Effect of Low Fresh Gas Flows on Intraoperative Hypothermia Among Neonates Undergoing Abdominal Surgeries: A Randomized Controlled Trial.

INTRODUCTION

Intraoperative hypothermia remains a frequent and under-recognized complication in neonates undergoing surgery despite standard preventive measures. Low-flow anesthesia, by increasing rebreathing and conserving heat and humidity, may offer a thermo-protective effect. In this study, we compare the incidence of intraoperative hypothermia between low-flow (1 L/min) vs. routine-flow (2 L/min) anesthesia in neonates undergoing abdominal surgery.

METHODS

After obtaining written informed consent from parents or legal guardians, 160 neonates scheduled for elective or emergency abdominal surgery were randomized into two groups: Group L (low-flow, 1 L/min) and Group C (control, 2 L/min). Core temperature was continuously monitored intraoperatively. The primary outcome was the incidence of intraoperative hypothermia (core temperature < 36°C). Secondary outcomes included changes in core temperature, minimum and maximum intraoperative temperature, percentage of surgical time spent under hypothermia, time to extubation, blood loss, transfusion requirements, use of inotropes, and postoperative ventilation.

RESULTS

The incidence of intraoperative hypothermia was significantly lower in group L compared to group C (75% vs. 90%, p = 0.01). The median (IQR) drop in core temperature from baseline was smaller in group L as compared to group C [0.80°C (0.60-1.10) vs. 1.20°C (0.90-1.50), p < 0.001]. Minimum core temperature was higher in group L [35.5°C (35.20-35.90) vs. 35°C (34.80-35.40), p < 0.001]. The percentage of surgical time spent under hypothermia (< 36°C) was significantly lower in group L [50.3% (95% CI: 43.3-57.3)] compared to group C [65.6% (95% CI: 58.6-72.6), p = 0.003]. While intraoperative blood loss was slightly higher in the low-flow group, the clinical impact was minimal. Other outcomes, including extubation time, inotrope use, and hypoxia incidence, were comparable between groups.

CONCLUSION

Low-flow anesthesia technique at 1 L/min is a safe and effective approach for reducing the incidence and duration of intraoperative hypothermia in neonates undergoing abdominal surgery.

TRIAL REGISTRATION: Clinical Trial Registry of India (www.ctri.nic.in): CTRI/2022/11/047532.