Medical Study Guide

8/6/2019 Medical Study Guide

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OVERVIEW

Healthcare professionals use a variety of heating and cooling devices to achieve therapeutic goals, including the localapplication of heat and cold and generalized warming to prevent perioperative hypothermia. This study guide begins with areview of the physiology of human thermoregulation. Therapeutic uses of localized heat and cold are discussed, withemphasis on the use of heating and cooling pads that contain circulating water. Measures that can be taken to maintainperioperative normothermia are described. Factors contributing to unplanned perioperative hypothermia are listed, andpossible adverse outcomes of hypothermia are discussed. Suggestions are offered for temperature monitoring during the

perioperative period, and general temperature management strategies are explained. The applications of various activewarming and cooling devices are examined, including conductive and convective blankets, fluid warmers, airway heatingand humidification, cardiovascular heating/cooling, and ECMO heaters.

OBJECTIVES

Upon completion of this continuing education activity, the participant should be able to:

1. Explain how physiological and behavioral mechanisms maintain the bodys core temperature within a narrow range.

2. Discuss therapeutic applications of local heat and cold.

3. Outline appropriate temperature monitoring in the perioperative period, along with general temperature managementstrategies.

4. Describe several types of active perioperative warming and cooling devices, focusing on conductive and convectiveblankets, fluid warmers, and cardiovascular heating and cooling.

INTENDED AUDIENCE

This self-study is intended for nurses and other healthcare professionals interested in learning more about the therapeuticuses of heat and cold.

CONTINUING NURSING EDUCATION INFORMATION

Instructions for Obtaining Credit

This booklet is intended for use as a stand-alone self-study activity. We suggest that you take the following steps to com-plete this activity:

1. Read the overview and objectives for this educational activity and compare them with your own learning objectives.

2. Read the booklet, paying particular attention to those areas that reflect the objectives.

3. Consult the glossary or a dictionary for definitions of unfamiliar words.

4. Complete the post-test. If some areas are unclear, review those sectionsof the booklet.

5. For further information, consult the References and Suggested Readings.

To receive CE credit for this unit:

Complete the registration and evaluation form.

Write a check for $12.00 payable to HealthStream.

Send the completed registration form with the evaluation and test question responses and check to:

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THERAPEUTIC USES OF HEAT AND COLD


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HealthStream2170 South Parker Road, Suite 140Denver, Colorado 80231Phone: (303) 745-5996 Fax: (303) 745-5856Web Site: www.healthstream.comE-mail: [email protected]

ACCREDITATION/CREDIT HOURS

ANCC Credit

HealthStream is accredited as a provider of continuing nursing education by the American Nurses Credentialing CentersCommission on Accreditation. This offering, for2 contact hours, is provided by an agency accredited by the AmericanNurses Credentialing Centers Commission on Accreditation and will meet relicensure requirements in the following manda-tory states: Alabama, Alaska, Arkansas, Delaware, Kansas, Kentucky, Louisiana, Massachusetts, Michigan, Minnesota,Nebraska, Nevada, New Hampshire, New Mexico, Ohio, Texas, Utah, West Virginia, and Wyoming.

State Board Approval

Provider approved by the California Board of Registered Nursing, Provider Number CEP13221, for2 contact hours. Inaddition, HealthStream is a State Board approved provider of Nursing CE in the following states:

Florida: NCE2344 Iowa: 272

Obtaining full credit for this offering depends upon completion, regardless of circumstances, from beginning to end. Licens-ees in all states must provide their license numbers for record keeping purposes.

The certificate of completion, issued at the conclusion of this activity, must be retained in the participants recordsfor at least four (4) years as proof of completion.

At the conclusion of this activity, an Iowa nurse attendee, if he/she so desires, may submit the evaluation form directly toIowa Board of Nursing (400 SW 8th Street, Suite B, Des Moines, IA 50309-4685).

VERIFICATION OF COMPLETION

You will receive a certificate by mail after completing the study guide. The certificate pertains only to completion and isintended for record keeping purposes. It does not, in any way, attest to clinical competence.

Participants who misplace certificates and require proof of completion may submit a request for verification. HealthStreammay only accept requests from actual participants. Submit requests to:

HealthStream2170 South Parker Road, Suite 140

Denver, Colorado 80231-5711

Phone: (303) 745-5996 Fax: (303) 745-5856Website: www.healthstream.com

E-mail: [email protected]


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DISCLAIMER

Accredited status as a provider refers only to continuing education activities and does not imply ANCC Commission on

Accreditation endorsement of any commercial products.

EXPIRATION DATE

This nursing activity was planned and produced in accordance with ANCC Commission on Accreditation. This material was

originally produced in June 2004 and can no longer be produced after June 2007 without being updated. Therefore, nursingcredit will not be issued after June 2007.

SUPPORT

Grant funds have been provided by Cincinnati Sub-Zero.

PLANNING COMMITTEE

Janet K. Schultz, RN, MSN Denver, Colorado

Business Director, Live Workshops

HealthStream

Sheilagh Liston, RGN, RN, BSN Denver, Colorado

Program Manager

HealthStream

EXPERT REVIEWER

Mary Leaven ONeal, RN, MN, CNOR Denver, Colorado

Director of Certification

Certification Board Perioperative Nursing

DISCLOSURE STATEMENT

HealthStream requires that discussion of off-label and/or investigational uses of drug/devices be disclosed to readers. Off-

label and/or investigational uses of drug/devices will be noted in the content of the study guide.


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INTRODUCTION

Humans are endothermic animals. That means we maintain our body temperature close to a predetermined set pointoften defined at 37 Ceven under cold or hot environmental conditions. The familiar body temperature of 37 C (98.6 F)is only an average. Many healthy people have a temperature 0.6 C or more above or below that. The set point also canvary by 0.3 to 0.6 C at different times of the day, during REM sleep, and just before ovulation. It is also altered in fever,which may occur as a reaction to infection, medications, severe trauma or injury, or other medical conditions.

It is important to note that, when we talk about body temperature, were usually referring to the temperature of the bodyscorethe internal body organs, particularly the heart, lungs, and brain. The temperature at the peripherythe append-ages, skin, and muscleis less critical for the overall metabolic processes in the body. Temperature can vary from site tosite and it is often different at the core than at the periphery.

Heat Exchange

The body loses heat to the environment in four ways:

Radiation. Radiation is the loss of heat to the environment due to the temperature gradient. Heat radiates away fromthe body if the skin temperature is greater than the temperature of the surrounding environment.

Conduction. Conduction is the direct transfer of heat energy from a warmer object to a cooler one, without noticeable

movement in the conducting medium. Typically, there is direct contact with the source of heat or cold.Convection. In convection, heat is transferred to or from a moving medium, such as moving air or water. Moleculesof the moving medium that are against the surface of the body are heated, move away, and are replaced by newmolecules, which are also heated. The familiar concept of wind chill is an example of how body heat is lost to theenvironment through convection (moving air).

Evaporation. Evaporation is conversion of water from a liquid to a gas, as when sweat is excreted and evaporatesinto the air.

Similarly, heat can be gainedby increasing the metabolic rate or by radiation, convection, or conduction.

Thermoregulation

Even in the presence of extreme environmental temperatures, we maintain our core temperature within narrow limitsthrough a combination of behavioral and physiological responses. The physiological temperature control system consists ofperipheral and central thermoreceptors, an integrating control center, and an efferent response system.

