Incidence and associated factors of perioperative hypothermia in adult patients at a university-based, tertiary care hospital in Thailand.

BACKGROUND: Inadvertent perioperative hypothermia is an unintentional drop in core body temperature to less than 36 °C perioperatively and is associated with many negative outcomes such as infection, a prolonged stay in a recovery room, and decreased patient comfort. OBJECTIVE: To determine the incidence of postoperative hypothermia and to identify the associated factors with postoperative hypothermia in patients undergoing head, neck, breast, general, urology, and vascular surgery. The incidences of pre- and intraoperative hypothermia were examined as the intermediate outcomes. MATERIALS AND METHODS: A retrospective chart review was conducted in adult patients undergoing surgery at a university hospital in a developing country for two months (October to November 2019). Temperatures below 36 °C were defined as hypothermia. Univariate and multivariate analyses were used to identify factors associated with postoperative hypothermia. RESULTS: A total of 742 patients were analyzed, the incidence of postoperative hypothermia was 11.9% (95% CI 9.7%-14.3%), and preoperative hypothermia was 0.4% (95% CI 0.08%-1.2%). Of the 117 patients with intraoperative core temperature monitoring, the incidence of intraoperative hypothermia was 73.5% (95% CI 58.8-90.8%), and hypothermia occurred most commonly after anesthesia induction. Associated factors of postoperative hypothermia were ASA physical status III-IV (OR = 1.78, 95%CI 1.08-2.93, p = 0.023) and preoperative hypothermia (OR = 17.99, 95%CI = 1.57-206.89, p = 0.020). Patients with postoperative hypothermia had a significantly longer stay in the PACU (100 min vs. 90 min, p = 0.047) and a lower temperature when discharged from PACU (36.2 °C vs. 36.5 °C, p < 0.001) than those without hypothermia. CONCLUSION: This study confirms that perioperative hypothermia remains a common problem, especially in the intraoperative and postoperative periods. High ASA physical status and preoperative hypothermia were associated factors of postoperative hypothermia. In order to minimize the incidence of perioperative hypothermia and enhance patient outcomes, appropriate temperature management should be emphasized in patients at high risk. REGISTRATION: Clinical Trials.gov (NCT04307095) (13/03/2020).

The Development of the Inadvertent Perioperative Hypothermia Knowledge Test (IPH-KT).

PURPOSE: This study aimed to develop the inadvertent perioperative hypothermia knowledge test (IPH-KT) for health care professionals and examine its validity and reliability. DESIGN: The methodological and cross-sectional study design was used. METHODS: The research was carried out with 326 nursing students in Turkey. Data for the study were collected using a demographic information form and the IPH-KT. FINDINGS: The item difficulty index and item distinctiveness index of the questions included in the draft form of the 25-item test ranged from 0.03 to 0.81 and from 0.25 to 0.99, respectively. After the analyses, 8 items were excluded from the draft test, and the final version of the test consisted of 17 questions. The item difficulty index of the final test ranged from 0.30 to 0.96, and the item distinctiveness index ranged from 0.33 to 0.81. The reliability of the test was determined using the Kuder-Richardson formula 20 and found to be 0.72, indicating high internal consistency. Therefore, the IPH-KT was accepted as a reliable test. CONCLUSIONS: The study revealed that the questions in the IPH-KT had varying difficulty levels and a high ability to discriminate between individuals with knowledge of IPH and those without. The results demonstrated that the test had good content and face validity and showed high reliability for measuring the IPH knowledge of nursing students.

Comparison of two different uses of underbody forced-air warming blankets for the prevention of hypothermia in patients undergoing arthroscopic shoulder surgery: a prospective randomized study.

