Epidural versus general anesthesia, ambient operating room temperature, and patient age as predictors of inadvertent hypothermia

The Influence of Total Fat Mass and Skeletal Muscle Mass Index on the Occurrence of Perioperative Hypothermia in Patients Undergoing Open Gastrectomy

Background

Perioperative hypothermia, a common occurrence in patients undergoing general anesthesia, is defined as a core body temperature below 36°C. The relationship between patient body composition and the incidence of hypothermia remains underreported. This study aims to elucidate the association between body composition and perioperative hypothermia in patients undergoing open gastrectomy.

Methods

Patients undergoing open gastrectomy were enrolled in the study. Patients whose bladder temperature was lower than 36°C were allocated to the hypothermia group, and the other patients were allocated to the control group. The patient's body composition was evaluated by bioelectrical impedance analysis.

Results

A total of sixty-eight patients participated in this study. Among them, 34 experienced perioperative hypothermia (bladder temperature below 36°C) and were classified into the hypothermia group, while the remaining 34 were placed in the control group. The hypothermia group had a significantly higher body surface area per body weight. Additionally, the hypothermia group exhibited significantly lower total fat mass, skeletal muscle mass index, and basal metabolic rate (P < 0.05). However, body fat percentage and visceral fat mass did not differ significantly between the groups. Multivariate analysis identified total fat mass below 11.2 kg (HR 4.51, 95% CI: 1.35-15.03, P = 0.014) and skeletal muscle mass index below 10.06 kg/m2 (HR 5.61, 95% CI: 1.86-16.93, P = 0.002) as independent risk factors for perioperative hypothermia.

Conclusions

Low total fat mass and a low skeletal muscle mass index are significant risk factors for perioperative hypothermia in patients undergoing open gastrectomy. These risk factors could improve the accuracy of identifying high-risk patients for perioperative hypothermia.

Outpatient-Based High-Volume Liposuction: A Retrospective Review of 310 Consecutive Patients

BACKGROUND

Currently, the definition of large-volume liposuction is the removal of 5 L or more of total aspirate. Higher volumes of lipoaspirate come into consideration with higher BMIs, because more than 5 L is often required to achieve a satisfactory aesthetic result. The boundaries of what lipoaspirate volume is considered safe are based on historical opinion and are constantly in question.

OBJECTIVES

Because to date there have been no scientific data available to support a specific safe maximum volume of lipoaspirate, the authors discuss necessary conditions for safe high-volume lipoaspirate extraction.

METHODS

This retrospective study included 310 patients who had liposuction of ≥5 L over a 30-month period. All patients had 360° liposuction alone or in combination with other procedures.

RESULTS

Patient ages ranged from 20 to 66 with a mean age of 38.5 (SD = 9.3). Average operative time was 202 minutes (SD = 83.1). Mean total aspirate was 7.5 L (SD = 1.9). An average of 1.84 L (SD = 0.69) of intravenous fluids and 8.99 L (SD = 1.47) of tumescent fluid were administered. Urine output was maintained above 0.5 mL/kg/hr. There were no major cardiopulmonary complications or cases requiring blood transfusion.

CONCLUSIONS

High-volume liposuction is safe if proper preoperative, intraoperative, and postoperative protocols and techniques are employed. The authors believe that this bias should be modified and that sharing their experience with high-volume liposuction may help guide other surgeons to incorporate this practice with confidence and safety for better patient outcomes.

LEVEL OF EVIDENCE: 3

Enhanced recovery after surgery (ERAS) for vascular surgery: an evidence map and scoping review

BACKGROUND

Enhanced recovery after surgery (ERAS) interventions aim to improve patient outcomes. Vascular surgery patients have unique requirements and it is unclear which ERAS interventions are supported by an evidence base.

METHODS

We conducted a scoping review to identify ERAS randomized controlled trials (RCTs) published in the biomedical or nursing literature. We assessed interventions for applicability to vascular surgery and differentiated interventions given at preadmission, preoperative, intraoperative, and postoperative surgery stages. We documented the research in an evidence map.

RESULTS

We identified 76 relevant RCTs. Interventions were mostly administered in preoperative (23 RCTs; 30%) or intraoperative surgery stages (35 RCTs; 46%). The majority of studies reported mortality outcomes (44 RCTs; 58%), but hospital (27 RCTs; 35%) and intensive care unit (9 RCTs; 12%) length of stay outcomes were less consistently described.

CONCLUSION

The ERAS evidence base is growing but contains gaps. Research on preadmission interventions and more consistent reporting of key outcomes is needed.

Measurement of exhaled breath temperature in patients under general anesthesia: A feasibility study

The aim of the present study was to investigate the respiratory parameters that influence the exhaled breath temperature (EBT) and the feasibility of using the latter to monitor the core temperature under general endotracheal anesthesia. A total of 20 patients undergoing abdominal surgery were included in the present study. At the first stage of the experiment, the respiratory rate was adjusted, while the other respiratory parameters [tidal volume, inspiratory and expiratory time ratio (TI:TE), and positive end expiratory pressure (PEEP)] were maintained at a constant level. At the second stage, the tidal volume was adjusted, while the other respiratory parameters were maintained at a constant level. At the third stage, the TI:TE was adjusted, while the other parameters were maintained at a constant level. At the fourth stage, PEEP was adjusted, while the other parameters were maintained at a constant level. In each experiment, the EBT, the maximum temperature of exhaled air in each min, the inhaled air temperature and the nasopharyngeal temperature (T nose) were recorded every min. During the first stage of the experiment, no significant difference was noted in the EBT at different levels of respiratory rate. During the second, third and fourth stage, no significant difference was noted in the EBT at different tidal volumes, TI:TE and PEEP, respectively. The EBT was significantly correlated with the T nose. Overall, the present study demonstrated that the EBT of patients undergoing abdominal surgery under general endotracheal anesthesia was not affected by the examined respiratory parameters and that it could be considered a feasible method of monitoring core temperature.

Effect of active and passive warming on preventing hypothermia and shivering during cesarean delivery: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Perioperative hypothermia and shivering commonly occur in pregnant women undergoing cesarean section. The warming method is usually used to prevent hypothermia and shivering. However, the effect of active warming (AW) prior to passive warming (PW) on the perioperative outcomes of pregnant women and their offspring remains controversial.

