- Email: [email protected]
Nurses' Knowledge of Inadvertent Hypothermia
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Nurses’ Knowledge of Inadvertent Hypothermia JOSEPHINE HEGARTY, PHD, MSC, RNT, BSC, RGN; ELLA WALSH, MSC, BSC, DIP NURSING, RGN; AILEEN BURTON, MSC, BSC, RGN; SHEILA MURPHY, RGN, RM, HDIP NURSING MANAGEMENT; FIONUALA O’GORMAN, MSC ED, BSC, ENB 176, RGM, RGN; GRÁINNE MCPOLIN, HDIP ANAESTHETIC NURSING, BA, RGN
I
n the perioperative environment, between 60% and 90% of patients inadvertently become hypothermic.1 Hypothermia not only has significant negative consequences for the health of the patient, but also incurs economic expense for society in terms of increased hospital stay and additional procedures and diagnostic tests. Thus, it is paramount that all perioperative nurses possess an in-depth understanding of inadvertent hypothermia, including risk factors, complications, and methods of prevention and treatment. It is only through use of this knowledge that nurses can effectively fulfill their roles in the assessment, treatment, and prevention of hypothermia. A comprehensive literature review revealed a paucity of research pertaining to nurses’ knowledge of hypothermia. We designed this study to gain an understanding of perioperative nurses’ knowledge in relation to accidental hypothermia in the perioperative setting.
BACKGROUND Accidental hypothermia in perioperative patients is associated with poor patient outcomes. At the very least, it subjects patients to an unpleasant sensation of cold.2 It also has much more significant negative consequences, which have been detailed in the literature (Table 1). The magnitude of these adverse consequences should alert all nurses to their important role in reducing and alleviating the occurrence of this problem. DEFINING NORMOTHERMIA AND HYPOTHERMIA. The control of body temperature within a defined range is crucial in the maintenance of a stable environment in the human body, thus enabling optimal © AORN, Inc, 2009
function.2 The literature, however, presents varying definitions of normothermia (ie, normal body temperature). For example, the American Society of PeriAnesthesia Nurses (ASPAN) clinical guideline for the prevention of unplanned perioperative hypothermia defines normothermia as “a core temperature range from 36° C to 38° C (96.8° F to 100.4° F).”3 Meanwhile, the National Institute for Health and Clinical Excellence (NICE) 2008 guideline for the management of inadvertent perioperative hypothermia in adults defined the expected normal temperature range of adult patients as between 36.5° C and 37.5° C (97.7° F to 99.5° F).4 Kiekkas et al1 concur with this definition of normothermia. Just as the literature presents varying definitions of normothermia, it also presents varying definitions of hypothermia.
ABSTRACT Inadvertent hypothermia can have significant consequences in the perioperative setting. Knowing how to recognize and manage inadvertent hypothermia is an important aspect of perioperative nursing. A quantitative, descriptive study was conducted at an annual perioperative nursing conference to evaluate nurses’ knowledge regarding the prevention of inadvertent perioperative hypothermia. Significant variations in responses regarding definitions of hypothermia and normothermia were noted. In addition, nurses identified a plethora of factors that prevent them from maintaining normothermia in their patients. These factors mandate a need for educational interventions and the adoption of practice guidelines in the clinical area. Key words: inadvertent hypothermia, normothermia, practice guidelines. AORN J 89 (April 2009) 701-713. © AORN, Inc, 2009.
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TABLE 1
Adverse Consequences of Inadvertent Perioperative Hypothermia • Increased blood loss, thus increasing allogenic transfusion requirements • Increased incidence of wound infections • Prolonged recovery and postanesthesia care unit stay • Postanesthesia shivering • Myocardial ischemia • Thermal discomfort • Cardiac complications • Impaired medication metabolism • Coagulopathy • Increased mortality in trauma patients • Impaired immune function • Deep vein thrombosis
1-5
1,3-8
1-3,5-8
6-8
3,6
2,8
2,4,5,7,8
3,5,7,8
3,5,7-9
5
8
8
1. Doufas AG. Consequences of inadvertent hypothermia. Best Pract Res Clin Anaesthesiol. 2003;17(4): 535-549. 2. Torossian A; TEMMP (Thermoregulation in Europe Monitoring and Managing Patient Temperature) Study Group. Survey on intraoperative temperature management in Europe. Eur J Anaesthesiol. 2007; 24(8):668-675. 3. Bitner J, Hilde L, Hall K, Duvendack T. A team approach to the prevention of unplanned postoperative hypothermia. AORN J. 2007;85(5):921-929. 4. Hooper VD. Adoption of the ASPAN clinical guideline for the prevention of unplanned perioperative hypothermia: a data collection tool. J Perianesth Nurs. 2006;21(3):177-185. 5. Recommended practices for the prevention of unplanned perioperative hypothermia. Perioperative Standards and Recommended Practices. Denver, CO: AORN, Inc; 2009:491-504. 6. Kiekkas P, Poulopoulou M, Papahatzi A, Panagiotis S. Effects of hypothermia and shivering on standard PACU monitoring of patients. AANA J. 2005;73(1):47-53. 7. Insler SR, Sessler DI. Perioperative thermoregulation and temperature monitoring. Anesthesiol Clin. 2006;24(4):823-837. 8. Leslie K, Sessler DI. Perioperative hypothermia in the high-risk surgical patient. Best Pract Res Clin Anaesthesiol. 2003;17(4):485-498. 9. Wheeler D. Temperature regulation. Surgery. 2006;24(12):446-451.
Kiekkas et al state, the strict physiological definition of hypothermia in humans is a core temperature more than 1 [standard deviation] less than the mean value under resting conditions in a thermoneutral environment.1(p47) Meanwhile, Kempainen and Brunette define accidental hypothermia as “an unintentional decrease in core temperature to below 35° C (95° F).”5(p192) The NICE guideline defines hypothermia as a core temperature of less than 36º C (96.8° F).4 Some consensus is evident in that AORN’s “Recommended practices for the prevention of unplanned perioperative hypothermia” also defines hypothermia as “a core body temperature less than 36° C (96.8° F).”6(p491) Simi-
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larly, the ASPAN clinical guideline defines hypothermia as a core temperature of less than 36° C (96.8° F).3 Several authors concur with this definition.7-9 RISK FACTORS. Many risk factors for the development of hypothermia, including extremes of age, have been identified in the literature. Older adults are particularly prone to the development of the condition.5,6,10-13 This is primarily because older persons lose heat more rapidly than younger persons because of decreased fat and muscle mass. In addition, changes in vascular tone in the older adult inhibit vasoconstriction and thus decrease heat production. Furthermore, general anesthesia or major regional anesthesia impairs the thermoregulatory mechanisms of an older person to a greater extent those of a younger person.6
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Research literature has identified that infants and neonates are at an increased risk of developing hypothermia6,10,11 because of their increased ratio of body surface area to body mass. Infants also are unable to shiver to generate heat in response to hypothermia.5 Certain health conditions also increase patients’ risk of becoming hypothermic. These include hypothyroidism, other endocrine disorders, cardiac disorders, arthritis, paralysis, extensive body burns, cachexia, trauma, hypoglycemia, intoxication, myocardial infarction, and head or spinal cord injuries.5,11,13 The surgical experience also increases patients’ risk of developing hypothermia. This is because the body and internal organs are exposed to lower environmental temperatures, wet preparation solutions are used on the skin’s surface, and the body is unable to shiver and vasoconstrict when the patient is anesthetized during surgery.1,6,14 It is important to note that in certain surgeries (eg, neurosurgeries, cardiac surgeries), hypothermia is warranted and is thus induced. For the purposes of this article, however, we focused solely on inadvertent hypothermia in the perioperative setting.
LITERATURE REVIEW To date, the area of nurses’ knowledge in relation to hypothermia remains underinvestigated. In fact, we located only two studies— one in a perioperative environment and one in a general hospital setting—conducted between 2003 to 2008.15,16 IRELAND ET AL. In a study using a survey design, Ireland et al15 investigated nurse and medical staff member knowledge and understanding of issues surrounding accidental or exposure hypothermia in trauma patients. A secondary aim of their study was to increase staff members’ awareness about evaluating and documenting temperature. A 14-item survey tool was administered to all medical (n = 41) and nursing (n = 99) staff members employed in the Emergency and Trauma Centre of the Alfred Hospital Australia, Melbourne, Victoria. Ninety-six surveys were returned, yielding a response rate of 69%. Results revealed that nursing and medical staff members were unsure of how to define hypo-
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Conditions that increase patients’ risk of becoming hypothermic include hypothyroidism, other endocrine disorders, cardiac disorders, arthritis, paralysis, extensive body burns, cachexia, trauma, hypoglycemia, intoxication, myocardial infarction, and head or spinal cord injuries.