BACKGROUND: Forced-air warming (FAW) is an effective method of preventing inadvertent perioperative hypothermia (IPH). However, its warming effects can be influenced by the style and position of the FAW blanket. This study aimed to compare the effects of underbody FAW blankets being placed under or over patients in preventing IPH. METHODS: Patients (n=100) undergoing elective arthroscopic shoulder surgery in the lateral decubitus position were randomized into either under body (UB) group or the over body (OB) group (50 per group). The body temperature of the patients was recorded from baseline to the end of anesthesia. The incidences of postoperative hypothermia and shivering were also collected. RESULTS: A steady decline in the body temperature was observed in both groups up to 60 minutes after the start of FAW. After 60 minutes of warming, the OB group showed a gradual increase in the body temperature. However, the body temperature still decreased in UB group until 75 minutes, with a low of 35.7℃ ± 0.4℃. Then the body temperature increased mildly and reached 35.8℃ ± 0.4℃ at 90 minutes. After 45 minutes of warming, the body temperature between the groups was significantly different (P < 0.05). The incidence of postoperative hypothermia in the UB group was significantly higher than that in the OB group (P = 0.023). CONCLUSIONS: The body temperature was significantly better with the use of underbody FAW blankets placed over patients than with them placed under patients. However, there was not a clinically significant difference in body temperature. The incidence of postoperative hypothermia was much lower in the OB group. Therefore, placing underbody FAW blankets over patients is recommended for the prevention of IPH in patients undergoing arthroscopic shoulder surgery. TRIAL REGISTRATION: This single-center, prospective, RCT has completed the registration of the Chinese Clinical Trial Center at 13/1/2021 with the registration number ChiCTR2100042071 . It was conducted from 14/1/2021 to 30/10/2021 as a single, blinded trial in Sichuan Provincial Orthopedic Hospital.

Using a Normothermia Bundle With Perioperative Prewarming to Reduce Patient Hypothermia.

PURPOSE: To determine if implementing a normothermia bundle, which includes preoperative forced-air warming blankets, reduces incidence of inadvertent perioperative hypothermia (IPH). DESIGN: Intervention study using retrospective chart review. METHODS: Patients received a preoperative forced-air warming blanket and temperature management with the normothermia bundle. Temperature status data was collected from patient charts to evaluate the incidences of IPH and findings from this data analysis was used to measure improvement in perioperative temperature management. FINDINGS: Of 200 patients, 63 (31.5%) remained normothermic, 37 (18.5%) had at least one documented hypothermic temperature, and 100 (50%) had no documented temperature during the intraoperative phase of care. Although compliance with intraoperative temperature monitoring decreased by 13% postintervention, the incidence of documented IPH in reviewed records was decreased by 3.6-fold. CONCLUSION: Implementing a normothermia bundle that includes a preoperative forced-air warming blanket may lower the incidences of IPH, especially in surgical cases lasting over 120 minutes.

Comparing Forced-Air to Resistive-Polymer Warming for Perioperative Temperature Management: A Retrospective Study.

PURPOSE: Compare perioperative temperature management between forced-air warming (FAW) and resistive-polymer heating blankets (RHBs). DESIGN: A retrospective, quasi-experimental study. METHODS: Retrospective data analysis of nonspine orthopedic cases (N = 426) over a one-year period including FAW (n = 119) and RHBs (n = 307). FINDINGS: FAW was associated with a significantly higher final intraoperative temperature (P = .001, d = 0.46) than the RHB. The incidence of hypothermia was not found to be significantly different at the end (P = .102) or anytime throughout surgery (P = .270). Of all patients who started hypothermic, the FAW group had a lower incidence of hypothermia at the end of surgery (P = .023). CONCLUSIONS: FAW was associated with higher final temperatures and a greater number of normothermic patients than RHBs. However, no causal relationship between a warming device and hypothermia incidence should be assumed.

"Keeping Them Warm"-A Randomized Controlled Trial of Two Passive Perioperative Warming Methods.