Afferent input.Afferent thermal input comes from anatomically distinct cold and warmth receptors, which may beperipheral or central. Although the skin contains both cold and warmth receptors, there are 10 times as many coldreceptors as warmth receptors.1

Central control. The bodys central control mechanism (thermostat) is located in the hypothalamus, which has threefunctions in temperature regulation. Specifically, the hypothalamus: 1) integrates thermal signals from peripheral andcore structures; 2) compares mean body temperature with the predetermined set pointthe narrow temperature

range across which there is no efferent response; and 3) coordinates the appropriate efferent response.2

Efferent response. Efferent responses to heat and cold include cutaneous vasodilation or vasoconstriction, piloerec-tion, sweating, and shivering. If the arterial blood flowing through the thermoregulatory center in the hypothalamus isabove the set point, the hypothalamus initiates impulses that cause heat loss through vasodilation and sweating.Vasodilation of the cutaneous vessels of the skin allows greater volumes of blood to reach the skin surface andthereby dissipates excess heat. Sweating cools the body through evaporative cooling. A blood temperature belowtheset point causes the hypothalamus to relay impulses that result in vasoconstriction, decreasing blood flow to theperiphery, and thereby decreasing heat loss. In the pilomotor response, the hairs become more erect to create a layerof still air that reduces convective heat loss. Shivering generates heat through an increase in the chemical reactionsrequired for muscle activity. (Shivering is not effective for very long and comes at a high metabolic cost.) Nonshivering


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THERAPEUTIC USES OF HEAT AND COLDthermogenesis occurs mainly by sympathetic stimulation of special brown adipose tissue. In adults, the amount ofbrown adipose tissue is small, but in infants, nonshivering thermogenesis may double heat production.

Humans also have the ability to alter their behavior in response to extreme heat or cold. Increasing or decreasing activitycauses corresponding changes in heat production. Likewise, putting on or taking off layers of clothing regulates the rate ofheat loss. In humans, behavioral responses are quantitatively the most effective thermoregulatory mechanism.

A variety of therapeutic modalities are available that either use the bodys natural thermoregulatory mechanisms to relievepain or encourage healing or enhance the bodys ability to maintain a normal core temperature. Superficial applications of

heat and cold are well known therapeutic interventions. Appropriate application of heat and cold therapies can relieve pain,reduce swelling, and encourage rehabilitation. During the perioperative experience, when anesthetic-induced impairment ofthermoregulatory control and a cool environment combine to reduce core temperature below normal levels, a variety ofinterventions are available to maintain normothermia. The remainder of this study guide describes these interventions.

LOCAL COLD THERAPY

The use of local cold therapy (cryotherapy) dates back to the ancient Greeks. Hippocrates, Aristotle, and Galen all mentionthe use of cold treatments for acute injury.3 Cold drinks and baths and natural ice and snow were used as the first forms ofcold therapy before the introduction of artificial ice in 1755. In the 1940s, cold began to be used extensively for the treat-

ment of acute and subacute injuries and for rehabilitation.Therapeutic Modalities

Today, cryotherapy techniques utilize conduction and convection as a means of cooling injured tissues.4 Intramusculartemperatures can be reduced by 3 to 7 C, which is helpful in reducing local metabolism, inflammation, and pain. 5 Thecost, sophistication, and availability of superficial cold modalities vary. They include:6

Ice. Ice water is a good and inexpensive method of cold therapy if the extremity or part to be treated can be im-mersed. For less accessible areas, an ice stick or block can be moved back and forth over the painful area in amassaging motion.

Cold packs. Cold packs are available commercially in many sizes and shapes. They are usually composed of a

pliable gel in a thin plastic pouch that can be stored in the freezer until needed. They may retain their cold for up to 30minutes after application.

Compression devices. Cold therapy compression units are devices in which ice water or cooled water flows througha blanket or cuff, providing immediate cooling to an affected area. One such device uses an insulated jug filled withcold water and attached to a cuff. Elevating the jug fills and pressurizes the cuff. The amount of compression iscontrolled by gravity, and is proportional to the elevation of the cooler. When the patients body heat warms the water,it is re-chilled simply by lowering the cooler. Similar units with a hand pump attached may be filled and operated fromthe same position, with no lifting required. (See Figure 1.) More complicated cold therapy units employ electrically orbattery-operated pumps and refrigerators with variable temperature settings. In these units, cold water circulates in arandom flow pattern throughout specially designed cold therapy pads.

Vapocoolant sprays. Topical vapocoolant sprays contain either fluoromethane or ethyl chloride. They are useful torelieve pain of muscle spasm and trigger points, but must be used very carefully to prevent tissue damage.


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Figure 1. Portable Cold Therapy Unit.

Physiologic Effects

Localized cold therapy is used primarily after orthopaedic surgery or injury to reduce swelling and as a pain managementtool. Depending on the application method and duration, the physiologic effects of cold therapy may include:7,8

Pain relief. By reducing the speed of impulses conducted by nerve fibers, cold inhibits the sensation of pain. Thereare four natural stages of sensation with cold therapy: 1) an uncomfortable sensation of cold; 2) stinging; 3) burningor aching; and 4) numbness.

Decreased hemorrhage/swelling/edema. Localized cold therapy causes vasoconstriction, which decreases hemor-rhage and swelling within injured tissues.

Muscle relaxation. Decreases in muscle spasm are seen with cold therapy, although the exact mechanisms for thisare unclear. It may be mediated through reflex reduction in motor nerve activity secondary to response to increased

activity in cold receptors.

Reduced inflammation. Cryotherapy is effective in acute stages of inflammation, before range-of-motion exercises,and after physical activity/rehabilitation.

Cautions and Contraindications

General precautions for cryotherapy include the need to protect the skin from cold injury with a layer of intervening material,and limiting exposure to 20 minutes. A convenient schedule is alternating 20-minute periods of application and removal.Acute care based thermal electric or compressor cooled systems have the ability to preset and hold a specific temperatureand provide continual cold therapy with minimal chance of tissue injury. It is also necessary to use caution when applyingcold on or near superficial nerves.

Cryotherapy is contraindicated for patients with:9

A decreased level of consciousness

An inability to provide feedback about tissue temperature

Hypersensitivity to cold (eg, Raynauds phenomenon, prior history of frostbite)

Marked hypertension

Arteriosclerosis

Diminished circulation


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LOCAL HEAT THERAPY

Superficial heat can heat tissues at a depth limited to 1 to 2 cm. Deeper tissues are generally not heated by superficial heat,due to the thermal insulation of subcutaneous fat and the increased cutaneous blood flow, which dissipates the heat. 10

Therapeutic Modalities

Localized heat therapy usually utilizes some form of conductive heating. As in cold therapy, the cost, sophistication, andavailability of superficial heating devices vary. Choosing the most appropriate superficial heating method depends on the

shape and area to be treated, the depth of the target tissue, whether concurrent exercise is desired, the expected durationof treatment, and more pragmatic factors, such as expense and ease of application. The use of many heat therapy devicesin hospital settings is limited because of the safety issues associated with commonly used heating devices. 11

Options for local heat therapy include:12

Hot water bottles.Although used frequently in the home environment, hot water bottles can create problems relatedto the temperature of the bottle. If the water used to fill the bottle is too hot, direct application of the bottle on the skincan cause a burn. If the bottle becomes damaged or the screw top becomes loose, it could lead to a water leak and ascald.

