Randomized double-blind trial comparing effects of low-flow vs high-flow anesthesia on postoperative lung functions using respirometer.

BACKGROUND AND AIMS

Modern anesthetic practice utilizes low-flow anesthesia with evolving evidence on its pulmonary effects. Studies comparing measurement of vital capacity and inspiratory reserve volume using respirometer in both low-flow and high-flow anesthesia are sparse. We evaluated the effects of low-flow and high-flow anesthesia on postoperative pulmonary functions using respirometer.

MATERIAL AND METHODS

This was a prospective randomized double blind study wherein One hundred and ten patients undergoing peripheral surgeries under general anesthesia were allocated into two groups Group I- Low-flow anesthesia with O2 + N2O + Sevoflurane (0.5L + 0.5L + 3.5%) and Group II- High-flow anesthesia with O2 + N2O + Sevoflurane (2L + 2L + 2%). The difference in vital capacity (VC), inspiratory reserve volume (IRV), and peak expiratory flow rates (PEFR) from the preoperative period were compared in both the groups postoperatively.

RESULTS

The difference in VC, IRV, and PEFR measured in both the groups between the preoperative and postoperative period were found to be similar and statistically insignificant ( - 0.173, 1.00 and 0.213 respectively). The difference in single breath count (SBC), breath holding time (BHT), and respiratory rates (RR) were also similar in both the groups ( - 0.101, 0.698, and 0.467) respectively.

CONCLUSIONS

The pulmonary effects of low-flow anesthesia are comparable with the high-flow ones in patients undergoing elective surgeries under general anesthesia.