PURPOSE: Inadvertent perioperative hypothermia is a common problem for patients undergoing surgery. Heat redistribution from the body's core to the periphery after induction of anesthesia is the major contributor. DESIGN: A prospective randomized controlled trial was conducted to determine if reflective blankets are more effective than cotton blankets in reducing the core-peripheral temperature gradient and increasing peripheral compartment heat content during the preoperative phase among adult patients undergoing elective surgery of less than 1 hour. About 328 adult patients undergoing general anesthesia were randomly allocated into two groups. METHODS: Data were analyzed using independent t tests for continuous variables and chi-square tests for categorical variables. FINDINGS: There was a significantly smaller reduction in temporal artery/foot temperature gradient (1.13 vs 1.64°C, P < .001) and a significant increase in foot temperature (0.64 vs 0.11°C, P < .001) in the reflective blanket group. CONCLUSIONS: Reflective blankets are more effective than cotton blankets in warming patients' periphery and reducing core-peripheral temperature gradient preoperatively. AUSTRALIAN NEW ZEALAND CLINICAL TRIALS REGISTRY NUMBER: ACTRN12614000931673 (retrospective registration).

Inadvertent perioperative hypothermia prevention strategies for urology surgical patients who received a blood transfusion: A retrospective analysis.

OBJECTIVES: This study aimed to establish whether hypothermia was present in patients who required a blood transfusion and underwent a urology procedure, as well as identify staff knowledge and understanding. PATIENTS AND METHODS: A staff survey was conducted with respondents from a range of clinical settings, with some staff working across more than one area. A retrospective review of 46 medical records was conducted between January 2021 and July 2022. All data were exported into an Excel spreadsheet and analysed. RESULTS: Staff (70%) were unaware of guidelines informing thermoregulation practices; however, 90% understood the importance of normothermia in the perioperative environment. Medical record review demonstrated temperature monitoring and intervention implementation varied across the perioperative journey, with 20% of patients hypothermic on admission and 89% of the cohort having two or more risk factors. CONCLUSION: There is no formal process for the management of inadvertent perioperative hypothermia throughout the patient journey at the hospital. A variety of intrinsic factors (age, patient comorbidities, American Society of Anaesthesiologists score) and external factors (patient waiting times, anaesthetic modality, type of procedure, environmental influences), impact each patient's risk of inadvertent perioperative hypothermia.

Perioperative active warming strategies in children: a protocol for a multicentre, prospective, randomized controlled trial.

Introduction: Inadvertent perioperative hypothermia (IPH) refers to a core body temperature lower than 36.0 °C, which can contribute to many adverse events. The special physiological characteristics in children further increase the incidence of IPH. Therefore, it is very important to perform effective perioperative warming measures for children. Traditional passive warming measures with additional layers have limited thermal insulation effects. Active warming measures might be the better choice, and most measures have achieved good effects in adults. This study combines a variety of active warming measures to propose perioperative active warming strategies and aims to verify the feasibility and thermal insulation effects of perioperative active warming strategies in children. Methods: This study is a multicentre, prospective, randomized controlled trial. From August 2022 to July 2024, 400 paediatric patients undergoing elective surgery will be recruited in four centres and randomly divided into the active warming strategies group and control group at a ratio of 1:1. The primary outcome is the perioperative cumulative hypothermia effect value (Σ ΔTi × Δti, i = 1…, n). Multiple complications covering the anaesthesia recovery period and postoperative hospitalization will be considered as secondary outcomes to comprehensively analyse the prognosis. Trial registration: ClinicalTrials.gov identifier: ChiCTR2200062168. Registered on July 26th, 2022. Registered with the name of "Perioperative Active Warming Strategies in Children: A multicenter, prospective, randomized controlled trial". URL:http://www.chictr.org.cn/showproj.aspx?proj=172778.

Effect of Forced-Air Warming Blanket on Perioperative Hypothermia in Elderly Patients Undergoing Laparoscopic Radical Resection of Colorectal Cancer.

