Active Warming Group Research Articles

Effect of Prewarming on Postoperative Hypothermia, Vital Signs, and Thermal Comfort: A Randomized Controlled Trial.

This study aimed to determine the effects of preoperative active and passive warming on postoperative hypothermia, vital signs, and perception of thermal comfort in patients scheduled to undergo elective open abdominal surgery. This was a randomized controlled study. The study sample comprised 90 patients (30 in the active warming group, 30 in the passive warming group, and 30 in the control group) who agreed to participate and met the research criteria. According to the comparison of patients' vital signs, a statistically significant difference was observed in terms of patients' preoperative body temperature values (χ2 = 56.959; p = 0.000). A comparison of the patients' postoperative thermal comfort perception scores yielded a statistically significant difference (χ2 = 39.693; p = 0.000). Postoperative comfort scores in the active warming group were significantly higher than those in the passive warming and control groups. In conclusion, warming methods are effective in preventing undesirable postoperative hypothermia. The time to reach normothermia after surgery was shorter, vital signs were at a desirable level, and thermal comfort perceptions were higher in patients who were prewarmed. ClinicalTrials.gov (Identifier: NCT04997694).

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.

The efficacy of active warming in preventing unplanned hypothermia during perioperative period in pediatric surgery patients in a tertiary care center

Aim: To investigate the effects of using the active warming method on children with hypothermia in the perioperative period and examining the effects of hypothermia on awakening time, pain, shivering and hospital stay. Methods: This study included patients 18 years of age and younger who underwent surgery in the pediatric surgery department of a tertiary hospital. The active warming group consisted of 28 patients and the control group consisted of 29 patients. The first group of patients was actively warmed during the surgery and the second group was treated as the control group and did not actively receive any warming therapy. Preoperative body temperatures of the cases were measured. In addition, body temperatures were recorded every 15 minutes in the intraoperative and postoperative periods. Results: There was no statistically significant difference in preoperative body temperature between the control group and the active warming group. When body temperature were examined in the intraoperative period, there was no significant difference between the groups at the first 15 minutes of operation; however, the mean of the body temperature in active warming group was significantly higher than the control group at the 30th, 45th , and 60th minutes of operation. It was determined that patients in the control group had a longer stay in the hospital and the amount of time for waking at the end of the anesthesia was shorter in the active heating group than in the control group. Conclusions: The results of our study suggest that active heating with a carbon fiber resistant system is an effective method to prevent unplanned hypothermia in operated children.

Efficacy of forced-air warming and warmed intravenous fluid for prevention of hypothermia and shivering during caesarean delivery under spinal anaesthesia: A randomised controlled trial.

Peri-operative hypothermia and shivering are frequent events in patients during caesarean delivery under spinal anaesthesia. We assessed the efficacy of combined pre-anaesthetic forced-air warming in combination with warmed intravenous fluid infusion for preventing hypothermia and shivering during caesarean delivery under spinal anaesthesia. A randomised controlled study. A tertiary care teaching hospital from July 2017 to April 2018. A total of 50 pregnant women, American Society of Anaesthesiologists physical status 2, aged 20 to 45 years, scheduled for caesarean delivery under spinal anaesthesia. Patients were enrolled and randomised into two groups: an active warming group (n = 25), which received combined pre-anaesthetic whole body forced-air warming for 15 min and prewarmed intravenous fluids, and a control group, which received no active warming or warmed fluids (C group; n = 25). Spinal anaesthesia was induced with 10 mg bupivacaine containing fentanyl (10 μg). Tympanic membrane temperature and shivering severity were measured at baseline and every 10 min during surgery, and then every 10 min for 1 h postoperatively. Neonatal outcomes (tympanic membrane temperature at birth, umbilical venous blood pH, Apgar score) were also recorded. The incidences of peri-operative hypothermia (0 vs. 48%, P < 0.001) and shivering (22 vs. 52%, P = 0.031) were significantly lower in the active warming than in the C group. The maximum temperature change was also significantly lower in the active warming than in the C group. Maternal thermal comfort scores were higher in the active warming than in the C group. Neonatal parameters were not significantly different between the groups. The combination of pre-anaesthetic forced-air warming and warmed intravenous fluid infusions appears to be effective for preventing hypothermia and shivering during caesarean delivery under spinal anaesthesia. This trial was registered with Clinical Trials.gov (identifier: NCT03256786).