METHODS

This study aimed to investigate the effects of AW and PW on maternal and newborn perioperative outcomes during cesarean delivery. According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, PubMed, Embase, Scopus, and the Cochrane Library were used to search for randomized controlled trials (RCTs) up to August 7, 2022. The Cochrane risk of bias assessment tool was used to assess articles selected for the systematic review. Continuous data were analyzed using weighted mean differences (WMDs) with 95% confidence intervals (CIs), and categorical data were analyzed by the random-effects model.

RESULTS

A total of 1241 participants from twelve RCTs were selected for the final meta-analysis. AW was associated with a lower risk of maternal hypothermia (RR: 0.77, 95% CI: 0.63-0.93, P = 0.007) and shivering (RR: 0.56, 95% CI: 0.37-0.85; P = 0.007). AW was associated with high maternal temperature (WMD: 0.27, 95%CI: 0.14 to 0.40, P < 0.001). No significant difference was observed between AW and PW in terms of hypothermia (RR: 0.60, 95% CI: 0.24-1.51, P = 0.278), temperature (WMD: 0.31, 95% CI: - 0.00 to 0.62; P = 0.050), and umbilical vein PH in newborns (WMD: -0.00; 95% CI: - 0.02 to 0.02, P = 0.710).

CONCLUSIONS

These findings suggested that AW can better prevent maternal hypothermia and shivering than PW. In contrast, no significant effect was observed in newborns. Overall, the quality of the included studies is high due to RCTs, low risk of bias, consistency, and precision. We identified the quality of the overall evidence from the survey to be GRADE I.

Comparison of two forced air warming systems for prevention of intraoperative hypothermia in carcinoma colon patients: a prospective randomized study

Hypothermia is common occurrence in patients undergoing colonic surgeries. We hypothesized that the underbody forced air warming blankets will be better than conventional over-body forced air warming blankets for prevention of hypothermia during laparoscopic colon surgeries. After ethics approval, sixty patients undergoing elective laparoscopic colon surgeries were randomly divided into two groups to receive warming by underbody forced air warming blanket (n = 30) or over-body forced air warming blanket (n = 30). In the operating room, epidural catheter was inserted and thereafter warming was started with the forced air warmer with temperature set at 44 °C. Intraoperatively core temperature (using nasopharyngeal probe), vitals, incidence of postoperative shivering and time to reach Aldrete Score of 10 in the postoperative period were recorded. The core temperature was higher with an underbody blanket at 60 min (36.1 ± 0.5 °C vs. 35.7 ± 0.5 °C, P = 0.005), 90 min (35.9 ± 0.5 °C vs. 35.6 ± 0.5 °C, P = 0.009), 120 min (35.9 ± 0.5 °C vs. 35.5 ± 0.4 °C, P = 0.007), and 150 min (35.9 ± 0.5 °C vs. 35.6 ± 0.4 °C, P = 0.011). In the post anesthesia care unit, the time to reach an Aldrete score of 10 was also less in the underbody blanket group (14.3 ± 2.5 min vs. 16.8 ± 3.6 min) (P = 0.003). However, there were no clinically meaningful differences in any outcome. Underbody and over-body blankets were comparably effective in preventing hypothermia in patients undergoing laparoscopic colorectal surgery under general anaesthesia.Trial registration CTRI (2019/06/019,576). Date of Registration: June 2019, Prospectively registered.

Comparison of the Occurrence of Postoperative Shivering Between Sevoflurane and Desflurane Anesthesia

General anesthetic agents can change the shivering threshold. Sevoflurane and desflurane are widely used as inhalational anesthetics and have also been reported to lower the shivering threshold in a dose-dependent manner. Although the comparison of postoperative shivering (POS) between total intravenous anesthesia and inhalational anesthesia has been reported, there have been no reports on a direct comparison between sevoflurane and desflurane anesthesia and the occurrence of POS in open abdominal surgery. After obtaining approval from the Ethics Review Committee (2020-261), 683 adult patients who underwent open radical surgery for uterine, cervical, or pancreatic cancer under general anesthesia using inhalational anesthetics at Kyushu University hospital between December 2012 and March 2020 were included in this retrospective study. The odds ratio (OR) for the occurrence of POS between the two groups (sevoflurane and desflurane) was calculated. Multivariable-adjusted analysis was performed using possible factors affecting POS. Furthermore, propensity score (PS) matching was conducted using these factors. The multivariable-adjusted OR for the occurrence of shivering in the desflurane group (62 occurrences/356 patients) was 1.06 (95% confidence interval [CI]: 0.69-1.62, p = 0.79) compared with the sevoflurane group (77/327, reference). Similarly, after PS matching, the crude OR for the occurrence of shivering in the desflurane group (47/210) was 1.09 (95% CI: 0.68-1.75, p = 0.72) compared with the sevoflurane group (44/210, reference). Similar results were obtained in the stratified analysis by sex and age. The occurrence of POS is not different between sevoflurane and desflurane anesthesia.

Development and internal validation of an algorithm to predict intraoperative risk of inadvertent hypothermia based on preoperative data

Intraoperative hypothermia increases perioperative morbidity and identifying patients at risk preoperatively is challenging. The aim of this study was to develop and internally validate prediction models for intraoperative hypothermia occurring despite active warming and to implement the algorithm in an online risk estimation tool. The final dataset included 36,371 surgery cases between September 2013 and May 2019 at the Vienna General Hospital. The primary outcome was minimum temperature measured during surgery. Preoperative data, initial vital signs measured before induction of anesthesia, and known comorbidities recorded in the preanesthetic clinic (PAC) were available, and the final predictors were selected by forward selection and backward elimination. Three models with different levels of information were developed and their predictive performance for minimum temperature below 36 °C and 35.5 °C was assessed using discrimination and calibration. Moderate hypothermia (below 35.5 °C) was observed in 18.2% of cases. The algorithm to predict inadvertent intraoperative hypothermia performed well with concordance statistics of 0.71 (36 °C) and 0.70 (35.5 °C) for the model including data from the preanesthetic clinic. All models were well-calibrated for 36 °C and 35.5 °C. Finally, a web-based implementation of the algorithm was programmed to facilitate the calculation of the probabilistic prediction of a patient's core temperature to fall below 35.5 °C during surgery. The results indicate that inadvertent intraoperative hypothermia still occurs frequently despite active warming. Additional thermoregulatory measures may be needed to increase the rate of perioperative normothermia. The developed prediction models can support clinical decision-makers in identifying the patients at risk for intraoperative hypothermia and help optimize allocation of additional thermoregulatory interventions.

