chances that the isolated sinus beats will organize into a rhythm supporting the return of spontaneous circulation. An excellent ECG example of this phenomenon can be found in the paper by Valenzuela et al. on interruptions of chest compressions during emergency medical systems resuscitation.

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There is a significant subset of the resuscitative community who advise moving away from mouth to mouth ventilation in the community, although this has yet to be formally reflected in advanced cardiac life support (ACLS) algorithms. It has been clearly shown over many studies that bystander CPR increases survival rates from out of hospital cardiac arrest. Following a witnessed, sudden collapse, several studies show that survival rates achieved when bystanders deliver compression only CPR are the same as those achieved with CPR that includes rescue breathing. Some investigators have reported higher survival rates following the introduction of minimally interrupted cardiac resuscitation (MICR), a strategy that de-emphasizes ventilation during initial resuscitation by paramedic personnel. Guidelines were released by the American Heart Association on 31 March 2008, designed for civilians who are not emergency response personnel, such as firefighters, EMT’s, paramedics or hospital personnel. The guideline technique is called ‘Hands only CPR’ and it calls for trained or untrained bystanders to do only chest compressions when someone collapses from a cardiac arrest. The new and simplified guidelines issued by the American Heart Association are designed to encourage more people to perform CPR. The theory is based on the fact that people say they did not perform CPR because they thought they would do something wrong or they did not want to do mouth to mouth. Although these real world observations show that CPR without ventilation in adults has comparable results to those with mouth to mouth, it is hoped that the head tilt/chin lift, jaw thrust manoeuvres will remain to be considered of value recognizing the soft tissue obstruction of the airway and the value of including passive oxygenation.

There is good evidence that hyperventilation is harmful during cardiac arrest. Hyperventilation causes increased thoracic pressure, decreased cerebral and coronary perfusion, and poorer survival rates. This approach of giving ventilation (in the early phase of arrest) less priority is only relevant for adult collapse. A recent study has shown that the outcome for children after out of hospital cardiac arrest is better if they receive both chest compressions and rescue breathing from bystanders. This finding makes sense when you consider that the majority of child collapse scenarios are due to hypoxia resulting in compromised cardiac output from severe bradycardia or asystole. This fact is reflected in the child collapse algorithm for CPR having five initial breaths then a ratio of 15 compressions to two breaths, i.e.: the emphasis is on ventilation.

Recent studies also advocate a reduced role for endotracheal intubation in community arrests. Jerry Nolan (Intensivist/anaesthetist and current Co-chair of ILCOR) at the 2010 NZRC conference questioned tracheal intubation as the ‘gold standard’ during cardiac arrest. He said pre-hospital studies failed to show any benefit from tracheal intubation during CPR and many show harm. This is also a trend developing at in hospital cardiac arrests internationally. It is recognized that intubation is an advanced skill which many medical officers attending arrests do not possess. To acknowledge this, placement of a supraglottic airway is promoted. This gives valuable resuscitation time back to the priority areas of defibrillation, chest compressions and ventilation. He said that in the United Kingdom unless the intubater is very experienced and competent and can successfully intubate in less than one minute, then the airway choice in an arrest should be supraglottic such as a laryngeal tube (seen here on the right), an I-gel or Proseal LMA (laryngeal mask airway). Minimally interrupted cardiac resuscitation (MICR) is the goal. When

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we pause our compressions, blood flow falls to zero, this takes up to 20 seconds to build up again. There is a risk of compromise to CPR and defibrillation if the rescuer becomes focused on and distracted by the need to intubate or gain IV access. It is vital that chest compressions and early defibrillation are the priority. With a supraglottic airway in place the compression to ventilation ratio should remain at 30:2 (in an adult), only changing to continuous compressions and 10 ventilations per minute when or if the patient is intubated.

