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PLEASE READ THE ARTICLE BELOW AND HELP ME ANSWER THE QUESTIONS LISTED AT THE END OF THIS ARTICLES: CLINICAL SCHOLARSHIP The Comparison of Two Recovery Room Warming Methods for Hypothermia Patients Who Had Undergone Spinal Surgery Hsiu-Ling Yang, RN, BSN1, Hsiu-Fang Lee, RN, MSN2, Tsung-Lane Chu, RN, MSN3, Yu-Yun Su, RN, BSN4, Lun-Hui Ho, RN, MSN5, & Jun-Yu Fan, RN, PhD6 1 Staff, Department of Nursing, Chang Gung Medical Foundation, LinKou Branch, Tao-Yuan, Taiwan, R.O.C. 2 Nursing Supervisor, Department of Nursing, Chang Gung Medical Foundation, LinKou Branch, Tao-Yuan, Taiwan, R.O.C. 3 Director, Department of Nursing, Chang Gung Medical Foundation, Linkou Branch, Tao-Yuan, Taiwan, R.O.C. 4 Quality Manager, Council for Quality Health Care, Chang Gung Medical Foundation, LinKou Branch, Tao-Yuan, Taiwan, R.O.C. 5 Deputy-Director, Department of Nursing, Chang Gung Medical Foundation, Linkou Branch, Tao-Yuan, Taiwan, R.O.C. 6 Lambda Beta-At-Large, Associate professor, Department of Nursing, Chang Gung University of Science and Technology, Tao-Yuan, Taiwan, R.O.C Key words Hypothermia, postoperative, spinal surgery, warming method Correspondence Dr. Jun-Yu Fan, Department of Nursing, Chang-Gung University of Science and Technology, 261 Wen-Hwa 1st Road, Kwei-Shan, Tao-Yuan, Taiwan, R.O.C 333. E-mail: jyfan@gw.cgust.edu.tw Accepted September 10, 2011 doi: 10.1111/j.1547-5069.2011.01426.x Abstract Purpose: The purpose of this study was to compare the time needed to reach a specified temperature and the efficiency of two warming methods–warm cotton blankets and a radiant warmer–for hypothermia patients in a postanesthetic care unit (PACU) after spinal surgery. Design: This study was conducted according to a quasi-experimental design. Data were collected from a medical referral center in northern Taiwan. A total of 130 post–spinal surgery patients with hypothermia were recruited in the study. Methods: Of the 130 patients in the PACU, 65 were warmed by the radiant warmer (group R); whereas the other 65 patients were warmed by warm cotton blankets (group B). Tympanic temperature was measured for each patient every 10 min until it reached 36C in the PACU. Analysis of covariance and generalized estimating equation regression analysis were performed to compare the time needed to reach a specified temperature and the efficiency of the two warming methods, respectively. Findings: Both groups were similar in their baseline characteristics. After adjusting for temperature upon arrival at the PACU, group R needed a significantly shorter time for rewarming to 36C than group B (F [1, 125] = 58.17, p < .001). The results of the generalized estimating equation also showed that the radiant warmer was more efficient than warm cotton blankets in increasing patients’ body temperatures to 36C (2 = 37.44, p < .001). None of the patients appeared to have wound infections, and there were no differences in the length of hospital stay or medical costs for current hospitalization in both groups. Conclusions: Using the radiant warmer may be a more efficient method than providing warm cotton blankets for warming post–spinal surgery hypothermia patients in the PACU. Clinical Relevance: For hospitals that are unable to use forced-air warming to warm postsurgical hypothermia patients in the PACU, the radiant warmer is a more efficient device to rewarm patients. 2 Journal of Nursing Scholarship, 2012; 44:1, 2–10. C 2011 Sigma Theta Tau International Yang et al. Warming Hypothermia Patients Surgical patient hypothermia is a common phenomenon that may occur before, during, or after operations. Numerous preoperative, intraoperative, and postoperative hypothermia-related research studies have been conducted since 1980. Studies have reported that postoperative hypothermia, defined as having a core temperature of less than 36C, occurs in 20% to 60% of all patients (Defina & Lincoln, 1998; Vaughan, Vaughan, & Cork, 1981). Spinal surgery involves a wide spectrum of procedures during which the spinal cord, nerve roots, and blood vessels are frequently at risk for injury (Gonzalez, Jeyanandarajan, Hansen, Zada, & Hsieh, 2009). For patients undergoing spinal surgery, intraoperative active warming is difficult, since they are placed in the prone position, which allows only the legs to be covered with warming devices (Murat, Berniere, & Constant, 1994). The following questions thus arise: what can the clinical staff do to decrease this inadvertent hypothermia after spinal surgery, and which of the devices readily available in hospitals are the most effective for rewarming these patients in the PACU? Literature Review Thermoregulatory Mechanisms Humans are capable of maintaining homeostasis under fluctuating environmental conditions. For example, under normal circumstances, body temperature usually remains between 36.5C and 37.5C, with most changes being within 1C (Cooper, 2006). The center for regulation of body temperature is situated in the hypothalamus, which is responsible for the precise balancing of heat production and conservation, heat loss, and redistribution of heat via three major thermoregulatory mechanisms: vasoconstriction, shivering, and sweating (Wagner, 2006a). In surgical patients undergoing general or major regional anesthesia, hypothermia develops immediately after the induction of anesthesia because heat is redistributed from the center of the body to the periphery (Wagner, 2006b). Anesthetic agents suppress thermoregulatory control, especially heat production mechanisms, including blood vessel constriction and shivering (Sessler, 1997), leading to a greater chance of postoperative hypothermia. Temperature Changes During General Anesthesia