Electric heating pads. As with other heat therapies, electric heating pads can lead to serious burns if left unattended

or used inappropriately. Electric heating pads are not recommended for use in hospitals.Hot packs. Hot packs, also known as hydrocollator packs, usually contain a silicate gel in a cotton bag. They areplaced in a hot water tank and then applied over layers of towels for 20 to 30 minutes. Gel packs can potentially beoverheated and, once applied, they readily lose their heat. Wheat-based heat packs are designed to be heated in amicrowave, where the risk of overheating remains. Other safety risks related to wheat-based hot packs are associ-ated with infection control and allergic reactions. Hot packs may be preferred over heat lamps if the patient feels thatradiant heat dries the skin or where the patient prefers moist heat.

Heat lamps. Heat lamps warm tissues by converting radiant energy to heat. They often use 250-watt incandescentbulbs and are usually placed about 40 to 50 cm from the patient. With radiant heat lamps, intensity is controlled bythe light source, distance, type/quality of reflector, and air movement. Heat lamps may be preferred over hot packs if

the patient is difficult to position or cannot tolerate pressure.

Circulating fluid hot packs. In hospitalized patients, circulated warm-fluid hot packs minimize the potential for burnsdue to prolonged superficial heat application. With these devices, a pump, connecting hose, and localized tempera-ture therapy pad (Figure 2) are used to deliver a safe and consistent therapeutic level of localized heat. Safetyfeatures that may be incorporated into a heat therapy pump include audible and visual alarms for patient and productprotection; automatic shutdown if the unit tips over or when the water level is too low; and a built-in handle that allowsthe caregiver to easily place the unit on a table or stand near the patients bed.

Hydrotherapy. Hydrotherapy can include total immersion in a large hot tub or tank. Partial immersion is available forupper or lower extremities by whirlpool baths.

Paraffin baths. Paraffin baths are used primarily to treat contractures, particularly for patients with rheumatoidarthritis, hand contractures, or scleroderma. For therapeutic use, the paraffin bath is maintained at the melting point ofparaffin in a thermostatically controlled insulated container. The patient may either continuously immerse the treatedpart for 20 to 30 minutes, or may repetitively dip and remove the treated area from the paraffin.


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Figure 2. Localized Heating Therapy Unit.

Deep heat can be provided by ultrasound, short-wave diathermy, and microwave devices. It can increase the temperatureof the tissues to a depth of 3 to 5 cm.13

Physiologic Effects

The sedative, antispasmodic, analgesic, and decongestive effects of heat therapy are well known. Among other things, it isindicated for painful muscle spasms, abdominal muscle cramping, menstrual cramps, and superficial thrombophlebitis.Local application of heat therapy has the following physiologic effects on surface body tissues:14

Pain relief. Local heat therapy has been used for decades to relieve muscular and joint pain, including arthritis, backpain, and dysmenorrhea. It may reduce pain by altering pain nerve fiber conduction speeds or raising nerve painthresholds. Direct heat application to tender spastic muscle areas may alleviate pain secondary to muscle spasm.

Improved healing. Local vasodilation increases blood flow to an injured region, thereby increasing the delivery ofleukocytes and antibodies. Other beneficial effects of increased blood flow to the tissues include facilitation of drain-

age and a wash-out effect, purging the tissues of debris and byproducts of tissue injury.

Connective tissue effects. Heat therapy promotes relaxation via lengthening of the collagen tissue within muscles,tendons, and ligaments, and thereby aids in stretching and restoration of joint motion.

Fracture treatment. Localized heat may be applied to a fracture using a heat lamp or heating pad. In this application,heat promotes healing by increasing blood flow to the injury.15

Cautions and Contraindications

Burns are a risk when using heat therapy. Other potential problems associated with heat therapy include skin-drying effectsand difficulty with application to regions requiring therapy. In addition, heat therapy is contraindicated for patients with: 16

An inability to provide feedback about tissue temperature (eg, decreased level of consciousness, decreased sensa-tion, or altered mental status)

An acute injury less than 2 days old. (Heat can increase joint swelling if injury is acute.)

Inflammation

Superficial or skin infection. Heat should not be used where damaged or abnormally sensate skin is present.

Hemorrhage. A bleeding diathesis is a contraindication, because heat increases blood flow and vascular permeability.Heat also can increase bleeding in the presence of very recent soft tissue injury, such as muscle strains, traumatictendonitis, and ligament sprains.


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THERAPEUTIC USES OF HEAT AND COLDMalignancy. Heating over malignancies is contraindicated, because it can accelerate tumor growth and metastasis.

In addition, heat should not be applied to the gonads or to a fetus. Tissues with inadequate vascular supply should not beheated, because increased metabolic demands can lead to ischemic necrosis.17

PREVENTING PERIOPERATIVE HYPOTHERMIA

The prevention of perioperative hypothermia is another widespread application of superficial heating. During the

perioperative period, a variety of factors combine to interfere with the patients normal behavioral and physiological ther-moregulatory mechanisms. Anesthesia abolishes behavioral mechanisms, and it has the potential to disrupt the physiologi-cal mechanisms of thermoregulation. Sedatives and general anesthetics tend to promote heat loss by delaying vasocon-striction and shiveringthe normal autonomic responses to decreases in core body temperature. In combination with therelatively cold operating room environment, open body cavities, and administration of blood or intravenous (IV) fluids, thesefactors result in unplanned perioperative hypothermia in the majority of surgical patients.18 In the first 30 minutes afterinduction of general anesthesia, core temperature usually decreases 0.5 to 1.5 C.19 Unless active warming measures aretaken, the immobile, vasodilated patient in a cold operating room will lose body heat, 20 potentially resulting in adverseoutcomes. Postoperative return to normothermia occurs when brain anesthetic concentration decreases sufficiently to againtrigger normal thermoregulatory defenses; however, residual anesthesia and opioids given for treatment of postoperativepain decrease the effectiveness of these responses. Consequently, return to normothermia often takes 2 to 5 hours,

depending on the degree of hypothermia and the age of the patient.21

Recent studies have proven that patients maintained at normothermic conditions before, during, and after surgery experi-ence fewer adverse outcomes, and thus, incur lower healthcare costs.22 When it comes to improving perioperative out-comes, a few degrees can make all the difference. Interventions that can help maintain perioperative normothermia includepassive insulation, convective (warmed air) warming blankets, conductive (water-filled) warming blankets, fluid warmersand, in certain specialties, cardiopulmonary bypass and extracorporeal membrane oxygenation (ECMO).

For some procedures, patient cooling is desirable. Hypothermia is frequently used during cardiac surgery, because itprovides substantial protection against cardiac and cerebral ischemia. For the same reason, it is also used during certainneurosurgical procedures, especially aneurysm repair.

Definitions

No consistent definitions of normothermia and hypothermia are found in the literature, but a panel convened by the AmericanSociety of PeriAnesthesia Nurses (ASPAN) agreed that normothermia is best defined as a core temperature range from 36 Cto 38 C (96.8 F to 100.4 F). Hypothermia is defined as a core temperature less than 36 C. ASPAN guidelines further statethat hypothermia may be present regardless of temperature reading if the patient describes feeling cold or presents withcommon signs and symptoms of hypothermia, such as shivering, peripheral vasoconstriction, and piloerection.23

Passive hyperthermia (a core temperature above 38 C) can result from excessive use of warming devices and inappropri-ate monitoring of body core temperature. It is treated easily by discontinuing active warming devices and removing exces-sive insulation from the patient. The dangerous increase in body temperature that occurs during malignant hyperthermia

results from an enormous increase in metabolic heat produced by internal and skeletal muscles that is triggered by succinyl-choline and volatile anesthetics.

Factors Contributing to Hypothermia

Factors that contribute to a patients risk of perioperative hypothermia include, but are not limited to: 24,25

Patient age. Infants, children, and patients older than 60 years are more susceptible.