A recent study conducted in Arizona demonstrates results that triple the survival rates for out of hospital cardiac arrest victims. Using the new approach, MICR as mentioned earlier, focus is on maximizing blood flow to the heart and brain through a series of coordinated interventions. The protocol in this study comprised of an initial series of 200 uninterrupted chest compressions, then heart rhythm analysis with a single shock, 200 immediate post-shock chest compressions before the pulse check, early administration of adrenaline to stimulate the heart, and delayed placement of an endotracheal tube. Among 886 patients who suffered cardiac arrest in two cities, survival to hospital discharge increased from 4 of 218 patients (1.8%) in the before MICR training group to 36 of 668 patients (5.4%) in the after MICR training group.

I was fortunate enough to attend the New Zealand Resuscitation Council (NZRC) Conference ‘On the Horizon’ in Auckland in May 2010. This event explored current research and future directions in CPR. The use of drugs in advanced life support for managing cardiac arrest was investigated and reported by Professor Ian Jacobs (Hon. Secretary of ILCOR). He presented current evidence with specific reference to adrenaline. Prof Jacobs showed that although adrenaline improves the coronary perfusion in the short term it can compromise cerebral perfusion and doesn’t appear to improve long term survival. In fact no resuscitation drug has been shown to improve survival to discharge. He cautioned us that our priority in CPR is still very much compressions, defibrillation and oxygenation/ventilation.

Peter Jones, Emergency Physician at ADHB, discussed the use of CPR prior to defibrillation. In keeping with other research findings presented here, he found although CPR may improve the myocardial response to defibrillation, early defibrillation in adult collapse is still the gold standard. That is, the evidence still supports our current stance of early defibrillation except when the myocardium has had a delay in perfusion i.e. no CPR post arrest.

Andy Swain (NZRC) studied survival from out of hospital cardiac arrest in NZ following the 2005 resuscitation guideline changes. He confirmed the recent evidence which has prompted us to not use atropine in asystole and only to use it in arrests with extreme bradycardia. His study suggests that the new guidelines may have contributed to an improvement of survival to hospital but not to discharge. Also whilst the guideline changes have resulted in decreased shock success rates, return of spontaneous circulation and survival to hospital admission have both increased.

Jerry Nolan reported that even when performed well, chest compressions produce vital organ perfusion that is less than 30% of normal. The quality of CPR achieved by rescuers deteriorates rapidly over time. The availability now of modified defibrillators that record compression rate and depth, ventilation rate, and provide visual and auditory cues has enabled investigators to document poor quality CPR after both in and out of hospital cardiac arrest. Early anecdotal

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data suggests that these feedback devices do indeed improve quality of CPR and suggest that two minutes intervals is a good time to change the person doing compressions.

St John New Zealand have recently trialed these devices and found they aided improvement in technique. St John NZ is currently in the process of introducing these to their service nationwide. Their gadget of choice is the Q-CPR. This includes a small ‘puck’ sensor which is placed under the hands of the chest compressor to check and measure compression rate, depth, recoil and pauses. This provides feedback to the defibrillator unit. A voice will prompt any

improvements needed. It has a memory and can be connected to USB ports on computers to check on the effectiveness of the CPR. ST John NZ recognize that in chest compressions maximum flow is achieved by maximum alternative positive and negative pressure in the chest. We know that high ventilation rates reduce the blood flow and drive down end tidal carbon dioxide (etCO2) to dangerously low levels. This knowledge is reflected in the 2005 guidelines of ventilating at a rate of 10 breaths per minute in an intubated patient during CPR. However, it is widely recognized that a more natural rhythm for a ventilating rescuer (particularly one in crisis mode) is 20 - 30 ventilations per minute, so a device which monitors and feeds back our tempo will assist with keeping our ventilations at the recommended rate. People can tend to think a gizmo (such as the Q-CPR) will improve outcomes, which it may well, but it is crucial to always focus on the basics first and foremost.

