Effects of epidural anesthesia on thermal sensation

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.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-05054-7.

An Overview of the Implications for Perianesthesia Nurses in terms of Intraoperative Changes in Temperature and Factors Associated with Unintentional Postoperative Hypothermia

Patients undergo surgery and anaesthesia on a daily basis across the United States and throughout the world. A major source of worry for these patients continues to be inadvertent hypothermia, once core temperature <36°C (96.8°F). Despite well-documented adverse physiological consequences, anaesthesia nurses continue to have a difficult task in keeping patient warmth pre-/peri-/post-surgical procedure. Thermostasis within postoperative patient necessitates the collaboration of many individuals. In order to provide safe and high-quality treatment, it is essential to use the most up-to-date data to guide therapeutic procedures targeted at achieving balance body temperature in surgical patients. Providing a review of the physiology of perioperative temperature variations and the comorbidities linked with accidental intraoperative hypothermia, this article will also provide preventive and treatment methods.

Effect of Preoperative Oral Carbohydrate Loading on Body Temperature During Combined Spinal-Epidural Anesthesia for Elective Cesarean Delivery

BACKGROUND

Intraoperative hypothermia is a common complication after neuraxial block in cesarean delivery. At least 1 animal study has found that carbohydrate loading can maintain the body temperature of rats during general anesthesia, but it is unclear whether carbohydrate loading is beneficial for body temperature maintenance in parturient women during combined spinal-epidural anesthesia (CSEA) for elective cesarean delivery.

METHODS

Women undergoing elective cesarean delivery were randomized into a control group (group C), an oral carbohydrate group (group OC), or an oral placebo group (group OP), with 40 women in each group. Core body temperature (Tc) and body surface temperature (Ts) before and after cesarean delivery, changes in Tc (ΔTc) and Ts (ΔTs), and the incidence of side effects (eg, intraoperative shivering) were compared among the groups.

RESULTS

The postoperative Tc (core body temperature after cesarean delivery [Tc2]) of group OC (36.48 [0.48]°C) was higher than those of group C (35.95 [0.55]°C; P < .001), and group OP (36.03 [0.49]°C; P = .001). The ΔTc (0.30 [0.39]°C) in group OC was significantly smaller than those in group C (0.73 [0.40]°C; P = .001) and group OP (0.63 [0.46]°C; P = .0048).

CONCLUSIONS

Oral carbohydrate loading 2 hours before surgery facilitated body temperature maintenance during CSEA for elective cesarean delivery.

Efficacy of prophylactic epidural ketamine for reducing shivering in patients undergoing caesarean section with combined spinal-epidural anesthesia

Intravenous ketamine is known to inhibit postoperative shivering; however, at present, there has been little research on whether this effect may be achieved with epidural application. The aim of the present study was to evaluate the efficacy and safety of epidural ketamine as a prophylactic agent to prevent shivering in patients undergoing caesarean section during combined spinal-epidural anesthesia. A prospective, randomized, double-blind study was performed. A total of 60 patients who were undergoing elective caesarean section under combined spinal-epidural anesthesia and had an American Society of Anesthesiologists physical status of I or II were recruited. Patients were randomly allocated to group S (epidural administration of normal saline; n=30) or group K (epidural ketamine 0.5 mg/kg; n=30). An investigator, blinded to the treatment groups, graded postoperative shivering using a 4-point scale and postoperative sedation on a 5-point scale. Operative time, hemodynamic changes and side effects, including hypotension, bradycardia, nausea and hallucinations, were recorded. The results demonstrated that patients' characteristics were not significantly different between groups. Heart rate, peripheral capillary oxygen saturation (SpO₂) values and Apgar scores at 1 and 5 min also did not differ significantly between groups. The incidence and severity of shivering in group K was significantly reduced compared with group S (P<0.05). The mean arterial pressure (MAP) was significantly different in groups S and K compared with baseline values at 10, 30 and 60 min (P<0.05). Furthermore, MAP values at 10, 30 and 60 min were significantly higher in group K compared with in group S (P<0.05). The results of the present study suggest that epidural administration of prophylactic low-dose ketamine may be an effective strategy for preventing postoperative shivering.

Prevention of hypothermia in children under combined epidural and general anesthesia: a comparison between upper- and lower-body warming

BACKGROUND

Children receiving combined epidural and general anesthesia may be at greater risk of hypothermia. Active warming should be undertaken to combat heat loss. With combined epidural and general anesthesia heat loss from the lower body may be greater than from the upper body because of shift of blood towards the vasodilated lower body. We assumed that application of the warming blanket to the lower body might provide better protection against hypothermia. To test this hypothesis, lower-body warming (LBW) was compared with upper-body warming (UBW) in a randomized comparative study.

METHODS

Children subjected to open urologic surgery under combined epidural and general anesthesia were randomly allocated to either UBW n = 38 or LBW n = 35 using a forced-air warming blanket. Core and peripheral skin temperatures were monitored. Temperature gradients between forearm and fingertip during LBW and between leg and toe during UBW were calculated. The warmer was set at 32 degrees C, room temperature was around 22 degrees C and fluids were infused at ambient room temperature.

RESULTS

The changes in core temperature were comparable and parallel in both groups. Core temperature decreased significantly in each group at 1 h after induction compared with basal values. Temperature gradients at forearm-fingertip and at leg-toe were also comparable in both groups. Recovery was uneventful and no patient shivered in the recovery room.

CONCLUSIONS

Lower body warming is as effective as UBW in prevention of hypothermia in children subjected to combined epidural and general anesthesia.

Physiology and clinical relevance of induced hypothermia

Experimental evidence and clinical experience suggest that mild hypothermia protects numerous tissues from damage during ischemic insult. However, the extent to which hypothermia becomes a valued therapeutic option will depend on the clinician's ability to rapidly reduce core body temperature and safely maintain hypothermia. To date, general anesthesia is the best way to block autonomic defenses during induction of mild-to-moderate hypothermia; unfortunately, general anesthesia is not an option in most patients likely to benefit from therapeutic hypothermia. Induction of hypothermia in awake humans is complicated by both the technical difficulties related to thermal manipulation and the remarkable efficacy of thermoregulatory defenses, especially vasoconstriction and shivering. The most effective thermal manipulation devices are generally invasive and, therefore, more prone to complications than surface methods. In an effort to inhibit thermoregulation in awake humans, several agents have been tested either alone or in combination with each other. For example, the combination of meperidine and buspirone has already been applied to facilitate induction of hypothermia in human trials. However, pharmacological induction of thermoregulatory tolerance to cold without excessive sedation, respiratory depression, or other serious toxicity remains a major focus of current therapeutic hypothermia research.