Maintaining intraoperative normothermia reduces blood loss in patients undergoing major operations: a pilot randomized controlled clinical trial

BackgroundInadvertent intraoperative hypothermia (core temperature < 36 °C) is a common but preventable adverse event. This study aimed to determine whether active intraoperative warming reduced bleeding in patients undergoing major operations: open thoracic surgery and hip replacement surgery.Methods/DesignThe study was a pilot, prospective, parallel two-arm randomized controlled trial. Eligible patients were randomly allocated to two groups: passive warming (PW), with application of a cotton blanket (thermal insulation), or active warming (AW), with a forced-air warming system. The primary endpoint was intraoperative blood loss, and secondary endpoints were surgical-site infection, cardiovascular events, and length of stay in the post-anesthesia care unit, intensive care unit, and hospital.ResultsSixty-two patients were enrolled. Forced-air active warming maintained intraoperative normothermia in all AW subjects, whereas intraoperative hypothermia occurred in 21/32 (71.8%) of PW patients (p = 0.000). The volume of blood loss was more in the PW group (682 ± 426 ml) than in the AW group (464 ± 324 ml) (p < 0.021), and the perioperative hemoglobin value declined more in the PW group (28.6 ± 17.5 g/L) than in the AW group (21.0 ± 9.9 g/L) (p = 0.045). However, there were no difference in other clinical outcomes between two groups.ConclusionIntraoperative active warming is associated with less blood loss than passive warming in open thoracic and hip replacement operations in this pilot study.Trial registrationThis trial was registered with Clinicaltrials.gov (Identifier: NCT02214524) on 27 August 2014.

Effectiveness of Active Warming Intervention for Women Undergoing Cesarean Section: A Systematic Review and Meta-analysis

Purpose The aim of this study was to synthesize the best available evidence for active warming interventions during cesarean section. Methods A database search was done for randomized controlled trials utilizing active warming interventions. Maternal temperature, shivering and neonatal temperature were evaluated as outcome variables. Data were analyzed using Cochrane Review Manager software Version 5.3. Results Thirteen studies including 1306 patients were reviewed. The degree of lowering of maternal temperature decreased in the warmed fluids (MD 0.51; p=.004) and warming mattress interventions (MD 0.22; p<.001) compared with control groups. Incidence of shivering was also lower in the active warming group (OR 0.55; p=.003). There was no statistically significant difference in maternal temperature with a forced air warming intervention (MD 0.64; p=.15) or in neonatal temperature (MD 0.12; p=.26). Conclusion Findings show that with warmed fluids and warming mattresses applied during cesarean sections maternal temperature decline was reduced and also the incidence of shivering declined, but no significant effect was observed for forced air warming interventions. These findings provide a basis for developing a warming guideline for women having a cesarean section and will help to improve the quality of care for cesarean section patients. 주요어: ì œì™•ì ˆê°œ, ì €ì²´ì˜¨, 체온, ì „ìœ¨, ê³ ì°° Key words: Cesarean section, Hypothermia, Temperature, Shivering, Review

Tourniquet application after local forearm warming to improve venodilation for peripheral intravenous cannulation in young and middle-aged adults: A single-blind prospective randomized controlled trial

