Comparison between upper body and full underbody forced-air warming blanket in pediatric patients undergoing cardiovascular interventions under general anesthesia: a randomized controlled trial

Abstract

Background: Pediatric patients undergoing cardiovascular interventions outside the operating room are at high risk of perioperative hypothermia. We aimed to compare the effects of upper body and full underbody forced-air warming blankets on the time-weighted deviation of esophageal temperature outside the target range (36.5-37.5 °C) during general anesthesia.

Methods: In this randomized controlled study, 88 children (age < 15 years) scheduled for elective cardiovascular interventions under general anesthesia were randomly assigned to the upper body (n = 44) or full underbody (n = 44) group. After the induction of anesthesia, warming blankets were applied and heated using a forced-air warmer to maintain an esophageal temperature of 36.5-37.5 °C. The primary outcome was the time-weighted average deviation of esophageal temperature outside the desired range, defined as the total deviation in temperature divided by the duration spent outside the target range. Secondary outcomes included use of additional warming or cooling methods, temperature trends, thermal comfort, and adverse events. Statistical comparisons were performed using t-tests or chi-square tests, with p < 0.05 considered significant.

Results: The time-weighted averages of periods out of the desired temperature range were comparable between the two groups (upper body vs. full underbody, 0.213 ± 0.212 °C vs. 0.265 ± 0.277 °C; mean difference, 0.053; 95% confidence interval [CI], - 0.052 to 0.157; p = 0.318). The incidence of hyperthermia (> 37.5 °C) was 9.09% (upper body) and 0% (full underbody, p = 0.125). The duration of hypothermia (< 36.5 °C) was 58.82 ± 48.83 min (upper body) and 70.03 ± 53.20 min (full underbody; mean difference, 11.20 min; 95% CI, - 10.44 to 32.85; p = 0.318). The incidence rates of adverse events were 4.55% (upper body) and 15.91% (full underbody, p = 0.159).

Conclusions: Both warming methods showed comparable time-weighted averages of temperatures outside the desired range, suggesting similar effectiveness. However, careful monitoring is essential to mitigate the risks of hyperthermia and skin-related complications and ensure patient safety during pediatric cardiovascular interventions.

Trial registration number: NCT05349734 (registered at clinicaltrials, principal investigator: Hee-Soo Kim, registration date: April 26,2022).

Keywords: Cardiac intervention; Forced-air warming; Hypothermia; Pediatric anesthesia.

Fig. 1

Application of warming blankets (A) Full underbody warming blanket positioned beneath the patient. (B) Upper body warming blankets covered from the navel to the upper limbs and head. The red circles indicate the locations of femoral vein puncture during cardiac catheterization

Fig. 2

Study protocol

Fig. 3

Consolidated standards of reporting trials (CONSORT) diagram

Fig. 4

Comparison of core temperature progression in 5-min intervals in full underbody and upper body warming methods. The boxplots represent the distribution of temperature each 5-minute interval. Blue boxplots correspond to the full underbody warming method, while the red boxplots correspond to the upper body warming method. The median temperature is indicated by the colored lines within each box. The mean temperature progression over time is plotted as lines with markers. The blue line with circular markers represents the mean temperature for the full underbody warming method, while the red line with circular markers represents the mean temperature for the upper body warming method. There was no group difference observed at any of the time points

Fig. 5

Example of skin-related adverse event observed after intraoperative warming. A photograph of a pediatric patient showing a linear erythematous mark with mild indentation on the back after use of a full underbody forced-air warming blanket. The mark resolved spontaneously without the need for treatment. This represents one of the skin-related adverse events recorded in the study