Innovation in Medical Electronic Devices and Technologies

Akshay Srivastava Lokesh V Dr Shashidhara H L UG program L& T limited Professor and KRP Department of TE Strategic planning initiative (IPM) Department of TC PESIT, Bangalore Mysore PESIT, Bangalore Abstract Health can be defined as a state of complete physical, mental and social well being. Years ago, detecting diseases, disorders and curing them was either impossible or totally dependent on expertise of the doctor. Over decades the advancement in technology, medical electronics too has witnessed significant changes which has improved the quality of life of every human being. This paper focuses on the study of the growth of medical electronics and its impact on diagnosis and treatment of human disorders and diseases. This review also deals with certain devices distributed by different medical electronics vendors and their specifications.

1. Medical Equipment

1.1 Types Medical equipment is designed to aid in the diagnosis, monitoring or treatment of medical conditions. These can be broadly classified in the following 5 categories.

1. Diagnostic equipment, such as ultrasound, MRI (Magnetic Resonance Imaging) machines, PET (Positron Emission Tomography) x-ray scanners, includes medical imaging machines, used to aid in diagnosis.

2. Therapeutic equipment includes infusion pumps, medical lasers and LASIK surgical machines. Life support equipment such as, medical ventilators, heart-lung machines, ECMO (Extra Corporeal Membrane Oxygenation), and dialysis machines, is used maintain a patient's bodily function.

3. Medical monitors allow medical staff to measure a patient's medical state. Monitors may measure patient vital signs and other parameters including ECG (Electrocardiograph), EEG (Electroencephalogram), blood pressure, and dissolved gases in the blood.

4. And finally medical laboratory equipment automates or helps analyze blood, urine and genes. A Biomedical equipment technician or BMET is a vital component of the healthcare delivery system and is responsible for maintaining a facility's medical equipment. 1.2 Brief Invention History Year Equipment Inventor 1540 Artificial Limb Ambroise Pare 1630 Obstetric Forceps Peter Chamberlen 1714 Mercury Thermometer Gabriel Fahrenheit 1816 Stethoscope René Laennec 1895 X-ray Wilhelm Röntgen 1903 Electrocardiograph Willem Einthoven 1956 Endoscope Basil Hirschowitz 1957 Artificial Pacemaker C. Walton Lillehei and Earl Bakken 1973 CT (CAT) Scan Scan Godfrey Hounsfield and Allan Cormack 1979 Ultrasound Scan Ian Donald 1982 Artificial Heart Robert Jarvik