Perioperative temperature management: a survey of 6 Asia-Pacific countries

BACKGROUND

Anesthesia leads to impairments in central and peripheral thermoregulatory responses. Inadvertent perioperative hypothermia is hence a common perioperative complication, and is associated with coagulopathy, increased surgical site infection, delayed drug metabolism, prolonged recovery, and shivering. However, surveys across the world have shown poor compliance to perioperative temperature management guidelines. Therefore, we evaluated the prevalent practices and attitudes to perioperative temperature management in the Asia-Pacific region, and determined the individual and institutional factors that lead to noncompliance.

METHODS

A 40-question anonymous online questionnaire was distributed to anesthesiologists and anesthesia trainees in six countries in the Asia-Pacific (Singapore, Malaysia, Philippines, Thailand, India and South Korea). Participants were polled about their current practices in patient warming and temperature measurement across the preoperative, intraoperative and postoperative periods. Questions were also asked regarding various individual and environmental barriers to compliance.

RESULTS

In total, 1154 valid survey responses were obtained and analyzed. 279 (24.2%) of respondents prewarm, 508 (44.0%) perform intraoperative active warming, and 486 (42.1%) perform postoperative active warming in the majority of patients. Additionally, 531 (46.0%) measure temperature preoperatively, 767 (67.5%) measure temperature intraoperatively during general anesthesia, and 953 (82.6%) measure temperature postoperatively in the majority of patients. The availability of active warming devices in the operating room (p < 0.001, OR 10.040), absence of financial restriction (p < 0.001, OR 2.817), presence of hospital training courses (p = 0.011, OR 1.428), and presence of a hospital SOP (p < 0.001, OR 1.926) were significantly associated with compliance to intraoperative active warming.

CONCLUSIONS

Compliance to international perioperative temperature management guidelines in Asia-Pacific remains poor, especially in small hospitals. Barriers to compliance were limited temperature management equipment, lack of locally-relevant standard operating procedures and training. This may inform international guideline committees on the needs of developing countries, or spur local anesthesiology societies to publish their own national guidelines.

Incidence of postoperative shivering decreased with the use of acetaminophen: a propensity score matching analysis

OBJECTIVES

The incidence of postoperative shivering is known to be inversely associated with core body temperature. However, previous studies have pointed out that the threshold of shivering could be affected by peripheral temperature or anesthetic agents. These reports pointed specific drugs, though, anesthesia techniques have since advanced considerably. This study aimed to investigate factors associated with postoperative shivering in the context of the current body warming practice.

METHODS

The institutional clinical research ethics committee of Kyushu University approved the study protocol (IRB Clinical Research number 2019-233). This retrospective study involved 340 patients who had undergone radical surgery for gynecological cancer treatment under general anesthesia at our center from December 2012 to June 2019. Logistic regression analysis was performed to estimate the odds ratio (OR) for the incidence of postoperative shivering.

RESULTS

Postoperative shivering developed in 109 out of 340 patients. After multivariate-adjusted logistic regression, the incidences of postoperative shivering decreased significantly with increasing patient age (OR = 0.96; 95%CI: 0.93-0.98; p = 0.0004). Volatile anesthesia technique was less inclined to shiver after surgery than TIVA (OR = 0.55; 95%CI: 0.30-0.99; p = 0.04). Acetaminophen was much less used in the shivering group than in the non-shivering group (OR = 0.49; 95%CI: 0.25-0.94; p = 0.03).

CONCLUSIONS

This study indicated that the development of shivering in patients receiving the anesthetic technique currently used in our hospital was associated with use of acetaminophen or volatile agents, and patient age.

Risk factors for postoperative hypothermia in the post-anesthetic care unit: a prospective prognostic pilot study

Background

Design and setting

Methods

Results

Conclusion

Intraoperative hypothermia is a significant prognostic predictor of radical cystectomy especially for stage II muscle-invasive bladder cancer

The objective of this study was to evaluate intraoperative hypothermia as a predictor of complication and prognosis in patients with muscle-invasive bladder cancer treated with radical cystectomy.The data of 124 patients treated with radical cystectomy for muscle-invasive bladder cancer in our department, from 2003 to 2016, were retrospectively collected. The patients were divided into 2 groups according to the lowest intraoperative deep body temperature, that is, the hypothermia group (<96.8°F) and the normothermia group (≥96.8°F). Preoperative and intraoperative variables were compared among the 2 groups, and factors associated with complications, recurrences, and survivals were analyzed.Sixty-eight (54.8%) of the 124 patients presented intraoperative hypothermia. There was no significant difference in the patient's characteristics between the 2 groups. Postoperative complications (Clavien-Dindo ≤III) of any types occurred in 15 patients (22.1%) in the hypothermia group, as compared with 8 patients (14.3%) in the normothermia group (P = .27). The hypothermia group had a higher pathologic stage (P = .029) and a higher recurrence rate within 12 months (P = .013), as compared with the normothermia group. Intraoperative hypothermia was an independent prognostic factor for overall survival in all patients (hazard ratio [HR] 2.47; 95% confidence interval [CI], 1.01-2.85; P = .047). When stratified by disease stage, stage II intraoperative hypothermia was an independent prognostic factor for disease-free survival (HR 3.35; 95% CI, 1.27-8.83; P = .015) and overall survival (HR 4.24; 95% CI, 1.38-12.9; P = .011).This study suggests that intraoperative hypothermia could be a significant predictor for recurrence and survival in muscle-invasive bladder cancer treated with radical cystectomy.

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 pre-warming on perioperative hypothermia during holmium laser enucleation of the prostate under spinal anesthesia: a prospective randomized controlled trial

Background

The purpose of this study is to assess whether the application of preoperative forced air warming set to high temperature (> 43 °C) for brief period can increase temperature on admission to the postanesthesia care unit (PACU) and prevent hypothermia or shivering during holmium laser enucleation of the prostate performed under spinal anesthesia.

Methods

Fifty patients were enrolled were assigned randomly to receive passive insulation (control group, n = 25) or forced-air skin surface warming for 20 min before spinal anesthesia (pre-warming group, n = 25). The primary outcome was temperature at PACU admission.