Patient physical status

Type of anesthesia used


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Body size. Thin, obese, or pregnant patients with a lack of tissue mass or a large body surface are more likely tobecome hypothermic.

Length and type of surgical procedure. Patients scheduled for open thoracic, abdominal, gynecologic, or genitouri-nary procedures are at greater risk.

Ambient temperature. The first perioperative hour in a 21 C room is associated with the greatest heat loss.

Adverse Effects of Hypothermia

Most surgical patients are at risk of at least one proven complication of mild hypothermia, including morbid myocardialoutcomes, coagulopathy, wound infection, and prolonged postoperative recovery.26 Significant adverse outcomes confirmedby published research include:27

Patient discomfort. Thermal discomfort, shivering, and fatigue can occur when core temperature decreases by 1 C.

Untoward cardiac events. Cardiac morbidity is the leading cause of death in the perioperative period.28 Re-warmingpatients quickly after cardiac surgery keeps the metabolic rate, oxygen consumption, and myocardial workload lowand it reduces length of stay in recovery room.

Coagulopathy. In-vitro studies indicate that platelet function and the coagulation pathway are impaired by hypother-mia. Research has shown that mild perioperative hypothermia significantly increases intra- and postoperative blood

loss,29 possibly necessitating blood transfusions.

Wound infection. The presence of intraoperative hypothermia triggers thermoregulatory vasoconstriction. Vasocon-striction in turn decreases the partial pressure of oxygen in tissues, which lowers resistance to infection. 30

Delayed wound healing. Vasoconstriction-induced tissue hypoxia also may decrease the strength of the healingwound. The hydroxylases that catalyze the cross-linking of collagen in the formation of scar tissue are dependent onoxygen tension in wound tissue.31

Altered drug metabolism. Hypothermia decreases a patients metabolism, resulting in a need for greater amounts ofanesthetics. It also contributes to delayed emergence from anesthesia.

Delayed PACU discharge. Delayed discharge from the postanesthesia care unit (PACU) is not surprising, because

mild hypothermia increases anesthetic potency, decreases drug metabolism, reduces cognitive performance, and isassociated with cardiovascular instability. In one study, intraoperative core hypothermia delayed post-anestheticrecovery nearly 40 minutes, even when return to normothermia was not a discharge criterion. When a core tempera-ture greater than 36 C was also required, discharge was delayed nearly 90 minutes in hypothermic patients. 32

Prolonged hospitalization. Hospitalization may be prolonged by wound infections or by delayed wound healing.

Costs of Unplanned Perioperative Hypothermia

Meta-analysis calculated that hypothermia averaging only 1.5 C below normal caused cumulative adverse outcomes thatadded $2500 to $7000 per surgical patient to hospitalization costs.33 (See Table 1.) Significant factors associated withelevated costs of patient care include:34

Increased length of PACU, intensive care unit (ICU), and hospital stay

Increased red blood cell, plasma, and platelet use

Increased need for mechanical ventilation

Increased cardiac problems and associated costs


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THERAPEUTIC USES OF HEAT AND COLDTable 1. Costs associated with unplanned perioperative hypothermia.35

Factor Cost

Adverse outcomes $2500 to $7000Delayed anesthetic recovery 2 to 5 hours of recovery room care, @ $100 per hour Extended ICU stay $1000 per dayExtended hospital stay $465 per day

Cost of warmers per use Convection warmer, $10Anesthesia circuit humidifier, $5Intravenous fluid warmer, $10Genitourinary irrigation fluid warmer, $50

Temperature Management Strategies

Management of perioperative hypothermia requires the coordinated efforts of anesthesia providers, surgeons, andperioperative, perianesthesia, and critical care nurses. It has been recommended that, unless hypothermia is specifically

indicated (eg, for protection against ischemia), intraoperative core temperature should be maintained at >36 C.36 Regulartemperature monitoring, general temperature-regulating measures, and a range of medical devices can be used to helpachieve this goal, including the following:

Convective (warmed air) warming blankets

Conductive (circulating water) warming and cooling blankets

Fluid warmers

Airway heating and humidification

Cardiovascular heating/cooling

ECMO

Even for patients who are normothermic, proactive warming measures should be instituted in the preoperative period. Thegeneral strategy is to start active cutaneous warming as soon as patients are admitted to the pre-surgical holding area. Pre-warming is then continued until patients are transferred to the operating room, 37 where intraoperative warming methods areused. Warming may be continued postoperatively until normothermia is achieved.

Temperature Monitoring

The American Association of Nurse Anesthetists (AANA) recommends that body temperature be monitored continuously onall pediatric patients receiving general anesthesia, and when indicated, on all other patients.38 Because malignant hyper-thermia remains a risk in all patients, patient safety is enhanced if body temperature is monitored in most patients undergo-

ing general anesthesia that exceeds 30 minutes. Ideally, body temperature might be monitored continuously; however, 15-minute intervals probably are sufficient in most patients. It also has been recommended that temperature be measured orreliably estimated during regional anesthesia when changes in body temperature are intended, anticipated, or suspected.39

It is the responsibility of the practitioner to determine the best method for monitoring patient temperature and to use thetemperature-monitoring device correctly, while considering accessibility of the site, patient comfort, and safety. During theperioperative period, when core temperature changes rapidly, the relationship between the temperatures measured atvarious body sites may differ considerably.40


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Adjusted skin temperatures and rectal temperatures reflect core temperatures reasonably well, but may becomeunreliable during a malignant hyperthermia crisis.41 Single patient use skin surface probes attach easily to the skinwith an adhesive-backed foam pad for use in a wide range of medical and surgical applications.

Infrared tympanic monitoring is the preferred route of temperature measurement preoperatively and postoperatively.Tympanic membrane thermometers record temperature close to the hypothalamus and are rapid and convenient.Their accuracy is dependent on the operator, patient anatomy, and the instrument used.42

Intraoperative core temperature may be measured in the pulmonary artery, distal esophagus, nasopharynx, or

tympanic membrane.

Oral, axillary, and bladder temperature monitoring provide an estimate of core temperature.

Sterile single-use temperature probes come packaged in sterile, sealed pouches ready to use. After use, they are simplydisconnected and thrown away. Disposability means no chance of cross-contamination. Single-use probes save time andexpense of cleaning, handling, and reprocessing. In addition, they are a readily identifiable patient charge item.

NOTE: When monitoring temperature, it is important to document the method and site of recording.

Temperature-Regulation Strategies

General temperature regulation strategies that do not require the use of specially designed medical equipment include the

following:

Provide passive insulation. Passive insulation may include warmed cotton blankets, socks, and/or a heat covering.A single layer of almost any passive insulator reduces cutaneous heat loss by roughly 30%. This is a clinically impor-tant amount and is sometimes sufficient to restore a thermal steady state. The efficacies of routinely available insula-tors (i.e., plastic bags, a single layer of surgical draping, a cotton blanket, or a space blanket) are similar. Even thebest passive warming methods rarely reduce heat loss even by 50%. Not surprisingly, active warming systemsmaintain normothermia better than passive insulation.43

Limit evaporative cooling. Lessen the amount of evaporative cooling by limiting the amount of skin surface exposedduring positioning and skin preparation, limiting the time between prepping of the skin and draping, and preventingsurgical drapes from becoming wet.

Increase ambient temperature. Consider increasing the ambient temperature to a minimum of 20C to 24C (68Fto 75F).