 2. History of Medical Equipment This part focuses on the history of the of physiological monitors, blood pressure measurements & monitoring, 2.1 Physiological Monitors 1950’s: Early Warning Systems for “Cardiac Accidents” Himmelstein and Scheiner reported in a 1952 paper that in January of 1950 they began using an instrument they devised called it the “Cardiotachoscope” and found it useful during surgery. The device consisted of include a CRT to view the ECG, a heart rate indicator, alarms for high and low heart rates, and a connection to a conventional electrocardiograph for printouts. The ECG waveform would show only a second or two of new data and the trace has been described as a bouncing ball with a comets tail. Longer persistence CRT’s with slower fading showed more of the waveform clearly. Systems of the 1950’s and early 1960’s made less of a distinction between the equipment roles of monitoring and defibrillation or pacing and were often intended to be used together as a diagnostic and this concept is more closely related to hospital crash cart: a defibrillator/monitor with integrated non-invasive pacing. In fact, detection of low heart rate and initiation of an alarm or therapy was a primary objective of this technology. The frequency response of the ECG monitor was often less than comparable electrocardiographs of the period. But the advantage of the monitor was the immediacy of the information and the ability to generate alarms. Most monitors initially came as circular displays having a radius of 3 to 5 inches and with 1 or 2 waveforms traces. Controls on these monitors were more like that of current day oscilloscopes with lead selection, focus adjustment, intensity or brightness control, sensitivity or gain control and so on. 1960’s: Proliferation Into Critical Care During the next decade, Electrodyne devices played a prominent role in modeling ECG systems. The model PM-65 that appeared around 1956 incorporated, a cardioscope mounted on top of a large pacemaker and introduced physiologic monitors into a clinical setting. Other companies such as Levinthal Electronic Products Inc, came up with “Duo trace Cardioscopes” which showed two waveforms simultaneously. The 1960’s featured monitoring systems whose intended functions and configurations were the process of using telemetry to monitor physiologic signals occurred early in this decade as well. Unlike modern central monitors which are capable of displaying waveforms from eight or more bedsides simultaneously, earlier central monitors were often identical to the bedside monitors. The “central” would be connected to all of the bedsides by cabling in a star pattern to a separate switching box which would allow data to be switched over one bed at a time for viewing on the central. Some sophisticated monitors used for a central monitor or for surgery had traditional 17” diagonal television tubes, which were occasionally mounted in a vertical “portrait” orientation and could display a waveform from eight different beds while taping it simultaneously. Vendors such as Burdick, Birtcher, Dallons, Air Shields, and Electrodyne offered a complete line of pacemakers, defibrillators, and physiologic monitoring systems (with a central) in the early 1960’s. It was during this time that Electrodyne replaced its PM-65 with Pacemaker Alarm Monitor, the PMS-5. Dallons released a twin-beam cardioscope in 1960 which was initially used for pre-flight checking of the space suits biomedical sensor systems. Dallons also subsequently released a couple of versions of its twin-beam unit in the form a fetal/maternal ECG monitor and as an ECG/EEG monitor such as the CS-3X. The use of disposable flexible electrodes appeared in the middle of the decade. By the mid 1960’s most prominent vendors offered equipment in modular pieces which included separate devices for central monitoring of alarm conditions such as heart rate indication, temperature indication, pacing, tape memory, etc. Though initially these modules were rack mounted, Sanborn (Later Hewlett Packard) was the first to offer modular pieces in self contained enclosures. In 1966, Sanborn even offered a

numeric readout accessory module for blood pressures, temperatures, and heart rate and these were achieved using Nixie tubes up until the early to mid 1970’s and were then replaced by LED displays. Though transistorized equipment appeared in late 1950, vacuum tubes were still used till late 1960’s as they were more reliable, mature and had better performance than the transistors then. Vendors also replaced their circular CRT’s with rectangular and larger CRT’s. Products such as Space Lab’s 170-1103, Hewlett Packard’s 7803A and Honeywell bedside monitor, had 7” to 8” CRT’s with the screen with graduations and numerals to allow reading of the heart rate. 1970’s: The Impact of Digital Electronics The decade of the 1970’s saw some significant improvements in the presentation of the displayed waveforms and information as a result of the incorporation of digital electronics and, microprocessors. Real time (centrally controlled and processed) arrhythmia analysis appeared at the beginning of the decade and evolved over the duration of the 1970’s. Standards documents which established minimum performance criteria for physiologic monitors began appearing from several bodies such as the "Specification for Biomedical Monitoring Systems" X-1414 of 1970 from the Veterans Administration. “Memory monitors” appeared at the beginning of this decade. These monitors incorporated analog to digital converters and small memories to briefly store several seconds of incoming data. The stored data was then used to maintain the waveforms for a longer time on the display and hence creating a non-fading persistent display. The waveform could either be scrolling horizontally or made stationary on the screen. Modern monitors permit selection of either of these modes of display and also allow cascading of data. Electrodyne claims to have introduced the first non-fade patient monitoring system, the “Computa View”, in 1972. The Westinghouse patient monitoring system of 1970 featured an “exclusive” heart rate computer with automatic gain control. This system as well as others from this period, such as those from General Electric and Mennen-Greatbatch, began incorporating isolated ECG inputs for patient electrical safety. Interfacing to computer was the need of the day for arrhythmia analysis. In 1970, Smith Kline Instruments offered monitors which could interface to a computer and could be used for PVC detection and other tasks. The instruments also had integrated numerical displays on the front panel. The Mennen-Greatbatch (model 515/G Cardio/Sentinel monitor) of 1972 included pacemaker spike detection and rejection capabilities. The Siemens Sirecust 300 DU of 1978 offered pacemaker spike rejection and could still permit viewing of the spikes but would not count them. The unit also featured high frequency protection from electrosurgical equipment. The middle of this decade say the introduction of microprocessors and Spacelabs claims to have launched the first (bedside) monitoring system which incorporated microprocessor technology in 1974. By 1978 some vendors such as Hewlett Packard and Philips began integrating the heart rate information on CRT displays (in models HP78341A and HP78342A and Philips model CM-120) and hence changed from a bar-graph display to a numeric LED display located next to the CRT. The 1980s’: Modularity and Bedside Arrhythmia Analysis The 1980’s witnessed further significant evolution in patient monitors. Arrhythmia analysis became available at the bedside. Monitors became computerized and had color displays, monitoring networks became more sophisticated. The beginning of the decade witnessed some new developments in monitors themselves. There was also a significant increase in size of the display which increased the number of waveform output from two to six. Siemens introduced the Sirecust Series 400 in 1980 which had notable enhancements such as bed-to-bed or “interbed” viewing, parameter modules, and membrane-switch design. The new “hot-swappable” modularity, which appeared in the 1980s’, was meant to allow adjustment of the actual parameters available to be measured from one patient to the next. The advantage of this modularity