In 1995, Matsukawa and colleagues observed healthy volunteers in a 22C environment for 2.5 hr and found that their core temperature did not fluctuate significantly. However, at 1, 2, and 3 hr after general anesthesia, core body temperature dropped by 1.6C ± 0.3C, 1.1C ± 0.3C, and 2.8C ± 0.5C, respectively. Sessler reported similar results in 2000. According to Sessler, there are three phases reflecting a typical hypothermic pattern during general anesthesia. During the first phase (1 hr of anesthesia), the patient’s core temperature drops by 0.5C to 1.5 because heat is redistributed from the body to the extremities. In the second phase (2–3 hr of anesthesia), the temperature drops linearly because the amount of heat lost is greater than that produced. In the third phase (3–5 hr of anesthesia), also known as the plateau phase, the temperature remains constant because the amount of heat lost is equal to that produced. In addition to anesthetic agents, extrinsic factors such as a cold operating room environment, the length and type of surgical procedure, infusion of a cold sterile solution, and duration of exposure of the body cavity, as well as intrinsic factors such as patient health status, body size, and age, may place patients at risk for hypothermia (Scott, Leaper, Clark, & Kelly, 2001). Hypothermia Complications Numerous studies have reported that severe hypothermia can cause physical discomfort and even health risks, including shivering, cardiac ischemia or arrest, decreased immune function, increased blood loss and the need for a blood transfusion during the operation, increased wound infection, increased mortality, extended nursing time or admission due to organ failure, extended retention time in the PACU, increased medical costs, and decreased patient satisfaction (Buggy & Crossley, 2000; Fleisher, Metzger, Lam, & Harris, 1998; Flores-Maldonado, Medina-Escobedo, Rios-Rodriguez, & Fernandez-Dominguez, 2001; Frank et al., 1993; Hildebrand, Giannoudis, van Griensven, Chawda, & Pape, 2004; Kurz, Sessler, & Lenhardt, 1996; Leinonen, Leino-Kilpi, & Jouko, 1996; Panagiotis, Maria, Argiri, & Panagiotis, 2005; Schmied, Kurz, Sessler, Kozek, & Reiter, 1996). Thus, careful monitoring with regard to preventing or decreasing the occurrence of hypothermia is an important duty of the clinical nursing staff in both the operating and recovery rooms. Warming Devices The use of rewarming devices for managing postoperative hypothermia has been reported since 1986. In 1990, Sessler and Moayeri examined the efficacy of four postoperative warming devices, including a pair of 250- W infrared heating lamps, thermal ceiling MTC XI WL (500 W), circulating-water blankets, and forced-air warming (FAW) system, by measuring cutaneous heat 3 Warming Hypothermia Patients Yang et al. loss or gain with thermal flux transducers. They also evaluated the correlation between forehead temperature and tympanic temperature in five healthy unanesthetized volunteers. The results showed that the use of FAW and circulating-water blankets decreased heat loss and raised skin temperaturemore than the other two radiant devices examined. In 1991, Giuffre, Finnie, Lynam, and Smith conducted a randomized controlled trial (RCT) to determine the efficiency of three warming devices, specifically FAW, radiant heater lamps, and warmed cotton blankets, in 90 postoperative patients admitted to the PACU with a body temperature of 35C. The results showed that there were no statistically significant differences in the mean time required to reach the temperature criterion of 36C for patient discharge (p = .06) or in the mean time required to satisfy all criteria for discharge from the PACU (p = .71) among the groups warmed by FAW, radiant heater lamps, and warmed cotton blankets. Giuffre et al. further divided patients into shivering and nonshivering groups. Among patients who experienced shivering and were rewarmed by using the three devices, there were no differences in either the mean rewarming time to reach 36C (p = .91) or in the mean time required to satisfy all criteria for discharge from the PACU (p = .84). In patients in the nonshivering group, the FAW method was significantly more rapid (mean of 121.7 min, p = .01) than both radiant heater lamps (184.7 min) and warmed cotton blankets (198.7 min). Weyland et al. (1994) conducted an RCT study to compare the rewarming rate efficiency of three warming devices (radiant heater, FAW, and cotton blankets) and to examine the effects of these devices on postoperative oxygen uptake in 35 awake, extubated, postoperative patients in the postoperative recovery room. Their results showed no significant differences in the central rewarming rate among the groups warmed with radiant heaters (n = 11), FAW (n = 12), and cotton blankets (n = 12), with rewarming rates of 0.81C/hr, 0.76C/hr, and 0.70C/hr, respectively. The lack of statistical significance in their study may be attributable to the small sample size. Torrie, Yip, and Robinson (2005) conducted an RCT to compare the efficacy and thermal comfort of radiant warming and FAW in patients undergoing transurethral resection of the prostate under spinal anesthesia. The results showed that there was a statistically significant difference, but no clinically relevant difference, in the final intraoperative rectal temperatures of patients in the radiant warming and FAW groups, with temperatures of 36.1C and 36.4C, respectively (p = .003). Several clinical studies have demonstrated that FAW is effective in preventing intraoperative hypothermia or treating postoperative hypothermia (Andrzejowski, Hoyle, Eapen, & Turnbull, 2008; Bitner, Hilde, Hall, & Duvendack, 2007; Kimberger et al., 2008; Ng et al., 2003; Perl, Brauer, & Quintel, 