The study aimed to evaluate the effect of forced-air warming blanket combined with conventional thermal insulation measures on inadvertent perioperative hypothermia (IPH) in elderly patients undergoing laparoscopic radical resection of colorectal cancer. A total of 70 elderly patients undergoing laparoscopic radical resection of colorectal cancer with general anesthesia were included, and divided into conventional warming treatment (CT) group or forced-air warming treatment (FT) group. In the FT group, based on the conventional warming strategy, patients received prewarming with the forced-air warming blanket (38°C) for ≥20 minutes before induction of anesthesia, and received this treatment continuously during operation. The core body temperature, recovery time from anesthesia, extubating time, and length of stay in the postanesthesia care unit were recorded. The incidence of IPH and postoperative shivering was observed. The incidence of IPH was significantly lower, and average minimum body temperature during the operation was significantly higher in the FT group than that in the CT group (5.7% vs. 22.8% and 36.23°C vs. 35.89°C, respectively). The intraoperative body temperature decreased less (0.32°C vs. 0.69°C), the recovery time from anesthesia was faster (12.8 minutes vs. 17.1 minutes), and the incidence of postoperative shivering was less (2.8% vs. 28.6%) in the FT group than the CT group. In elderly patients undergoing laparoscopic radical resection of colorectal cancer, use of forced-air warming blankets combined with conventional warming measures is more effective to maintain normal body temperature during the perioperative period and reduce the incidence of IPH.

Resistant fabric warming is a viable alternative to forced-air warming to prevent inadvertent perioperative hypothermia during hemiarthroplasty in the elderly.

BACKGROUND: Surgical site infection (SSI) is associated with inadvertent perioperative hypothermia (IPH). This can be prevented by active patient warming. However, results from comparisons of warming techniques are conflicting. They are based mostly on elective surgery, are from small numbers of patients, and are dominated by the market leader, forced-air warming (FAW). Furthermore, the definition of hypothermia is debatable and systematic reviews of warming systems conclude that a stricter control of temperature is required to study the benefits of warming. AIM: To analyse core temperatures in detail in a large subset of elderly patients who took part in a randomized trial of patient warming following hemiarthroplasty who had received constant zero-flux thermometry to record their temperature. METHODS: Regression models with a fixed effect for warming group and covariates related to temperature were compared for 257 participants randomized to FAW or resistant fabric warming (RFW) from a prior clinical trial. FINDINGS: Those in the RFW group were -0.08°C cooler and had a cumulative hypothermia score -1.87 lower than those in the FAW group. There was no difference in the proportion of hypothermic patients at either <36.5°C or <36.0°C. CONCLUSIONS: This is the first study to provide accurate temperature measurements in patients undergoing a procedure predominantly under regional rather than general anaesthetic. It shows that RFW is a viable alternative to FAW for preventing IPH during hemiarthroplasty. Further studies are needed to measure the benefits of patient warming in terms of clinically important outcomes.

Prevention and management of perioperative hypothermia in adult elective surgical patients: A systematic review.

BACKGROUND: Body temperature is tightly regulated with hormonal and cellular metabolism for normal functioning; however perioperative hypothermia is common secondary to anesthesia and surgical exposure.Prevention and maintaining body temperature should be started 1-2hrs before induction of anesthesia, to do this both active and passive warming system are effective to prevent complications associated with perioperative hypothermia. METHODS: The aim of this systematic review is to develop a clear clinical practice protocol in prevention and management of perioperative hypothermia for elective adult surgical patients.The study is conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline 2020. After formulating clear criteria for the evidences to be included an appropriate method of searching was conducted by using the Pub Med, Google scholar and Cochrane library using the following MeSH terms: (inadvertent hypothermia AND anesthesia, hypothermia AND perioperative management and thermoregulation AND anesthesia) were used to draw evidences.After a reasonable amount of evidences were collected, appraisal and evaluation of study quality was based on WHO 2011 level of evidence and degree of recommendation. Final conclusions and recommendations are done by balancing the benefits and downsides of alternative management strategies for perioperative management of hypothermia.This systematic review registered with research registry unique identifying number (UIN) of "reviewregistry1253" in addition the overall AMSTAR 2 quality of this systematic review is moderate level. DISCUSSION: Preserving a patient's body temperature during anesthesia and surgery is to minimize heat loss by reducing radiation and convection from the skin, evaporation from exposed surgical areas, and cooling caused by the introduction of cold intravenous fluids. CONCLUSION: Hypothermia is least monitored complication during anesthesia and surgery results cardiac abnormalities, impaired wound healing, increased surgical site infections, shivering and delayed postoperative recovery, and coagulopathies.