Convective Warming and Cooling

Warmed air devices typically consist of an electrically powered heater/blower unit and a patient cover. The blowers areavailable in various sizes and configurations to generate a flow of warm air across the skin. When the moving air is warmerthan the skin, convection results in heat gain. Most covers are made of some combination of fabric, plastic, or paper, andmost are disposable and designed for single patient use.

The features of warmed air devices vary from manufacturer to manufacturer. Choose a convective warming unit with the

following characteristics:A high flow rate that ensures rapid and efficient patient warming. There are distinct differences in the amount of airbeing circulated by the different types of convective warming units.

Built-in safety monitoring systems with over- and under-temperature safety controls that alert caregivers withaudible and visible alarms if temperatures exceed or fall below temperature settings

A universal bracket and an IV pole clamp that attaches easily to operating room tables, stretchers, bed ends, siderails, or IV poles for out-of-the-way convenience


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THERAPEUTIC USES OF HEAT AND COLDConvective air therapy warming blankets for the PACU and OR should conform to the patients body to deliver evenlydistributed airflow and warmth without a hint of blowing air. The heated air should diffuse through the lower drape materialto warm patients without causing discomfort to medical personnel. Upper and lower body styles provide the coverage of astandard blanket, along with extra material for the shoulders and feet. Blankets should be able to be applied by a singlecaregiver, and should remain in place even on restless patients. While additional blankets or sheets will increase theeffectiveness of convective air therapy warming blankets, their use is optional.

In a randomized study of 300 patients undergoing unilateral total knee replacement, warmed air warming was significantlymore efficient and cost-effective than two cotton blankets or reflective blankets in maintaining perioperative normothermia.The initial cost of the warmed air warming system was compensated by the savings in reduced recovery room stay and inthe cost of treating complications associated with hypothermia.44

For delicate imaging and surgical procedures, a warming tube surrounds the patient with comforting convective warmthwithout interfering with the procedure. Because patients are enveloped in warmth through surround air, distortion ofradiographic images or interference with the performance of imaging equipment can be avoided. A warming tube is uniquelydesigned to provide warming therapy by surrounding the patient, not covering the patient. Used outside of the imaging field,a warming tube does not interrupt the flow of electronic information between imaging equipment and receptors, cannot

distort images critical to the successful outcome of diagnostic imaging procedures, and effectively warms the patient. Thewarming tube inflates around the patient and both are covered with a sheet or blanket. The warming tube does not have tobe removed, nor is treatment interrupted to gain patient access.

NOTE: The practice of free hosing (use of a convective warming unit without a disposable blanket) is extremely danger-ous. Traumatic thermal injuries have been reported from failing to properly attach the blanket to the hose. The temptation tosimply place the hose under a sheet or blanket should be avoided at all costs. 45

In a prospective randomized study, when convective warming blankets were used throughout the perioperative period tomaintain normothermia, postoperative morbid cardiac events occurred 55% less frequently than in patients receiving routinethermal care (warming of IV fluids and blood, heat-moisture exchanger in the respiratory circuit, paper drapes, and warmed

cotton blankets, but no convective warming). Postoperative ventricular tachycardia also occurred less frequently in thenormothermic group than in the hypothermic group.46

Conductive Warming and Cooling

Circulating water is also a useful warming mechanism. Dual-purpose hyper-hypothermia conductive water therapy systemsoffer a cost-effective and convenient way to warm or cool patients. Conductive therapy can be applied under and/or over apatient, but the efficacy of posterior positioning is limited by a number of factors directly related to the mattress positionbelow the patient. Circulating water mattresses are more effective when positioned over patients than under them. 47

A water-channel design with a random flow pattern permits efficient heat exchange, resulting in quicker patient temperature

changes. (See Figure 3.) A random flow pattern yields a faster, more efficient circulationup to 3 times faster than otherflow patterns. The result is even temperature distribution and better heating and cooling rates for conductive warming andcooling. Uniform distribution of water temperature yields consistent and even conductive heating and cooling rates. Arandom flow pattern also allows the blanket to be filled while a patient is in place. Color-coded hoses and self-sealing quickconnectors simplify setup and keep water from draining from the unit when not in use. Microprocessor-controlled conductivewater therapy systems with higher flow rates result in quicker heating or cooling, with a more consistent water temperatureat the blanket.


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Figure 3. Conductive Warming and Cooling Blanket.

Conductive blankets may be designed for single or multiple uses. Single-use blankets wrapped on both sides with a non-woven material eliminate the need for an additional thermal-robbing layer between the blanket and the patient. Multiple-use

blankets are constructed of durable, easy-to-clean material that resists punctures and will not allow penetration of blood,soil, or debris. Setup is simplified through the use of permanently attached hoses. Disposable covers are available that helpincrease the lifespan of single-use and reusable blankets by preventing stains and reducing cleanup time.

Conductive warming systems have been demonstrated to re-warm cardiac surgical patients 45 minutes faster than convec-tive-air warming blankets. Studies also have shown that conductive water therapy is faster and more efficient than a reflec-tive blanket approach to re-warming post-op patients.

Single-purpose (warming only) conductive systems offer effective microprocessor-controlled total body hyperthermiatherapy in a compact, convenient, and cost-effective system. A total body system allows hyperthermia care in the OR,recovery room, emergency room, and ICU environments without the expense of dual-application systems. At about half thecost of a hyper-hypothermia unit, a single-purpose system offers convenient and cost-effective total body hyperthermiacare. Microprocessor control ensures accuracy and safety. A self-monitoring system provides precise, continuous warmingat a set temperature. Independent safety limits combined with audible and visible alarms protect both patient and unit.

Specific patient assessments may dictate the temperature setting (i.e., cross-clamping or vascular irregularity), but ingeneral OR staff should provide the highest temperature gradient differential to provide effective temperature management.

Fluid Warmers

When cold fluids are infused into a warm patient, conductive heat transfer occurs from the patient to the fluid. Transfusion oftwo units of packed red blood cells at 4 C will lower a patients core temperature by 0.5 C. The infusion of 1 L of crystal-loid at room temperature will cause a similar heat loss.48 Heat loss caused by cold intravenous fluids thus becomes signifi-cant when large amounts of crystalloid solution or blood are administered.

Fluid warmers are widely used to minimize this heat loss. Whenever a patient needs massive or rapid infusions of IVsolutions or blood, the fluid should be warmed or cooled to temperatures appropriate to the surgical need. Large amounts offluid used to irrigate a wound during surgery also should be warmed. Fluid warming prevents heat loss, but it does not warmpatients to any important extent, because it is unsafe to heat fluids much above normal body temperature. Fluid warming istherefore not a substitute for cutaneous insulation warming and will not keep patients normothermic when used alone.49


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THERAPEUTIC USES OF HEAT AND COLDSeveral types of fluid warmers are available to do this safely. All require special IV tubing and are designed to warm thesolutions just before administration. A high-quality blood and infusion warmer heats blood and infusions reliably and acrossa full range of clinically relevant flow rateseven very low flow rates. An insulated line prevents heat loss before the bloodor infusion reaches the patient. Microprocessor control ensures consistent, reliable performance.