BackgroundLocal forearm warming before tourniquet application is often used to promote venodilation for peripheral intravenous cannulation; however, few studies have compared the effect of tourniquet application with and without local warming on vein size. ObjectiveTo evaluate the effectiveness of tourniquet application after local forearm warming with that of tourniquet application alone in young and middle-aged adults. DesignA single-blind, prospective, parallel group, randomized controlled trial. SettingA national university in Japan. ParticipantsSeventy-two volunteers aged 20–64 years. MethodsParticipants were randomly allocated to one of two groups: tourniquet application for 30s after forearm application of a heat pack warmed to 40°C±2°C for 15min (active warming group; n=36) or tourniquet application for 30s after applying a non-warmed heat pack for 15min (passive warming group; n=36). The primary outcomes were vein cross-sectional area on the forearm, measured after the intervention by blinded research assistants using ultrasound. Secondary outcomes were shortest diameter, and longest diameter of vein on the forearm, forearm skin temperature, body temperature, pulse, systolic blood pressure, and diastolic blood pressure. All outcomes were assessed at the same site before and immediately after the intervention, once per participant. ResultsVein cross-sectional area, shortest vein diameter, and longest vein diameter were significantly increased in the active warming group compared with the passive warming group (p <0.01). Tourniquet application after local warming was superior to tourniquet application alone in increasing vein cross-sectional, shortest diameter, and longest diameter (between-group differences of 2.2mm2, 0.5mm, and 0.5mm, respectively), and in raising skin temperature (between-group difference: 5.2°C). However, there were no significant differences in body temperature, pulse, or systolic or diastolic blood pressure between the groups. There were no adverse events associated with either intervention. ConclusionTourniquet application after local warming was associated with increased forearm vein size when compared with tourniquet application alone, and was demonstrated as being safe. Thus, with demonstrable effects on vein size, we recommend local warming before tourniquet application as a safe and effective technique for improving venodilation.

Active Warming Utilizing Combined IV Fluid and Forced-Air Warming Decreases Hypothermia and Improves Maternal Comfort During Cesarean Delivery: A Randomized Control Trial.

The aim of this study was to apply both IV fluid and forced-air warming to decrease perioperative hypothermia in women undergoing cesarean delivery with spinal anesthesia. The authors hypothesize that combined-modality active warming (AW) would increase maternal temperature on arrival at the postanesthesia care unit (PACU) and decrease the incidence of maternal perioperative hypothermia (<36°C) compared with no AW. Forty-six healthy women (n = 23 per group) undergoing scheduled cesarean delivery with spinal anesthesia (10-12 mg bupivacaine + 10 μg fentanyl) were enrolled in this double-blinded, randomized controlled trial. Women were randomly assigned to receive either AW (warmed IV fluid and lower body forced-air warmer) or no warming (NW; blankets only). SpotOn Monitoring System was used to measure core temperature intraoperatively and for 1 hour postoperatively. The primary outcome measure was maternal temperature on arrival at the PACU. Secondary outcome measures included incidence of maternal perioperative hypothermia (<36°C), incidence of shivering, thermal comfort scores (0-100 scale), Apgar scores, and umbilical cord blood gas analysis. Demographic, obstetric, and surgical data were similar between study groups. The AW group (35.9°C ± 0.5°C) had a significantly higher temperature on arrival at the PACU compared with the NW group (35.5°C ± 0.5°C, P = 0.006; 95% confidence interval of mean difference, 0.1°C-0.7°C). Fourteen (64%) women in the AW group and 20 (91%) in the NW group were hypothermic during the study period (P = 0.031). Median (interquartile range) thermal comfort scores were 100 (95-100) in the AW group and 90 (70-100) in the NW group (P = 0.008). There were no significant differences in the incidence of intraoperative shivering (22% in the AW and 45% in the NW groups; P = 0.11), Apgar scores, or umbilical vein blood gas values between the study groups. Fluid combined with forced-air warming is effective in decreasing the incidence of perioperative hypothermia and improving maternal thermal comfort. However, despite multimodal AW, the majority of women became hypothermic, and shivering was not prevented. The findings suggest that combined AW for cesarean delivery with spinal anesthesia is difficult, and only modest benefit should be expected.

Interventions for treating inadvertent postoperative hypothermia.

