Int Surg 2015;100:105–108 DOI: 10.9738/INTSURG-D-13-00155.1

Value of Extended Warming in Patients Undergoing Elective Surgery Tarik J. Wasfie, Kimberly R. Barber Department of General Surgery, Grand Blanc, Michigan and Department of Clinical Research, Grand Blanc, Michigan

Perioperative temperature management is imperative for positive surgical outcomes. This study assessed the clinical and wellbeing benefits of extending normothermia by using a portable warming gown. A total of 94 patients undergoing elective surgery were enrolled. They were randomized pre-operatively to either a portable warming gown or the standard warming procedure. The warming gown stayed with patients from pre-op to operating room to postrecovery room discharge. Core temperature was tracked throughout the study. Patients also provided responses to a satisfaction and comfort status survey. The change in average core temperature did not differ significantly between groups (P ¼ 0.23). A nonsignificant 48% relative decrease in hypothermic events was observed for the extended warming group (P ¼ 0.12). Patients receiving the warming gown were more likely to report always having their temperature controlled (P ¼ 0.04) and significantly less likely to request additional blankets for comfort (P ¼ 0.006). Clinical outcomes and satisfaction were improved for patients with extended warming. Key words: Perioperative warming  Hypothermia  Warming gown  Patient warming unit

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ntra-operative management of core temperature has been shown to reduce postoperative complications including infections, risk of blood transfusions, and length of hospital stay.1 Core temperature at induction has been demonstrated to be a significant risk for development of perioperative hypothermia.2 Research findings in support of avoiding hypothermia (core temperature ,368) during surgery and the impact of lower temperature on patient

recovery is well documented.3,4 These include increased bleeding during surgery, increased infection rates, increased length of stay, as well as, ultimately, a higher mortality rate.1,5,6 Perioperative normothermia has also been shown to reduce postoperative complications.3 Most recently it has been suggested that active warming commencing preoperatively is more effective in achieving normothermic admission temperatures

Corresponding author: Kimberly Barber, PhD, Genesys Regional Medical Center, One Genesys Parkway, Office of Research, Suite 2442, Grand Blanc, MI 48439. Tel.: 810-606-7724; Fax: 810-606-5882; E-mail: [email protected] Int Surg 2015;100

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to postanesthesia recovery than warming commenced intra-operatively.4 That complications are reduced with preoperative warming is well established. These findings further suggest that extended warming significantly reduces rates of hypothermia over the standard warming just during surgery and at this time, no study has been performed. This study was conducted with three objectives in mind. The first objective was to compare rates of hypothermia (core temp , 368) recorded intraoperatively in both a standard warming procedure group and an extended perioperative warming group. The second objective was to examine the association between normothermia extension and well-being. The third objective was to describe the costs of extended warming (peri-operative warming gown) and compare it to the standard warming procedure.

Methodology The study was an open-label, randomized, controlled trial (RCT) that assigned patients to receive either extended warming (achieved by use of a warming garment with portable warming unit; 3M, Eden Prairie, MN) at time of pre-operative preparation or standard warming at the time of induction in the operating room. This study was approved by the hospital’s Institutional Review Board. Warming for both groups was conducted to maintain a core body temperature of at least 368. The expanded warming group continued their warming from pre-op through surgery and into recovery and discharge or transfer. The Control group was warmed per standard anesthesia protocol at time of induction and maintained through the procedure until transfer to recovery. Warming items were removed from control patients in recovery. Patients undergoing elective surgical procedures, with operation time scheduled to last 1 hour or more, were recruited to participate in this study. A total of 96 patients consented and were randomized. One group received extended warming (the perioperative warming garment; Arizant Healthcare, Inc., a 3M Co., Eden Prairie, Minnesota) and the other group received standard warming procedures (Bair Hugger 3M Co., St. Paul, MN, and warmed blankets). There were 46 patients who received extended warming and 48 patients who received standard warming procedures. In the pre-operative area, each patient’s core temperature was measured and recorded by a nurse. In the operating room, core temperature is 106