Results

The pre-warming group had a significantly higher temperature on admission to the PACU than the control group (35.9 °C [0.1] vs 35.6 °C [0.1], P = 0.023; 95% confidence interval of mean difference, 0.1 °C–0.5 °C). The trend of decreasing core temperature intraoperatively was not different between groups (P = 0.237), but intraoperative core temperature remained approximately 0.2 °C higher in the pre-warming group (P = 0.005). The incidence of hypothermia on admission to the PACU was significantly lower in the pre-warming group (56% vs 88%, P = 0.025). Shivering occurred in 14 patients in the control group, and 4 patients in the pre-warming group (P = 0.007).

Conclusion

Brief pre-warming at 45 °C increased perioperative temperature and decreased the incidence of hypothermia and shivering. However, it was not sufficient to modify the decline of intraoperative core temperature or completely prevent hypothermia and shivering. Continuing pre-warming to immediately before induction of spinal anesthesia or combining pre-warming with intraoperative active warming may be necessary to produce clearer thermal benefits in this surgical population.

Trial registration

This trial was registered with Clinicaltrials.gov, NCT03184506, 5th June 2017.

Short-term complications of anesthetic technique used in hip fracture surgery in elderly people

Postoperative complications of fracture are one of the main problems in older patients with hip fracture. In this study, complications were observed 48 hours after surgery in different anesthetic procedures. This prospective cross sectional study was carried out over a 12-month period. All subjects over 55 years of age undergoing hip fracture surgery were selected for study with ASA class (American Society of Anesthesiology: one, two and three). After determining the vital signs in the operating room, anesthesia type (general, spinal and epidural) and various variables were recorded. It was observed that the spinal anesthesia method had the lowest level of postoperative disturbances of consciousness and had the shortest duration in terms of duration of time. On the other hand, general anesthesia was the least in terms of blood transfusion. Finally, epidural anesthetic method showed the least amount of pain 48 hours after operation and the least changes in blood pressure and heart rate.

Effects of Ambient Temperature and Forced-air Warming on Intraoperative Core Temperature

Background

The effect of ambient temperature, with and without active warming, on intraoperative core temperature remains poorly characterized. The authors determined the effect of ambient temperature on core temperature changes with and without forced-air warming.

Methods

In this unblinded three-by-two factorial trial, 292 adults were randomized to ambient temperatures 19°, 21°, or 23°C, and to passive insulation or forced-air warming. The primary outcome was core temperature change between 1 and 3 h after induction. Linear mixed-effects models assessed the effects of ambient temperature, warming method, and their interaction.

Results

A 1°C increase in ambient temperature attenuated the negative slope of core temperature change 1 to 3 h after anesthesia induction by 0.03 (98.3% CI, 0.01 to 0.06) °Ccore/(h.°Cambient) (P &lt; 0.001), for patients who received passive insulation, but not for those warmed with forced-air (–0.01 [98.3% CI, –0.03 to 0.01] °Ccore/[h.°Cambient]; P = 0.40). Final core temperature at the end of surgery increased 0.13°C (98.3% CI, 0.07 to 0.20; P &lt; 0.01) per degree increase in ambient temperature with passive insulation, but was unaffected by ambient temperature during forced-air warming (0.02 [98.3% CI, –0.04 to 0.09] °Ccore/°Cambient; P = 0.40). After an average of 3.4 h of surgery, core temperature was 36.3° ± 0.5°C in each of the forced-air groups, and ranged from 35.6° to 36.1°C in passively insulated patients.

Conclusions

Ambient intraoperative temperature has a negligible effect on core temperature when patients are warmed with forced air. The effect is larger when patients are passively insulated, but the magnitude remains small. Ambient temperature can thus be set to comfortable levels for staff in patients who are actively warmed.

Hypothermia in Total Joint Arthroplasty: A Wake-Up Call

BACKGROUND

Total joint patients are particularly vulnerable to perioperative hypothermia (PH) (combined effects of anesthesia, radiation, and convective heat loss from exposed skin surfaces and cool temperatures in the operating room). There are limited studies on PH in these patients.

METHODS

In a retrospective review of 204 patients undergoing primary hip and 179 undergoing primary knee replacement surgeries, time and temperature parameters were collected from the electronic health records from preoperative and postoperative recovery room nursing assessments, intraoperative anesthesia records, and floor nursing notes. Basic patient demographic data was recorded. Chi-squared and paired t-tests were used to compare between hypothermic and normothermic groups.

RESULTS

At the time of incision, 60 of 179 (34%) total knee arthroplasty (TKA) patients and 80 of 204 (39%) total hip arthroplasty (THA) patients were hypothermic. In THA patients, 65% remained hypothermic for the duration of anesthesia compared to 33% of TKA patients. The largest drop in core body temperature in both THA and TKA patients occurred between preoperative holding and induction of anesthesia. In THA patients, spinal anesthesia had a significantly higher occurrence of PH. No significant patient factor was found to increase risk.

CONCLUSION

Emphasis on preoperative holding protocols, decreasing time from operating room entry to incision, and increasing ambient room temperature could reduce risk of hypothermia in total joint replacement patients.

Intrathecal Morphine-Related Perioperative Hypothermia in Women Undergoing Cesarean Delivery: A Retrospective Case-Control Study

PURPOSE

Rates of inadvertent perioperative hypothermia among women undergoing spinal anesthesia for cesarean delivery are reported to be high. Intrathecal morphine has been noted to have a potentially potent effect on thermoregulation. This retrospective case-control study sought to investigate the incidence of perioperative hypothermia in women undergoing cesarean delivery with and without intrathecal morphine and to describe any clinical factors associated with the condition, the identification of which would provide direction for nursing priorities in the care of the condition.

DESIGN

A retrospective case-controlled study design was used.

METHODS

The charts of 358 women who had undergone emergency or elective cesarean delivery under spinal anesthesia were reviewed: 179 having received intrathecal morphine and 179 having received spinal anesthesia without intrathecal morphine (control group). SPSS (IBM, Armonk, New York), version 22, was used for data analysis, including logistic regression to predict the outcome of hypothermia across the study population.

FINDINGS

There was no significant difference (P = .62; 95% confidence interval, -0.09 to 0.15) in mean postoperative temperature for the morphine group (mean postanesthesia care unit arrival temperature, 35.91°C; standard deviation, 0.59) and the no morphine group (mean postanesthesia care unit arrival temperature, 35.88°C; standard deviation, 0.52). However, within groups, the temperature decline preoperatively to postoperatively was statistically (and clinically) significant.