Inadvertent postoperative hypothermia (a drop in core body temperature to below 36°C) occurs as an effect of surgery when anaesthetic drugs and exposure of the skin for long periods of time during surgery result in interference with normal temperature regulation. Once hypothermia has occurred, it is important that patients are rewarmed promptly to minimise potential complications. Several different interventions are available for rewarming patients. To estimate the effectiveness of treating inadvertent perioperative hypothermia through postoperative interventions to decrease heat loss and apply passive and active warming systems in adult patients who have undergone surgery. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2014, Issue 2), MEDLINE (Ovid SP) (1956 to 21 February 2014), EMBASE (Ovid SP) (1982 to 21 February 2014), the Institute for Scientific Information (ISI) Web of Science (1950 to 21 February 2014) and the Cumulative Index to Nursing and Allied Health Literature (CINAHL), EBSCO host (1980 to 21 February 2014), as well as reference lists of articles. We also searched www.controlled-trials.com and www.clincialtrials.gov. Randomized controlled trials of postoperative warming interventions aiming to reverse hypothermia compared with control or with each other. Three review authors identified studies for inclusion in this review. One review author extracted data and completed risk of bias assessments; two review authors checked the details. Meta-analysis was conducted when appropriate by using standard methodological procedures as expected by The Cochrane Collaboration. We included 11 trials with 699 participants. Ten trials provided data for analysis. Trials varied in the numbers and types of participants included and in the types of surgery performed. Most trials were at high or unclear risk of bias because of inappropriate or unclear randomization procedures, and because blinding of assessors and participants generally was not possible. This may have influenced results, but it is unclear how the results may have been influenced. Active warming was found to reduce the mean time taken to achieve normothermia by about 30 minutes in comparison with use of warmed cotton blankets (mean difference (MD) -32.13 minutes, 95% confidence interval (CI) -42.55 to -21.71; moderate-quality evidence), but no significant difference in shivering was noted. Active warming was found to reduce mean time taken to achieve normothermia by almost an hour and a half in comparison with use of unwarmed cotton blankets (MD -88.86 minutes, 95% CI -123.49 to -54.23; moderate-quality evidence), and people in the active warming group were less likely to shiver than those in the unwarmed cotton blanket group (Relative Risk=0.61 95% CI= 0.42 to 0.86; low quality evidence). There was no effect on mean temperature difference in degrees celsius at 60 minutes (MD=0.18°C, 95% CI=-0.10 to 0.46; moderate quality evidence), and no data were available in relation to major cardiovascular complications. Forced air warming was found to reduce time taken to achieve normothermia by about one hour in comparison to circulating hot water devices (MD=-54.21 minutes 95% CI= -94.95, -13.47). There was no statistically significant difference between thermal insulation and cotton blankets on mean time to achieve normothermia (MD =-0.29 minutes, 95% CI=-25.47 to 24.89; moderate quality evidence) or shivering (Relative Risk=1.36 95% CI= 0.69 to 2.67; moderate quality evidence), and no data were available for mean temperature difference or major cardiovascular complications. Insufficient evidence was available about other comparisons, adverse effects or any other secondary outcomes. Active warming, particularly forced air warming, appears to offer a clinically important reduction in mean time taken to achieve normothermia (normal body temperature between 36°C and 37.5°C) in patients with postoperative hypothermia. However, high-quality evidence on other important clinical outcomes is lacking; therefore it is unclear whether active warming offers other benefits and harms. High-quality evidence on other warming methods is also lacking; therefore it is unclear whether other rewarming methods are effective in reversing postoperative hypothermia.

Local warming and insertion of peripheral venous cannulas: single blinded prospective randomised controlled trial and single blinded randomised crossover trial

Objective: To determine whether local warming of the lower arm and hand facilitates peripheral venous cannulation.Design: Single blinded prospective randomised controlled trial and single blinded randomised crossover trial.Setting: Neurosurgical unit...