Given the encouraging initial results from St John, it seems logical for mechanical devices that produce better more consistent organ perfusion to be beneficial. Two recently invented mechanical devices, the Lund University Cardiopulmonary Assist System (LUCAS) and a load distributing band called Autopulse, are in relatively common use internationally, but currently there is no robust data to show that they improve survival after cardiac arrest. Animal data on the autopulse system, which compresses at a rate of 80 per minute, suggests it works but this device failed miserably in initial clinical trials. The autopulse, seen here being demonstrated on an intubated mannequin, can be synchronized with a defibrillator of the same brand so that the defibrillator will fire when the chest is expanding in order to get the most successful shock.

The LUCAS, seen here on the left, is a pneumatic mechanical device used in cardiac arrest which is designed to replace cardiac compressions. A Norwegian paramedic, Willy Vistung, came up with the idea of this mechanical chest compression device in 1991. Animal testing was started in 1996 in collaboration with Professor Stig Steen at the University Hospital in Lund, Sweden. It was first marketed and used for humans in 2002. It has a big suction cup on the chest which actively pulls the chest up to decrease intrathoracic pressure. This has shown to have an increased coronary perfusion pressure in pigs. It is optimal for the diastolic pressure to be augmented like this because as we know, the coronary arteries fill during diastole.

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Mechanical devices such as LUCAS and autopulse may improve haemodynamics but there is currently no data on human outcomes compelling enough to prove this yet. Large scale randomized control trials of these devices are now underway and it hoped that these will eventually enable treatment recommendations to be made.

The impedance threshold device (ITD) is another mechanical adjunct designed to improve coronary perfusion pressure. Shown here on the right, this device deliberately partially obstructs the airway to enhance negative pressure in the chest to improve venous return. Eventually the valve in this unit will open (the device is attached to a bag mask ventilator) at -16cmH20 to provide oxygenation and ventilation. This enhanced vacuum pulls more blood back to the heart, doubling blood flow during CPR.

Simulation is an area which has come a long way since the first Resuscianne was produced in 1960. Although these sort of low fidelity devices are still in widespread use and continue to be a useful training aid, much more sophisticated computer driven high fidelity devices are now available. An example of this would be the Sim man 3G produced by Laerdal.

Judith Finn (ILCOR) tells us that high fidelity simulation in medicine is a useful teaching method for clinical situations that, although infrequent, are critical in nature and require maintenance of a high level skill and preparedness. Cardiac arrest resuscitation clearly fits this description. It is argued that a high fidelity simulation experience allows the participants to suspend disbelief and perform in a manner that more closely reflects the way they would act in

caring for a real patient in a comparable situation. Although the evidence for the efficacy of high fidelity versus low fidelity techniques in resuscitation training remains equivocal it is thought that as training scenarios develop to be more complex high fidelity has been shown to provide more knowledge in student learning outcomes.

When considering this evolution of CPR one can’t ignore the tremendous progress made in the last fifty years in the realm of post resuscitation care. Our modern facilities such as cardiac

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catheter laboratories (offering timely coronary reperfusion with percutaneous coronary intervention), coronary care units and intensive care units have made a vast improvement to long term survival. The pharmaceutical agents available now have greatly improved outcomes. The treatment a patient receives after return of spontaneous circulation (ROSC) has been seen to significantly influence their neurological outcome. Sadly though, the survival rate after out of hospital and in hospital cardiac arrest has not improved much over the last decade. The guidelines focus mainly on treatment until ROSC.

Peberdy and Ornato suggest that post resuscitation care could be the missing link in the Chain of Survival. They write: “It is ludicrous to commit tremendous fiscal and personnel resources to evaluating therapies for improving survival from the cardiac arrest event itself without acknowledging that the current state of post resuscitation care is widely variable and most often performed by clinicians unfamiliar with specific post resuscitation medical care.” There has been a consistent pattern of improved short term survival from cardiac arrest that more often than not does not translate into a significantly increased neurologically intact, long-term survival.

