Intraoperative Forced-air Warming Research Articles

SP9.8 An Audit of Intraoperative Hypothermia Rates in Adults Undergoing Emergency Surgery in a Tertiary General Surgical Unit and Evaluation of the Efficacy of Preoperative and Intraoperative Forced-Air Warming on Achieving Intraoperative Normothermia

Abstract Aims Surgical site infections (SSIs) inflict significant economic burden on the NHS. Preoperative and intraoperative hypothermia are risk factors for SSIs. Evidence shows that maintenance of intraoperative normothermia significantly reduces SSI rates. Perioperative SSI bundles addressing factors including hair removal, antibiotic prophylaxis, skin preparation, drape positioning, and hypothermia are critical to improving SSI rates. We aim to audit rates of intraoperative hypothermia in our surgical caseload and evaluate the efficacy of preoperative and intraoperative forced-air warming through bespoke gowns in achieving intraoperative normothermia. Methods We conducted a retrospective audit of the intraoperative core temperatures of all adult patients undergoing surgical procedures on the emergency theatre list of a general surgery department and who had a temperature at knife-to-skin recorded (n=88). We then ran a prospective trial, outfitting patients listed for surgery (n=15) with forced-air warming gowns. Patients underwent forced-air warming with the gowns for 45 minutes on the surgical ward, throughout anaesthetic induction, and intraoperatively. Patient core temperature was measured at baseline, upon arrival at the anaesthetic room, and at knife-to-skin. Results Baseline audit data showed over 18% of patients were hypothermic at knife-to-skin. Contrastingly, 100% of patients wearing forced-air warming gowns were normothermic at knife-to-skin. The mean core temperature at knife-to-skin was significantly higher in patients wearing warming gowns (p=0.012). Conclusions Forced-air warming gowns are superior to traditional hospital gowns, blankets and surgical access forced-air warming devices in achieving intraoperative normothermia. They are an effective, sustainable, and cost-neutral, ‘all-in-one’ alternative to current perioperative protocol and will reduce SSI rates.

Forced-air warming and continuous core temperature monitoring with zero-heat-flux thermometry during cesarean section: a retrospective observational cohort study

BackgroundOver 30% of parturients undergoing spinal anesthesia for cesarean section become intraoperatively hypothermic. This study assessed the magnitude of hypothermic insult in parturients and newborns using continuous, high-resolution thermometry and evaluated the efficiency of intraoperative forced-air warming for prevention of hypothermia. MethodsOne hundred and eleven parturients admitted for elective or emergency cesarean section under spinal anesthesia with newborn bonding over a 5-month period were included in this retrospective observational cohort study. Patients were divided into two groups: the passive insulation group, who received no active warming, and the active warming group, who received convective warming through an underbody blanket. Core body temperature was continuously monitored by zero-heat-flux thermometry and automatically recorded by data-loggers. The primary outcome was the incidence of hypothermia in the operating and recovery room. Neonatal outcomes were also analyzed. ResultsThe patients in the passive insulation group had significantly lower temperatures in the operating room compared to the actively warmed group (36.4°C vs. 36.6°C, p = 0.005), including temperature at skin closure (36.5°C vs. 36.7°C, p = 0.017). The temperature of the newborns after discharge from the postanesthetic care unit was lower in the passive insulation group (36.7°C vs. 37.0°C, p = 0.002); thirteen (15%) of the newborns were hypothermic, compared to three (4%) in the active warming group (p < 0.01). ConclusionForced-air warming decreases perioperative hypothermia in parturients undergoing cesarean section but does not entirely prevent hypothermia in newborns while bonding. Therefore, it can be effectively used for cesarean section, but special attention should be given to neonates.

Effect of active warming during general anaesthesia on post-operative body temperature, shivering, thermal comfort, pain, nausea and vomiting in adult patients: a randomized clinical trials protocol

&lt;p&gt;&lt;strong&gt;Background: &lt;/strong&gt;This study aims to investigate the effects of individual and combined use of intraoperative forced-air warming and warmed intravenous and irrigation fluids on post-operative body temperature, shivering, thermal comfort, pain, nausea and vomiting in adult patients receiving general anaesthesia.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods: &lt;/strong&gt;This is a randomised controlled clinical trial. A 2x2 factorial design will used in the experiment. Eligible patients will be randomly assigned to one of four groups. We attempt to report this randomized controlled trial to comply with the spirit. The study population will consist of 120 adult patients receiving general anaesthesia at university hospitals in Turkey. After the induction of anaesthesia, the first group (n=30) will be warmed with only forced-air warming device, the second group (n=30) will receive only warmed intravenous and irrigation fluids, forced-air warming as well as warmed intravenous (IV) and irrigation fluids will be applied to the third group (n=30), the fourth group (n=30) will consist of the control group without any intervention. Blood and blood products to be applied intraoperatively to all groups will be heated to 37°C.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusions:&lt;/strong&gt; The primary outcome measures are post-operative body temperature, shivering, thermal comfort, pain, nausea and vomiting. The primary results will be subjected to a one-way analysis of variance for covariant such as amount of bleeding and volume of intraoperative fluids.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Trial registration: &lt;/strong&gt;The trial has been registered in clinical trials: https://clinicaltrials.gov/. Registration number: NCT04907617).&lt;/p&gt;