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continuously recorded by the monitor every 5 minutes. The temperature was obtained from the esophageal tube. The monitor records the temperature and the averages of multiple measurements throughout the procedure. A nurse also conducted a verbal pre-operative assessment about the patients’ demographic information, general health status, personal needs, feelings, comfort levels, and hospital experience and recorded the responses. The preoperative core temperature and the operative average core temperature were obtained and noted for the study by the nurse, In the postoperative area, a third measurement of core temperature was taken and recorded. All hypothermic events were recorded and documented in the medical record. A study nurse conducted postoperative assessments on apprehension, anxiety, and perceived comfort. Perceived comfort levels and states of apprehension and anxiety were measured by survey response using a 4-point Likert scale. The average change in levels from baseline was then compared by group. Comfort was determined by self-reported response to a question on whether the patient believed that the hospital team was keeping their temperature controlled at a comfortable level. Apprehension was measured from questions on self-reported levels of calmness or tenseness, and anxiety was measured from questions on self-reported levels of nervousness. Descriptive statistics and a 2-sample t test between percentages were conducted to calculate change from baseline for all assessments, as well as the 3 core temperature measurements.

Results A total of 94 subjects were included—46 in the extended warming group and 48 in the control group. The average age was 50.1 years (51.8 years and 48.5 years, respectively). Overall, 69% were female (79% and 58%, respectively) and 90% were Caucasian (89% and 92%, respectively). The mean core temperature in pre-op for the extended warming group was 36.88 and was 36.68 for the control group. During the procedure, the extended warming group had a slightly higher mean temperature (36.258) then controls (35.48) and was maintained through recovery (extended warming group: 36.758 versus controls: 36.58). Overall, there were 15 hypothermic events (core temperatures below 368) recorded (5 in the extended warming group and 10 in the control group). The difference equates to a 48% relative decrease in Int Surg 2015;100

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Table 1 Average core temperatures by intervention group

Mean (SD) Pre-operation Intra-operation Postoperation

Extended warming

Standard warming

Overall

36.80 (0.39) 36.25 (0.59) 36.75 (0.39)

36.59 (0.32) 35.38 (0.52)* 36.63 (0.39)

36.69 (0.37) 35.80 (0.38) 36.68 (0.39)

*Significant drop in core temperature following baseline for the standard warming group only (P , 0.001).

hypothermia incidence for the extended warming group which statistically approaches significance (RRD ¼ 0.48; P ¼ 0.12). The advantage was also observed during the pre-operative phase for which 1 event occurred in the control group and no events occurred in the extended warming group. Average core temperatures during pre-, intraand post-operation did not differ significantly between the two groups (Table 1). The temperatures for the extended warming group had slightly higher temperatures recorded than those in the standard warming group. Core temperatures increased 0.68 in the extended warming group and 0.48 in the standard group from baseline to recovery (P , 0.001). The postoperative assessment on wellbeing demonstrated increased comfort and convenience for those patients having extended warming. Patients that received extended warming were more likely to self-report post operation that their body temperature was always controlled and maintained at a comfortable level than those who received standard warming procedures (67% versus 42%, P ¼ 0.04; Fig. 1). Patients that received standard warming procedures were more likely to require extra blankets for warmth postoperation than those in the extended warming group (42% versus 16%, P ¼ 0.006; Fig. 2).

Fig. 2 Perception of need for additional warming (percent requesting additional warming).