thermia, as evidenced by the array of responses with regard to the cut-off temperature for hypothermia. This uncertainty may be partly a result of discrepancies in the literature regarding definitions of hypothermia. Additionally, results revealed that nurses and physicians were unfamiliar with simple means of preventing heat loss or of rewarming patients. Simple rewarming techniques that are readily available in the Emergency and Trauma Centre were infrequently listed. These included minimization of exposure (n = 8), removal of wet clothing/bandages (n = 3), and provision of dry linen (n = 1). Contrarily, rewarming strategies rarely used in the Emergency and Trauma Centre—including warm cavity lavage, cardiopulmonary bypass, and heat packs—were frequently identified. This perhaps suggests an awareness of sophisticated rewarming strategies from the literature but a failure to implement simple strategies in practice. Results revealed that all respondents could list at least one rewarming strategy, with 95 respondents able to list three rewarming strategies. When asked to list common complications associated with hypothermia, the participants described complications in detail. The complications of metabolic acidosis and coagulopathy were infrequently reported, even though these AORN JOURNAL •
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The lack of research examining nurses’ knowledge of hypothermia provides a compelling impetus for further study in this area.
are well described in the literature.14,17-19 When asked to outline factors that prevented or limited them from obtaining a patient’s temperature, respondents identified the following factors: • anatomical injury (n = 26), • access to the patient (n = 10), • access to the necessary equipment (n = 8), and • patient acuity (n = 3). Despite these obstacles, it is essential that temperature be monitored. Overall, the results of this study emphasize the need for educating nurses and physicians about hypothermia. The authors recommended the development of a best-practice guideline to assist staff members in the unit in the monitoring and overall management of hypothermia, which could thus lead to an improvement in patient outcomes. EVANS AND KENKRE. In a quantitative, descriptive study conducted in 2006, Evans and Kenkre16 examined the current practice of temperature management in a medium-sized acute general hospital in South Wales, United Kingdom. Using a self-administered survey tool, researchers collected baseline data on patterns of temperature measurement with respect to health care occupational group, frequency of temperature measurement, and equipment used. Secondly, the researchers sought information on the knowledge of health care practitioners with regard to infrared tympanic thermometry (IRTT). Finally, information was collected on any training received in the use of IRTT. A cross-sectional sample of staff members was recruited from within the hospital. Completed questionnaires were returned by 139 staff members, including • 51 (37.0%) who were nursing auxiliary
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grade (ie, nursing assistants); 48 (34.5%) who were staff nurse grade; and 29 (20.9%) who were sister grade (ie, clinical nurse manager). Data were missing for 11 (7.9%). Evans and Kenkre16 found that temperature measurement is frequently undertaken by all grades of nursing staff members. The researchers also revealed, however, that the group most involved in temperature measurement were the nursing auxiliary grade staff members who had the fewest years of clinical experience. In fact, a one-way analysis of variance (ANOVA) confirmed a relationship between reduced frequency of checking patient temperatures and increased years of experience in the clinical role. The remainder of this study focused on the frequency of use of various temperature measuring equipment and staff member knowledge regarding the technological workings of this equipment. Although, undoubtedly, the frequency of use of temperature monitoring equipment and staff member knowledge in relation to the technological workings of this equipment is important, our study is concerned with nurses’ knowledge in relation to hypothermia and not temperature monitoring equipment. Therefore, it is beyond the scope of this article to examine these results16 in detail.
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PERIOPERATIVE IMPLICATIONS The lack of research examining nurses’ knowledge of hypothermia provides a compelling impetus for further study in this area. Given the detrimental consequences associated with hypothermia, we were eager to determine nurses’ knowledge base on this topic. After baseline nursing knowledge levels have been established, interventions required to augment and improve nurses’ knowledge can be designed.
DESIGN, SETTING,
AND
SAMPLE
We employed a quantitative, descriptive design. After receipt of protocol approval from the relevant clinical research ethics committee, we recruited a volunteer convenience sample of all delegates in attendance at the National Annual Conference of the Irish Anaesthetic and Recovery Nurses Association that took place in the Republic of Ireland, Waterford City, October
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13, 2007. Participants were informed in an informational leaflet that their participation was voluntary and that all information provided by them would be kept confidential. The leaflet also detailed the aims and objectives of the study. There was no identifying information in any of the questionnaires, thus ensuring participant anonymity. All completed questionnaires were placed in a sealed box and we collected them at the close of the conference. Completion of the questionnaire implied consent. Of 198 delegates in attendance, 130 completed questionnaires, thus yielding a response rate of 66%.
INSTRUMENT The survey package consisted of two survey tools both adapted with permission from the primary authors of each questionnaire15,20 to suit nurses working in the perioperative environment. This adaptation was based on a review of the literature and the researchers’ knowledge and clinical expertise. The survey package included two demographic questions, nine questions designed to assess nurses’ knowledge,15 and a 23-item Likert scale based on risk factors for the development of intraoperative hypothermia.20 The nine questions asked participants to define hypothermia and list • factors that can lead to hypothermia in a patient undergoing anesthesia or surgery, • sources of potential heat loss in an adult, • techniques participants used within their clinical practices to ensure that patients do not develop hypothermia, and • complications that are associated with hypothermia for patients who have had surgery and anesthesia. Participants also were asked if patients’ temperatures were routinely monitored in their clinical areas and if within their clinical practice there was anything that prevented or limited them in maintaining normothermia in the patients that they cared for. The final question in the questionnaire was adapted from an article by Macario and Dexter20 in which clinical anesthetists and physician researchers were asked to prioritize a number of risk factors for the development of intraoperative hypothermia. Participants in our study
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were asked to estimate the relevant importance of each risk factor (ie, 23 potential risk factors in total) on a Likert scale of 1 to 10, with 1 implying “not likely to be important” and 10 implying “most likely to be important.” The higher the rating for each question, the greater the perceived importance of that risk factor. Surveys were completed by two expert perioperative nurses to assess content validity. The Cronbach’s alpha for this 23-item hypothermia risk factor scale was found to be satisfactory at 0.876. For social sciences scales, the normally acceptable standard for the Cronbach’s alpha is 0.6,21 with levels above 0.7 being desirable.22,23 Although the high Cronbach’s alpha generated for the 23-item scale could be attributed to the large number of items, the item-total correlations for each item within the 23-item scale were all > 0.3, thus implying that all items within this scale are measuring the same attribute (ie, risk factors in the development of hypothermia).
DATA ANALYSIS All raw data were coded and entered into Statistical Package for the Social Sciences, version 15, 2007. Responses to all closed-ended items were reported individually as frequencies and percentages. Meanwhile, responses to all open-ended questions were transcribed in full. Members of the research study team reviewed these responses to identify emergent themes. We then recoded these items with ordinal descriptors.
RESULTS Of the 198 surveys that were handed out, 130 were returned. The demographics of the study population included various work specialties and levels of qualification (Table 2). This represented a response rate of 65.7%. The majority of respondents had more than four years of experience working in the perioperative area. Specifically, respondents spent most of their time working in • anesthetic nursing—14.6% (n = 19); • recovery nursing—30% (n = 39); • intraoperative nursing—13.1% (n = 17); or • a combination of two or more of the above—36.9% (n = 48). AORN JOURNAL •
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One respondent identified “other—management” as the area in which he or she spent the most time, and data were missing for six respondents (4.6%). In relation to current level of qualification, the majority of respondents (45.4%, n = 59) identified themselves as registered general nurse (RGN). The next largest group were those registered nurses with a postgraduate qualification in perioperative nursing. When asked to select the cut-off point for hypothermia, respondents were divided: • 38.5% (n = 50) of participants chose 36° C (96.8º F), • 39.2% (n = 51) chose 35º C (95º F), • 11.5% (n = 15) chose 34º C (91.4º F), and • 8.5% (n = 11) chose 33º C (93.2º F). Data were missing for three respondents (2.3%). When respondents were questioned about the major sources of potential heat loss in an adult, • 53.1% (n = 69) identified the skin,
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28.5% (n = 37) identified the head, 9.2% (n = 12) identified the torso, and 6.9% identified a combination. Data were missing for three respondents (2.3%). When asked how best to define normothermia, the majority of participants identified it as occurring between 36º C and 37º C (96.8º F and 98.6º F) (Table 3). Regarding whether temperatures are routinely monitored in clinical areas, just under half of participants (n = 55, 42.3%) answered yes. Meanwhile, 43.8% (n = 57) answered “yes as required based on the assessment of the patient,” and 8.5% (n = 11) answered no. Data were missing for seven respondents (5.4%). Furthermore, 50 participants (38.5%) identified factors that prevent or limit the maintenance of normothermia. With regard to these, the most frequently identified factors were temperature control of the room (n = 7), surgeon preference (n = 5), overexposure (n = 5), lack of equipment (n = 4), and no air conditioning (n = 3). Other identified factors included TABLE 2 • lack of national tool (n = 2), Demographics of Survey Respondents • positioning (n = 1), • patient condition (n = 1), Perioperative experience Responses Percentage • type of surgery (n = 1), < 12 months 7 5.4 • no preoperative warming 1-3 years 25 19.2 (n = 1), > 4 years 98 75.4 • lack of staff member experience (n = 1) and lack of Level of qualification Responses Percentage knowledge of staff (n = 1); Registered general nurse (RGN) 59 45.4 • laminar air flow system RGN with a BSc 23 17.7 (n = 1), RGN with other postgraduate • wet bed sheets (n = 1), course in perioperative nursing 29 22.3 • use of electric blankets Other 18 13.8 (n = 1), Missing data 1 0.8 • fast throughput of patients (n = 1), and • a combination of factors TABLE 3 (n = 14). Perception of Normothermia A number of open-ended questions also were included Temperature range Responses Percentage in the questionnaire. The first 36° C to 36.5° C (96.8° F to 97.7° F) 16 12.3 of these asked participants to 36° C to 37° C (96.8° F to 98.6° F) 43 33.1 identify three common contrib36° C to 37.5° C (96.8° F to 99.5° F) 36 27.7 utory factors to the develop36.5° C to 37.5° C (97.7° F to 99.5° F) 26 20.0 ment of hypothermia. A total Missing data 9 7.0 of 74 factors were identified,
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with some participants identifying three factors and others identifying one or two. Table 4 provides a summary of the 10 most commonly identified factors. Participants also identified a wide range of techniques used in the clinical area to ensure that patients do not develop hypothermia. Each participant was able to identify at least one factor, including • warming devices (eg, forced-air devices) (n = 92); • use of a fluid or blood warmer (n = 71); • controlling the environmental temperature (n = 37); • provision of adequate heat with blankets (n = 36); • regular checking of patients’ temperatures (n = 24); and • use of foil hats, leggings, or drapes (ie, foil wrapping used to prevent heat loss) (n = 19). When asked to identify common complications associated with hypothermia for patients who have had surgery or anesthesia, each participant could identify at least two complications. Complications that participants listed included • delayed recovery (n = 45), • postoperative shivering (n = 31), • hypotension (n = 27), • increased postoperative pain (n = 26), and • delayed wound healing (n = 20). Finally, participants were asked to rate factors in the development of hypothermia on a scale of 1 to 10 (Table 5). Major surgery with a large uncovered area was rated as extremely important by many of the participants. Also, being a neonate of younger than one month was considered an extremely important factor in the development of hypothermia.