Forced-Air Convection Versus Underbody Conduction Warming Strategies to Maintain Perioperative Normothermia in Patients Undergoing Total Joint Arthroplasty

BackgroundForced-air warming is an established strategy for maintaining perioperative normothermia. However, this warming strategy can potentially contaminate the surgical field by circulating nonsterile air. This study aimed to determine whether changing practice away from this method resulted in non-inferior rates of perioperative hypothermia.MethodsWe performed a chart review of primary total hip and knee arthroplasty patients from 2014 to 2017, when the strategy of intraoperative forced-air warming (FAW) was changed to preoperative FAW along with intraoperative underbody conduction warming (CW) with an underbody warming mattress. Data included patient temperatures throughout all phases of care, blood loss and transfusion requirements, length of postanesthesia care unit (PACU) and hospital stays, and 30-day infection and mortality.ResultsA total of 769 charts were reviewed; 349 patients underwent surgery before the practice change and 420 after. Mean (SD; 95% CI) body temperatures at the time of incision were lower for group 1 than for group 2 (34.55 vs 35.52 °C [0.97 °C; 95% CI, 0.72-1.23 °C]). The average nadir of intraoperative body temperature was lower for group 1 than for group 2 (difference of means, 0.44 °C; 95% CI, 0.18-0.71 °C). Group 2 had a higher percentage of patients who presented hypothermic (temperature <36.0 °C) on arrival in the PACU (12.9% vs 7.7%).ConclusionPreoperative convective warming combined with intraoperative underbody conductive warming maintains normothermia during primary total joint arthroplasty and is non-inferior to forced-air intraoperative warming alone.

The Effect of Forced-Air Warmer, Ondansetron or their Combination on Shivering in Pregnant Women Coming for Elective Cesarean Section under Spinal Anesthesia: A Prospective, Randomized Controlled Comparative Study.

Context:Perioperative shivering can occur in up to 85% of patients undergoing cesarean section under spinal anesthesia. It has many detrimental effects and disrupts early mother-child bonding. Therefore, it should ideally be prevented by either pharmacologic or nonpharmacological means.Aims:The primary aim of this study was to evaluate the efficacy of intraoperative forced-air warming, ondansetron or their combination in preventing perioperative shivering in patients undergoing elective cesarean section under spinal anesthesia.Settings and Design:A prospective randomized controlled comparative study done at the tertiary care center.Subjects and Methods:A total of 120 patients undergoing elective cesarean section under spinal anesthesia were randomly assigned to three groups. Group O received ondansetron 4 mg intravenously (i.v.) after giving block with no forced air warming. Group W received forced-air warming intraoperatively. Group C received ondansetron 4 mg i.v. after giving block plus intraoperative forced-air warming. Core temperature (tympanic membrane) and the arm skin temperature were measured and shivering was graded simultaneously.Statistical Analysis Used:Parametric data were analyzed using one-way ANOVA and Student's paired t-test where ever appropriate. Nonparametric data were analyzed using the Kruskal–Wallis and the Chi-square test. Values of P < 0.05 were considered statistically significant.Results:Shivering incidence was higher in Group O and Group W being 17.5% and 20%, respectively, and least in Group C being 5%. The incidence of Grade ≥3 shivering requiring rescue drug was lower in Group C (2.5%) compared to that of the Groups W (5%) and O (10%) but was not statistically significant (P = 0.21).Conclusions:Combined use of ondansetron and forced- air warmer was more effective in reducing the incidence of shivering in pregnant women during elective cesarean section than when used individually.

Effect of preoperative warming on intraoperative hypothermia: a randomized-controlled trial.

