Deliverable 2: The Clinical Problem

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journal homepage: www.jopan.org

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Research

TaggedH1Resistive Warming Mattress, Forced-Air Warming System, or a Combination of the Two in the Prevention of Intraoperative Inadvertent

Hypothermia: A Randomized TrialTaggedEnd

TaggedPAliye Okg€un Alcan, PhDa,*, Hakan Ayg€un, MDb, Cengizhan Kurt, MDc TaggedEnd

TaggedP

a Surgical Nursing Department, Izmir Bakircay University Faculty of Health Sciences, _Izmir, Tuerkey b Republic of Turkey Ministry of Health, _Izmir Provincial Health Directorate Bakırçay University Ç i�gli Training and Research Hospital, _Izmir, Turkey c Orthopedics and Traumatology Department, Izmir Bakircay University Faculty of Medicine, _Izmir, Turkey

TaggedEnd

TaggedEndTaggedEndConflict of Interest: None to report. TaggedEndData Availability Statement: This paper was presented

International & 12th National Turkish Surgical and Oper 13-16 January 2022, Antalya, Turkey. TaggedEnd* Address correspondence to: Aliye Okg€un Alcan, S

Izmir Bakircay University Faculty of Health Sciences, G Cd., 35665 Menemen/_Izmir, Turkey.

E-mail address: [email protected] (A. Okg€un Alc

https://doi.org/10.1016/j.jopan.2022.11.007 1089-9472/© 2022 American Society of PeriAnesthesia N

TAGGEDPA B S T R A C T

Purpose: To prevent intraoperative inadvertent hypothermia (IIH), resistive products and forced-air warming systems are often used simultaneously. There is insufficient evidence to show whether this application is clinically more effective than a single active warming device. The aim of this study is to compare the efficacy a single intraoperative active warming method with combined methods in IIH prevention. Design: A randomized, prospective, experimental study. Methods: This study was conducted between June and October 2021 in the operating room of a training and research hospital. The study sample consisted of 123 patients who underwent scheduled orthopedic surgery under spinal anesthesia, were young (18-64), and had an ASA risk score of I to III. The patients were divided into three groups preoperatively according to the stratified randomization technique. To prevent IIH, a resis- tive warming mattress was used in group 1; a forced-air warming system was used in group 2; and a combi- nation of the two methods were used in group 3. The body temperatures of the patients were measured and recorded every 15 minutes from admission to the operating room until the end of surgery. Findings: The mean intraoperative body temperature of the patients was 36.6§0.158C for group 1; 36.6§0.18C for Group 2 and 36.6§ 0.158C for Group 3. There was no difference between the groups in terms of body tem- perature. The overall incidence of IIH was 8.1%; 9.8% in group 1, 9.8% in group 2 and 4.9% in group 3. There was no statistically significant difference between the groups in terms of IIH (p < .05). Conclusions: This study supports the efficacy of using resistive warming mattress and forced-air warming sys- tems in preventing IIH. The use of both methods together made no difference in terms of IIH development.

© 2022 American Society of PeriAnesthesia Nurses. Published by Elsevier Inc. All rights reserved. TaggedEnd

TaggedEndTaggedPKeywords:

inadvertent hypothermia active warming intraoperative TaggedEnd

as an oral presentation in 4th ating Room Nursing Congress

urgical Nursing Department, azi Mustafa Kemal, Kaynaklar

an).

urses. Published by Elsevier Inc. All rights reserved.

TaggedPIntraoperative Inadvertent hypothermia (IIH), a common conse- quence of anesthesia, is defined as a central body temperature less than 36°C.1-3 Surgical patients are vulnerable to IIH because anes- thetic agents impair thermoregulatory control and also due to the prolonged exposure to a cold operating room. A 50% to 90% incidence of IIH has been reported. It is also estimated that IIH affects 70% of surgical patients.4,5TaggedEnd

TaggedPIIH causes peripheral vasoconstriction, decreased tissue perfusion, and decreased function of platelets. As a result, serious cardiac