was economical since by sharing modules with lesser-used parameters, such as cardiac output, a hospital would not have to fully load all bedside monitors with all parameters. Hewlett Packard introduced their modular Merlin system in 1989. HP promoted a wider patient data management concept for its monitors (HP78707A) from the early part of the decade. Twenty-seven years later, monitors are continuing to promote the provision of data management and presentation capabilities. Electronic automatic non-invasive blood pressure and pulse oximetry were two new notable parameters, which became available in the 1980’s. In 1983, the Burdick Color-Trend monitor (model M565) was introduced which would display different parameters with unique colors. Since color monitors were expensive color monitors took about a decade to be well established and standardized. Nihon Kohden claims to have been the first to supply bedside arrhythmia analysis with its Life Scope 10 OEC-5501 Heart Monitor, which was introduced in 1982. Spacelabs claims of being the first to allow viewing of real-time arrhythmia data at the bedside in 1979. In any event, by 1980, arrhythmia analysis was primarily available as a centrally coordinated feature of the central monitoring station of many systems such as the General Electric PDS3036, Becton Dickenson, The Siemens Sirecust 400 and the Hewlett Packard 78220. Around 1985, Spacelabs introduced the “PC” bedside monitor that incorporated a relatively large monochrome touch screen and relatively large parameter modules. These “PC’s” were replaced by their color screen version “PC2” with touch screens. Touch screen bedside monitors have not become predominant and data input is usually achieved by a combination of rotary menu selectors and membrane soft-key switches. The 1990s’: Mobility and Connectivity Portable monitors evolved to become quite capable and the continuum of care monitor was developed. Some monitors forayed into the employment of non-proprietary approaches to software connectivity. The Spacelabs PC Express transport monitor entered the market in 1990. This monitor included the Spacelabs Quicknet Interface of 1994 and the Siemens “Pick and Go” system of 1996. The entire monitor would travel with the patient and, unlike regular transport monitors, would be connected to a monitoring network after travel. Spacelabs also released PC Ranger in 1996 and the Marquette Eagle 4000 of 1999, which could stay connected to the network by wireless links. In 1995 the Spacelabs UCW monitor could interface with other hospital information systems such as the laboratory and pharmacy. This was implemented using their “Dynamic Network Access (DNA)”, called winDNA, which could run standard Windows applications. Hewlett Packard released their “LabVue” system that allowed monitors to display lab results in 1996. The HP Viridia system of 1997 incorporated the Windows NT operating system. Since CRT’s are heavy by nature, monochrome LCD monitors appeared in many monitors such as the HP component transport system and the Datascope Passport monitor. Flat screen amber electroluminescent displays were also deployed in Spacelab's PC Express and later with the Marquette Eagle system. Another design change was to shift the location of the patient connections to the side of the monitor. This design change allowed parameter modules to be inserted into the side of the monitor thereby keeping the dimensions of the monitor with less depth. The Early 21st Century and Beyond Monitors of the 1990’s usually had to be configured for the type of location such as the operation room versus emergency. During the 21st century, new generation of monitors which were designed to be flexible enough to remain with the patient through various stages of acuity and during transportation. These monitors leveraged the increased miniaturization of parameter modules and the lighter flat-screen technology. Transport monitors with their more limited subset of parameters are replaced by the more capable continuum of care monitors such as Siemens Infinity SC 9000XL monitor, which even offered connectivity to the internet. This allowed the clinician to use the internet or the hospitals intranet to remotely view a particular bedside monitors real-time waveforms, vital signs and trends