CONCLUSIONS

The results refute the suggestion that intrathecal morphine contributes to greater core temperature decline in this population; however, it does confirm that perioperative hypothermia is a prevalent concern for women undergoing cesarean delivery and that pre-emptive measures should be routinely considered by health care providers.

Temperature management under general anesthesia: Compulsion or option

Administration of general anesthesia requires continuous monitoring of vital parameters of the body including body temperature. However, temperature continues to be one of the least seriously monitored parameters perioperatively. Inadvertent perioperative hypothermia is a relatively common occurrence with both general and regional anesthesia and can have significant adverse impact on patients' outcome. While guidelines for perioperative temperature management have been proposed, there are no specific guidelines regarding the best site or best modality of temperature monitoring and management intraoperatively. Various warming and cooling devices are available which help maintain perioperative normothermia. This article discusses the physiology of thermoregulation, effects of anesthesia on thermoregulation, various temperature monitoring sites and methods, perioperative warming devices, guidelines for perioperative temperature management and inadvertent temperature complications (hypothermia/hyperthermia) and measures to control it in the operating room.

Intraoperative Hypothermia in Total Hip and Knee Arthroplasty

Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are common and successful orthopedic procedures, and as their frequency continues to increase substantially, the focus on limiting perioperative complications heightens. Intraoperative normothermia is recommended to minimize additional complications, but limited evidence exists regarding the effect of hypothermia on orthopedic patients. The purpose of this retrospective study was to determine the incidence of perioperative hypothermia in the setting of TKA and THA, and to evaluate its impact on complications and outcomes. The clinical records of 2580 consecutive patients who underwent TKA or THA at a single institution between January 1, 2011, and December 31, 2013 were reviewed. After excluding patients with complex or revision procedures, a total of 2397 patients comprised the study population. Patient demographic data, surgery-specific data, postoperative complications, length of hospital stay, and 30-day readmission were recorded. Patients with a mean intraoperative temperature less than 36°C were identified as hypothermic. Statistical analysis evaluated associations with hypothermia and the effect on complications and outcomes. The incidence of mean intraoperative hypothermia was 37%, 43.9%, and 32.6% for arthroplasty, THA, and TKA, respectively. General anesthesia was significantly associated with hypothermia (P<.001). Women and THA patients were at higher risk for hypothermia. In the arthroplasty and THA cohorts, longer operating room time and re-warmer use were associated with hypothermia (P=.010). Overall, hypothermia was associated with increased estimated blood loss, but no increase in associated transfusion was demonstrated (P=.006). Hypothermia was not associated with postoperative complications. [Orthopedics. 2017; 40(1):56-63.].

Prophylactic Use of Intravenous Clonidine Compared to Tramadol in Prevention of Intraoperative Shivering under Regional Anesthesia

OBJECTIVES

This study aimed to evaluate the relative efficacy of prophylactic intravenous (IV) clonidine and tramadol for control of intraoperative shivering following spinal anesthesia.

MATERIALS AND METHODS

After institutional ethical clearance, 142 patients were chosen from either gender, aged 20-60 years, physical status American Society of Anesthesiology Class I and II scheduled for elective infraumbilical surgery under spinal anesthesia. Patients were randomized into two groups: Group C (n = 71) received injection clonidine 50 μg) IV in 100 ml normal saline (NS) over 10 min and Group T (n = 71) received injection tramadol 50 mg IV. In 100 ml NS over 10 min after spinal anesthesia.

RESULTS

Incidence of shivering was not significant when compared between the two groups (P > 0.05). The axillary temperatures fell significantly in Group C from the baseline and remained at a significantly lower level up to 60 min after rescue drug was administered in patients who shivered. There was a similar fall in axillary temperature in Group T in patients having shivering, but the difference was not significant. When compared between the two groups among patients who shivered, the difference in fall of temperature was not significant. Side effects such as hypotension, bradycardia, and sedation were significantly more common in clonidine group, whereas nausea was significantly more common patients of tramadol group.

CONCLUSION

Prophylactic administration of both tramadol and clonidine is effective for controlling shivering under spinal anesthesia. However, tramadol is better because of higher response rate, less sedation, and lesser hemodynamic alterations.

Perioperative hypothermia: Causes, consequences and treatment

Perioperative hypothermia, core temperature below 36.0 °C, transpires due to disruption of thermoregulation by anesthesia coupled with cold exposure to procedural surroundings and cleansing agents. Although most publications have focused on thermoregulation disruption with general anesthesia, neuraxial anesthesia may also cause significant hypothermia. The clinical consequences of perioperative hypothermia are multiple and include patient discomfort, shivering, platelet dysfunction, coagulopathy, and increased vasoconstriction associated with a higher risk of wound infection. Furthermore, postoperative cardiac events occur at a higher rate; although it is unclear whether this is due to increased oxygen consumption or norepinephrine levels. Hypothermia may also affect pharmacokinetics and prolong postoperative recovery times and hospital length of stay. In order to combat perioperative hypothermia, many prevention strategies have been examined. Active and passive cutaneous warming are likely the most common and aim to both warm and prevent heat loss; many consider active warming a standard of care for surgeries over one hour. Intravenous nutrients have also been examined to boost metabolic heat production. Additionally, pharmacologic agents that induce vasoconstriction have been studied with the goal of minimizing heat loss. Despite these multiple strategies for prevention and treatment, hypothermia continues to be a problem and a common consequence of the perioperative period. This literature review presents the most recent evidence on the disruption of temperature regulation by anesthesia and perioperative environment, the consequences of hypothermia, and the methods for hypothermia prevention and treatment.

Prophylactic use of intravenous ondansetron versus ketamine - midazolam combination for prevention of shivering during spinal anesthesia: A randomized double-blind placebo-controlled trial

BACKGROUND

The aim of this study was to compare the efficacy intravenous (IV) ondansetron with ketamine plus midazolam for the prevention of shivering during spinal anesthesia (SA).

MATERIALS AND METHODS

Ninety patients, aged 18-65 years, undergoing lower extremity orthopedic surgery were included in the present study. SA was performed in all patients with hyperbaric bupivacaine 15 mg. The patients were randomly allocated to receive normal saline (Group C), ondansetron 8 mg IV (Group O) or ketamine 0.25 mg/kg IV plus midazolam 37.5 μg/kg IV (Group KM) immediately after SA. During surgery, shivering scores were recorded at 5 min intervals. The operating room temperature was maintained at 24°C.