Once the A B C’s are stabilized there are many tests to run, to gather baseline data on a post resuscitation patient. Revascularisation and anti arrhythmic therapy need to be considered. Comprehensive monitoring is performed. Therapeutic hypothermia is increasingly being used to preserve neurological function in selected cardiac arrest patients in the intensive care environment. This can be achieved using non invasive cooling blankets (such as the one seen here) or invasive intravenous cooling lines. ILCOR advanced life support task force has made the recommendation that: Unconscious adult patients with spontaneous circulation after out of hospital cardiac arrest should be cooled to 32°C to 34°C for 12 to 24 hours when the initial rhythm was VF and such cooling may also be beneficial for other rhythms or in hospital cardiac arrest.

Scientific studies are currently being undertaken to try to further understand the phenomena of global ischemic brain damage and myocardial dysfunction during the reperfusion phase following cardiac arrest. Several clinicians now suggest that more aggressive standardized post resuscitation treatment protocols be followed and that these be scientifically tested. The ultimate goals are to improve dismal survival rates, restore quality of life to the cardiac arrest survivors and determine the prognosis at the appropriate time so that the best care decisions can be made.

Even since the beginning of modern CPR in 1960 there have been regular changes to recommendations on the finer details of the ‘push and blow’ combination. First, there were an initial five quick breaths and then a 15 to 2 ratio of compression to ventilations. Then for a long time it was 5:1 … or was it? Like many people who have worked in health care over the last few decades I became confused at the constant changes to the adult and child collapse algorithms. The introduction of the precordial thump, for a witnessed (within two minutes) adult collapse where a defibrillator is not immediately available, acknowledges the possibility that a correctly applied blow can generate up to 45 Joules of energy which may revert VT (25% chance) or VF (2% chance), so is still considered a worthwhile endeavor. But take the blind finger sweep for

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example; this was removed completely from the guidelines in 2005. The reality is that the rationale for these and other changes were the result of exhaustive consultation and research. The American Heart Association put it best when they said: ‘Although the algorithms provide a good cookbook, the patient always requires a thinking cook’. This quote seems very relevant as we reflect on the evolution of modern CPR and eagerly anticipate the release of the new resuscitation guidelines due to be made public by the NZRC within the next year.The approach to saving a person in cardiac arrest has certainly changed from what the ancient Greek and Egyptians performed. CPR has now evolved into widespread general use, with international committee’s councils and associations. These produce consensus guidelines for professional and lay people, for people managing a cardiac arrest on their own outside hospital, and for professionals working as a team with modern technical equipment. I have no doubt that new methods will change in the future and newer methods will be introduced that will declare better results. We have seen how the elements of mouth to mouth ventilation, chest compression, and defibrillation each had to be discovered separately and integrated for reversal of sudden death to become a reality. The real challenge for the future is to fully understand the causes and triggers of VF and to develop preventative measures. So this is a story that will continue to evolve. I wonder how healthcare professionals in the future, will view the methods we currently use!

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References

16 September 2010 marks the 50th anniversary of modern resuscitation. It was this milestone that got me thinking about the subject. I found the further I investigated the more interested I became in learning about this topic. After searching a number of libraries, in both their print and electronic resources, I discovered very few books on the history of CPR. There were however, an extensive number of articles published on the internet, which touched on the subject. Since such limited print resources could be found I relied more heavily on these web pages, some of which, were better referenced than others. Some seemed to contradict one another. This made establishing historical facts a challenge. Increasingly though after referring to many sources a consistent theme occurred. I have tried wherever possible to ensure accuracy. I have also attempted to tell the story in my own words, to convey my understanding of the subject, although inevitably some factual content has been presented as it stood. For these facts and for any knowledge I have gained in researching this paper here is a comprehensive list of references used.

The New Zealand Resuscitation Council (NZRC) Certificate of Resuscitation and Emergency Care (CORE) Advanced Resuscitation for Health professionals level 7 manual 2007

Living with Mortality - The Troubled Dream of LifeD Callahan New York: Simon and Schuster; 1993.