Special high-volume systems with powerful heaters and little resistance to flow facilitate care of trauma victims and areuseful in other cases in which large amounts of fluid must be administered quickly.50

Most warming devices operate at a preset temperature. A setting of 41 C (106 F) is common to compensate for heat loss

after the fluid leaves the warmer and to ensure that the patient receives normothermic fluids. If a patient receives more thanone unit of blood or IV solution, the fluid warmer tubing should be changed according to the manufacturers recommenda-tions.51

Using an IV fluid warmer and convective warming blankets to keep patients temperatures near normal during colorectalsurgery dramatically reduced wound infections, sped healing, and shortened hospital stays by 2.6 days (approximately20%) compared to patients randomized to routine intraoperative thermal care. Patients assigned to the hypothermia groupalso required more transfusions of allogeneic blood.52

NOTE: Fluids should be heated or cooled in devices intended for that purpose. Microwaves and autoclaves should notbeused as warming devices. Microwaves do not heat uniformly, cannot be monitored, and are not designed for medical use. 53

Airway Heating and Humidification

Less than 10% of metabolic heat production is lost via the respiratory tract. Airway heating and humidification slightlyimproves core temperature in infants and children, but is of little value in adults.54

Cardiovascular Heating/Cooling Systems

Procedures performed with cardiopulmonary bypass differ from other types of surgery in that the heat exchange to thepump overshadows all other sources of heat loss or gain.55 Cardiovascular heating/cooling systems simplify the bloodtemperature control function during cardiovascular procedures. Such systems deliver heated/cooled water to a blood heatexchanger. Mechanical refrigeration means easy setup, quick response, and minimum cleanup. It also eliminates thepreconditioning process. It lowers the reservoir water temperatures at a rate that rapidly produces a significant reduction inblood temperature. Microprocessor control provides easier, more accurate operation. A large LED (light-emitting diode)readout allows monitoring at a glance. Built-in high and low safety thermostats and an external re-settable circuit breakerenhance safety.

Dual reservoirs double the efficiency of these devices. Independent heating and cooling permit instant changeover from onebath to the other. Each reservoir has its own control mechanism and temperature display. Some units can supply water to ablood heat exchanger or a hyper-hypothermia blanket, eliminating the need for a separate hyper-hypothermia machineduring the re-warming process.

Additional skin surface warming with a water mattress and forced warm air during these procedures can help to preserveperioperative thermal balance and may contribute to reduced bleeding after cardiac surgery. 56

Induced Hypothermia Following Cardiac Arrest

Preliminary studies in Europe and Australia published in the New England Journal of Medicine have suggested that inducedhypothermia used after restoration of spontaneous circulation decreases cerebral oxygen demand following cardiac arrest.Patients who have an initial rhythm of ventricular fibrillation are cooled to 32 to 34 degrees Celsius for 12 to 24 hours. 57,58

Further clinical studies to determine factors such as optimum and level of hypothermia are necessary.


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Extracorporeal Membrane Oxygenation (ECMO)

Extracorporeal membrane oxygenation uses an artificial heart-lung machine to take over the work of the lungs (and some-times also the heart). In newborns, ECMO is used to support or replace an infants underdeveloped or failing lungs byproviding oxygen and removing carbon dioxide waste products so the lungs can rest. It is also used to support a child oradult patients damaged, infected, or failing lungs for a few hours to allow treatment or healing.

A surgeon places tubes into large veins and/or arteries located on the right side of the neck or in the groin. Once in place,the tubes are connected to the ECMO circuit, and then the machine is turned on. The patients blood flows out through the

tube and through a membrane, where oxygen is added and carbon dioxide is removed. The blood is then warmed andreturned to the patient.59

With microprocessor-controlled safety and accuracy, an ECMO heater provides warm water to a blood heat exchanger,allowing precise maintenance of desired blood temperature. The heater automatically cycles on and off to maintain set pointwater temperature. An ECMO heater is an accurate, cost-effective, and reliable way to control blood temperature duringECMO procedures.

Patient Safety

Cold is well tolerated by human tissues; very low temperature or long exposure is required to cause injury. In contrast, thetolerance of human skin for high temperatures is relatively low. The best strategy for safe and effective warming is to heat

as much of the skin surface as possible. This allows a large total amount of heat to be transferred without excessivelyheating any one region.60

To avoid thermal burns or pressure necrosis that may occur when using temperature-regulating devices, they should beplaced in an effective and safe manner and monitored throughout the surgical procedure. Direct contact of the patients skinwith plastic surfaces should be avoided. Unless temperature-regulating blankets are designed for placement next to pa-tients skin, a thin cloth covering is needed to protect the patient.61

Skin integrity should be inspected before, periodically during (when possible), and after using devices such as ice packs,temperature-regulating blankets, and heat lamps. Individuals vary in their ability to tolerate heat and cold. Conditions thatpredispose patients to heat-related injury include age, immobility, body fat, open wounds, broken skin, edematous areas,abscesses, peripheral vascular disease, confusion or unconsciousness, nerve injuries, and/or regional anesthesia. 62

SUMMARY

The application of heat or cold can work with the bodys natural thermoregulatory mechanisms to achieve therapeutic goalsor prevent adverse outcomes. Superficial applications of heat and cold can relieve pain, reduce swelling, and encouragerehabilitation. In the perioperative environment, good temperature management helps reduce the incidence of unplannedperioperative hypothermia and its risks to patients. Hypothermia can be minimized by actively warming peripheral tissuesbefore induction of general or regional anesthesia. A reasonable thermal management strategy is to use warmed air orconductive warming in patients who cannot be kept normothermic with simple passive insulation. Fluid heating should beadded when large amounts of intravenous fluid are required. With good thermal management, patients will recover faster,

spend less time in the PACU/recovery room, and be discharged from the hospital sooner, all of which can save the hospitalmoney.


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GLOSSARY

Active warming Forced-air convective warming.

Afferent An axon conducting action potentials towards the central nervous system.

Brown adipose tissue A type of specialized fat known to convert fat calories into heat, thereby dissipatingexcess calories.

Conduction Transmission of heat through a substance from a region of high temperature to aregion of lower temperature without noticeable movement in the conducting medium.

Convection A process by which heat is transferred from one part of a fluid (or gas) to another bymovement of the fluid itself. In forced convection, hot fluid (gas) is transferred fromone region to another by a pump or fan.

Core The thermal compartment of the body composed of highly perfused tissues where thetemperature is uniform and high compared to the rest of the body.

Cryotherapy The use of cold temperature as a form of treatment for an injury.

Efferent An axon conducting action potentials outward from the central nervous system.

Endothermic Having a relatively high and constant body temperature mostly independent of thesurroundings; warm-blooded.

Evaporation The process by which a liquid is converted into a gaseous state.

Hydrocollator Steam heat packs filled with silicate gel that keeps them hot and moist; extremely hot;

water is heated to 150 to 160 F.

Hydrotherapy The use of water, ice, or steam to maintain or restore health; includes full-bodyimmersion, steam baths, saunas, and sitz baths.

Hyperthermia A core body temperature in excess of 38 C (100.4 F). Passive hyperthermia. Theresult of heating a patient excessively to a core body temperature exceeding normalvalues.

Hypothermia A decrease in core body temperature below 36 C (96.8 F).

Malignant hyperthermia Rapid onset of extremely high fever with muscle rigidity, precipitated by exogenousagents in genetically susceptible persons.

Nonshivering thermogenesis Increased heat production in response to cold stress by other than muscle contrac-tions (shivering), i.e., by brown adipose tissue.

Normothermia A core temperature of 36 C to 38 C (96.8 F to 100.4 F).


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Paraffin bath Dipping a body part in melted paraffin (wax) at a temperature of 126 to 130 F;building a paraffin glove that retains heat; used to treat arthritis, bruises, bursitis,gout, and spasms.

Passive insulation Warmed cotton blankets, reflective blankets, circulating water mattress, socks, headcovering, and limited skin exposure.

Piloerection Erection of hair, due to action of bundles of smooth muscle fibers attached to the

deep part of the hair follicles; causes goose bumps.