Protocol Implementation for Normothermia in Surgery Settings in Italy: Budget-Impact Analysis.

INTRODUCTION: Hypothermia is a well-known risk of the perioperative period and considered a preventable effect of anesthesia care. Nevertheless, it is not fully controlled, causing a number of adverse outcomes following surgical operations and thus increasing length of stay in hospital and treatment costs. The aim of this study was to assess the budget impact (BI) of the implementation of proactive strategies to prevent inadvertent perioperative hypothermia (IPH) in surgical patients in Italy, as recommended by international guidelines and by a good clinical practice (GCP) guideline of the Italian Society of Anesthesia, Analgesia, Reanimation, and Intensive Care. METHODS: BI was calculated over a 3-year period from the perspective of the Italian National Health Service (NHS). Model inputs were extracted from national literature when available and otherwise from international sources. The reference analytic model was based on the cost-effectiveness analysis of the National Institute for Health and Care Excellence clinical guidance 65. Estimates were based on assessments made about current malpractice in Italy and on a hypothesis of how future practice might change by implementing the GCP. Model output included overall BI results, variations in the number of warmed patients, medical-device average costs and use of mix. RESULTS: The base-case estimate quantified a decrease of 35% in extra days of hospital stay due to IPH and a net BI of -€60.92 million. CONCLUSION: Increasing protocol adoption for preventing IPH would lead to both clinical advantages and significant savings for the NHS. Its large diffusion in Italian hospitals is thus desirable.

The Effectiveness of Four Intervention Methods for Preventing Inadvertent Perioperative Hypothermia During Total Knee or Total Hip Arthroplasty.

Inadvertent perioperative hypothermia (IPH) occurs when a patient experiences a core temperature below 36° C (96.8° F) in perioperative settings and is a preventable risk factor for anesthesia- and surgery-related complications. Forced-air warming is an effective method to maintain normothermia. This study compared four interventions for preventing IPH for 120 patients undergoing primary elective unilateral total knee or total hip arthroplasty. The study was based on a time series nonequivalent comparison group design to investigate whether the incidence of IPH differed among treatment groups. We also sought to determine whether the patients' preoperative perceptions of warmth or cold correlated with core body temperatures. Patients receiving convective warming and prewarming appeared to experience fewer IPH events than patients in the other study groups. This study suggests that hypothermia is a common issue for patients undergoing total knee or total hip arthroplasty and that it may be possible to reduce its frequency.

Comparison of two forced-air warming devices during foot and ankle surgery: a randomised controlled trial.

Inadvertent perioperative hypothermia is a frequent problem associated with surgical patients which can have significant consequences during surgery and in the immediate postoperative period. We compared 35 randomised patients using over vs. under body forced air heating. There were no statistically significant differences between some demographic and surgical parameters such as: age, weight, height, body mass index, length of anaesthesia and operation. Statistically significant differences were found between the patient's admission to the operating room and 30 minutes and the end of the procedure on the under body patients group. This study analyses a uniform population of patients (Foot and Ankle Surgery) previously not studied and supports the use of under body blankets.

A nurse-led audit on the incidence and management of inadvertent hypothermia in an operating theatre department of an Irish hospital.

Inadvertent perioperative hypothermia (IPH) is a common problem associated with perioperative patients which can have significant consequences for them during surgery and in the immediate postoperative period. Recognising and managing IPH remains an important aspect of perioperative nursing and is a significant factor in maintaining patient safety, achieving positive surgical outcomes and patient satisfaction. A nurse-led clinical audit was undertaken in the operating theatre department of a major teaching hospital in Ireland to establish the incidence and management of IPH in the department. One hundred (n = 100) patients were included in the audit, both children and adults. Results of the audit were used to inform quality improvement initiatives, with the purpose of improving patient care standards in the operating theatre department in that hospital.