RESULTS

The incidences of shivering were 18 (60%) in Group C, 6 (20%) in Group KM and 8 (26.6%) in Group O. The difference between Groups O and Group KM with Group C was statistically significant (P < 0.05). No significant difference was noted between Groups KM with Group O in this regard (P > 0.05). Peripheral and core temperature changes throughout surgery were not significantly different among three groups (P > 0.05). Incidence (%) of hallucination was not significantly different between the three groups (0, 3.3, 0 in Group O, Group KM, Group C respectively, P > 0.05).

CONCLUSION

Prophylactic use of ondansetron 8 mg IV was comparable to ketamine 0.25 mg/kg IV plus midazolam 37.5 μg/kg IV in preventing shivering during SA.

The effect of aging on the cutaneous microvasculature

Aging is associated with a progressive loss of function in all organs. Under normal conditions the physiologic compensation for age-related deficits is sufficient, but during times of stress the limitations of this reserve become evident. Explanations for this reduction in reserve include the changes in the microcirculation that occur during the normal aging process. The microcirculation is defined as the blood flow through arterioles, capillaries and venules, which are the smallest vessels in the vasculature and are embedded within organs and tissues. Optimal strategies to maintain the microvasculature following surgery and other stressors must use multifactorial approaches. Using skin as the model organ, we will review the anatomical and functional changes in the microcirculation with aging, and some of the available clinical strategies to potentially mitigate the effect of these changes on important clinical outcomes.

The impact of heat stress on operative performance and cognitive function during simulated laparoscopic operative tasks

BACKGROUND

Increasing ambient temperature to prevent intraoperative patient hypothermia remains widely advocated despite unconvincing evidence of efficacy. Heat stress is associated with decreased cognitive and psychomotor performance across multiple tasks but remains unexamined in an operative context. We assessed the impact of increased ambient temperature on laparoscopic operative performance and surgeon cognitive stress.

STUDY DESIGN

Forty-two performance measures were obtained from 21 surgery trainees participating in the counter-balanced, within-subjects study protocol. Operative performance was evaluated with adaptations of the validated, peg-transfer, and intracorporeal knot-tying tasks from the Fundamentals of Laparoscopic Surgery program. Participants trained to proficiency before enrollment. Task performance was measured at two ambient temperatures, 19 and 26°C (66 and 79°F). Participants were randomly counterbalanced to initial hot or cold exposure before crossing over to the alternate environment. Cognitive stress was measured using the validated Surgical Task Load Index (SURG-TLX).

RESULTS

No differences in performance of the peg-transfer and intracorporeal knot-tying tasks were seen across ambient conditions. Assessed via use of the six bipolar scales of the SURG-TLX, we found differences in task workload between the hot and cold conditions in the areas of physical demands (hot 10 [3-12], cold 5 [2.5-9], P = .013) and distractions (hot 8 [3.5-15.5], cold 3 [1.5-5.5], P = .001). Participant perception of distraction remained greater in the hot condition on full scoring of the SURG-TLX.

CONCLUSION

Increasing ambient temperature to levels advocated for prevention of intraoperative hypothermia does not greatly decrease technical performance in short operative tasks. Surgeons, however, do report increased perceptions of distraction and physical demand. The impact of these findings on performance and outcomes during longer operative procedures remains unclear.

Anesthesia, microcirculation, and wound repair in aging

Age-related changes in skin contribute to impaired wound healing after surgical procedures. Changes in skin with age include decline in thickness and composition, a decrease in the number of most cell types, and diminished microcirculation. The microcirculation provides tissue perfusion, fluid homeostasis, and delivery of oxygen and other nutrients. It also controls temperature and the inflammatory response. Surgical incisions cause further disruption of the microvasculature of aged skin. Perioperative management can be modified to minimize insults to aged tissues. Judicious use of fluids, maintenance of normal body temperature, pain control, and increased tissue oxygen tension are examples of adjustable variables that support the microcirculation. Anesthetic agents influence the microcirculation of a combination of effects on cardiac output, arterial pressure, and local microvascular changes. The authors examined the role of anesthetic management in optimizing the microcirculation and potentially improving postoperative wound repair in older persons.

Survey on Postoperative Hypothermia Incidence In Operating Theatres of Kocaeli University

OBJECTIVE

Hypothermia is a common problem in anaesthetized patients and an important risk factor for mortality and morbidity. Our aim was to identify the incidence of hypothermia in our operating theatres. We also aimed to find the circumstances to which hypothermia could be related.

METHODS

After obtaining the ethics committee approval and informed patient consent, patients with operation times longer than 30 minutes were included into the study for a one month period. Demographical data of the patients, type and duration of surgeries, temperatures measured pre and postoperatively from the tympanic membrane with an infrared thermometer were recorded. Temperatures below 35°C were accepted as hypothermia.

RESULTS

A total number of 564 patients were enrolled to the study (305 women and 259 men). The ages of patients varied from 1 month to 84 years (mean 38.5±20.7). Hypothermia incidence was calculated as 45.7%. When the factors related to hypothermia were considered, age, type and duration of surgery and amount of fluids administered were found to be significant contributors to the development of hypothermia (p<0.05).

CONCLUSION

Postoperative hypothermia is a common problem in our clinic. Therefore, we suggest that temperature monitoring and patient warming should be a routine procedure during anaesthesia management.

Perioperative hypothermia in patients undergoing major colorectal surgery

BACKGROUND

Perioperative hypothermia occurs frequently and can have serious health-related and financial consequences. Despite multiple warming methods available, perioperative hypothermia remains prevalent. To be effective, preventative measures must be timely and target patients most at risk. The aim of this retrospective review was to document the incidence and patterns of hypothermia in patients undergoing major colorectal surgery.

METHODS

Hospital records were used to obtain demographic and clinical information on 255 patients undergoing major colorectal surgery over one year. Temperatures were recorded from five perioperative time-points and correlated with potential contributing factors.

RESULTS

Most patients (74%) experienced mild hypothermia, which was most common intraoperatively. Elective patients experienced the greatest drop in temperature between admission and commencement of surgery while emergency patients experienced a similar drop intraoperatively. The most significant determinant of intraoperative hypothermia was core temperature at the start of surgery (P < 0.01). Factors increasing hypothermia at the start of surgery were an elective presentation, an arrival temperature below 36.5°C (P < 0.01) and an age greater than 70 years (P < 0.05).