The purpose of this study was to evaluate the effects of preoperative forced-air warming on intraoperative hypothermia. In this randomized-controlled trial, adult patients scheduled for elective, non-cardiac surgery under general anesthesia were stratified by scheduled surgical duration (< 2.5 hr or ≥ 2.5 hr) and then randomized to a pre-warming group using a BairPaws™ forced-air warming system for at least 30 min preoperatively or to a control group with warmed blankets on request. All patients were warmed intraoperatively via convective forced-air warming blankets. Perioperative temperature was measured using the SpotOn™ temperature system consisting of a single-use disposable sensor applied to the participant's forehead. The primary outcome was the magnitude of intraoperative hypothermia calculated as the area under the time-temperature curve for core temperatures < 36°C between induction of general anesthesia and leaving the operating room. Secondary outcomes included surgical site infections, packed red blood cell requirements, and 24 hr postoperative opioid consumption. Two hundred participants were analyzed (101 control; 99 pre-warmed). Pre-warmed participants had a lower median [interquartile range] magnitude of hypothermia than controls (0.00 [0.00-0.12] °C·hr-1 vs 0.05 [0.00-0.36] °C·hr-1, respectively; median difference, -0.01°C·hr-1; 95% confidence interval, -0.04 to 0.00°C·hr-1; P = 0.005). There were no between-group differences in the secondary outcomes. A minimum of 30 min of preoperative forced-air convective warming decreased the overall intraoperative hypothermic exposure. While redistribution hypothermia still occurs despite pre- and intraoperative forced-air warming, their combined application results in greater preservation of intraoperative normothermia compared with intraoperative forced-air warming alone. www.clinicaltrials.gov (NCT02177903). Registered 25 June 2014.

Association between perioperative hypothermia and patient outcomes after thoracic surgery: A single center retrospective analysis.

Hypothermia due to anaesthetic-induced impairment of thermoregulatory control and exposure to a cool environment is common in surgical patients. Peripheral vasodilation due to neuroaxial blockade may aggravate hypothermia. There is few data on perioperative hypothermia in patients undergoing thoracic surgery under combined general and regional anesthesia. We reviewed all thoracic surgical patients between 2006 and 2011 to determine the incidence and extent of hypothermia with or without an epidural anesthesia and evaluated its effect.Around 339 patients underwent lung resection procedures with intraoperative forced-air warming: 197 with general and epidural anesthesia (GA + EPI), 199 with general anesthesia alone (GA). Statistical analyses were performed to determine the association between hypothermia (T < 36°C) and transfusion requirements, length of stay (LOS) in the intensive care unit (ICU), hospital LOS, and in hospital mortality.The overall incidence of hypothermia was 64.3%. Multivariate regression analysis revealed three significant risk factors for the development of hypothermia: long induction time (P = .011), small body surface area (P = .003), and application of more fluid intraoperatively (P < .001). Factors determining the extent of hypothermia were: receiving an open thoracotomy (P = .009), placement and use of an epidural catheter (P = .002), and a lower body mass index (BMI) (P < .001). Additional epidural anesthesia reduced core temperature by 0.26°C (95% CI -0.414 to -0.095°C, P < .05). There was no difference in transfusion requirements, ICU LOS or mortality between both groups. Hospital LOS was longer in patients with hypothermia.More than half of all thoracic patients suffered from hypothermia. A long induction time, small body surface area, and large intraoperative fluid application were independent risk factors for the development of perioperative hypothermia. Additional epidural anesthesia to general anesthesia did not increase the incidence of hypothermia but decreased body core temperature to an-albeit not clinically significant-degree. Patients scheduled for thoracic surgery will probably benefit from an additional period of prewarming prior to induction to reduce the high incidence of perioperative hypothermia.

Effects of aggressive warming on intraoperative temperature and cardiac troponin I in patients undergoing radical resection of esophageal carcinoma