Reducing Implant Infection in Orthopaedics (RIIiO): Results of a pilot study comparing the influence of forced air and resistive fabric warming technologies on postoperative infections following orthopaedic implant surgery.

BACKGROUND: Active warming during surgery prevents perioperative hypothermia but the effectiveness and postoperative infection rates may differ between warming technologies. AIM: To establish the recruitment and data management strategies needed for a full trial comparing postoperative infection rates associated with forced air warming (FAW) versus resistive fabric warming (RFW) in patients aged >65 years undergoing hemiarthroplasty following fractured neck of femur. METHODS: Participants were randomized 1:1 in permuted blocks to FAW or RFW. Hypothermia was defined as a temperature of <36°C at the end of surgery. Primary outcomes were the number of participants recruited and the number with definitive deep surgical site infections. FINDINGS: A total of 515 participants were randomized at six sites over a period of 18 months. Follow-up was completed for 70.1%. Thirty-seven participants were hypothermic (7.5% in the FAW group; 9.7% in the RFW group). The mean temperatures before anaesthesia and at the end of surgery were similar. For the primary clinical outcome, there were four deep surgical site infections in the FAW group and three in the RFW group. All participants who developed a postoperative infection had antibiotic prophylaxis, a cemented prosthesis, and were operated under laminar airflow; none was hypothermic. There were no serious adverse events related to warming. CONCLUSION: Surgical site infections were identified in both groups. Progression from the pilot to the full trial is possible but will need to take account of the high attrition rate.

The health economic benefits of perioperative patient warming for prevention of blood loss and transfusion requirements as a consequence of inadvertent perioperative hypothermia.

Active warming of patients is recommended by The National Institute for Health and Care Excellence (NICE) to prevent inadvertent perioperative hypothermia (IPH). This paper examines the cost effectiveness of one consequence of IPH, an increase in blood loss and the resulting transfusion risk. We quantified the risk and modelled two patient pathways, one with and one without warming, across two different surgery types. We were able to demonstrate the cost effectiveness of active warming based on one consequence even allowing for uncertainties in the model.

Does the addition of active body warming to in-line intravenous fluid warming prevent maternal hypothermia during elective caesarean section? A randomised controlled trial.

INTRODUCTION: Inadvertent perioperative hypothermia occurs frequently during elective caesarean section but perioperative active body warming is not widely used. There is a paucity of evidence of its use in the obstetric population, and no applicable guidelines. We set out to identify a superior active warming method for preventing inadvertent perioperative hypothermia. METHODS: Following ethical approval, 132 women presenting for uncomplicated elective caesarean section under spinal anaesthesia were recruited. All participants received in-line intravenous fluid warming and were randomised to one of three parallel groups: no active body warming; forced air warming; and conduction mattress warming. The primary outcome was the difference in mean core temperature, measured on admission to the recovery room, between study groups. Core temperature and thermal comfort were measured perioperatively at 15-min intervals. Estimated blood loss, haemoglobin change, length of hospital stay and neonatal core temperature were also recorded. RESULTS: One-hundred-and-thirty-one women completed the study. There was no significant difference in mean core temperature on admission to the recovery room (36.6°C vs. 36.6°C vs. 36.6°C, η2=0.005, P=0.74). Maternal hypothermia was prevented in all groups with only 0.3% hypothermic at any of the temperature measurements (3/1016). There was no difference in mean neonatal core temperature (36.3°C vs. 36.3°C vs. 36.3°C, η2=0.003, P=0.82); however, 59.4% (76/128) of all neonates were hypothermic. CONCLUSION: In-line intravenous fluid warming is sufficient to prevent maternal hypothermia and maintain core temperature. The addition of active body warming conferred no added benefit.