Effects of Preinduction and Intraoperative Warming During Major Laparotomy

We have investigated the influence of active warming before and during operation on blood loss, transfusion requirements, duration of stay in the post-anaesthesia care unit (PACU) and perioperative costs in 40 patients undergoing major abdominal surgery. Patients were allocated randomly to one of two groups: in the study group (n = 20), patients were actively warmed using forced air for 30 min before induction of general anaesthesia and during anaesthesia. Passive protection against heat loss consisted of circulating water mattresses, blankets and fluid warming devices, and was used both in the active warming group and in the control group (n = 20). At the end of surgery the change in core temperature was significantly less in the group of actively warmed patients (0.5 (SD 0.8) degree C vs 1.5 (0.8) degree C; P < or = 0.01). Blood loss and transfusion requirements were less in the actively warmed patients, who had a shorter duration of stay in the PACU (94 (SD 42) min vs 217 (169) min; P < or = 0.01) and a 24% reduction in total anaesthetic costs.

Effects of preinduction and intraoperative warming during major laparotomy

We have investigated the influence of active warming before and during operation on blood loss, transfusion requirements, duration of stay in the post-anaesthesia care unit (PACU) and perioperative costs in 40 patients undergoing major abdominal surgery. Patients were allocated randomly to one of two groups: in the study group (n = 20), patients were actively warmed using forced air for 30 min before induction of general anaesthesia and during anaesthesia. Passive protection against heat loss consisted of circulating water mattresses, blankets and fluid warming devices, and was used both in the active warming group and in the control group (n = 20). At the end of surgery the change in core temperature was significantly less in the group of actively warmed patients (0.5 (SD 0.8) degree C vs 1.5 (0.8) degree C; P < or = 0.01). Blood loss and transfusion requirements were less in the actively warmed patients, who had a shorter duration of stay in the PACU (94 (SD 42) min vs 217 (169) min; P < or = 0.01) and a 24% reduction in total anaesthetic costs.

Prevention of hypothermia during hip surgery: effect of passive compared with active skin surface warming

We have measured aural canal (core) and skin temperatures, and body heat content in 45 patients undergoing elective hip arthroplasty. They received general anaesthesia which included thiopentone, vecuronium and enflurane and nitrous oxide in oxygen. Patients were allocated randomly to three groups: group 1, control (n = 15), received no intraoperative warming device; group 2 had passive skin surface warming (metallized plastic sheet, Thermolite (n = 15); and group 3 had active skin surface warming (forced heated air, Bair-Hugger) (n = 15). Duration of surgery, fluid administration and the temperature and relative humidity of the operating theatre were similar for the three groups. Core temperature and mean body heat content decreased significantly during surgery in groups 1 and 2 (aural canal temperature 1.5 and 1.0 degrees C, and mean body heat content 287 and 189 kJ, respectively), while in group 3 these variables remained near preoperative values (P = 0.001). Mean skin and hand temperatures decreased in the control group, increased in the active warming group and were unchanged in the passive warming group (P < 0.005), indicating that the forced heated air system was very efficient in providing thermal homeostasis during surgery, while the metallized plastic sheet was able to insulate the skin only from radiant and convective heat losses, without attenuating the reduction in core temperature.

Prevention of body temperature reduction (afterdrop) following hypothermic perfusion

This study investigated the possibility of preventing the postoperative reduction in body temperature (afterdrop) which followed a period of hypothermic cardiopulmonary bypass. In addition to warming all the infused fluids and inspired gases, the patients also had active warming by way of a system of hot water mattresses and limb jackets. In the eight male patients randomly allocated to the active treatment there were no significant changes on the central (aural) temperature in the five hours following the end of perfusion. The eight male control patients showed significant ( p&lt;0.05) falls in central temperature from 36.5 (0.3)°C at the end of bypass to 35.3 (0.2)°C and 35.0 (0.2)°C at one and two hours postperfusion. In addition, the mean skin temperatures were always significantly higher in the active warming group during the study period. This maintenance of a stable body temperature was reflected in the carbon dioxide production, which showed no significant changes in the actively warmed group. In the control group the carbon dioxide production was reduced from the preoperative value of 189 (26)ml/min (mean (SEM)) to 155 (9.2)ml/min ( p&lt;0.05) at two hours postperfusion. These data show that afterdrop following perfusion can be prevented by an aggressive rewarming policy and suggest that this may have beneficial effects in producing a metabolically and physiologically more stable patient.