TaggedEndTaggedPcomplications, coagulation disorders, delayed wound healing, wound infection, and pressure injury may occur. All or these may result in prolonged hospital stay, increased cost, morbidity, and mortality rates for the patient. It also leads to a decrease in patient satisfaction by causing increased patient discomfort.2,3,6-10 Therefore, maintain- ing normothermia in surgical patients is important in terms of pre- venting complications, ensuring patient safety, and increasing the quality of care.10,11 TaggedEnd

TaggedPA variety of active and passive warming methods are available for preventing IIH.1,3,10 The United Kingdom National Institute of Health and Clinical Excellence (NICE) recommends warming patients with a forced air warming device intraoperatively. If a forced air warming device is unsuitable, a resistive warming mat- tress or blanket should be considered.1 Many experimental and meta-analysis studies have indicated that active warming systems are a more effective method of preventing IIH than passive systems.5,12-15 TaggedEnd

TaggedEndA. Okg€un Alcan et al. Journal of PeriAnesthesia Nursing 38 (2023) 611−615

TaggedPIn clinical practice, a combination of active warming approaches is usually used to prevent IIH. However, there is insufficient evidence to show whether this is more clinically effective than use of a single active warming device.1,13 Few studies have compared the efficacy of combined warming strategies.16-18 Therefore, this study was carried out to compare the efficacy of a single intraoperative active warming method versus combined methods in IIH prevention. TaggedEnd

TaggedH1Methods TaggedEnd

TaggedPThis prospective, parallel, randomized trial was conducted from June to October 2021 in the operating rooms of a research and train- ing hospital. TaggedEnd

TaggedH2Study Sample TaggedEnd

TaggedPThe study sample is consisted of 123 patients who met the inclu- sion criteria. Patients with the following criteria were included: ages 18 and 64 years, American Society of Anesthesiologists (ASA) physi- cal status class I, II or III, and undergoing scheduled orthopedic sur- gery lasting more than 30 minutes under spinal anesthesia. Exclusion criteria were being morbidly obese or cachectic, having preoperative body temperature below 368C, and scheduled for surgery under general anesthesia. A prior power analysis using the G-power 3.1 sta- tistical program calculated the sample size as 41 patients per group with 0.85 power, alpha of 0.05, and an effect size of 0.40. TaggedEnd

TaggedH2Randomization TaggedEnd

TaggedPThe patients were allocated by stratified randomization in the preoperative period based on gender to limited inequalities that may arise between groups. Then the permutation method was used to cre- ate equality between the layers. With permutation block randomiza- tion, six blocks of six and a block of five were created. After the blocks were created at the last stage for randomization, the random numbers table was randomly randomized on the computer (www. random.org). The lottery method was used to determine which letter would represent the groups. Participants were divided into three groups with an allocation ratio of 1:1:1. The patients were randomly allocated to one of three equal-sized groups (n = 41 each). The researchers responsible for data collection of warming allocation were not blinded and the researcher responsible for data analysis was blinded. TaggedEnd

TaggedH2Warming Procedure TaggedEnd

TaggedPDuring admission to the operating room, all patients were warmed via blankets as per routine institutional practice. All intrave- nous fluids (500 mL or more) and blood products were warmed to 37°C using a warming cabinet. After the patients were positioned on the operating table, warming was started immediately after standard monitoring, anesthesia induction, and surgical draping procedures were completed. The baseline warming temperature was set at 38°C for all patients. For normothermic patients, the warming temperature was maintained at 38°C. If the body temperature of the patients was above 37.5°C, the warming was interrupted. For hypothermic patients, the warming temperature was adjusted to 39°C to 43°C to maintain normothermia. The warming process continued throughout the surgery. Patients were encouraged to inform researchers of any discomfort regarding warming method at any time during surgery. The rewarming methods in the study groups were as follows: TaggedEnd

TaggedPGroup 1: Resistive Warming Mattress Group TaggedEnd TaggedPPatients in Group 1 were warmed with a reusable resistive

heating mattress (Stihler Electronics, Germany) during surgery. The

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TaggedEndTaggedPresistive heating mattress was laid on the operating table before the patient was placed on the operating table. A cotton sheet was placed as a barrier between the patient and the entire surface of the mat- tress. The mattress was disinfected with alcohol-based disinfectants prior to use on another patient. TaggedEnd