2006; Wadhwa et al., 2007). The most effective strategy for reducing unplanned hypothermia in surgical patients was to prewarm patients using an FAW device. However, Weirich (2008) indicated that FAW is not widely used because it causes contamination, increases the ambient operating room temperature because of passive warming, and decreases recovery efforts because of inconsistent practice and lack of guidance. In the current study, the use of a forced-air device to rewarm patients post–spinal surgery was limited due to (a) restricted space in the preoperative waiting area; (b) rapid turnover rate; (c) the need for frequent examination of the wound condition for bleeding; and (d) mandatory postsurgical assessment of neuromuscular function. Purpose In order to identify which device is more effective for warming patients after spinal surgery, we compared the rewarming time required and the efficiency of two warming methods–warm cotton blankets and a radiant warmer– for rewarming hypothermia patients in the PACU after spinal surgery. Methods Design, Setting, and Samples This study was conducted using a quasi-experimental design. Data were collected from a 3,477-bed medical referral center in northern Taiwan. The referral center had 60 operating rooms, and 58,475 operations were performed in 2008. At this center, approximately 120 to 200 patients undergo spinal surgery each month, an average of 6 to 10 spinal surgery patients per day; thus, the number of potentially eligible patients was more than sufficient to provide adequate data for the study. The PACU has 31 beds with a staff-to-patient ratio of 1:2. Patients who underwent spinal surgery (posterior approach only) between July and November 2008 and who met the following criteria were considered to be potential participants. To be included in this study, the patients were required (a) to be older than 18 years and to have provided consent to participate in the study; (b) to have been under general anesthesia during surgery; (c) to be conscious and able to communicate; (d) to have no fever for 72 hr before the study; (e) to have an operation time of 3 to 6 hr; (f) to have an operational wound of 10 to 15 cm; and (g) to have a tympanic temperature between 34C and 35.5C upon arrival at the PACU. Patients who were 4 Yang et al. Warming Hypothermia Patients transferred to an intensive care unit were excluded from the study. Initially, 800 patients met criteria “a” through “f”, but among these, only 130 met criterion “g”. Therefore, a total of 130 post–spinal surgery hypothermia patients were recruited to participate in the PACU. Among the 670 excluded patients, 122 were excluded because their operation time was either less than 3 hr (n = 80) or longer than 6 hr (n = 42), and 548 were excluded because their tympanic temperature was either below 34.0C (n = 80) or above 35.5C (n = 468). The characteristics of the excluded patients were similar to those of the included patients. Measurements and Warming Devices The measurement procedures and warming devices used included a tympanic temperature thermometer, warm cotton blankets, a radiant warmer, and demographic characteristics. Tympanic temperature thermometer. A CGM infrared ear thermometer OPUS 1000 series with probe covers (Chang Gung Medical Supplies & Equipment Corp., Taipei, Taiwan) was used to check tympanic temperature at 10-min intervals during the data collection period. The OPUS 1000 series meets the American Society for Testing and Materials standards E 1965–98 and NE 12470–5. The measuring range of the thermometer is between 20.0C and 44.0C, calibrated according to the manufacturer’s recommendations. The accuracy is ± 0.2C for temperatures in the range of 35.0C to 42.0C. Among temperature measurement methods, monitoring the tympanic temperature may most closely represent the core temperature since the measurement is the closest to the pulmonary artery (Chan, Ho, Huang, & Huang, 2000; Erickson, Meyer, & Ore, 1994; Ferrara-Love, 1991). Warm cotton blankets (Group B). All doublethickness green cotton blankets (150 cm × 90 cm, 0.5 kg/each) were kept in a blanket warmer maintained at 60C for at least 1 hr before use. Immediately after the blanket was removed from the oven, its temperature was approximately 38C. The PW810 Radiant Patient Warmer. was introduced in 1999 by the Fisher & Paykel Healthcare Corporation Limited (Auckland, New Zealand). This radiant warmer utilizes focused energy to raise skin temperature rapidly and effectively. The transfer of radiant energy requires direct exposure of the skin, and only the skin perpendicular to the heat source maximally absorbs energy. The facial skin has more capillary loops per unit area and generally more vessels per unit volume than other skin areas, and it is closer to the hypothalamus, which easily establishes the thermal gradient required for core rewarming. Using a skin sensor, the temperature alarm was set at 1C lower or higher than the set temperature 10 times per second to minimize accidental burning. Procedures This project was approved by the institutional review board of Chang Gung Memorial Hospital (IRB no. 97– 0521C). All patients hospitalized for spinal surgery were admitted 1 day prior to the operation. The investigators listed all potential candidates and examined the inclusion criteria. They visited each patient and explained the purpose of the study to the potential candidates and their families. On the day of operation, the investigators revisited the patients, invited potential candidates in the waiting area to participate in the study, and obtained written informed consent. Neither the patients nor the PACU staff members were blinded. Immediately following the operation, all potential