Our understanding of the relative importance of the parameters will increase in the years to come and we will learn what to watch for. The trend towards the development of non-invasive techniques will continue. In the near future, there may be some overlap between physiologic monitoring and medical imaging because of the inherent non-invasive nature of medical imaging.

Disclaimer: Please note that the text above includes comments on monitors used currently and in the past and does not comment on others and this and any information herein is not meant to be construed as an endorsement or condemnation of any devices and are opinions of the authors. Although specific systems are mentioned in connection with new developments, this does not imply that the system was the first or the only system with that feature. 2.2 Blood Pressure Measurements Blood pressure refers to the force exerted by circulating blood on the walls of blood vessels, and constitutes

one of the principal vital signs. The pressure of the circulating blood decreases as blood moves through arteries, arterioles, capillaries, and veins; the term blood pressure generally refers to arterial blood pressure, i.e., the pressure in the larger arteries, arteries being the blood vessels which take blood away from the heart. The systolic pressure is defined as the peak pressure in the arteries, which occurs near the beginning of the cardiac cycle; the diastolic pressure is the lowest pressure. Typical values for a resting, healthy adult human are

approximately 120 mmHg systolic and 80 mmHg diastolic (written as 120/80 mmHg, and spoken as "one twenty over eighty"), with large individual variations. These variations are not static and undergo natural variations from one heartbeat to another and these variations are controlled by food, drugs, physical activities and nutrition. Hypertension refers to blood pressure being abnormally high, as oppose hypotension, when it is abnormally low. The first recorded instance of the measurement of blood pressure was in 1733 by the Reverend Stephen Hales. When he inserted a brass pipe into an artery of a horse, he observed that the blood in the pipe was rising and concluded that this must be due to a pressure in the blood. This method was invasive in nature and hence not appropriate for clinical measurements. It was in 1847 that human blood pressure was recorded. The method used Carl Ludwig's kymograph with catheters inserted directly into the artery. Ludwig's kymograph consisted of a U-shaped manometer tube connected to a brass pipe cannula into the artery. The manometer tube had an ivory float onto which a rod with a quill was attached. This quill would sketch onto a rotating drum hence the name 'kymograph', 'wave writer' in Greek. However blood pressure could still only be measured by invasive means.