DISCUSSION The prevention and management of hypothermia centers on the correct assessment of each individual’s risk for hypothermia, use of preventative strategies, monitoring of patients’ temperatures routinely during the perioperative period, and employment of appropriate rewarming strategies. Because nurses are primarily responsible for these aspects of care during the perioperative period, it follows that
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TABLE 4
Top 10 Perceived Factors for Hypothermia Development Factor identified Theatre environment temperature Body exposure Length of surgery Fluid and blood loss Anesthesia-induced bradycardia Patient age Cold infusion fluids Prolonged exposure Shock Fasting
Responses 58 40 35 29 21 19 14 9 9 8
nurses’ knowledge surrounding the concept of hypothermia is central to its successful prevention and management. The nurses who took part in this study were highly experienced, with the majority having more than four years of perioperative experience. In addition, many of these nurses had postregistration qualifications. Because the respondents were experienced and well-educated, we anticipated that these nurses would be quite knowledgeable about hypothermia, because thermoregulation is a fundamental aspect of nursing practice. We found, however, that nurses were unsure of the correct definitions of hypothermia and normothermia. These conflicting perceived definitions may be a result of the lack of clarity in the literature as to a standard definition of hypothermia. This highlights the need for standardized guidelines—such as those developed by the National Institute for Health and Clinical Evidence,4 AORN,6 and ASPAN3—to be used in practice. The majority of participants defined normothermia as 36º C and 37º C (96.8º F and 98.6º F), which is not concurrent with either the NICE guideline protocol4 or the ASPAN clinical guidelines3 for the prevention of unplanned hypothermia. This uncertainty highlights the need for the adoption of standardized guidelines to aid nurses in their clinical practice. It also highlights the need for the development of continuing educational programs to keep practitioners up to AORN JOURNAL •
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common contributory factor to the development of hypothermia in responses to the Question: At what point on a scale of 1 to 10 open-ended question (n = 40). would you rate the following in the development A similar factor, major surgery of hypothermia, with 10 being the highest risk? with a large uncovered area, Factor Mean score was rated by 93.8% of particiMajor surgery with a large uncovered area 9.9 Neonate < 1 month 9.8 pants (n = 122) as extremely Patient with 3rd degree burns 9.6 important. Blood loss was Major surgery 9.5 identified as a common conPediatric surgery 9.4 tributory factor in responses Surgery > 2 hours in duration 9.4 to the open-ended question. Older patient 8.9 This also was rated as an Cardiac surgery 8.9 extremely important factor by Operating theatre room < 18° C (64.4° F) 8.8 Patient hypothermic before surgery 8.6 73.1% (n = 95) of participants. More than 30 mL/kg blood loss 8.6 These concurring answers 8.5 Patient undergoing thoracotomy indicate that participants had Thin patient 7.9 accurate knowledge of factors Level of spinal anesthesia 7.7 that contribute to the developOpen pelvic/abdominal surgery 7.7 ment of hypothermia. General anesthesia 7.4 There were a number of OR temperature 18° C to 20° C (64.4° F to 68° F) 6.9 Spinal/epidural anesthesia 6.8 factors identified as extremely 5.2 OR temperature 20° C to 22° C (68° F to 71.6° F) important in the 23-item scale Use of a tourniquet 5.2 relating to risk of developNormal body temperature before surgery 4.9 ment of hypothermia; howevA small surgical procedure 4.0 er, participants did not identify many of these potential risk date with the current best evidence. factors in the open-ended question, including The evidential lack of uniformity in the litneonate younger than one month old. Particierature with regard to some definitions and pants identified the patient’s age as an imporpreventative measures may have contributed tant factor, which to a certain degree accounts to some of the varying responses within this for this. In addition, a patient with third-degree survey. The tools used in this study allowed us burns was rated as extremely important by 119 to assess nurses’ knowledge in relation to hypo- participants (91.5%). This did not feature in thermia from both a quantitative and a qualita- responses to the open-ended question despite tive perspective, thus increasing the depth of the the fact that third-degree burns are a major condata ascertained. Overall, staff members in this tributory factor.5,11,13 survey displayed extensive knowledge in the Irrigation fluid below body temperature also area of hypothermia prevention. was rated as an extremely important factor by CONTRIBUTING FACTORS. When participants were 83.8% of participants (n = 109). Cold infusion asked in an open-ended question to list three fluid was cited only 14 times in responses to the common factors that contribute to the developopen-ended question, however. The reality is ment of hypothermia, the most frequently identhat cold infusion fluids are a major risk factor tified factor was OR environment exposure. in the development of hypothermia.17 When asked to rate certain factors in the develMoreover, despite the fact that general anesopment of hypothermia, a similar factor, OR thesia is a major risk factor in the development of temperature < 18° C (64.4° F), was also considhypothermia because of “the loss of behavioral ered to be extremely important by more than response to cold and impairment of thermoreguhalf of the respondents (53.8%, n = 70). Addilatory heat preserving mechanisms,”4(p4) fewer tionally, body exposure was identified as a than half of the respondents (n = 60, 46.2%) rated
TABLE 5
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it as a major risk factor. It did not feature at all in responses to the open-ended question. Overall, it was encouraging to see that participants were able to identify a wide range of contributing factors in the development of hypothermia. The fact that some important factors (eg, cold irrigation fluids, blood loss) were rated as important by participants in the 23-item Likert scale risk factor listing but were not listed in response to the open-ended question suggests that although participants had the knowledge, they were unable to recall all factors spontaneously without prompting. This further suggests that preformulated guidelines that would prompt practitioners on the important factors would be helpful in the clinical area. PREVENTION. When asked about preventing hypothermia in the clinical area, participants cited a wide range of techniques. The most frequently identified technique was the use of warming devices (eg, forced-air warming devices). Use of a forced-air warming device is recommended for all patients undergoing anesthesia in the NICE clinical guideline for inadvertent perioperative hypothermia.4 The ASPAN hypothermia guideline3 recommends that forced-air warming devices be initiated only if the patient is hypothermic, however. The AORN guideline6 recommends that forcedair warming is used to prevent hypothermia in patients undergoing anesthesia and in rewarming patients after cardiopulmonary bypass. Participants also cited using a fluid/blood warmer (n = 71) as an important technique to prevent hypothermia. The NICE clinical guideline for inadvertent perioperative hypothermia4 supports this; however, the ASPAN hypothermia guideline3 states that fluid warming devices should be used if the patient is hypothermic and not as a preventative measure. Meanwhile, the AORN guideline6 recommends that warming IV fluids only be considered where large volumes (ie, > 2L/hour) are being transfused. Thirdly, participants identified control of environmental temperature as an important preventative measure in the development of hypothermia. Both the NICE clinical guideline4 and the ASPAN guideline3 support this. The NICE guideline4 specifies that the OR suite temperature should be at least 21° C (69.8° F), and
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the ASPAN hypothermia guideline3 states that the room temperature should be at a minimum of 20° C to 24° C (68° F to 75° F). The AORN guideline also alludes to the importance of OR temperature in particular for infants and neonates.6
With regard to factors that prevent nurses from maintaining normothermia in their patients, it was surprising to see that in a health service that encourages nurses to be autonomous practitioners, one of the most frequently identified factors was surgeon preference.