patients were fully covered by several warm blankets, and a comforter (a type of blanket measuring 200 cm × 160 cm, weighing 2 kg/each, filled with polyester fiber, with an outer shell covered by 100% cotton) was placed on top of the green cotton blankets to decrease heat convection. The patients were then transported from the operating room to the PACU. The temperature was set at 19.0C and 24.0C in the OR and PACU, respectively. All potential patients had their tympanic temperatures examined twice at 1-min intervals as the baseline temperature upon arrival at the PACU. They were supplied with supplemental oxygen until discharge from the PACU irrespective of whether they were shivering. Their vital signs were examined at 10-min intervals, and a cotton cap was wrapped around their heads. At the time, only those potential patients with a tympanic temperature between 34.0C and 35.5C were included. The enrolled hypothermic spinal surgery patients were then assigned to either group B or group R on the basis of the last digit of their chart number. Odd and even numbers were assigned to group B and group R, respectively. The investigators followed hospital guidelines in terms of the discharge criteria from the PACU. None of the enrolled patients were discharged from the PACU until they (a) were fully awake and able to call for help if necessary; (b) had clear airways and could breathe spontaneously; (c) were maintaining a blood oxygenation level of 95% on room air; (d) had been physiologically stable with acceptable vital signs for 15 to 30 min; (e) had a tympanic temperature of 36.0C; (f) had no apparent postsurgical complications such as active bleeding; (g) had controlled and tolerable levels of postoperative pain 5 Warming Hypothermia Patients Yang et al. (the visual analog scale, which assesses pain level on a scale of 0–10, was used); (h) had minimal nausea and vomiting; and (i) had orders and prescriptions for all required oxygen, intravenous fluids, and medicines. Besides the clinical criteria outlined above, our hospital also implements the Modified Aldrete Scoring System as a standardized written criteria as part of the decision to discharge a patient from the PACU (Aldrete, 1998). A score of 8 (maximum is 10) is needed to discharge a patient. Lastly, an anesthesiologist’s approval is required for each patient’s discharge. Groups Patients in group B received three warm cotton blankets fully covering them from the neck to the toes. A comforter was placed on top of the blankets at all times during the PACU period to decrease heat conduction with the PACU environment. The blanket was placed by removing the topmost comforter, placing three new warm cotton blankets on the top of the old cooled blankets, removing the three old cooled blankets simultaneously, and finally placing a fresh comforter on top of the new warm blankets. The three warmed blankets were replaced simultaneously every 30 min, although the frequency of blanket changes was not clearly defined in previous studies. On the basis of the study by Giuffre et al. (1991), as well as personal clinical experience, the investigators decided to replace the three blankets every 30 min in order to keep the blankets from cooling too quickly. The patients in group R initially also received three warm cotton blankets fully covering them from the neck to the toes. A comforter was placed on top of the blankets all the time but was not replaced during the patient’s stay in the PACU. Group R also received a PW81 radiant warmer, with an irradiance of 32 mW/cm2 at 100% heater power mounted 68 cm above the head (including facial area) and neck area. The temperature alarm was set at 37.5C to minimize burn accidents. During temperature measurements, the radiant warmer was moved to the patient’s other side to eliminate the possible effect of the warmer on the thermometer. The investigators measured tympanic temperature at 10-min intervals using the same CGM infrared ear thermometer OPUS 1000 series on the same ear, until the tympanic temperature reached 36.0C. Data Analysis The data were analyzed using SPSS version 17 software for Windows (SPSS Inc., Chicago, IL, USA), and the significance level was set at p < .05. Besides the descriptive statistics, an independent t-test, analysis of covariance (ANCOVA), and generalized estimating equation (GEE) regression analysis were used to compare the time needed in the PACU and the efficiency of the two warming methods in increasing patients’ body temperatures to 36.0C. Results Sample Description In this study, we enrolled a total of 130 patients (53.8% female, n = 70) with a mean age of 67.0 ± 13.3 years (range 19.2–86.2 years). Laminectomy was the most common surgical procedure (n = 66, 50.8%), followed by spinal fusion (n = 57, 43.8%) and discectomy (n = 7, 5.4%). More than half (85/130, 65.4%) of the patients did not have any comorbidities. The characteristics of the two groups were similar (Table 1). We further examined the groups to determine whether there were differences in the patient characteristics at different temperatures. Both groups were divided into three different temperature subgroups on the basis of the baseline temperature at the time of admission to the PACU: 34.00C to 34.50C (low), 34.51C to 35.00C (medium), and 35.01C to 35.50C (high). A two-way analysis of variance and chi-square test were performed to examine any differences in characteristics among these three different subgroups between the two treatment groups. Importantly, no significant differences were found. Time Spent in the PACU The time required to reach 36C ranged from 10 to 120 min (mean 43.54 ± 27.12 min) for group R and 10 to 160 min (mean 76.77 ± 36.19 min) for group B. The time needed