Cardiopulmonary Resuscitation Edited by: Joseph P Ornato and Mary Ann PeberdyChapter one History of the Science of CPR M.S. Eisenberg

Dealing with Death a handbook of practices, procedures and lawSecond Edition Jennifer Green and Michael Green 2006

Resuscitation 2010 - On the HorizonNZRC National Conference Auckland, New Zealand

Effect on high-fidelity simulation on Paediatric Advanced Life Support training in paediatric house staffA randomised trial by A J Donoghue, DR Durbin, F M Nadel, G R Stryjewski, S I Kost, V M Nadkarni et al.Paediatric Emergency Care 2009; 25(3):139-144

Post-resuscitation care - is it the missing link in the Chain of Survival?Peberdy, M.A. & Ornato, J.P. Resuscitation 2005; 64:135-137

History of CPRhttp://en.wikipedia.org/wiki/History_of_CPR

Highlights of the History of Cardiopulmonary Resuscitation (CPR)http://www.americanheart.org/presenter.jhtml?identifier=3012990

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http://www.americanheart.org/presenter.jhtml?identifier=3012990

http://en.wikipedia.org/wiki/History_of_CPR


The History of CPR Texas on site CPRhttp://www.texasonsitecpr.com/History.html

History of CPR U.K Divershttp://www.ukdivers.net/history/cpr.htm

What Is the History of CPR?http://www.ehow.com/facts_5405391_history-cpr.html

A brief history of resuscitationhttp://www.nzma.org.nz/journal/117-1193/868/

The development of CPRhttp://www.nzma.org.nz/journal/121-1284/3312/

History of Cardiac Resuscitationhttp://www.nzrc.org.nz/index.php?option=com_content&task=view&id=37&Itemid=88

Resuscitation Mattershttp://www.ampa.co.nz/Carey_Resuscitation%20Matters.v2.pdf

History of Ventilationhttp://www.frca.co.uk/article.aspx?articleid=100408

Pinching, electrocution, ravens’ beaks, and positive pressure ventilation: a brief history of neonatal resuscitationhttp://fn.bmj.com/content/91/5/F369.full

One hundred years of artificial ventilationhttp://www.frca.co.uk/documents/100%20YEARS%20VENTILATION%20BOOKLET.pdf

William Harvey - Wikipediahttp://en.wikipedia.org/wiki/William_Harvey

Andreas Vesalius - Wikipediahttp://en.wikipedia.org/wiki/Andreas_Vesalius

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http://en.wikipedia.org/wiki/Andreas_Vesalius

http://en.wikipedia.org/wiki/William_Harvey

http://www.frca.co.uk/documents/100%20YEARS%20VENTILATION%20BOOKLET.pdf

http://fn.bmj.com/content/91/5/F369.full

http://www.frca.co.uk/article.aspx?articleid=100408

http://www.ampa.co.nz/Carey_Resuscitation%20Matters.v2.pdf

http://www.nzrc.org.nz/index.php?option=com_content&task=view&id=37&Itemid=88

http://www.nzma.org.nz/journal/121-1284/3312/


http://www.ehow.com/facts_5405391_history-cpr.html

http://www.ukdivers.net/history/cpr.htm

http://www.texasonsitecpr.com/History.html


John Hunter - Wikipediahttp://en.wikipedia.org/wiki/John_Hunter_(surgeon)

Daniel Callahan - Wikipediahttp://en.wikipedia.org/wiki/Daniel_Callahan

Energy settings for mono- and biphasic defibrillation: guideline of the New Zealand Resuscitation Councilhttp://www.nzma.org.nz/journal/117-1193/875/

Knowledge and attitudes towards cardiopulmonary resuscitation in the communityhttp://www.nzma.org.nz/journal/117-1193/870/

The Prone Pressure (Schafer) Method of Resuscitationhttp://www.ncbi.nlm.nih.gov/pmc/articles/PMC1707753/?log%24=activity

Back-Pressure Arm-Lift Artificial Respirationhttp://www.ncbi.nlm.nih.gov/pmc/articles/PMC2030759/pdf/pubhealthreporig01076-0066.pdf

Back-pressure arm-lift artificial respirationhttp://ukpmc.ac.uk/articles/PMC2030759;jsessionid=B904823455CDAC105F86A2E0D56DC493.jvm4