NURSING CHALLENGES. Lastly, with regard to factors that prevent nurses from maintaining normothermia in their patients, participants cited a number of factors. It was surprising to see that in a health service that encourages nurses to be autonomous practitioners, one of the most frequently identified factors was surgeon preference. The majority of nurses reported frequent monitoring of temperature in the clinical area (n = 55). An additional 43.8% (n = 57) reported that temperature is monitored as required based on the assessment of the patient. Encouragingly, just nine participants answered no to this question. Given the detrimental consequences associated with hypothermia, neglecting to conduct regular monitoring could have catastrophic effects for patients.
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quality problems.22 The current study, as with all research studies, has a number of limitations. The sample used in this study was chosen from a group of attendees at a national perioperative conference. The fact that these people voluntarily attended such a conference may imply that they were especially vigilant with regard to their professional obligations for continuing education. This fact may in turn imply that the group as a whole was quite knowledgeable, perhaps limiting generalization of results to the wider population of perioperative nurses. Another limitation of this study was its small sample size. Perhaps if this study were carried out with a larger sample, the results would be more representative of the entire population of perioperative nurses. The cross-sectional design of this study did not allow the opportunity to assess nurses’ knowledge over time to gauge whether knowledge levels change. Perhaps if a longitudinal design were employed, one could assess nurses’ knowledge, implement educational sessions, and then reassess the nurses’ knowledge at a later stage. Finally, this study is descriptive in nature. Although this has served as a useful starting point for investigation of the issue, additional research is required to investigate the issue further. This may involve conducting a correlational study to compare knowledge with practice.
RECOMMENDATIONS FOR CLINICAL PRACTICE, EDUCATION, AND FUTURE RESEARCH Clinical guidelines for the prevention and management of inadvertent perioperative hypothermia need to be readily available for practitioners and adopted for use in the perioperative environment. The NICE clinical guidelines, the AORN recommended practices for the prevention of unplanned hypothermia, and the ASPAN clinical guideline for the prevention of unplanned perioperative hypothermia are available. Furthermore, nurse managers should be cognizant of the need to organize regular educational sessions about hypothermia for staff members. The detrimental consequences associated with hypothermia cannot be underestimated. Educational sessions would allow practitioners to keep up to date with best research evidence and allow for
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the exchange of clinical expertise. From a research perspective, there is a lack of research in the area of nurses’ knowledge regarding hypothermia and, crucially, a complete absence of higher-level evidence. Perhaps conducting a randomized, controlled trial to investigate nurses’ knowledge before and after an educational intervention would be useful. In addition, we believe that conducting an observational study to monitor nurses’ activities in relation to hypothermia prevention and management would be most useful. Acknowledgements: The authors thank Sharyn Ireland, RN, Dip, HSc, BNurs, CritCareCert, ACCN, MEd, clinical nurse specialist, Emergency and Trauma Centre, The Alfred, Melbourne, for her permission to use the staff survey tool that she and her colleagues developed to explore nursing and medical knowledge regarding hypothermia management. The authors also thank Alex Macario, MD, MBA, professor of anesthesia and health research and policy program director, Anesthesia Residency Department of Anesthesia, Stanford University, California, for his permission to use the listing of risk factors in the development of intraoperative hypothermia generated from his paper, “What are the Most Important Risk Factors for a Patient’s Developing Intraoperative Hypothermia?” Special thanks to members of the IARNA committee, most especially Eilis Daly, BSc, Dip Nursing, RGN, MSc, clinical nurse manager, Day Procedures Unit, South Infirmary Victoria University Hospital, Cork, Ireland; Ann Hogan, HDip (Perioperative Nursing), RGN, MSc, clinical nurse manager, Recovery Unit, Waterford Regional Hospital, Waterford, Ireland; Lorraine O’Rourke, RGN, HDip Perioperative Nursing, clinical nurse manager, South Infirmary University Hospital, Cork, Ireland; Lorraine Murphy, PG Dip, MSc, professional learning facilitator, Nursing and Midwifery Planning Development Unit, Health Services Executive South, Ireland; Breda Needham, RGN, HDip Nursing Studies, clinical nurse manager, Surgical Day Theatres, Mid Western Regional Hospital, Limerick, Ireland; and Brigid Fitzpatrick-Laffan, HDip (Perioperative Nursing), Dip (Health Services Management), RN, RM, clinical nurse manager, Theatre, Mid Western Regional Hospital, Limerick, Ireland. Finally, a special word of thanks is extended to the nurses who participated in this study.
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REFERENCES 1. Kiekkas P, Poulopoulou M, Papahatzi A, Panagiotis S. Effects of hypothermia and shivering on standard PACU monitoring of patients. AANA J. 2005; 73(1):47-53. 2. Hegarty J. Perioperative temperature regulation: management of hypothermia. The All-Ireland Journal of Nursing and Midwifery. 2003;2(9)18-19. 3. Clinical guideline for the prevention of unplanned perioperative hypothermia. American Society of PeriAnesthesia Nurses. http://www.aspan.org/Clinical Practice/ClinicalGuidelines/Hypothermia/tabid/325 5/Default.aspx. Accessed February 3, 2009. 4. Management of inadvertent perioperative hypothermia in adults. April 2008. National Institute for Health and Clinical Excellence. http://www.nice .org.uk/Guidance/CG65. Accessed February 3, 2009. 5. Kempainen RR, Brunette DD. The evaluation and management of accidental hypothermia. Respir Care. 2004;49(2):192-205. 6. Recommended practices for the prevention of unplanned perioperative hypothermia. In: Perioperative Standards and Recommended Practices. Denver, CO: AORN, Inc; 2009:491-504. 7. Young VL, Watson ME. Prevention of perioperative hypothermia in plastic surgery. Aesthet Surg J. 2006;26(5):551-571. 8. Doufas AG. Consequences of inadvertent hypothermia. Best Pract Res Clin Anaesthesiol. 2003;17(4): 535-549. 9. Lenhardt R. Monitoring and thermal management. Best Pract Res Clin Anaesthesiol. 2003;17(4):569-581. 10. Ayres U. Older people and hypothermia: the role of the anaesthetic nurse. Br J Nurs. 2004;13(7):396-403. 11. Day MP. Hypothermia: a hazard for all seasons. Nursing. 2006;36(12 Pt 1):44-47. 12. Evered A. Hypothermia: risk factors and guidelines for nursing care. Nurs Times. 2003;99(49):40-43. 13. Neno R. Hypothermia: assessment, treatment and prevention. Nurs Stand. 2005;19(20):47-52. 14. Leslie K, Sessler DI. Perioperative hypothermia in the high-risk surgical patient. Best Pract Res Clin Anaesthesiol. 2003;17(4):485-498. 15. Ireland S, Murdoch K, Ormrod P, et al. Nursing and medical staff knowledge regarding the monitoring and management of accidental or exposure hypothermia in adult major trauma patients. Int J Nurs Pract. 2006;12(6):308-318. 16. Evans J, Kenkre J. Current practice and knowledge of nurses regarding patient temperature measurement. J Med Eng Technol. 2006;30(4):218-223. 17. Bitner J, Hilde L, Hall K, Duvendack T. A team approach to the prevention of unplanned postoperative hypothermia. AORN J. 2007;85(5):921-929. 18. Insler SR, Sessler DI. Perioperative thermoregulation and temperature monitoring. Anesthesiol
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Clin. 2006;24(4):823-837. 19. Wheeler D. Temperature regulation. Surgery. 2006;24(12):446-451. 20. Macario A, Dexter F. What are the most important risk factors for a patient’s intraoperative hypothermia? Anesth Analg. 2002;94(1):215-220. 21. Kline P. The Handbook of Psychological Testing. 2nd ed. London, England: Routledge; 2000. 22. Polit DF, Beck CT. Nursing Research Principles and Methods. 7th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2004. 23. Pallant J. SPSS Survival Manual: A Step By Step Guide to Data Analysis Using SPSS (Version 15). 3rd ed rev. Berkshire, United Kingdom: Open University Press (McGrath-Hill Education); 2007.
Josephine Hegarty, PhD, MSc, RNT, BSc, RGN, is an associate professor at the Catherine McAuley School of Nursing and Midwifery, Brookfield Health Sciences Complex, University College Cork, Ireland. Ella Walsh, MSc, BSc, Dip Nursing, RGN, is a lecturer at Catherine McAuley School of Nursing and Midwifery, Brookfield Health Sciences Complex, University College Cork, Ireland. Aileen Burton, MSc, BSc, RGN, is a lecturer at Catherine McAuley School of Nursing and Midwifery, Brookfield Health Sciences Complex, University College Cork, Ireland. Sheila Murphy, RGN, RM, HDip Nursing Management, is a clinical nurse manager, theatre recovery, at Cork University Hospital, Wilton, Cork, Ireland. Fionuala O’Gorman, MSc Ed, BSc, ENB 176, RGM, RGN, is a perioperative programme facilitator, Cork University Hospital, and immediate past president of the Irish Anaesthetic and Recovery Nurses Association, Wilton, Cork, Ireland. Gráinne McPolin, HDip Anaesthetic Nursing, BA, RGN, Clinical Facilitator, Major Theatres, Galway University Hospital, Galway, Ireland.