to reach a temperature of 36.0C was significantly shorter for group R than for group B (t(128) = 5.92, p < .001). The data were examined further to determine whether the time for a temperature of 36.0C at different temperatures was different. The results showed that all three temperature subgroups (low, medium, and high) in group B needed a significantly longer time to reach 36.0C (p < .001) than any subgroup of group R, with ratios of 1.55 (114.12 vs. 73.75 min), 1.50 (74.80 vs. 50.00 min), and 2.12 (51.30 vs. 24.19 min), respectively. Even though there were no differences in the basic characteristics of the three subgroups or between the two treatment groups, potential confounders such as age, sex, weight, health status, amount of blood loss during the operational period, amount of solution used during the operation, length of the operation, temperature at extubation, and temperature upon arrival at the PACU might 6 Yang et al. Warming Hypothermia Patients Table 1. Characteristics of the Two Groups Warm cotton blankets (n = 65) Radiant warmer (n = 65) Total (N = 130) Characteristics Mean ± SD Age (years) 62.01 ± 13.67 63.48 ± 13.06 62.75 ± 13.33 Weight (kg) 61.30 ± 12.08 65.06 ± 11.55 63.18 ± 11.92 n (%) Gender Male 29 (22.2) 31 (23.8) 60 (46.2) Female 36 (27.7) 34 (26.2) 70 (53.8) Spinal surgery method Laminectomy 34 (26.2) 32 (24.2) 66 (50.8) Spinal fusion 26 (20.0) 31 (23.8) 57 (43.8) Discectomy 5 (3.8) 2 (1.5) 7 (5.4) Spinal surgery location Cervical 11 (8.5) 13 (10.0) 24 (18.5) Thoracic 3 (2.3) 3 (2.3) 6 (4.6) Lumbar 51 (39.2) 49 (37.7) 100 (76.9) No. of comorbidities 0 38 (29.2) 47 (36.2) 85 (65.4) 1 25 (19.2) 17 (13.1) 42 (42.3) 2 2 (1.5) 0 (0) 2 (1.5) 3 0 (0) 1 (0.8) 1 (0.8) Usage of warmer lamp during operation No 3 (2.3) 8 (6.2) 11 (8.5) Yes 62 (47.4) 67 (43.8) 129 (91.5) Mean ± SD Doses of anesthesia medication Atropine (mg) 0.16 ± 0.21 0.11 ± 0.19 0.13 ± 0.20 Fentanyl (g) 166.92 ± 54.68 160.77 ± 29.96 163.85 ± 44.03 Propofol (mg) 64.77 ± 48.16 70.77 ± 46.61 67.77 ± 47.30 Xylocaine (mg) 8.85 ± 9.95 13.85 ± 18.34 11.35 ± 14.91 Cisatracurium (mg) 7.43 ± 5.04 8.59 ± 4.61 8.01 ± 4.84 Citosol (mg) 68.85 ± 93.34 56.15 ± 92.28 62.50 ± 92.67 Rocuronium (mg) 14.77 ± 23.66 10.77 ± 22.73 12.77 ± 23.20 Amount of blood loss 478.92 ± 450.62 551.69 ± 554.81 515.31 ± 504.77 Amount of solution 769.23 ± 251.20 676.92 ± 240.94 723.08 ± 249.51 Length of operation (min) 254.18 ± 47.07 268.18 ± 50.43 261.18 ± 49.09 Tympanic temperature C Waiting room 36.38 ± 0.40 36.35 ± 0.47 36.37 ± 0.44 Initial operation 35.69 ± 0.45 35.62 ± 0.52 35.65 ± 0.49 Extubation 34.71 ± 0.45 34.70 ± 0.46 34.70 ± 0.45 Admitted to PACU 34.86 ± 0.42 34.92 ± 0.49 34.89 ± 0.44 Discharge from PACU 36.18 ± 0.21 36.25 ± 0.31 36.21 ± 0.27 n (%) Wound infection 0 (0) 0 (0) 0 (0) Mean ± SD Length of stay in hospital (days) 10.46 ± 5.18 9.82 ± 7.00 10.14 ± 6.14 Medical cost during hospitalization (NTD) 112,440.62 ± 55,688.91 105,495.75 ± 75,209.42 108,968.18 ± 66,008.05 Note. NTD = New Taiwan Dollar; PACU, postanesthesia care unit. p < .05. place patients at risk for hypothermia and could influence the length of stay in the PACU. Significant relationships were found between the length of stay in the PACU and the temperature at extubation (r = 0.45, p < .01), and between the length of stay in PACU and the temperature upon arrival at the PACU (r = 0.68, p < .01). The investigators decided that only the “temperature upon arrival at the PACU” should be defined as a covariate in the current study because this temperature most closely reflected the patients’ body temperatures at that specific 7 Warming Hypothermia Patients Yang et al. Table 2. Rewarming Rates of the Two Warming Methods, and Time Needed Rewarming to 36C in the Three Temperature Subgroups Average rewarming Time needed rewarming Time needed rewarming Groups n rate (mean C/hr) to 36C (mean min ± SD) to 36.0C (B/R ratio) t p Warm cotton blankets 65 1.03 76.77 ± 36.19 1.76 5.92 <.001 Radiant warmer 65 1.83 43.54 ± 27.12 34.00–34.50C (low) Warm cotton blankets 17 114.12 ± 30.04 1.55 4.22 <.001 Radiant warmer 16 73.75 ± 23.06 34.51–35.00C (medium) Warm cotton blankets 25 74.80 ± 24.34 1.50 3.72 <.001 Radiant warmer 18 50.00 ± 16.80 35.01–35.50C (high) Warm cotton blankets 23 51.30 ± 26.51 2.12 4.37 <.001 Radiant warmer 31 24.19 ± 15.66 Note. B/R ratio = ratio of warm cotton blankets to radiant warmer. time point. ANCOVA showed that the main effects of the two rewarming methods were significantly different after controlling for the “temperature upon arrival at the PACU,” F (1, 125) = 58.17, p < .001. Group R needed less time for rewarming to 36.0C than group B (46.17 vs. 76.06 min, respectively, p < .001). Efficiency of the Two Warming Methods The average rate of rewarming to a temperature of 36.0C was 1.83C/hr and 1.03C/hr, respectively, for group R and group B. In the current study, the investigators examined each enrolled participant’s temperature every 10 min; that is, each patient may have had a different temperature measurement frequency while staying in the PACU. GEE analysis was chosen to resolve the cluster data issue and to analyze the efficiency of the two warming methods because it suited the current study design (repeated measurements) and had the advantage of a robust standard error (within-subject residual). The results showed that group R exhibited a higher warming rate than group B (2 = 37.44, p < .001). In summary, the radiant warmer was more efficient than warm cotton blankets in raising patients’ body temperatures post–spinal surgery. Table 2 presents the time needed rewarming and the efficiency of the two warming methods. Discussion Efficiency of the Warming Methods The current study shows that the radiant warmer helped increase