CONCLUSIONS

Mild hypothermia in patients undergoing major colorectal surgery is common, despite preventative measures. Core temperatures prior to commencement of the operation should be optimized with both active and passive warming measures, particularly for older patients and those arriving with lower core temperatures. Elective patients should also have their temperatures monitored as closely, if not more closely, than emergency patients. Preventing early declining trends in core temperature may positively influence later perioperative temperatures and improve outcomes.

Prospective evaluation of ambient operating room temperature on the core temperature of injured patients undergoing emergent surgery

BACKGROUND

Although uncomfortable for the operating team, trauma operating room (OR) temperatures have traditionally been kept warm in an attempt to mitigate intraoperative heat loss. The purpose of this study was to examine how ambient OR temperatures impact core temperature in patients undergoing emergent surgery for trauma.

METHODS

Injured adult patients requiring emergent surgery at a Level 1 trauma center were prospectively enrolled between July 2008 and January 2010. Standardized warming measures were used for all patients. Ambient OR temperature was recorded in 5-minute intervals with the Fourier Microlog EC600 temperature data logger. Intraoperative core patient temperatures were compared with ambient OR temperature. Patients experiencing intraoperative core temperature decreases were compared with those who did not, to examine the impact of ambient temperature changes on the risk of perioperative hypothermia.

RESULTS

During the 18-month study period, 118 patients requiring emergent surgery (73% laparotomy, 5% thoracotomy, 7% combined, 15% other) were enrolled. Incidence of hypothermia (<35°C) at admission to the OR was 29.7%. Crude mortality increased as the final patient core temperature achieved in the OR decreased (4.2% for temperatures >35°C and as high as 50% for temperatures ≤32°C). Overall, core temperature decreased in 46 patients (39.0%) but remained stable or increased by the end of the procedure in 72 (61%). There were no significant differences in the admission temperature, clinical demographics, or volume of fluids and blood products between the two groups. In a forward logistic regression analysis, a lower ambient OR temperature was not associated with a drop in the patient's core temperature.

CONCLUSION

In this prospective study, the ambient OR temperature did not affect the core temperature of injured patients undergoing emergent surgery.

LEVEL OF EVIDENCE

Prognostic study, level III; therapeutic study, level IV.

Contemporary perioperative care strategies

Background

Historically, the preoperative and postoperative care of patients with gastrointestinal cancer was provided by surgeons. Contemporary perioperative care is a truly multidisciplinary endeavour with implications for cancer-specific outcomes.

Methods

A literature review was performed querying PubMed and the Cochrane Library for articles published between 1966 to 2012 on specific perioperative interventions with the potential to improve the outcomes of surgical oncology patients. Keywords used were: fast-track, enhanced recovery, accelerated rehabilitation, multimodal and perioperative care. Specific interventions included normothermia, hyperoxygenation, surgical-site infection, skin preparation, transfusion, non-steroidal anti-inflammatory drugs, thromboembolism and antibiotic prophylaxis, laparoscopy, radiotherapy, perioperative steroids and monoclonal antibodies. Included articles had to be randomized controlled trials, prospective or nationwide series, or systematic reviews/meta-analyses, published in English, French or German.

Results

Important elements of modern perioperative care that improve recovery of patients and outcomes in surgical oncology include accelerated recovery pathways, thromboembolism and antibiotic prophylaxis, hyperoxygenation, maintenance of normothermia, avoidance of blood transfusion and cautious use of non-steroidal anti-inflammatory drugs, promotion of laparoscopic surgery, chlorhexidine–alcohol skin preparation and multidisciplinary meetings to determine multimodal therapy.

Conclusion

Multidisciplinary management of perioperative patient care has improved outcomes.

Unplanned perioperative hypothermia and agreement between oral, temporal artery, and bladder temperatures in adult major surgery patients

Accurate body core temperature measurement is essential in perioperative areas to quickly recognize and address abnormal temperatures. The purposes of this prospective, descriptive study were to accurately identify unplanned perioperative hypothermia (UPH) in 64 elective major surgery patients; to describe factors that increased the risk of UPH; to describe active/passive warming measures; to describe thermal comfort in patients with and without UPH; and to compare oral, temporal artery, and bladder temperatures. Based on bladder temperatures, 52% of the patients had UPH in the operating room (OR) and 42% on postanesthesia care unit (PACU) admission. The temporal artery thermometer did not detect any hypothermia. Descriptive data and Bland-Altman plots showed lack of agreement between the temporal artery thermometer readings and those of the oral and bladder thermometers. The patient's thermal comfort report did not accurately reflect hypothermia. Factors found to increase the risk of UPH included older age, BMI lower than 30, and OR ambient temperature lower than 68°F. All but one patient had active warming in the OR; active warming was infrequently used in the PACU. Based on our findings and findings in previous studies, we do not recommend using the temporal artery thermometer in perioperative areas. To prevent UPH, we recommend aggressive use of convective and conductive warming measures in perioperative areas and increasing OR ambient temperatures.

Retrospective study of the prevalence of postanaesthetic hypothermia in dogs

The anaesthetic records of 1525 dogs were examined to determine the prevalence of postanaesthetic hypothermia, its clinical predictors and consequences. Temperature was recorded throughout the anaesthesia. At the end of the procedure, details coded in were: hyperthermia (>39.50°C), normothermia (38.50°C-39.50°C), slight (38.49°C-36.50°C), moderate (36.49°C-34.00°C) and severe hypothermia (<34.00°C). Statistical analysis consisted of multiple regression to identify the factors that are associated with the temperature at the end of the procedure. Before premedication, the temperature was 38.7 ± 0.6°C (mean ± sd). At 60, 120 and 180 minutes from induction, the temperature was 36.7 ± 1.3°C, 36.1 ± 1.4°C and 35.8 ± 1.5°C, respectively. The prevalence of hypothermia was: slight, 51.5 per cent (95 per cent CI 49.0 to 54.0 per cent); moderate, 29.3 per cent (27.1-31.7 per cent) and severe: 2.8% (2.0-3.7%). The variables that associated with a decrease in the temperature recorded at the end of the anaesthesia were: duration of the preanesthetic time, duration of the anaesthesia, physical condition (ASA III and ASA IV dogs showed lower temperatures than ASA I dogs), the reason for anaesthesia (anaesthesia for diagnostic procedures or thoracic surgery reduce the temperature when compared with minor procedures), and the recumbency during the procedure (sternal and dorsal recumbencies showed lower temperatures than lateral recumbency). The temperature before premedication and the body surface (BS) were associated with a higher temperature at the end of the anaesthesia, and would be considered as protective factors.