TaggedPGroup 2: Forced-Air Warming System Group TaggedEnd TaggedPPatients in Group 2 were warmed with a sterile disposable forced-

air warming system (Mistral-air plus, Netherlands) during surgery. The patients’ entire body except surgical site was covered with a forced-air warming overbody blanket after anesthesia induction and patient positioning. The used blankets were thrown away in medical waste containers at the end of the surgery. TaggedEnd

TaggedPGroup 3: Combination of Resistive Heating Mattress and Forced-Air Warming System Group TaggedEnd

TaggedPPatients in Group 3 were warmed with a reusable resistive heat- ing mattress (Stihler Electronics, Germany) and a forced-air warming system (Mistral-air plus, Netherlands) during surgery. In this group, the resistive heating mattress was initially placed as described in Group 1. Then the forced-air warming system blanket was placed based as per the protocol for Group 2.TaggedEnd

TaggedH2Outcome Measures TaggedEnd

TaggedPThe primary outcome was the incidence of IIH, defined as a body temperature below 36°C. The body temperature of all patients was measured immediately upon arrival (baseline), then every 15 minutes up to the end of the surgery with a precalibrated infrared tympanic thermometer. Right and left tympanic temperatures were measured, and the average of the measured temperatures was recorded. Also, the researchers observed for episodes of shivering or cyanosis throughout surgery. All patients were asked whether they felt cold during surgery as well as to score their self-rated satisfaction with the warming method on a 10 cm visual analog scale at the end of the surgery. TaggedEnd

TaggedH2Instruments TaggedEnd

TaggedPData were collected via a Data Collection Form developed by the researchers. The form consisted of questions regarding patient demo- graphics, medical history, the type of surgery and anesthesia, the temperature and humidity values of the operating room, the intrao- perative body temperatures, and the patient’s level of satisfaction regarding intraoperative warming methods. All patients participating in this study were trained on the 10 cm visual analog satisfaction scale (0 cm = not at all satisfied, 10 cm = extremely satisfied) in the ward preoperatively. TaggedEnd

TaggedH2Ethical Consideration TaggedEnd

TaggedPThis study was approved by the noninterventional clinical research ethics committee of a university (Date = 10.06.2021 Number = 301). Written permission was obtained from the executive manage- ment of the hospital where the study was conducted. Informed con- sent was obtained from all participants. TaggedEnd

TaggedH2Statistical Analyses TaggedEnd

TaggedPData were analyzed using the Statistical Package for the Social Sci- ences for Windows version 21.0 (IBM SPSS Inc, Armonk, NY). Descrip- tive data were expressed as numbers, percentages, and mean values. Normal distribution of the numerical data was assessed using the Shapiro-Wilk test. chi-squared, Fisher’s exact and Kruskal-Wallis

TaggedEndTable 1 Distribution of Individual Characteristics of Patients According to Group

Group 1 Group 2 Group 3 Test

Age (y) 51.51 § 12.04 53.10 § 12.65 51.61 § 13.61 X2:0.361 p:.835 Gender

Female 56.1% (n:23) 58.5% (n:24) 51.2% (n:21) X2:0.794 p:.658 Male 43.9% (n:18) 41.5% (n:17) 48.8% (n:20)

Body mass index (kg/m2) 26.92§4.72 26.00§3.24 26.13§3.94 X2:0.198 p:.906 Comorbidities

Yes 53.7% (n:22) 73.2% (n:30) 70.7% (n:29) X2:0.127 p:.104 No 46.3% (n:19) 26.8% (n:11) 29.3% (n:12)

Allergies Yes 14.6% (n:6) 12.2% (n:5) 19.5% (n:8) X2:0.647 p:0.543 No 85.4% (n:35) 87.8% (n:36) 80.5% (n:33)

ASA Score I 12.2% (n:5) 4.9% (n:2) 7.3% (n:3) X2:2.571 p:.663 II 82.9% (n:34) 90.2% (n:37) 82.9% (n:34) III 4.9% (n:2) 4.9% (n:2) 9.8% (n:4)

OR temperature (°C) 20.13§0.81 20.0§0.78 20.00§0.85 X2:2.976 p:.226 Humidity level of OR (%) 51.80§5.53 52.37§4.70 51.67§5.19 X2:0.397 p:.820 Duration of surgery (minutes) (median) 70.0 95.0 73.0 X2:0.395 p:0.821

OR, operating room.