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Nurses’ Knowledge of Inadvertent Hypothermia JOSEPHINE HEGARTY, PHD, MSC, RNT, BSC, RGN; ELLA WALSH, MSC, BSC, DIP NURSING, RGN; AILEEN BURTON, MSC, BSC, RGN; SHEILA MURPHY, RGN, RM, HDIP NURSING MANAGEMENT; FIONUALA O’GORMAN, MSC ED, BSC, ENB 176, RGM, RGN; GRÁINNE MCPOLIN, HDIP ANAESTHETIC NURSING, BA, RGN
I
n the perioperative environment, between 60% and 90% of patients inadvertently become hypothermic.1 Hypothermia not only has significant negative consequences for the health of the patient, but also incurs economic expense for society in terms of increased hospital stay and additional procedures and diagnostic tests. Thus, it is paramount that all perioperative nurses possess an in-depth understanding of inadvertent hypothermia, including risk factors, complications, and methods of prevention and treatment. It is only through use of this knowledge that nurses can effectively fulfill their roles in the assessment, treatment, and prevention of hypothermia. A comprehensive literature review revealed a paucity of research pertaining to nurses’ knowledge of hypothermia. We designed this study to gain an understanding of perioperative nurses’ knowledge in relation to accidental hypothermia in the perioperative setting.
BACKGROUND Accidental hypothermia in perioperative patients is associated with poor patient outcomes. At the very least, it subjects patients to an unpleasant sensation of cold.2 It also has much more significant negative consequences, which have been detailed in the literature (Table 1). The magnitude of these adverse consequences should alert all nurses to their important role in reducing and alleviating the occurrence of this problem. DEFINING NORMOTHERMIA AND HYPOTHERMIA. The control of body temperature within a defined range is crucial in the maintenance of a stable environment in the human body, thus enabling optimal © AORN, Inc, 2009
function.2 The literature, however, presents varying definitions of normothermia (ie, normal body temperature). For example, the American Society of PeriAnesthesia Nurses (ASPAN) clinical guideline for the prevention of unplanned perioperative hypothermia defines normothermia as “a core temperature range from 36° C to 38° C (96.8° F to 100.4° F).”3 Meanwhile, the National Institute for Health and Clinical Excellence (NICE) 2008 guideline for the management of inadvertent perioperative hypothermia in adults defined the expected normal temperature range of adult patients as between 36.5° C and 37.5° C (97.7° F to 99.5° F).4 Kiekkas et al1 concur with this definition of normothermia. Just as the literature presents varying definitions of normothermia, it also presents varying definitions of hypothermia.
ABSTRACT Inadvertent hypothermia can have significant consequences in the perioperative setting. Knowing how to recognize and manage inadvertent hypothermia is an important aspect of perioperative nursing. A quantitative, descriptive study was conducted at an annual perioperative nursing conference to evaluate nurses’ knowledge regarding the prevention of inadvertent perioperative hypothermia. Significant variations in responses regarding definitions of hypothermia and normothermia were noted. In addition, nurses identified a plethora of factors that prevent them from maintaining normothermia in their patients. These factors mandate a need for educational interventions and the adoption of practice guidelines in the clinical area. Key words: inadvertent hypothermia, normothermia, practice guidelines. AORN J 89 (April 2009) 701-713. © AORN, Inc, 2009.
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TABLE 1
Adverse Consequences of Inadvertent Perioperative Hypothermia • Increased blood loss, thus increasing allogenic transfusion requirements • Increased incidence of wound infections • Prolonged recovery and postanesthesia care unit stay • Postanesthesia shivering • Myocardial ischemia • Thermal discomfort • Cardiac complications • Impaired medication metabolism • Coagulopathy • Increased mortality in trauma patients • Impaired immune function • Deep vein thrombosis
1-5
1,3-8
1-3,5-8
6-8
3,6
2,8
2,4,5,7,8
3,5,7,8
3,5,7-9
5
8
8
1. Doufas AG. Consequences of inadvertent hypothermia. Best Pract Res Clin Anaesthesiol. 2003;17(4): 535-549. 2. Torossian A; TEMMP (Thermoregulation in Europe Monitoring and Managing Patient Temperature) Study Group. Survey on intraoperative temperature management in Europe. Eur J Anaesthesiol. 2007; 24(8):668-675. 3. Bitner J, Hilde L, Hall K, Duvendack T. A team approach to the prevention of unplanned postoperative hypothermia. AORN J. 2007;85(5):921-929. 4. Hooper VD. Adoption of the ASPAN clinical guideline for the prevention of unplanned perioperative hypothermia: a data collection tool. J Perianesth Nurs. 2006;21(3):177-185. 5. Recommended practices for the prevention of unplanned perioperative hypothermia. Perioperative Standards and Recommended Practices. Denver, CO: AORN, Inc; 2009:491-504. 6. Kiekkas P, Poulopoulou M, Papahatzi A, Panagiotis S. Effects of hypothermia and shivering on standard PACU monitoring of patients. AANA J. 2005;73(1):47-53. 7. Insler SR, Sessler DI. Perioperative thermoregulation and temperature monitoring. Anesthesiol Clin. 2006;24(4):823-837. 8. Leslie K, Sessler DI. Perioperative hypothermia in the high-risk surgical patient. Best Pract Res Clin Anaesthesiol. 2003;17(4):485-498. 9. Wheeler D. Temperature regulation. Surgery. 2006;24(12):446-451.
Kiekkas et al state, the strict physiological definition of hypothermia in humans is a core temperature more than 1 [standard deviation] less than the mean value under resting conditions in a thermoneutral environment.1(p47) Meanwhile, Kempainen and Brunette define accidental hypothermia as “an unintentional decrease in core temperature to below 35° C (95° F).”5(p192) The NICE guideline defines hypothermia as a core temperature of less than 36º C (96.8° F).4 Some consensus is evident in that AORN’s “Recommended practices for the prevention of unplanned perioperative hypothermia” also defines hypothermia as “a core body temperature less than 36° C (96.8° F).”6(p491) Simi-
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larly, the ASPAN clinical guideline defines hypothermia as a core temperature of less than 36° C (96.8° F).3 Several authors concur with this definition.7-9 RISK FACTORS. Many risk factors for the development of hypothermia, including extremes of age, have been identified in the literature. Older adults are particularly prone to the development of the condition.5,6,10-13 This is primarily because older persons lose heat more rapidly than younger persons because of decreased fat and muscle mass. In addition, changes in vascular tone in the older adult inhibit vasoconstriction and thus decrease heat production. Furthermore, general anesthesia or major regional anesthesia impairs the thermoregulatory mechanisms of an older person to a greater extent those of a younger person.6
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Research literature has identified that infants and neonates are at an increased risk of developing hypothermia6,10,11 because of their increased ratio of body surface area to body mass. Infants also are unable to shiver to generate heat in response to hypothermia.5 Certain health conditions also increase patients’ risk of becoming hypothermic. These include hypothyroidism, other endocrine disorders, cardiac disorders, arthritis, paralysis, extensive body burns, cachexia, trauma, hypoglycemia, intoxication, myocardial infarction, and head or spinal cord injuries.5,11,13 The surgical experience also increases patients’ risk of developing hypothermia. This is because the body and internal organs are exposed to lower environmental temperatures, wet preparation solutions are used on the skin’s surface, and the body is unable to shiver and vasoconstrict when the patient is anesthetized during surgery.1,6,14 It is important to note that in certain surgeries (eg, neurosurgeries, cardiac surgeries), hypothermia is warranted and is thus induced. For the purposes of this article, however, we focused solely on inadvertent hypothermia in the perioperative setting.
LITERATURE REVIEW To date, the area of nurses’ knowledge in relation to hypothermia remains underinvestigated. In fact, we located only two studies— one in a perioperative environment and one in a general hospital setting—conducted between 2003 to 2008.15,16 IRELAND ET AL. In a study using a survey design, Ireland et al15 investigated nurse and medical staff member knowledge and understanding of issues surrounding accidental or exposure hypothermia in trauma patients. A secondary aim of their study was to increase staff members’ awareness about evaluating and documenting temperature. A 14-item survey tool was administered to all medical (n = 41) and nursing (n = 99) staff members employed in the Emergency and Trauma Centre of the Alfred Hospital Australia, Melbourne, Victoria. Ninety-six surveys were returned, yielding a response rate of 69%. Results revealed that nursing and medical staff members were unsure of how to define hypo-
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Conditions that increase patients’ risk of becoming hypothermic include hypothyroidism, other endocrine disorders, cardiac disorders, arthritis, paralysis, extensive body burns, cachexia, trauma, hypoglycemia, intoxication, myocardial infarction, and head or spinal cord injuries.