patients’ body temperatures to 36.0C faster than the warmed cotton blankets. Despite adjusting for the covariate (temperature upon arrival to the PACU), the results of the present study were not consistent with those of a previous study by Giuffre et al. (1991). This inconsistency might be attributable to the lack of definition of “post-surgery patients” in the study by Giuffre et al., which may have caused large variability within the three study groups and therefore diminished the effects of intervention. In terms of efficiency (or rewarming rate), the current study also differs from the study by Weyland et al. conducted in 1994. In the present study, the rewarming rate was higher when a radiant warmer was used than when warm cotton blankets were used (1.83C/hr vs. 1.03C/hr), while in the study by Weyland et al., no significant differences were found between the rates of rewarming by the radiant warmer and the cotton blankets (0.81C/hr and 0.70C/hr, respectively). The lack of statistical significance in the study by Weyland et al. may be due to the small sample size (N = 35). From a medical costs perspective, delayed recovery in the PACU is expensive because the medical costs incurred are similar to those incurred in the intensive care unit. In the current study, use of the radiant warmer device did result in greater efficiency of rewarming and a shorter recovery time in the PACU than use of warm cotton blankets to raise the body temperature of post–spinal surgery patients, and this might have decreased medical costs in part because of the shorter length of stay in the PACU. As an added advantage, the radiant warmer is more ecologically friendly than comparable electrical warming methods such as FAW, which is more expensive and requires large amounts of water and detergents to wash. Study Limitations and Suggestions The primary limitation of this study is that these findings cannot be generalized since only individuals who 8 Yang et al. Warming Hypothermia Patients had undergone spinal surgery were selected. It is not clear whether these findings would be clinically relevant to patients undergoing different types of surgery, such as open thoracic or open abdominal surgery. The prevalence of post–spinal surgery hypothermia in the current study was underestimated (reported to be 130 of 800 = 16.25%), because some patients experiencing hypothermia following spinal surgery were not included, such as patients with operation times longer than 6 hr and patients with tympanic temperatures below 34.0C, as mentioned in the Design, Setting, and Samples section. In terms of postoperative outcome parameters, blood loss during the operation, length of stay in the PACU, wound infection, mortality during hospitalization, and medical costs were measured. During the study period, no patients spontaneously commented that the radiant warmer provided any thermal comfort, but patients in the warm cotton blankets group did complain that the blankets cooled rapidly. The investigators believe that patients likely felt more thermal comfort when the radiant warmer was used than when the warm cotton blankets were used, but this aspect was not systemically investigated. For future studies, parameters such as body mass index, degree of shivering, thermal comfort, patient satisfaction, and postoperative pain levels should be included for detailed investigation. Conclusions The results presented in this report showed that the radiant warmer device required significantly less time for rewarming and was more efficient in raising body temperature than warm cotton blankets in post–spinal surgery hypothermia patients. Recent clinical studies have provided evidence that using FAW during the intraoperative period may prevent hypothermia, thus avoiding serious postoperative complications. Unfortunately, FAW equipment is still unavailable in many hospitals because of certain limitations mentioned in the objectives subsection. For hospitals or facilities that are unable to use FAW to warm surgical patients during the perioperative period, the present results suggest an evidencebased reason to choose a radiant warming device to efficiently warm post–spinal surgery hypothermia patients in the PACU. Acknowledgments Our study was funded by grant CMRPG370311 at Linkou Chang Gung Memorial Hospital to Hsiu-Ling Yang, principal investigator. Clinical Resources American Society of Anesthesiologists: http:// www.asahq.org American Society of PeriAnesthesia Nurses: http:/ /www.aspan.org AORN, Association of Perioperative Registered Nurses: http://www.aorn.org International Anesthesia Research Society: http://www.anesthesia-analgesia.org/; http:// www.anesthesia-analgesia.org/content/96/1/171. full.pdf+html Association for Perioperative Practice: http://www. afpp.org.uk/home Wild Iris Medical Education: http://www. nursingceu.com/courses/249/index nceu.html References Aldrete, J. A. (1998). Modifications to the postanesthesia score for use in ambulatory surgery. Journal of Perianesthesia Nursing, 13(3), 148–155. Andrzejowski, J., Hoyle, J., Eapen, G., & Turnbull, D. (2008). Effect of prewarming on post-induction core temperature and the incidence of inadvertent perioperative hypothermia in patients undergoing general anaesthesia. British Journal of Anaesthesia, 101(5), 627–631. Bitner, J., Hilde, L., Hall, K., & Duvendack, T. (2007). A team approach to the prevention of unplanned postoperative hypothermia. AORN Journal, 85(5), 921–929. Buggy, D. J., & Crossley, A. W. (2000). Thermoregulation, mild perioperative hypothermia and postanaesthetic shivering. British Journal of Anaesthesia, 84(5), 615–628. Chan, Y-J., Ho, L-H., Huang, T-H., & Huang, C-C. (2000). Accuracy of infrared ear thermometry and traditional body temperatures for medical intensive care unit patients. Journal of Nursing, 47(2), 53–63. Cooper, S. (2006). The effect of preoperative warming on patients’ postoperative temperatures. AORN Journal, 83(5), 1073–1084. Defina, J., & Lincoln, J. (1998). Prevalence of inadvertent hypothermia during the perioperative period: A quality assurance and performance improvement study. Journal of Perianesthesia Nursing, 13(4), 229–235. Erickson, R. S., Meyer, L. T., & Ore, P. (1994). Accuracy of infrared ear thermometry and other temperature methods in adults. American Journal of Critical Care, 3(1), 40–53. Ferrara-Love, R. A. (1991). Comparison of tympanic and pulmonary artery measures of core temperatures. Journal of Post Anesthesia Nursing, 6(3), 161–164. 