The first non-invasive method was devised by Karl Vierordt, in 1855, which used inflatable cuff around the arm to constrict the artery. In 1881, Samuel Siegfried Karl Ritter von Basch invented the sphygmomanometer. His device consisted of a water-filled bag connected to a manometer. The manometer was used to determine the pressure required to obliterate the arterial pulse, and this method was non-invasive in nature. However von Bacsh's design never won a keen following, many physicians of the time being skeptical of new technology, claiming that it sought to replace traditional ideas of diagnosis. It was only in 1896 that Scipione Riva-Rocci developed the mercury sphygmomanometer which was the prototype of the modern mercury sphygmomanometer. An inflatable cuff was placed over the upper arm to constrict the brachial artery. This cuff was connected to a glass manometer filled with mercury to measure the pressure exerted onto the arm. Although many modern blood pressure devices no longer use mercury, blood pressure values are still universally reported in millimeters of mercury (mmHg). Riva-Rocci's sphygmomanometer was spotted by the American neurosurgeon Harvey Cushing while he was travelling through Italy. Seeing the potential benefit he returned to the US with the design in 1901. After the design was modified for more clinical use, the sphygmomanometer became commonplace. Observing the pulse disappearance via palpitation would only allow the measuring physician to observe the point when the artery was fully constricted. In 1905, Nikolai Korotkoff observed that certain the characteristic sounds at certain points of inflation and deflation of cuffs were made by the constriction of the artery. These Korotkoff sounds were caused by the abnormal passage of blood through the artery, corresponding to the systolic and diastolic blood pressures. Even to this day, a stethoscope is used to listen for the sounds of blood flowing through the artery. Modern developments have led to more accurate auscultatory sphygmomanometers, and newer oscilliometric models. These sphygmomanometers measure the pressure imparted onto the cuff by the turbulent blood squirting through the constricted artery over a range of cuff pressures. This data is used to estimate the systolic and diastolic blood pressures. 2.3 Blood Pressure Monitoring There are numerous ways of measurement of blood pressure of which, some important methods are discussed below. Invasive Catheterization Method: This method was employed by Reverend Stephen Hales, in 1733 in which, a long glass tube upright into an incision in an artery. The pumping action of the heart generated a pressure force, causing the blood level to rise in the tube. This method was very dangerous to patients and involved great amount of blood loss. The Manual Auscultatory Method: In 1905, Korotkoff described the auscultatory sounds, which became the foundation for the auscultatory technique. This is the most common method of blood pressure measurement today. An air-filled cuff is wrapped around the patient's upper arm. The cuff is inflated to occlude the brachial artery. As the cuff is allowed to deflate, a stethoscope is placed over the patient's brachial artery (distal to the cuff) to listen for the Korotkoff sounds as the cuff deflates. The auscultatory technique is based on the ability of the human ear to detect and distinguish sounds. Inherent in this method is the possibility for measurement error due to differences in hearing acuity from clinician to clinician. Unqualified or inexperienced personnel may be more susceptible to outside noise, other interference, or inconsistent assessment of Korotkoff sounds. The Automated Auscultatory Method: These devices apply sound-based algorithms to estimate systolic and diastolic blood pressure. By using a microphone, these devices lack validation ability. In addition to noise-artifact sensitivity, these sound-dependent algorithms may not work properly if the patient has conditions such as hypotension (i.e. low blood pressure), where the Korotkoff sounds may be muted.

The Oscillometric Method: The term "oscillometric" refers to any measurement of the oscillations caused by the arterial pressure pulse. These oscillations are the direct results of the coupling of the occlusive cuff to the artery. These devices do not use microphones and therefore, cuff placement and external noise are not significant problems though they were sensitive to patients’ movements. The majority of monitors on the market today are either oscillometric or auscultatory in nature.

Figure: Oscillometric Method waveform Ambulatory Blood Pressure Monitoring: Ambulatory blood pressure monitors measure patient blood pressure over a predetermined length of time (typically 24 hours) outside the clinic as the patients follow their normal daily routine. The purpose of ambulatory blood pressure monitoring (ABPM) is to obtain a profile of the patient's blood pressure under conditions that are more representative of the patient's lifestyle than those inherent in a clinical environment. This monitoring method led to the identification of white coat hypertension and the circadian rhythm of blood pressure. Note that white coat hypertension is generally defined as "a persistently elevated clinic blood pressure and a normal pressure at other times." and circadian rhythm of blood pressure is a decrease in blood pressure levels from periods of wakefulness to period of sleep. The patient receives instruction on the correct use of the monitor, and wears the device. Then, the patient leaves the clinic and follows a normal daily routine. Periodically, the monitor takes a measurement and stores the results. When the monitoring period is over, the patient returns to the clinic. The clinician downloads the data from the monitor which is about 70-100 samples of blood pressures. ABPM may be cost effective by reducing the number of patients who are mislabeled as hypertensive and subsequently undergo hypertension management therapy. One twenty-four hour ABPM session using Pulse Dynamic technology may provide reliable information regarding blood pressure, arterial compliance, left ventricular contractility, and dipper/non-dipper classification. This decreases the need for exhaustive testing and allows quicker, easier diagnosis and treatment program development. 2.4 Electrocardiograph In 1856 Kollicker and Mueller discovered the electrical activity of the heart when a frog sciatic nerve/gastrocenemius preparation fell onto an isolated frog heart and both muscles contracted synchronously. This discovery led to the invention to electrocardiographs. Alexander Muirhead attached wires to a feverish patient's wrist to obtain a record of the patient's heartbeat while studying for his DSc (in electricity) in 1872 at St Bartholomew's Hospital. This activity was directly recorded and visualized using a Lippmann capillary electrometer by the British physiologist John Burdon Sanderson. The first to systematically approach the heart from an electrical point-of-view was Augustus Waller, working in St Mary's Hospital in Paddington, London. His electrocardiograph machine consisted of a Lippmann capillary electrometer fixed to a projector. The trace from the heartbeat was projected onto a photographic plate which was itself fixed to a toy train and thus enabled real-time measurement of heartbeats. The breakthrough came when Willem Einthoven, working in Leiden, The Netherlands, used the string