thermia, as evidenced by the array of responses with regard to the cut-off temperature for hypothermia. This uncertainty may be partly a result of discrepancies in the literature regarding definitions of hypothermia. Additionally, results revealed that nurses and physicians were unfamiliar with simple means of preventing heat loss or of rewarming patients. Simple rewarming techniques that are readily available in the Emergency and Trauma Centre were infrequently listed. These included minimization of exposure (n = 8), removal of wet clothing/bandages (n = 3), and provision of dry linen (n = 1). Contrarily, rewarming strategies rarely used in the Emergency and Trauma Centre—including warm cavity lavage, cardiopulmonary bypass, and heat packs—were frequently identified. This perhaps suggests an awareness of sophisticated rewarming strategies from the literature but a failure to implement simple strategies in practice. Results revealed that all respondents could list at least one rewarming strategy, with 95 respondents able to list three rewarming strategies. When asked to list common complications associated with hypothermia, the participants described complications in detail. The complications of metabolic acidosis and coagulopathy were infrequently reported, even though these AORN JOURNAL •
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The lack of research examining nurses’ knowledge of hypothermia provides a compelling impetus for further study in this area.
are well described in the literature.14,17-19 When asked to outline factors that prevented or limited them from obtaining a patient’s temperature, respondents identified the following factors: • anatomical injury (n = 26), • access to the patient (n = 10), • access to the necessary equipment (n = 8), and • patient acuity (n = 3). Despite these obstacles, it is essential that temperature be monitored. Overall, the results of this study emphasize the need for educating nurses and physicians about hypothermia. The authors recommended the development of a best-practice guideline to assist staff members in the unit in the monitoring and overall management of hypothermia, which could thus lead to an improvement in patient outcomes. EVANS AND KENKRE. In a quantitative, descriptive study conducted in 2006, Evans and Kenkre16 examined the current practice of temperature management in a medium-sized acute general hospital in South Wales, United Kingdom. Using a self-administered survey tool, researchers collected baseline data on patterns of temperature measurement with respect to health care occupational group, frequency of temperature measurement, and equipment used. Secondly, the researchers sought information on the knowledge of health care practitioners with regard to infrared tympanic thermometry (IRTT). Finally, information was collected on any training received in the use of IRTT. A cross-sectional sample of staff members was recruited from within the hospital. Completed questionnaires were returned by 139 staff members, including • 51 (37.0%) who were nursing auxiliary
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grade (ie, nursing assistants); 48 (34.5%) who were staff nurse grade; and 29 (20.9%) who were sister grade (ie, clinical nurse manager). Data were missing for 11 (7.9%). Evans and Kenkre16 found that temperature measurement is frequently undertaken by all grades of nursing staff members. The researchers also revealed, however, that the group most involved in temperature measurement were the nursing auxiliary grade staff members who had the fewest years of clinical experience. In fact, a one-way analysis of variance (ANOVA) confirmed a relationship between reduced frequency of checking patient temperatures and increased years of experience in the clinical role. The remainder of this study focused on the frequency of use of various temperature measuring equipment and staff member knowledge regarding the technological workings of this equipment. Although, undoubtedly, the frequency of use of temperature monitoring equipment and staff member knowledge in relation to the technological workings of this equipment is important, our study is concerned with nurses’ knowledge in relation to hypothermia and not temperature monitoring equipment. Therefore, it is beyond the scope of this article to examine these results16 in detail.
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PERIOPERATIVE IMPLICATIONS The lack of research examining nurses’ knowledge of hypothermia provides a compelling impetus for further study in this area. Given the detrimental consequences associated with hypothermia, we were eager to determine nurses’ knowledge base on this topic. After baseline nursing knowledge levels have been established, interventions required to augment and improve nurses’ knowledge can be designed.
DESIGN, SETTING,
AND
SAMPLE
We employed a quantitative, descriptive design. After receipt of protocol approval from the relevant clinical research ethics committee, we recruited a volunteer convenience sample of all delegates in attendance at the National Annual Conference of the Irish Anaesthetic and Recovery Nurses Association that took place in the Republic of Ireland, Waterford City, October
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13, 2007. Participants were informed in an informational leaflet that their participation was voluntary and that all information provided by them would be kept confidential. The leaflet also detailed the aims and objectives of the study. There was no identifying information in any of the questionnaires, thus ensuring participant anonymity. All completed questionnaires were placed in a sealed box and we collected them at the close of the conference. Completion of the questionnaire implied consent. Of 198 delegates in attendance, 130 completed questionnaires, thus yielding a response rate of 66%.
INSTRUMENT The survey package consisted of two survey tools both adapted with permission from the primary authors of each questionnaire15,20 to suit nurses working in the perioperative environment. This adaptation was based on a review of the literature and the researchers’ knowledge and clinical expertise. The survey package included two demographic questions, nine questions designed to assess nurses’ knowledge,15 and a 23-item Likert scale based on risk factors for the development of intraoperative hypothermia.20 The nine questions asked participants to define hypothermia and list • factors that can lead to hypothermia in a patient undergoing anesthesia or surgery, • sources of potential heat loss in an adult, • techniques participants used within their clinical practices to ensure that patients do not develop hypothermia, and • complications that are associated with hypothermia for patients who have had surgery and anesthesia. Participants also were asked if patients’ temperatures were routinely monitored in their clinical areas and if within their clinical practice there was anything that prevented or limited them in maintaining normothermia in the patients that they cared for. The final question in the questionnaire was adapted from an article by Macario and Dexter20 in which clinical anesthetists and physician researchers were asked to prioritize a number of risk factors for the development of intraoperative hypothermia. Participants in our study
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were asked to estimate the relevant importance of each risk factor (ie, 23 potential risk factors in total) on a Likert scale of 1 to 10, with 1 implying “not likely to be important” and 10 implying “most likely to be important.” The higher the rating for each question, the greater the perceived importance of that risk factor. Surveys were completed by two expert perioperative nurses to assess content validity. The Cronbach’s alpha for this 23-item hypothermia risk factor scale was found to be satisfactory at 0.876. For social sciences scales, the normally acceptable standard for the Cronbach’s alpha is 0.6,21 with levels above 0.7 being desirable.22,23 Although the high Cronbach’s alpha generated for the 23-item scale could be attributed to the large number of items, the item-total correlations for each item within the 23-item scale were all > 0.3, thus implying that all items within this scale are measuring the same attribute (ie, risk factors in the development of hypothermia).
DATA ANALYSIS All raw data were coded and entered into Statistical Package for the Social Sciences, version 15, 2007. Responses to all closed-ended items were reported individually as frequencies and percentages. Meanwhile, responses to all open-ended questions were transcribed in full. Members of the research study team reviewed these responses to identify emergent themes. We then recoded these items with ordinal descriptors.
RESULTS Of the 198 surveys that were handed out, 130 were returned. The demographics of the study population included various work specialties and levels of qualification (Table 2). This represented a response rate of 65.7%. The majority of respondents had more than four years of experience working in the perioperative area. Specifically, respondents spent most of their time working in • anesthetic nursing—14.6% (n = 19); • recovery nursing—30% (n = 39); • intraoperative nursing—13.1% (n = 17); or • a combination of two or more of the above—36.9% (n = 48). AORN JOURNAL •
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One respondent identified “other—management” as the area in which he or she spent the most time, and data were missing for six respondents (4.6%). In relation to current level of qualification, the majority of respondents (45.4%, n = 59) identified themselves as registered general nurse (RGN). The next largest group were those registered nurses with a postgraduate qualification in perioperative nursing. When asked to select the cut-off point for hypothermia, respondents were divided: • 38.5% (n = 50) of participants chose 36° C (96.8º F), • 39.2% (n = 51) chose 35º C (95º F), • 11.5% (n = 15) chose 34º C (91.4º F), and • 8.5% (n = 11) chose 33º C (93.2º F). Data were missing for three respondents (2.3%). When respondents were questioned about the major sources of potential heat loss in an adult, • 53.1% (n = 69) identified the skin,
• • •
28.5% (n = 37) identified the head, 9.2% (n = 12) identified the torso, and 6.9% identified a combination. Data were missing for three respondents (2.3%). When asked how best to define normothermia, the majority of participants identified it as occurring between 36º C and 37º C (96.8º F and 98.6º F) (Table 3). Regarding whether temperatures are routinely monitored in clinical areas, just under half of participants (n = 55, 42.3%) answered yes. Meanwhile, 43.8% (n = 57) answered “yes as required based on the assessment of the patient,” and 8.5% (n = 11) answered no. Data were missing for seven respondents (5.4%). Furthermore, 50 participants (38.5%) identified factors that prevent or limit the maintenance of normothermia. With regard to these, the most frequently identified factors were temperature control of the room (n = 7), surgeon preference (n = 5), overexposure (n = 5), lack of equipment (n = 4), and no air conditioning (n = 3). Other identified factors included TABLE 2 • lack of national tool (n = 2), Demographics of Survey Respondents • positioning (n = 1), • patient condition (n = 1), Perioperative experience Responses Percentage • type of surgery (n = 1), < 12 months 7 5.4 • no preoperative warming 1-3 years 25 19.2 (n = 1), > 4 years 98 75.4 • lack of staff member experience (n = 1) and lack of Level of qualification Responses Percentage knowledge of staff (n = 1); Registered general nurse (RGN) 59 45.4 • laminar air flow system RGN with a BSc 23 17.7 (n = 1), RGN with other postgraduate • wet bed sheets (n = 1), course in perioperative nursing 29 22.3 • use of electric blankets Other 18 13.8 (n = 1), Missing data 1 0.8 • fast throughput of patients (n = 1), and • a combination of factors TABLE 3 (n = 14). Perception of Normothermia A number of open-ended questions also were included Temperature range Responses Percentage in the questionnaire. The first 36° C to 36.5° C (96.8° F to 97.7° F) 16 12.3 of these asked participants to 36° C to 37° C (96.8° F to 98.6° F) 43 33.1 identify three common contrib36° C to 37.5° C (96.8° F to 99.5° F) 36 27.7 utory factors to the develop36.5° C to 37.5° C (97.7° F to 99.5° F) 26 20.0 ment of hypothermia. A total Missing data 9 7.0 of 74 factors were identified,
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with some participants identifying three factors and others identifying one or two. Table 4 provides a summary of the 10 most commonly identified factors. Participants also identified a wide range of techniques used in the clinical area to ensure that patients do not develop hypothermia. Each participant was able to identify at least one factor, including • warming devices (eg, forced-air devices) (n = 92); • use of a fluid or blood warmer (n = 71); • controlling the environmental temperature (n = 37); • provision of adequate heat with blankets (n = 36); • regular checking of patients’ temperatures (n = 24); and • use of foil hats, leggings, or drapes (ie, foil wrapping used to prevent heat loss) (n = 19). When asked to identify common complications associated with hypothermia for patients who have had surgery or anesthesia, each participant could identify at least two complications. Complications that participants listed included • delayed recovery (n = 45), • postoperative shivering (n = 31), • hypotension (n = 27), • increased postoperative pain (n = 26), and • delayed wound healing (n = 20). Finally, participants were asked to rate factors in the development of hypothermia on a scale of 1 to 10 (Table 5). Major surgery with a large uncovered area was rated as extremely important by many of the participants. Also, being a neonate of younger than one month was considered an extremely important factor in the development of hypothermia.