Postoperative shivering Uncomfortable, rhythmic muscle contractions to maintain core temperature.

Preventive warming measures Initiation of passive insulation or active warming measures to maintain normothermia.

Thermoregulation Maintenance of the bodys core temperature within a tolerable range.

Unplanned perioperative An unexpected core temperature decrease to less than 36 C (96.8 F).hypothermia

Vapocoolant A topical spray for the control of pain associated with minor surgical procedures(lancing boils or incision and drainage of small abscesses), injections, and contu-sions.

Warming device A device used in the perioperative setting to assist with the control of body tempera-ture, usually to prevent hypothermia.


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POST-TEST

Multiple choice. Please choose the word or phrase that best completes the following statements.

1. Transfer of heat to or from a moving medium is called:

A. Radiation.

B. Conduction.

C. Convection.

D. Evaporation.

2. If the arterial blood flowing through the thermoregulatory center in the hypothalamus is above the set point, the effer-ent response includes:

A. Vasoconstriction.

B. Vasodilation.

C. Shivering.

D. Piloerection.

3. In humans, behavioral responses are quantitatively the most effective thermoregulatory mechanism.

A. True.

B. False.

4. After application, cold packs typically retain their cold for:

A. 5 minutes.

B. 15 minutes.

C. 30 minutes.

D. 60 minutes.

5. Localized cold therapy is most often used:

A. To reduce swelling and pain.

B. To promote healing.

C. To prevent perioperative hypothermia.

D. In cardiac surgery.


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6. Cryotherapy is contraindicated for patients with:

A. Inability to provide feedback about tissue temperature.

B. Raynauds phenomenon.

C. Arteriosclerosis.

D. All of the above.

7. Electric heating pads are not recommended for use in hospitals.

A. True.

B. False.

8. Compared to other methods of superficial heat application, circulated warm-fluid hot packs minimize the potential for:

A. Hemorrhage.

B. Burns.C. Swelling.

D. Pain.

9. Local application of heat:

A. Improves healing.

B. Relaxes connective tissue.

C. Relieves pain.


10. In patients with acute injuries, local heat may be applied:

A. Immediately.

B. After 12 hours.

C. After 24 hours.

D. After 2 days.

11. After surgery, return to normothermia often takes:

A. 20 to 30 minutes.

B. 60 to 90 minutes.

C. 2 to 5 hours.

D. 6 to 12 hours.


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THERAPEUTIC USES OF HEAT AND COLD12. Patients maintained at normothermic conditions before, during, and after surgery experience fewer adverse outcomes

and incur lower healthcare costs.

A. True.

B. False.

13. Normothermia can be defined as a core temperature of:

A. 36 C.

B. 38 C to 40 C.

C. 36 C to 38 C.

D. 34 C to 36 C.

14. Risk of unplanned perioperative hypothermia is higher than usual in:

A. Pregnant women.

B. Patients scheduled for abdominal procedures.

C. Obese patients


15. Research has shown that mild perioperative hypothermia significantly increases intra- and postoperative blood loss.

A. True.

B. False.

16. The preferred route of temperature measurement in the preoperative and postoperative periods is:

A. Infrared tympanic monitoring.

B. Skin temperature monitoring.

C. Esophageal temperature monitoring.

D. Axillary temperature monitoring.

17. Warmed air warming is also known as:

A. Conductive warming.

B. Convective warming.

C. Continuous warming.

D. None of the above.


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18. Conductive heating and warming blankets are most effective when positioned:

A. Above the patient.

B. Below the patient.

C. In a tubular shape surrounding the patient.

D. All positions are equally effective.

19. With the use of a fluid warming device, the infusion of 1 L of crystalloid at room temperature will cause a heat loss of:

A. 0.5 C.

B. 1.0 C.

C. 1.5 C.

D. 2.0 C.

20. Cardiovascular heat exchange systems are used for:A. Heating.

B. Cooling.

C. Both A and B.

D. Neither A nor B.

POST-TESTANSWERS

1.C

2.B

3.A

4.C

5.A

6.D

7.A

8.B

9.D

10.D

11.C

12.A

13.C

14.D

15.A

16.A

17.B

18.A

19.A

20.C


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REFERENCES

1. Buggy DJ, Crossley AWA. Thermoregulation, mild perioperative hypothermia and postanesthetic shivering. Br JAnaesth. 2000;84(5):615-628.

2. Charkoudian N. Skin blood flow in adult human thermoregulation: how it works, when it does not, and why. Mayo ClinProc. 2003;78(5):603-612.

3. McEwan M. Hypothermia physiology, signs, symptoms and treatment considerations. Search and Rescue Society of

British Columbia; 2003. Available at: http://www.islandnet.com/sarbc/hypo1.html. Accessed April 26, 2004.4. Kaul MP, Herring SA. Superficial heat and cold how to maximize the benefits. Physician and Sports Med. December

1994;22:65-74. Available at: http://www.corflex.com/pdf_files/Corflex_Superficial_Heat_Cold_Kaul_Herring.pdf.Accessed April 26, 2003.

5. Malanga G. Physical therapy: TENS, ultrasound, heat and cryotherapy. Available at: http://www.spineuniverse.com/print.php/article1853.html. Accessed April 26, 2004.

6. Plehn RV. All about pain. Available at: http://www.doctorsforpain.com/patient/therapy.html. Accessed April 26, 2004.

7. Klein MJ. Superficial heat and cold. Updated December 13, 2001. Available at: http://www.emedicine.com/pmr/topic201.htm. Accessed April 28, 2004.

8. Wnorowski D. Heat and cold therapy. Available at: http://www.genufix.com/heat_and_cold_therapy.htm. Accessed Apri26, 2004.

9. Veterans Administration, Office of Quality and Performance. Post operative pain: clinical practice guidelines. Availableat: http://www.oqp.med.va.gov/cpg/PAIN/PAIN_base.htm. Accessed May 4, 2004.

10. Malanga G. Physical therapy: TENS, ultrasound, heat and cryotherapy. Available at: http://www.spineuniverse.com/print.php/article1853.html. Accessed April 26, 2004.

11. Chandler A. Using heat therapy for pain management. Nurs Standard. 2002;17(9):40-42.

12. Aetna. Heating devices. Clinical policy bulletin No. 0540. Available at: http://www.aetna.com/cpb/data/CPBA0540.html.Accessed May 5, 2004.

13. Veterans Administration. Office of Quality and Performance. Post operative pain: clinical practice guidelines. Availableat: http://www.oqp.med.va.gov/cpg/PAIN/PAIN_base.htm. Accessed May 4, 2004.

14. Wnorowski D. Heat and cold therapy. Available at: http://www.genufix.com/heat_and_cold_therapy.htm. Accessed April26, 2004.

15. Fracture of the scaphoid. Available at: http://www.dynomed.com/encyclopedia/encyclopedia.cfm. Accessed May 4,2004.

16. Veterans Administration. Office of Quality and Performance. Post operative pain: clinical practice guidelines. Availableat: http://www.oqp.med.va.gov/cpg/PAIN/PAIN_base.htm. Accessed May 4, 2004.

17. Kaul MP, Herring SA. Superficial heat and cold how to maximize the benefits. Physician Sports Med. December

1994;22:65-74. Available at: http://www.corflex.com/pdf_files/Corflex_Superficial_Heat_Cold_Kaul_Herring.pdf.Accessed April 26, 2003.

18. Frank SM, Fleisher LA, Breslow MJ, et al. Perioperative maintenance of normothermia reduces the incidence ofmorbid cardiac events: a randomized clinical trial. JAMA. 1997;277(14):1127-1134.