Objective To observe the effects of aggressive warming on intraoperative temperature and cardiac troponin I (cTnI) in patients undergoing radical resection of esophageal carcinoma. Methods Ninety patients undergoing elective radical resection for esophageal carcinoma, aged 45-75 y, ASA Ⅰ or Ⅱ, and random stratification were performed according to the type of operation, then divided into aggressive warming group and routine group. All the patients were covered with the warming blanket at the lower extremities and abdomen. Fluid warming was used in both groups. Separately, aggressive warming group used the forced-air warming right after the patients entering the room to keep a final target core temperature≥36 ℃. However, in the routine group, intraoperative forced-air warming was used only when patient's core temperature decreased to less than 35 ℃ by turning off the warmer when the temperature reached 35.2 ℃ and switched to routine method. Nasopharyngeal temperatures of patients in two groups were recorded at 5 min after induction of anesthesia (T1), the beginning of the operation (T2), 60 min (T3), 120 min (T4), 180 min (T5) after incision and the end of operation(T6). Serum cTnI levels in the two groups were measured at 5 min after induction, 12, 24 h and 48 h after operation. The changes of temperature and serum cTnI were compared between two groups. Postoperative adverse events such as arrhythmia(including atrial fibrillation, supraventricular tachycardia, frequent ventricular premature), anastomotic fistula and lung abscess were also recorded. Results The core temperature in aggressive warming group was above 36 ℃ all the time, while in routine group, the temperature dropped to below 36 ℃ at the time point of T3, and was kept around 35 ℃ during the intraoperative period after T3. Eight patients in routine group experienced a period of hypothermia with the temperature <35 ℃ and used the rescue warming up. The concentrations of serum cTnI in aggressive warming group were significantly lower than those in the routine group at 24, 48 h after operation (P<0.05). The ratio of patients with postoperative serum cTnI elevation in aggressive warming group was significantly lower than that in routine group(14.3% vs 34.9%, P<0.05). Aggressive warming group also had lower rate of arrhythmia and anastomotic fistula (P<0.05) . Conclusions Aggressive warming can avoid the occurrence of hypothermia during the radical resection of esophageal carcinoma and prevent the elevation of serum troponin I after operation. Key words: Esophageal carcinoma; Radical resection; Body temperature protection; Troponin I

Comparative Study of Prevention of Hypothermia Using Preoperative as well as Intraoperative Forced Air Warming with Only Intraoperative Warming in Patients of Surgeries Under General Anaesthesia

Comparative Study of Prevention of Hypothermia Using Preoperative as well as Intraoperative Forced Air Warming with Only Intraoperative Warming in Patients of Surgeries Under General Anaesthesia

A novel thermal compression device for perioperative warming: a randomized trial for feasibility and efficacy

BackgroundInadvertent perioperative hypothermia (IPH) leads to surgical complications and increases length of stay. IPH rates are high with the current standard of care, forced air warming (FAW). Our hypothesis is that a prototype thermal compression device that heats the popliteal fossa and soles of the feet, with lower leg compression, increases perioperative temperatures and reduces IPH compared to the current standard of care.MethodsThirty six female breast surgery patients, at a tertiary academic hospital, were randomized to the device or intraoperative FAW (stage I) with a further 18 patients randomized to the device with a single heating area only (stage II, popliteal fossa or sole of the feet). Stage I: 37 patients recruited (final 36). Stage II: 18 patients recruited (final 18). Inclusion criteria: general anesthesia with esophageal monitoring for over 30 min, legs available and able to fit the device and no contraindications to leg heating or compression. The intervention was: Stage I: Investigational prototype thermal compression device (full device group) or intraoperative FAW. Stage II: Device with only a single heating location. Primary outcomes were perioperative temperatures and incidence of IPH. Secondary outcomes were local skin temperature, general and thermal comfort scores and presence of perioperative complications, including blood loss.ResultsMean temperatures in the full device group were significantly higher than the FAW group in the pre-operative (36.7 vs 36.4 °C, p < 0.001), early intraoperative (36.3 vs 35.9 °C, p < 0.001), intraoperative (36.6 vs 36.2 °C, p < 0.001) and postoperative periods (36.8 vs 36.5 °C, p < 0.001). The incidence of IPH in the device group was also significantly lower (16.7% vs 72.0%, p = 0.001). Thermal comfort scores were significantly higher in the full device group and hypothermia associated wound complications were higher in the FAW group.ConclusionsThe thermal compression device is feasible and has efficacy over the FAW. Further studies are recommended to investigate clinically significant outcomes.Trial registrationclinicaltrials.gov (NCT02155400)

Intra-Operative Warming with a Forced-Air Warmer in Preventing Hypothermia after Tourniquet Deflation in Elderly Patients

This randomized, single-blind study aimed to explore the effects of intra-operative warming with a forced-air warmer in the prevention of hypothermia after tourniquet deflation in elderly patients undergoing unilateral total knee replacement arthroplasty under general anaesthesia. Patients were randomized to receive either intra-operative warming using a forced-air warmer with an upper body blanket (warming group; n = 12) or no intra-operative warming (nonwarming group; n = 12). Oesophageal temperature was measured as core body temperature. At 30 min following tourniquet inflation, the core body temperature started to increase in the warming group whereas it continued to drop in the non-warming group. This difference was statistically significant. The final core body temperature after tourniquet deflation was significantly higher in the warming group (mean +/- SD 36.1 +/- 0.2 degrees C) than in the non-warming group (35.4 +/- 0.3 degrees C). Intra-operative forced-air warming increased the core body temperature before tourniquet deflation and prevented subsequent hypothermia in elderly patients under general anaesthesia.