galvanometer invented by him in 1901, which won him the Nobel Prize in medicine in 1924. Einthoven assigned the letters P, Q, R, S and T to the various deflections, and described the electrocardiographic features of a number of cardiovascular disorders. Though the basic principles of that era are still in use today, there have been many advances in electrocardiography over the years.

2.5 Temperature Temperature is by far the most measured parameter. It impacts the physical, chemical and biological world in numerous ways. Yet, a full appreciation of the complexities of temperature and its measurement has been relatively slow to develop. Galileo invented the first documented thermometer in about 1592. It was an air thermometer consisting of a glass bulb with a long tube attached. The tube was dipped into a cooled liquid and the bulb was warmed, expanding the air inside. As the air continued to expand, some of it escaped. When the heat was removed, the remaining air contracted causing the liquid to rise in the tube and indicating a change in temperature. This type of thermometer is sensitive, but is affected by changes in atmospheric pressure. Until about 260 years ago temperature measurement was very subjective. That is, measurement only involved representing temperature as hot, warm and cold and the concept of a standardized scale did not exist. By the early 18th century, as many as 35 different temperature scales had been devised. In 1714, Daniel Gabriel Fahrenheit invented both the mercury and the alcohol thermometer. Fahrenheit's mercury thermometer consists of a capillary tube which after being filled with mercury is heated to expand the mercury and expel the air from the tube. The tube is then sealed, leaving the mercury free to expand and contract with temperature changes. At the time, thermometers were calibrated between the freezing point of salted water and the human body temperature. (Salt added to crushed wet ice produced the lowest artificially created temperatures at the time). Fahrenheit subdivided this range into ninety-six points, giving his thermometers more resolution and a temperature scale very close to today's Fahrenheit scale. The early 1800's were very productive in the area of temperature measurement and understanding. William Thomson (later Lord Kelvin) postulated the existence of an absolute zero. Sir William Hershel, discovered that when sunlight was spread into a color swath using a prism, he could detect an increase in temperature when moving a blackened thermometer across the spectrum of colors. Hershel found that the heating effect increased toward and beyond the red in the region we now call 'infrared'. He measured radiation effects from fires, candles and stoves, and deduced the similarity of light and radiant heat. However it was not until well into the following century that this knowledge was exploited to measure temperature. In 1821 T J Seebeck discovered that a current could be produced by unequally heating two junctions of two dissimilar metals, the thermocouple effect. Also in 1821, Sir Humphrey Davy discovered that all metals have a positive temperature coefficient of resistance and that platinum could be used as an excellent temperature detector (RTD). The late 19th century saw the introduction of bimetallic temperature sensor. These thermometers contain no liquid but operate on the principle of unequal expansion between two metals. Since different metals expand at different rates, one metal that is bonded to another will bend in one direction when heated and will bend in the opposite direction when cooled. Although not as accurate as liquid in glass thermometers, BiMets are harder, easy to read and have a wider span, making them ideal for many industrial applications. The 20th century has seen the discovery of semiconductor devices, such as: the thermistor, the integrated circuit sensor, a range of non-contact sensors and also fiber-optic temperature sensors. The increments of the Kelvin scale were changed from degrees to Kelvins. Now we no longer say "one-hundred degrees Kelvin;" we instead say "one-hundred Kelvins". The "Centigrade" scale was changed to the "Celsius" scale, in honor of Anders Celsius. With advancements in technology, temperatures can now be measured to within about 0.001°C over a wide range, although it is not a simple task.