TaggedEndA. Okg€un Alcan et al. Journal of PeriAnesthesia Nursing 38 (2023) 611−615

TaggedEndTaggedPtests were used to analyze data. A P value <.05 was considered statis- tically significant. TaggedEnd

TaggedH1Results TaggedEnd

TaggedPDemographic data according to Group are shown in Table 1. Indi- vidual characteristics including age, gender, bodymass index, presence of comorbidities and allergies, ASA score, OR temperature, and humid- ity were homogeneous in three study Groups (Table 1).TaggedEnd

TaggedPThe distribution of the mean temperature values obtained every 15 minutes intraoperatively is shown in Figure 1. The average base- line body temperature was 36.8 § 0.288C for Group 1, 36.8 § 0.258C for Group 2, and 36.9 § 0.278C for Group 3. Baseline body tempera- tures of patients were similar in all three Groups (X2 = 2.508 P = .285). The average intraoperative body temperature was 36.68C § 0.158C for Group 1, 36.68C § 0.18C for Group 2, and 36.68C § 0.158C for Group 3. The average intraoperative body temperatures of patients were similar in the three Groups (X2 = 0.532 P = .770). Body temperature of the patients at the end of surgery was 36.78C § 0.208C for Group 1, 36.78C § 0.28C for Group 2, and 36.78C § 0.288C for Group 3. The average body temperatures of patients at the end of the surgery were similar in the three Groups (X2 = 1.804 P = .406).

TaggedFigure

Figure 1. Distribution of intraoperative body te

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TaggedEndTaggedPThere was no significant difference in body temperature values between the three Groups during the surgery (P > .05). TaggedEnd

TaggedPThe use of a resistive warming mattress intraoperatively increased the body temperature of the patients by 0.08§ 0.318C (range, -0.60 to 0.80) on average. The use of forced-air warming system intraopera- tively increased the body temperature of the patients by 0.128C § 0.298C (range, -0.50 to 0.80) on average. The use of resistive heating mattress and forced-air warming system together intraoperatively increased the body temperature of the patients by 0.138C § 0.358C (range, -0.50 to 1.10) on average. There was no significant difference in body temperature values between the three Groups during the surgery (X2 = 0.351 P = .839). TaggedEnd

TaggedPThe incidence of IIH and related outcomes is shown in Table 2. There was no significant difference between the three Groups in the incidence of IIH (X2 = 0.871 P = .647) and cyanosis (X2 = 2.050 P = .772). The rates of feeling cold (P = .008) and shivering (P = .002) during surgery were significantly higher than the other Groups in Group 3 (Table 2).TaggedEnd

TaggedPThe patients’ average satisfaction scores with the warming method were 8.10 § 1.56 in Group 1, 7.85 § 1.09 in Group 2 and 8.65 § 0.89 in Group 3. The satisfaction score of patients warmed with the combination of resistive heating mattress and forced-air warming

mperatures of patients according to group. TaggedEnd

TaggedEndTable 2 The Incidence of Intraoperative Inadvertent Hypothermia and Related Outcomes

Group 1 Group 2 Group 3 Test

Intraoperative inadvertent hypothermia 9.8% (n = 4) 9.8% (n = 4) 4.9% (n = 2) X2 = 0.871 P = .647 Feeling cold 43.9% (n = 18) 51.2% (n = 21) 73.2% (n = 30) X2 = 0.021 P = .008 Shivering 24.4% (n = 10) 34.1% (n = 14) 61.0% (n = 25) X2 = 12.280 P = .002 Cyanosis - 2.4% (n = 1) 4.9% (n = 2) X2 = 2.050 P = .772 Satisfaction scores 8.10 § 1.56 7.85 § 1.09 8.65 § 0.89 X2 = 10.699 P = .005

P < .05.