History of Performing CPRhttp://www.ehow.com/about_5516923_history-performing-cpr.html

Mouth to Mouth Rescue Breathing - Description of 1732 Resuscitation by William Tossachhttp://www.todayinsci.com/Events/Medical/Resuscitation.htm

Bernard Lown – A doctor with a big hearthttp://www.news.harvard.edu/gazette/1999/02.11/lown.html

AED Locations in New Zealandhttp://www.aedlocations.co.nz/

Defibrillation - Wikipediahttp://en.wikipedia.org/wiki/Defibrillation

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http://en.wikipedia.org/wiki/Defibrillation

http://www.aedlocations.co.nz/

http://www.news.harvard.edu/gazette/1999/02.11/lown.html

http://www.todayinsci.com/Events/Medical/Resuscitation.htm

http://www.ehow.com/about_5516923_history-performing-cpr.html

http://ukpmc.ac.uk/articles/PMC2030759;jsessionid=B904823455CDAC105F86A2E0D56DC493.jvm4

http://ukpmc.ac.uk/articles/PMC2030759;jsessionid=B904823455CDAC105F86A2E0D56DC493.jvm4

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2030759/pdf/pubhealthreporig01076-0066.pdf

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1707753/?log$=activity



http://en.wikipedia.org/wiki/Daniel_Callahan

http://en.wikipedia.org/wiki/John_Hunter_(surgeon)


Thomas Willis was one of the greatest men in 17th century medicine. (The resurrection of Anne Green)http://www.whonamedit.com/doctor.cfm/336.html

The Latest in CPR - Two New Techniques for Saving Victims of Cardiac Arresthttp://www.emsresponder.com/print/Firehouse-Magazine---EMS-Features/The-Latest-in-CPR/3$7714

Lund University Cardiopulmonary Assist System (LUCAS)http://survival-linx.com/news.asp?id=26Heimlich manoeuvrehttp://www.scribd.com/doc/24759297/Choking-Drowning-Prevented-by-Subdiaphragmatic-Compression-Heimlich-Hoffman-Canestri-8-75

Milestones in the history of Jolife (LUCAS)http://www.jolife.se/en/about_us/history

AutoPulse Non-Invasive Cardiac Support Pumphttp://www.zoll.com/medical-products/cardiac-support-pump/autopulse/

ResQPOD Impedance Threshold Devicehttp://www.advancedcirculatory.com/resqpod/POD_Prod_Sheet.pdf

Resuscitation centralhttp://www.resuscitationcentral.com/

Therapeutic Hypothermia after Cardiac Arresthttp://circ.ahajournals.org/cgi/content/full/108/1/118

International Liaison Committee on Resuscitationhttp://www.ilcor.org/en/home/

European Resuscitation Councilhttp://www.resuscitationjournal.com/

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http://www.resuscitationjournal.com/

http://www.ilcor.org/en/home/

http://circ.ahajournals.org/cgi/content/full/108/1/118

http://www.resuscitationcentral.com/

http://www.advancedcirculatory.com/resqpod/POD_Prod_Sheet.pdf

http://www.zoll.com/medical-products/cardiac-support-pump/autopulse/

http://www.jolife.se/en/about_us/history

http://www.scribd.com/doc/24759297/Choking-Drowning-Prevented-by-Subdiaphragmatic-Compression-Heimlich-Hoffman-Canestri-8-75

http://www.scribd.com/doc/24759297/Choking-Drowning-Prevented-by-Subdiaphragmatic-Compression-Heimlich-Hoffman-Canestri-8-75

http://survival-linx.com/news.asp?id=26

http://www.emsresponder.com/print/Firehouse-Magazine---EMS-Features/The-Latest-in-CPR/3$7714

http://www.emsresponder.com/print/Firehouse-Magazine---EMS-Features/The-Latest-in-CPR/3$7714

http://www.whonamedit.com/doctor.cfm/336.html

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