Major Medical Device Companies

Cook Group Edwards Lifesciences Boston Scientific CODAN GE Healthcare St. Jude Medical TUV Rheinland Johnson & Johnson Datascope Hospira Medtronic Vital Signs Abbott Laboratories Philips Integra Life Sciences Bespak Siemens Medical Solutions Stryker Corporation Conceptus Inc Spacelabs Healthcare Smith & Nephew Endotec Zimmer Go Medical Industries BD Atrium Medical Mindray Tyco Healthcare Adiana Agilent Technologies

4. Home Care Medical Equipment Air Ionizer: An air ionizer is a device which uses high voltage to ionize, or electrically charge, molecules of air. These machines can be designed either to generate specifically charged ions (all positive or all negative), or to create both polarities indiscriminately. Air Purifier: An air purifier is a device which removes contaminants from air. It is particularly beneficial for allergy sufferers and asthmatics and to reduce second-hand tobacco smoke. Artificial Limb: An artificial limb is a type of prosthesis that replaces a missing extremity, such as arms and legs. The type of artificial limb used is determined largely by the extent of an amputation or loss and location of the missing extremity. Artificial limbs may be needed for a variety of reasons, including disease, accidents, and congenital defects. Cannula: A cannula is a flexible tube which when inserted into the body is used either to withdraw fluid or insert medication. Crutch: Crutches are medical tools used in the event that one's leg or legs may be injured or unable to support weight. The term, crutch, can also refer to anything used by a person as a psychological or emotional prop, or to something used as an excuse not to engage in normal life activities. Infusion Pump: An infusion pump or perfusor infuses fluids, medication or nutrients into a patient's circulatory system. It is generally used intravenously, although subcutaneous, arterial and epidural infusions are occasionally used. Nasal Cannula: The nasal cannula is a device used in the hospital, in a pre-hospital setting, or at home to deliver supplemental oxygen to a patient or person in need of extra oxygen. This device consists of a plastic tube which fits behind the ears, and a set of two prongs which are placed in the nose or nares. Oxygen flows from these prongs.[1] The nasal cannula is connected to an oxygen tank, a portable oxygen generator, or to a wall connection in a hospital via a flow meter. Nebulizer: A nebulizer is a device used to administer medication to people in forms of a liquid mist to the airways. It is commonly used in treating cystic fibrosis, asthma, and other respiratory diseases. Orthosis: An orthosis is a device that is applied externally to a part of the body to correct deformity, improve function, or relieve symptoms of a disease by supporting or assisting the musculo-neuroskeletal system. The word is derived from ortho, meaning straight.

Oxygen Concentrator: An oxygen concentrator, also called an oxygen generator, is a device used to provide oxygen to a patient at substantially higher concentrations than those of ambient air, used as an alternative to tanks of compressed oxygen. Oxygen concentrators are also used to provide an economical source of oxygen in industrial processes. Positive Airway Pressure (CPAP): Positive airway pressure (PAP) is a method of respiratory ventilation used primarily in the treatment of sleep apnea, for which it was first developed. PAP ventilation is also commonly used for critically ill patients in hospital with respiratory failure, and in newborn infants (neonates). In these patients, PAP ventilation can prevent the need for endotracheal intubation, or allow earlier extubation. Prosthesis: Prosthesis is an artificial extension that replaces a missing body part. Prostheses are typically used to replace parts lost by injury (traumatic) or missing from birth (congenital) or to supplement defective body parts. Walkers: Walkers is a snack food manufacturer in the United Kingdom and Republic of Ireland best known for manufacturing crisps. Wheelchair: A wheelchair is a wheeled mobility device in which the user sits. The device is propelled either manually (by pushing the wheels with the hands) or via various automated systems. Wheelchairs are used by people for whom walking is difficult or impossible due to illness, injury, or disability. People with both sitting and walking disability often need to use a wheel bench.