TaggedEndA. Okg€un Alcan et al. Journal of PeriAnesthesia Nursing 38 (2023) 611−615

TaggedEndTaggedPsystem was significantly higher than patients randomized in the other two Groups (X2= 10.699 P = .005). TaggedEnd

TaggedH1Discussion TaggedEnd

TaggedPNICE recommends forced-air warming system as the gold standard for prevention of IIH.1 In clinical practice, generally a combination of warming methods are used.1 This study compared the effect of using active warming methods individually and in combination for the pre- vention of IIH. This study indicated a lower incidence of IIH in patients warmed with the combination of a resistive heating mattress and forced-air warming system than patients warmed only with an active method. However, the results of this study indicated that there was no significant difference in body temperature values between the three groups during the surgery. It should be emphasized that this warming combination modality did not prevent IIH totally, but the effect was synergistic.TaggedEnd

TaggedPIn an experimental animal study, it is reported that a combination of warmed and humidified insufflation of carbon dioxide in conjunc- tion with forced-air warming is an effective strategy in the preven- tion of IIH.19 Perez-Protto et al16 compared the effect of circulating- water garment and the combination of a circulating-water mattress and forced-air cover to prevent IIH during major upper-abdominal surgery. They concluded that both methods were comparably effec- tive in maintaining normothermia during surgery.16 In another study, the effect of combined forced-air warming, and circulating-water- mattress was compared with forced-air warming alone in patients undergoing open abdominal surgery. It was noted that mean body temperatures were similar in both groups.17 Similarly, Hi and Ar18

found that routine use of a forced-air warmer in the presence of another warming measure had no significant effect on the body tem- perature during breast lumpectomy. These results supported that the combination of active warming systems does not provide additional effect over that provided by using a single active warming method alone on IIH prevention. Furthermore, it is known that using more equipment does increase the cost, waste, and workload of surgical team. TaggedEnd

TaggedPZhang et al20 found that the combination of a forced-air warming system with an electric blanket is an effective method for elderly patients undergoing transurethral resection of the prostate to retain warmth and manage IIH. These findings were inconsistent with our results. This difference is thought to be related to the younger age of the patients in our study. Another study conducted in the postanes- thesia care unit, concluded that the combination of an electric blan- ket and a forced-air warming system was an effective rewarming method for children with postoperative hypothermia.21 TaggedEnd

TaggedPIt is well established that the use of forced-air warming is effective in increasing patient comfort, which is consistent with the results of this study.20,22 A previous study reported that the satisfaction scores of patients were significantly higher in patients warmed with a com- bination of active warming methods than those warmed with alone active method.20 The results of this study indicated that the satisfac- tion score of patients warmed with the combination of resistive heat- ing mattress and forced-air warming system was significantly higher

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TaggedEndTaggedPthan patients randomized to the other two Groups (X2=10.699 P = .005). TaggedEnd

TaggedH2Limitations TaggedEnd

TaggedPThere are limitations in this study. This study was conducted with younger patients undergoing orthopedic surgery. The results cannot be generalized for other types of surgeries and pediatric or elderly patients. Future studies should include a variety of patient types and surgical procedures to account for differences in length of surgery and ages of patients. This study cannot be generalized to emergen- cies. This study also did not examine the cost-effectiveness of the dif- ferent warming methods. Similar studies investigating the cost effectiveness of combined warming methods are warranted. In addi- tion, the amount of IV fluids used was not measured, and this can influence IIH outcomes. TaggedEnd

TaggedH1Conclusion TaggedEnd

TaggedPIn this study, the incidence of IIH ranged from 4.9% (Group 3) to 9.8% (Group 1 and Group 2). But there was no significant difference in intraoperative body temperatures and incidence of IIH between the three Groups. The combination of a resistive heating mattress and forced-air warming is significantly noninferior in maintaining intraoperative body temperature than using a single active warming method alone. This result suggests that the combination of active warming systems do not provide additional effect on IIH prevention. In addition, this practice also increased incidence of feeling cold and shivering and improved patient satisfaction. The results of this study can be used in decision-making of implementing IIH prevention pro- tocols. Also, future research is needed involving different patient Groups (elderly, children, hypothermic, etc.), different types of sur- gery, and different anesthesia technique. TaggedEnd

TaggedH1Acknowledgments TaggedEnd

TaggedPThe authors thank all the patients who have participated in this study. TaggedEnd

TaggedH1References TaggedEnd

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