19. Sessler DI. A proposal for new temperature monitoring and thermal management guidelines.Anesthesiol.1998;89(5):1298-1300.

20. Lien CA. Thermoregulation in the elderly. In: American Society of Anesthesiologists. Geriatric Anesthesiol. January 1,2002. Available at: http://www.asahq.org/clinical/geriatrics/PDFSyllabus5-011002.pdf. Accessed January 30, 2004.


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21. Sessler DI. Perioperative heat balance.Anesthesiol. 2000;92(2):578-596.

22. Mahoney CB, Odom J. Maintaining intraoperative normothermia: a meta-analysis of outcomes with costs.AANA J.1999;67(2):155-163.

23. American Society of PeriAnesthesia Nurses. Clinical guideline for the prevention of unplanned perioperative hypother-mia. October 2002. Available at: http://www.aspan.org/pdffiles/hypothermia_guideline10-02.pdf. Accessed January 30,2004.

24. AORN. Recommended practices for safe care through identification of potential hazards in the surgical environment.Standards, Recommended Practices, and Guidelines. Denver, CO: AORN Inc; 2004:301-307.

25. Welch TC. A common sense approach to hypothermia. AANA J. 2002;70(3):227-231.

26. Sessler DI. Complications and treatment of mild hypothermia.Anesthesiol. 2001;95(2):531-543.



29. Schmied H, Kurz A, Sessler DI, Kozek S, Reiter A. Mild hypothermia increases blood loss and transfusion require-ments during total hip arthroplasty. Lancet. 1996;347(8997):289-292.

30. Kurz A, Sessler DI, Lenhardt R. Perioperative normothermia to reduce the incidence of surgical-wound infection andshorten hospitalization. N Engl J Med. 1996;334(19):1209-1215.

31. Kurz A, Sessler DI, Lenhardt R. Perioperative normothermia to reduce the incidence ofsurgical-wound infection andshorten hospitalization. N Engl J Med. 1996;334(19):1209-1215.

32. Lenhardt R, Marker E, Goll V, et al. Mild intraoperative hypothermia prolongs postanesthetic recovery. Anesthesiol.1997;87(6):1318-1323.

33. Mahoney CB, Odom J. Maintaining intraoperative normothermia: a meta-analysis of outcomes with costs.AANA J.

1999;67(2):155-163.34. American Society of PeriAnesthesia Nurses. Clinical guideline for the prevention of unplanned perioperative hypother-

mia. October 2002. Available at: http://www.aspan.org/pdffiles/hypothermia_guideline10-02.pdf. Accessed January 30,2004.

35. Welch TC. A common sense approach to hypothermia.AANA J. 2002;70(3):227-231.

36. Sessler DI. A proposal for new temperature monitoring and thermal management guidelines.Anesthesiol.1998;89(5):1298-1300.


38. American Association of Nurse Anesthetists. Scope and standards for nurse anesthesia practice. Available at: http://

www.aana.com/crna/prof/scope.asp. Accessed January 30, 2004.

39. Sessler DI. A proposal for new temperature monitoring and thermal management guidelines. Anesthesiol.1998;89(5):1298-1300.




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THERAPEUTIC USES OF HEAT AND COLD42. American Society of PeriAnesthesia Nurses. Clinical guideline for the prevention of unplanned perioperative hypother-

mia. October 2002. Available at: http://www.aspan.org/pdffiles/hypothermia_guideline10-02.pdf. Accessed January 30,2004.


44. Ng SF, Oo CS, Loh KH, Lim PY, Chan YH, Ong BC. A comparative study of three warming interventions to determinethe most effective in maintaining perioperative normothermia.Anesth Analg. 2003;96(1):171-176.

45. Cooke RPD, Catchpole M. Maintaining perioperative normothermia: forced air warming devices require risk assess-ments before use. Brit Med J. 2003;326(7404):1457.



48. Morrison RC. Hypothermia in the elderly. Int Anesth Clin. 1988;26(2):124-133.



51. Hrouda BS. Warming up to i.v. infusion. Nurs. 2002;32(3):54-55.

52. Kurz A, Sessler DI, Lenhardt R. Perioperative normothermia to reduce the incidence of surgical-wound infection andshorten hospitalization. N Engl J Med. 1996;334(19):1209-1215.



55. Sessler DI. Perioperative heat balance.Anesthesiol. 2000;92(2):578-596.

56. Hohn L, Schweizer A, Kalangos A, Morel DR, Bednarkiewicz M, Licker M. Benefits of intraoperative skin surfacewarming in cardiac surgical patients. Br J Anaesth. 1998;80(3):318-323.

57. Bernard SA, Gray TW, Buist MD et al. Treatment of comatose survivors of out-of-hospital cardiac arrest with inducedhypothermia. N Eng J Med. 2002;346(8):557-563.

58. The Hypothermia after Cardiac Arrest Study Group. Mild therapeutic hypothermia to improve the neurologic outcomeafter cardiac arrest. N Eng J Med. 2002;346(8);549-556.

59. Turkington CA. Extracorporeal membrane oxygenation. Gale Encyclopedia of Medicine. 1999. Available at: http://www.findarticles.com/cf_dls/g2601/0005/2601000515/print.html. Accessed February 5, 2004.





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NOTES

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III. COMMENTS & SUGGESTIONS

1. Time required to complete this activity: ______________

2. What else do you need to learn about this topic?

3. What topic(s) would you like to have presented in the future?

EVALUATION OF INDEPENDENT EDUCATIONAL ACTIVITYTHERAPEUTIC USES OF HEAT AND COLD

EDI-310236

Project Number

Rate the following on a scale of 1-5. 1 = poor, 2 = fair, 3 = average, 4 = good, 5 = excellent. Each circle must be completely filled.Shade cirlces like this:mmlmm

1 2 3 4 5I. OBJECTIVES

To what extent did you achieve each of the following objectives?1. Explain how physiological and behavioral mechanisms maintain the body's core

temperature within a narrow range.2. Discuss therapeutic applications of local heat and cold.3. Outline appropriate temperature monitoring in the perioperative period, along with

general temperature management strategies.4. Describe several types of active perioperative warming and cooling devices,

focusing on conductive and convective blankets, fluid warmers, and cardiovasculareating and cooling.

Yes No

II. OVERALL ACTIVITY

To what extent . . .1. Did the objectives meet the overall goals/purpose of the self-study activity?2. Was the subject presented at an appropriate level?3. Was the content accurate and current?4. Were the self-assessment exercises related to the objectives?5. Was this learning method effective?6. Will the information be useful in your practice setting?7. Did this activity present issues and products in a fair, unbiased and balanced

manner?

1 2 3 4 5

8162205206


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CONTINUING EDUCATION REGISTRATION FORM


To receive 2 contact hours, please mail a check for $12.00, the ORIGINAL REGISTRATION FORMand evaluationforms to: HealthStream 2170 S. Parker Rd., Suite 140 Denver, CO 80231

First Name M.I.

Last Name

RN LPN ST CST Other ______________________ (Please Specify)

Are you licensed in the state of Florida? Yes No

Social Security Number*

License Number* State Expiration

Street Address

City State Zip Code

Phone Fax

E-mail Address

Hospital Affiliation

_________________________________________________________ _________________________________Signature Date

Project Number

EDI # 310236

* California, Florida, and Iowa nurses are required to provide license #.All others must provide either license # or SS# for data tracking purposes.All information obtained by HealthStream will remain strictly confidential.

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