9 Warming Hypothermia Patients Yang et al. Fleisher, L. A., Metzger, S. E., Lam, J., & Harris, A. (1998). Perioperative cost-finding analysis of the routine use of intraoperative forced-air warming during general anesthesia. Anesthesiology, 88(5), 1357–1364. Flores-Maldonado, A., Medina-Escobedo, C. E., Rios-Rodriguez, H. M., & Fernandez-Dominguez, R. (2001). Mild perioperative hypothermia and the risk of wound infection. Archives of Medical Research, 32(3), 227–231. Frank, S. M., Beattie, C., Christopherson, R., Norris, E. J., Perler, B. A., Williams, G. M., & Gottlieb, S. O. (1993). Unintentional hypothermia is associated with post-operative myocardial ischemia. Anesthesiology, 78(3), 468–476. Giuffre, M., Finnie, J., Lynam, D. A., & Smith, D. (1991). Rewarming postoperative patients: Lights, blankets, or forced warm air. Journal of Post Anesthesia Nursing, 6(6), 387–393. Gonzalez, A. A., Jeyanandarajan, D., Hansen, C., Zada, G., & Hsieh, P. C. (2009). Intraoperative neurophysiological monitoring during spine surgery: A review. Neurosurgical Focus, 27(4), E6. Hildebrand, F., Giannoudis, P. V., van Griensven, M., Chawda, M., & Pape, H. C. (2004). Pathophysiologic changes and effects of hypothermia on outcome in elective surgery and trauma patients. American Journal of Surgery, 187(3), 363–371. Kimberger, O., Held, C., Stadelmann, K., Mayer, N., Hunkeler, C., Sessler, D. I., et al. (2008). Resistive polymer versus forced-air warming: Comparable heat transfer and core rewarming rates in volunteers. Anesthesia & Analgesia, 107(5), 1621–1626. Kurz, A., Sessler, D. I., & Lenhardt, R. (1996). Perioperative normothermia to reduce the incidence of surgical-wound infection and shorten hospitalization. Study of Wound Infection and Temperature Group. New England Journal of Medicine, 334(19), 1209–1215. Leinonen, T., Leino-Kilpi, H., & Jouko, K. (1996). The quality of intraoperative nursing care: The patient’s perspective. Journal of Advanced Nursing, 24(4), 843–852. Matsukawa, T., Sessler, D. I., Sessler, A. M., Schroeder, M., Ozaki, M., Kurz, A., & Cheng, C. (1995). Heat flow and distribution during induction of general anesthesia. Anesthesiology, 82(3), 662–673. Murat, I., Berniere, J., & Constant, I. (1994). Evaluation of the efficacy of a forced-air warmer (bair hugger) during spinal surgery in children. Journal of Clinical Anesthesia, 6(5), 425–429. Ng, S. F., Oo, C. S., Loh, K. H., Lim, P. Y., Chan, Y. H., & Ong, B. C. (2003). A comparative study of three warming interventions to determine the most effective in maintaining perioperative normothermia. Anesthesia & Analgesia, 96(1), 171–176. Panagiotis, K., Maria, P., Argiri, P., & Panagiotis, S. (2005). Is postanesthesia care unit length of stay increased in hypothermic patients? AORN Journal, 81(2), 379–382. Perl, T., Brauer, A., & Quintel, M. (2006). Prevention of perioperative hypothermia with forced-air warming systems and upper-body blankets. Surgical Technology International, 15, 19–22. Schmied, H., Kurz, A., Sessler, D. I., Kozek, S., & Reiter, A. (1996). Mild hypothermia increases blood loss and transfusion requirements during total hip arthroplasty. Lancet, 347(8997), 289–291. Scott, E. M., Leaper, D. J., Clark, M., & Kelly, P. J. (2001). Effects of warming therapy on pressure ulcers– A randomized trial. AORN Journal, 73(5), 921–938. Sessler, D. I. (1997). Mild perioperative hypothermia. New England Journal of Medicine, 336(24), 1730–1737. Sessler, D. I. (2000). Perioperative heat balance. Anesthesiology, 92(2), 578–596. Sessler, D. I., & Moayeri, A. (1990). Skin-surface warming: Heat flux and central temperature. Anesthesiology, 73(2), 218–224. Torrie, J. J., Yip, P., & Robinson, E. (2005). Comparison of forced-air warming and radiant heating during transurethral prostatic resection under spinal anaesthesia. Anaesthesia and Intensive Care, 33(6), 733–738. Vaughan, M. S., Vaughan, R. W., & Cork, R. C. (1981). Postoperative hypothermia in adults: Relationship of age, anesthesia, and shivering to rewarming. Anesthesia & Analgesia, 60(10), 746–751. Wadhwa, A., Komatsu, R., Orhan-Sungur, M., Barnes, P., In, J. H., Sessler, D. I., & Lenhardt, R. (2007). New circulating-water devices warm more quickly than forced-air in volunteers. Anesthesia & Analgesia, 105(6), 1681. Wagner, V. D. (2006a). Unplanned perioperative hypothermia. AORN Journal, 83(2), 470–476. Wagner, V. D. (2006b). Unplanned perioperative hypothermia and surgical complications: Evidence for prevention. Perioperative Nursing Clinics, 1(3), 267–281. Weirich, T. L. (2008). Hypothermia/warming protocols: Why are they not widely used in the OR? AORN Journal, 87(2), 333–344. Weyland, W., Fritz, U., Fabian, S., Jaeger, H., Crozier, T., Kietzmann, D., & Braun, U. (1994). Postoperative warming therapy in the recovery room. A comparison of radiative and convective warmers. Anaesthesist, 43(10), 648–657. 10 Copyright of Journal of Nursing Scholarship is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.