There was a significant difference in the change in self-reported anxiety levels pre- to postoperatively between groups (P ¼ 0.001). Patients in the extended warming group had a 59% decrease in anxiety and patients in the standard warming group had a 49% decrease in anxiety (Fig. 3). There was a significant difference in the percentage of patients that reported a decrease in apprehension postoperatively between groups (P ¼ 0.001). The patients that received extended warming experienced a 61% decrease in apprehension from pre- to post-operation while those in the standard warming group had a 49% decrease. Overall satisfaction with the hospital from baseline to postop differed by group but did not reach statistical significance (extended warming: mean 1- point increase to post-op score of 8, standard warming: mean 1- point decrease to post op, P ¼ 0.89). Although the overall satisfaction with the hospital was high (mean ¼ 8.0 on a 10-point scale), 7 patients in the extended warming group increased their rating following the procedure while 6 patients in the standard warming group decreased their rating. The score for all other patients remained the same.

Fig. 1 Perceived comfort (percent reporting body temperature always controlled). Int Surg 2015;100

Fig. 3 Percent of patients feeling anxious.

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Discussion

Conclusion

These study results suggest that the use of an extended warming strategy may decrease hypothermic incidences among patients undergoing a broad range of surgeries. Because hypothermia can significantly impact patient outcomes during (bleeding), after (infection), and following surgery (mortality), a significant decrease in hypothermic events could have a correspondingly significant impact on patient safety. Although our intent was not to examine efficacy, demonstration of a relative 50% decreased trend among a moderately sized study sample consisting of a wide range of surgeries suggests important clinical implications for patient safety and quality improvement. The study also examined the association between normothermia maintenance and patient well-being. The results suggest that an extended warming strategy increases well-being, comfort, as well as convenience. Although anxiety and apprehension did decrease following surgery for all patients, this study showed an advantage to the extended warming group in all measures, including perceived comfort by a 20% or greater relative difference. The third objective was to review whether the cost of extended warming justified its use for all patients in terms of outcomes achieved. A descriptive cost analysis was performed on the 3M Flex gown and portable unit. The warming unit installation in the pre- and post-operative area is included in the price of the product. The cost for extended warming was $16 per patient or a total of $736. The cost of standard warming procedures includes the warming process, laundry, and replacement costs from wear and tear. After including staff time and supplies, those costs were estimated to be over $100 per patient. These outcomes, both clinical and wellbeing, favoring the extended warming group supports its use for surgery patients.

We conclude that it is sound practice to implement extended warming for surgery patients. This strategy reduced the number of hypothermic events and improved patient comfort and satisfaction without increasing the cost to the hospital.

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Acknowledgments The authors would like to thank Renee Saylor for her significant efforts in patient enrollment and data collection. As a disclaimer, the patient warming units utilized were provided by 3M. There was no other source of support.

References 1. Kurz A, Sessler DI, Lenhardt R. Perioperative normothermia to reduce the incidence of surgical wound infection and shorten hospitalization. Study of wound infection and temperature group. NEJM 1996;334(19):1209–1215 2. Stewart BT, Stitz RW, Tuch MM, Lumley JW. Hypothermia in open and laparoscopic colorectal surgery. Dis Colon Rectum 1999;42(10):1292–1295 3. Macario A, Dexter F. What are the most important risk factors for a patient’s developing intraoperative hypothermia? Anesth Analg 2002;94(1):215–220 4. Wagner K, Swanson E, Raymond CJ, Smith CE. Comparison of two convective working systems during major abdominal and orthopedic surgery. Can J Anaesth 2008;55(6):358–363 5. Plattner O, Xiong J, Sessler DI, Schmied H, Christensen R, Turakhia M et al. Rapid core to peripheral tissue heat transfer during cutaneous cooling. Anesth Analg 1996;82(5):925–930 6. Frank Sm, Fleisher LA, Breslow MJ, Higgins MS, Olson KF, Kelly S et al. Perioperative maintenance of normothermia reduces the incidence of morbid cardiac events: a randomized clinical trial. JAMA 1997;277(14):1127–1134

Int Surg 2015;100

Value of extended warming in patients undergoing elective surgery.

Perioperative temperature management is imperative for positive surgical outcomes. This study assessed the clinical and wellbeing benefits of extendin...
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