DISCUSSION The prevention and management of hypothermia centers on the correct assessment of each individual’s risk for hypothermia, use of preventative strategies, monitoring of patients’ temperatures routinely during the perioperative period, and employment of appropriate rewarming strategies. Because nurses are primarily responsible for these aspects of care during the perioperative period, it follows that
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TABLE 4
Top 10 Perceived Factors for Hypothermia Development Factor identified Theatre environment temperature Body exposure Length of surgery Fluid and blood loss Anesthesia-induced bradycardia Patient age Cold infusion fluids Prolonged exposure Shock Fasting
Responses 58 40 35 29 21 19 14 9 9 8
nurses’ knowledge surrounding the concept of hypothermia is central to its successful prevention and management. The nurses who took part in this study were highly experienced, with the majority having more than four years of perioperative experience. In addition, many of these nurses had postregistration qualifications. Because the respondents were experienced and well-educated, we anticipated that these nurses would be quite knowledgeable about hypothermia, because thermoregulation is a fundamental aspect of nursing practice. We found, however, that nurses were unsure of the correct definitions of hypothermia and normothermia. These conflicting perceived definitions may be a result of the lack of clarity in the literature as to a standard definition of hypothermia. This highlights the need for standardized guidelines—such as those developed by the National Institute for Health and Clinical Evidence,4 AORN,6 and ASPAN3—to be used in practice. The majority of participants defined normothermia as 36º C and 37º C (96.8º F and 98.6º F), which is not concurrent with either the NICE guideline protocol4 or the ASPAN clinical guidelines3 for the prevention of unplanned hypothermia. This uncertainty highlights the need for the adoption of standardized guidelines to aid nurses in their clinical practice. It also highlights the need for the development of continuing educational programs to keep practitioners up to AORN JOURNAL •
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common contributory factor to the development of hypothermia in responses to the Question: At what point on a scale of 1 to 10 open-ended question (n = 40). would you rate the following in the development A similar factor, major surgery of hypothermia, with 10 being the highest risk? with a large uncovered area, Factor Mean score was rated by 93.8% of particiMajor surgery with a large uncovered area 9.9 Neonate < 1 month 9.8 pants (n = 122) as extremely Patient with 3rd degree burns 9.6 important. Blood loss was Major surgery 9.5 identified as a common conPediatric surgery 9.4 tributory factor in responses Surgery > 2 hours in duration 9.4 to the open-ended question. Older patient 8.9 This also was rated as an Cardiac surgery 8.9 extremely important factor by Operating theatre room < 18° C (64.4° F) 8.8 Patient hypothermic before surgery 8.6 73.1% (n = 95) of participants. More than 30 mL/kg blood loss 8.6 These concurring answers 8.5 Patient undergoing thoracotomy indicate that participants had Thin patient 7.9 accurate knowledge of factors Level of spinal anesthesia 7.7 that contribute to the developOpen pelvic/abdominal surgery 7.7 ment of hypothermia. General anesthesia 7.4 There were a number of OR temperature 18° C to 20° C (64.4° F to 68° F) 6.9 Spinal/epidural anesthesia 6.8 factors identified as extremely 5.2 OR temperature 20° C to 22° C (68° F to 71.6° F) important in the 23-item scale Use of a tourniquet 5.2 relating to risk of developNormal body temperature before surgery 4.9 ment of hypothermia; howevA small surgical procedure 4.0 er, participants did not identify many of these potential risk date with the current best evidence. factors in the open-ended question, including The evidential lack of uniformity in the litneonate younger than one month old. Particierature with regard to some definitions and pants identified the patient’s age as an imporpreventative measures may have contributed tant factor, which to a certain degree accounts to some of the varying responses within this for this. In addition, a patient with third-degree survey. The tools used in this study allowed us burns was rated as extremely important by 119 to assess nurses’ knowledge in relation to hypo- participants (91.5%). This did not feature in thermia from both a quantitative and a qualita- responses to the open-ended question despite tive perspective, thus increasing the depth of the the fact that third-degree burns are a major condata ascertained. Overall, staff members in this tributory factor.5,11,13 survey displayed extensive knowledge in the Irrigation fluid below body temperature also area of hypothermia prevention. was rated as an extremely important factor by CONTRIBUTING FACTORS. When participants were 83.8% of participants (n = 109). Cold infusion asked in an open-ended question to list three fluid was cited only 14 times in responses to the common factors that contribute to the developopen-ended question, however. The reality is ment of hypothermia, the most frequently identhat cold infusion fluids are a major risk factor tified factor was OR environment exposure. in the development of hypothermia.17 When asked to rate certain factors in the develMoreover, despite the fact that general anesopment of hypothermia, a similar factor, OR thesia is a major risk factor in the development of temperature < 18° C (64.4° F), was also considhypothermia because of “the loss of behavioral ered to be extremely important by more than response to cold and impairment of thermoreguhalf of the respondents (53.8%, n = 70). Addilatory heat preserving mechanisms,”4(p4) fewer tionally, body exposure was identified as a than half of the respondents (n = 60, 46.2%) rated
TABLE 5
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it as a major risk factor. It did not feature at all in responses to the open-ended question. Overall, it was encouraging to see that participants were able to identify a wide range of contributing factors in the development of hypothermia. The fact that some important factors (eg, cold irrigation fluids, blood loss) were rated as important by participants in the 23-item Likert scale risk factor listing but were not listed in response to the open-ended question suggests that although participants had the knowledge, they were unable to recall all factors spontaneously without prompting. This further suggests that preformulated guidelines that would prompt practitioners on the important factors would be helpful in the clinical area. PREVENTION. When asked about preventing hypothermia in the clinical area, participants cited a wide range of techniques. The most frequently identified technique was the use of warming devices (eg, forced-air warming devices). Use of a forced-air warming device is recommended for all patients undergoing anesthesia in the NICE clinical guideline for inadvertent perioperative hypothermia.4 The ASPAN hypothermia guideline3 recommends that forced-air warming devices be initiated only if the patient is hypothermic, however. The AORN guideline6 recommends that forcedair warming is used to prevent hypothermia in patients undergoing anesthesia and in rewarming patients after cardiopulmonary bypass. Participants also cited using a fluid/blood warmer (n = 71) as an important technique to prevent hypothermia. The NICE clinical guideline for inadvertent perioperative hypothermia4 supports this; however, the ASPAN hypothermia guideline3 states that fluid warming devices should be used if the patient is hypothermic and not as a preventative measure. Meanwhile, the AORN guideline6 recommends that warming IV fluids only be considered where large volumes (ie, > 2L/hour) are being transfused. Thirdly, participants identified control of environmental temperature as an important preventative measure in the development of hypothermia. Both the NICE clinical guideline4 and the ASPAN guideline3 support this. The NICE guideline4 specifies that the OR suite temperature should be at least 21° C (69.8° F), and
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the ASPAN hypothermia guideline3 states that the room temperature should be at a minimum of 20° C to 24° C (68° F to 75° F). The AORN guideline also alludes to the importance of OR temperature in particular for infants and neonates.6
With regard to factors that prevent nurses from maintaining normothermia in their patients, it was surprising to see that in a health service that encourages nurses to be autonomous practitioners, one of the most frequently identified factors was surgeon preference.