Question Population and Sample

Was the population described? Was the sample described in sufficient detail? What was the sample design used? Was is the best possible sampling design used to enhance the sample’s representativeness? Was the sample size adequate? Was a power analysis used to estimate sample size?

Explanation / Answer

Population of the study was described as for hypothermia patients in a postanesthetic care unit (PACU) after spinal surgery.

Yes, the sample was sufficiently described as 130 patients divided into 2 groups of 65 patients each

"Of the 130 patients in the PACU, 65 were warmed by the radiant warmer (group R); whereas the other 65 patients were warmed by warm cotton blankets (group B). "

Sample Design :

Type of design: quasi-experimental design.

Data were collected from a medical referral center in northern Taiwan.

A total of 130 post–spinal surgery patients with hypothermia were recruited in the study.

Yes the best possible sampling design used to enhance the sample’s representativeness because the patients were equally divided into groups of 65 each

Yes the sample size was adequate because we need a minimum of 30 data points to consider the sample as a large sample size

We have 130 data points in total hence we have a large sample size

But if we consider the rewarming rates of different warming methods we have the following reult

Their results showed no significant differences in the central rewarming rate among the groups warmed with radiant heaters (n = 11), FAW (n = 12), and cotton blankets (n = 12), with rewarming rates of 0.81C/hr, 0.76C/hr, and 0.70C/hr, respectively. The lack of statistical significance in their study may be attributable to the small sample size.

This happens because n=11, or n=12 <30 hence the sample size is small

No power analysis was used to estimate sample size because different methods had different sample size which were small

In many cases it was mentioned that the results could not be generalised due to small sample size of patients for different methods

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