Effect of preoperative warming during cesarean section under spinal anesthesia

Background

Postoperative hypothermia and shivering is a frequent event in patients during cesarean section under spinal anesthesia. We assessed the effect of preoperative warming during cesarean delivery under spinal anesthesia for prevention of hypothermia and shivering.

Methods

Forty five patients undergoing elective cesarean section were randomly assigned to three groups. Group F received warmed intravenous fluid (40℃). Group A patients were actively warmed by forced air-warming. Group C was the control group. Forced air-warming and warmed fluid was maintained for the 15 min preceding spinal anesthesia. Core temperature (tympanic membrane) and the skin temperature of arm and thigh were measured and shivering was graded simultaneously.

Results

The core temperature at 45 min decreased less in Groups F and A than Group C (-0.5℃ ± 0.3℃ vs -0.6℃ ± 0.4℃ vs -0.9℃ ± 0.4℃, respectively; P = 0.004). The arm temperature at 15 min and 30 min exhibited a greater increase in Group A than Group F and Group C (P = 0.001 and P = 0.012, respectively). Leg temperature increased similarly among the three groups. The incidence of shivering was significantly less in Group A and Group F than Group C (20%, 13.3%, and 53.3%, respectively; P = 0.035).

Conclusions

Preoperative forced air-warming and warmed fluid prevents hypothermia and shivering in patients undergoing elective cesarean delivery with spinal anesthesia.

Sensory environment on health-related outcomes of hospital patients

BACKGROUND

Hospital environments have recently received renewed interest, with considerable investments into building and renovating healthcare estates. Understanding the effectiveness of environmental interventions is important for resource utilisation and providing quality care.

OBJECTIVES

To assess the effect of hospital environments on adult patient health-related outcomes.

SEARCH METHODS

We searched: the Cochrane Central Register of Controlled Trials (last searched January 2006); MEDLINE (1902 to December 2006); EMBASE (January 1980 to February 2006); 14 other databases covering health, psychology, and the built environment; reference lists; and organisation websites. This review is currently being updated (MEDLINE last search October 2010), see Studies awaiting classification.

SELECTION CRITERIA

Randomised and non-randomised controlled trials, controlled before-and-after studies, and interrupted times series of environmental interventions in adult hospital patients reporting health-related outcomes.

DATA COLLECTION AND ANALYSIS

Two review authors independently undertook data extraction and 'Risk of bias' assessment. We contacted authors to obtain missing information. For continuous variables, we calculated a mean difference (MD) or standardized mean difference (SMD), and 95% confidence intervals (CI) for each study. For dichotomous variables, we calculated a risk ratio (RR) with 95% confidence intervals (95% CI). When appropriate, we used a random-effects model of meta-analysis. Heterogeneity was explored qualitatively and quantitatively based on risk of bias, case mix, hospital visit characteristics, and country of study.

MAIN RESULTS

Overall, 102 studies have been included in this review. Interventions explored were: 'positive distracters', to include aromas (two studies), audiovisual distractions (five studies), decoration (one study), and music (85 studies); interventions to reduce environmental stressors through physical changes, to include air quality (three studies), bedroom type (one study), flooring (two studies), furniture and furnishings (one study), lighting (one study), and temperature (one study); and multifaceted interventions (two studies). We did not find any studies meeting the inclusion criteria to evaluate: art, access to nature for example, through hospital gardens, atriums, flowers, and plants, ceilings, interventions to reduce hospital noise, patient controls, technologies, way-finding aids, or the provision of windows. Overall, it appears that music may improve patient-reported outcomes such as anxiety; however, the benefit for physiological outcomes, and medication consumption has less support. There are few studies to support or refute the implementation of physical changes, and except for air quality, the included studies demonstrated that physical changes to the hospital environment at least did no harm.

AUTHORS' CONCLUSIONS

Music may improve patient-reported outcomes in certain circumstances, so support for this relatively inexpensive intervention may be justified. For some environmental interventions, well designed research studies have yet to take place.

Perioperative normothermia during major surgery: is it important?

PH caused by anesthesia-induced thermoregulatory inhibition and exposure to cold operating room environments still occurs in a significant proportion of patients undergoing major surgery. Although the association between specific perioperative temperatures (in and of themselves) and postoperative morbidity remains unclear, there is fair evidence to suggest that perioperative active warming may reduce the risk of postoperative cardiac events, bleeding, and SSIs. As such, proactive efforts by surgical teams to prevent PH are warranted and have become the standard of care at many institutions. Continued intraoperative monitoring of core temperature (ideally using esophageal probes) is recommended in all cases lasting more than 30 minutes, both to detect malignant hyperthermia and to maintain normothermia. Preoperative and/or intraoperative use of warmed forced-air devices is an effective way to minimize redistribution hypothermia following induction, whereas intraoperative use of warmed i.v. fluids helps reduce the potential for fluid-induced hypothermia and, in turn, optimizes rates of perioperative normothermia.

Effects of PEEP on the thermoregulatory responses during TIVA in patients undergoing tympanoplasty

BACKGROUND

During general anesthesia, core temperature decreases, largely due to heat loss caused by peripheral vasodilation, resulting in heat redistribution to peripheral tissues. Multiple factors contribute to body temperature regulation during general anesthesia. It was reported that baroreceptor unloading by positive end-expiratory pressure (PEEP) attenuates anesthetically-induced hypothermia. So, we evaluated the effects of PEEP on thermoregulatory responses during total intravenous anesthesia (TIVA).

METHODS

Forty healthy patients scheduled for tympanoplasty were allocated two groups, Group ZEEP (zero end-expiratory pressure, n = 20) and Group PEEP (PEEP application of 5 cmH(2)O, n = 20). Ambient temperature was maintained at 22-24℃, and anesthesia was induced and maintained with propofol-remifentanil. The core temperature and the temperature difference between forearm and fingertip skin were monitored before and after the induction of general anesthesia having a duration of 180 minutes.

RESULTS

The core temperature gradient (Ti-Tf) was higher in patients with ZEEP than with PEEP. The core temperature was maintained at a higher level in patients with PEEP. Additionally, the vasoconstriction threshold was higher in patients with PEEP.

CONCLUSIONS

It seems that PEEP attenuates anesthetically-induced hypothermia during TIVA.