NURSING CHALLENGES. Lastly, with regard to factors that prevent nurses from maintaining normothermia in their patients, participants cited a number of factors. It was surprising to see that in a health service that encourages nurses to be autonomous practitioners, one of the most frequently identified factors was surgeon preference. The majority of nurses reported frequent monitoring of temperature in the clinical area (n = 55). An additional 43.8% (n = 57) reported that temperature is monitored as required based on the assessment of the patient. Encouragingly, just nine participants answered no to this question. Given the detrimental consequences associated with hypothermia, neglecting to conduct regular monitoring could have catastrophic effects for patients.
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quality problems.22 The current study, as with all research studies, has a number of limitations. The sample used in this study was chosen from a group of attendees at a national perioperative conference. The fact that these people voluntarily attended such a conference may imply that they were especially vigilant with regard to their professional obligations for continuing education. This fact may in turn imply that the group as a whole was quite knowledgeable, perhaps limiting generalization of results to the wider population of perioperative nurses. Another limitation of this study was its small sample size. Perhaps if this study were carried out with a larger sample, the results would be more representative of the entire population of perioperative nurses. The cross-sectional design of this study did not allow the opportunity to assess nurses’ knowledge over time to gauge whether knowledge levels change. Perhaps if a longitudinal design were employed, one could assess nurses’ knowledge, implement educational sessions, and then reassess the nurses’ knowledge at a later stage. Finally, this study is descriptive in nature. Although this has served as a useful starting point for investigation of the issue, additional research is required to investigate the issue further. This may involve conducting a correlational study to compare knowledge with practice.
RECOMMENDATIONS FOR CLINICAL PRACTICE, EDUCATION, AND FUTURE RESEARCH Clinical guidelines for the prevention and management of inadvertent perioperative hypothermia need to be readily available for practitioners and adopted for use in the perioperative environment. The NICE clinical guidelines, the AORN recommended practices for the prevention of unplanned hypothermia, and the ASPAN clinical guideline for the prevention of unplanned perioperative hypothermia are available. Furthermore, nurse managers should be cognizant of the need to organize regular educational sessions about hypothermia for staff members. The detrimental consequences associated with hypothermia cannot be underestimated. Educational sessions would allow practitioners to keep up to date with best research evidence and allow for
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the exchange of clinical expertise. From a research perspective, there is a lack of research in the area of nurses’ knowledge regarding hypothermia and, crucially, a complete absence of higher-level evidence. Perhaps conducting a randomized, controlled trial to investigate nurses’ knowledge before and after an educational intervention would be useful. In addition, we believe that conducting an observational study to monitor nurses’ activities in relation to hypothermia prevention and management would be most useful. Acknowledgements: The authors thank Sharyn Ireland, RN, Dip, HSc, BNurs, CritCareCert, ACCN, MEd, clinical nurse specialist, Emergency and Trauma Centre, The Alfred, Melbourne, for her permission to use the staff survey tool that she and her colleagues developed to explore nursing and medical knowledge regarding hypothermia management. The authors also thank Alex Macario, MD, MBA, professor of anesthesia and health research and policy program director, Anesthesia Residency Department of Anesthesia, Stanford University, California, for his permission to use the listing of risk factors in the development of intraoperative hypothermia generated from his paper, “What are the Most Important Risk Factors for a Patient’s Developing Intraoperative Hypothermia?” Special thanks to members of the IARNA committee, most especially Eilis Daly, BSc, Dip Nursing, RGN, MSc, clinical nurse manager, Day Procedures Unit, South Infirmary Victoria University Hospital, Cork, Ireland; Ann Hogan, HDip (Perioperative Nursing), RGN, MSc, clinical nurse manager, Recovery Unit, Waterford Regional Hospital, Waterford, Ireland; Lorraine O’Rourke, RGN, HDip Perioperative Nursing, clinical nurse manager, South Infirmary University Hospital, Cork, Ireland; Lorraine Murphy, PG Dip, MSc, professional learning facilitator, Nursing and Midwifery Planning Development Unit, Health Services Executive South, Ireland; Breda Needham, RGN, HDip Nursing Studies, clinical nurse manager, Surgical Day Theatres, Mid Western Regional Hospital, Limerick, Ireland; and Brigid Fitzpatrick-Laffan, HDip (Perioperative Nursing), Dip (Health Services Management), RN, RM, clinical nurse manager, Theatre, Mid Western Regional Hospital, Limerick, Ireland. Finally, a special word of thanks is extended to the nurses who participated in this study.
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REFERENCES 1. Kiekkas P, Poulopoulou M, Papahatzi A, Panagiotis S. Effects of hypothermia and shivering on standard PACU monitoring of patients. AANA J. 2005; 73(1):47-53. 2. Hegarty J. Perioperative temperature regulation: management of hypothermia. The All-Ireland Journal of Nursing and Midwifery. 2003;2(9)18-19. 3. Clinical guideline for the prevention of unplanned perioperative hypothermia. American Society of PeriAnesthesia Nurses. http://www.aspan.org/Clinical Practice/ClinicalGuidelines/Hypothermia/tabid/325 5/Default.aspx. Accessed February 3, 2009. 4. Management of inadvertent perioperative hypothermia in adults. April 2008. National Institute for Health and Clinical Excellence. http://www.nice .org.uk/Guidance/CG65. Accessed February 3, 2009. 5. Kempainen RR, Brunette DD. The evaluation and management of accidental hypothermia. Respir Care. 2004;49(2):192-205. 6. Recommended practices for the prevention of unplanned perioperative hypothermia. In: Perioperative Standards and Recommended Practices. Denver, CO: AORN, Inc; 2009:491-504. 7. Young VL, Watson ME. Prevention of perioperative hypothermia in plastic surgery. Aesthet Surg J. 2006;26(5):551-571. 8. Doufas AG. Consequences of inadvertent hypothermia. Best Pract Res Clin Anaesthesiol. 2003;17(4): 535-549. 9. Lenhardt R. Monitoring and thermal management. Best Pract Res Clin Anaesthesiol. 2003;17(4):569-581. 10. Ayres U. Older people and hypothermia: the role of the anaesthetic nurse. Br J Nurs. 2004;13(7):396-403. 11. Day MP. Hypothermia: a hazard for all seasons. Nursing. 2006;36(12 Pt 1):44-47. 12. Evered A. Hypothermia: risk factors and guidelines for nursing care. Nurs Times. 2003;99(49):40-43. 13. Neno R. Hypothermia: assessment, treatment and prevention. Nurs Stand. 2005;19(20):47-52. 14. Leslie K, Sessler DI. Perioperative hypothermia in the high-risk surgical patient. Best Pract Res Clin Anaesthesiol. 2003;17(4):485-498. 15. Ireland S, Murdoch K, Ormrod P, et al. Nursing and medical staff knowledge regarding the monitoring and management of accidental or exposure hypothermia in adult major trauma patients. Int J Nurs Pract. 2006;12(6):308-318. 16. Evans J, Kenkre J. Current practice and knowledge of nurses regarding patient temperature measurement. J Med Eng Technol. 2006;30(4):218-223. 17. Bitner J, Hilde L, Hall K, Duvendack T. A team approach to the prevention of unplanned postoperative hypothermia. AORN J. 2007;85(5):921-929. 18. Insler SR, Sessler DI. Perioperative thermoregulation and temperature monitoring. Anesthesiol
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Clin. 2006;24(4):823-837. 19. Wheeler D. Temperature regulation. Surgery. 2006;24(12):446-451. 20. Macario A, Dexter F. What are the most important risk factors for a patient’s intraoperative hypothermia? Anesth Analg. 2002;94(1):215-220. 21. Kline P. The Handbook of Psychological Testing. 2nd ed. London, England: Routledge; 2000. 22. Polit DF, Beck CT. Nursing Research Principles and Methods. 7th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2004. 23. Pallant J. SPSS Survival Manual: A Step By Step Guide to Data Analysis Using SPSS (Version 15). 3rd ed rev. Berkshire, United Kingdom: Open University Press (McGrath-Hill Education); 2007.
Josephine Hegarty, PhD, MSc, RNT, BSc, RGN, is an associate professor at the Catherine McAuley School of Nursing and Midwifery, Brookfield Health Sciences Complex, University College Cork, Ireland. Ella Walsh, MSc, BSc, Dip Nursing, RGN, is a lecturer at Catherine McAuley School of Nursing and Midwifery, Brookfield Health Sciences Complex, University College Cork, Ireland. Aileen Burton, MSc, BSc, RGN, is a lecturer at Catherine McAuley School of Nursing and Midwifery, Brookfield Health Sciences Complex, University College Cork, Ireland. Sheila Murphy, RGN, RM, HDip Nursing Management, is a clinical nurse manager, theatre recovery, at Cork University Hospital, Wilton, Cork, Ireland. Fionuala O’Gorman, MSc Ed, BSc, ENB 176, RGM, RGN, is a perioperative programme facilitator, Cork University Hospital, and immediate past president of the Irish Anaesthetic and Recovery Nurses Association, Wilton, Cork, Ireland. Gráinne McPolin, HDip Anaesthetic Nursing, BA, RGN, Clinical Facilitator, Major Theatres, Galway University Hospital, Galway, Ireland.
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