Effect of infraorbital nerve block under general anesthesia on consumption of isoflurane and postoperative pain in endoscopic endonasal maxillary sinus surgery

Abstract

Purpose. The efficacy of infraorbital nerve block in reducing isoflurane consumption and postoperative pain was evaluated in patients undergoing endoscopic endonasal maxillary sinus surgery (ESS) under general anesthesia.

Methods. Fifty patients were randomly allocated to either the block group (n = 15) or the nonblock group (n = 25). After the establishment of general anesthesia with isoflurane, nitrous oxide, and oxygen, the patients received infraorbital nerve block with 1.0 ml of either 0.5% bupivacaine (block group) or normal saline (nonblock group) administered into the soft tissue in front of the infraorbital foramen. Systolic blood pressure during anesthesia and surgery was maintained at 85–90 mmHg by adjusting the inspiratory concentration of isoflurane, and its consumption was evaluated in both groups. Pain intensity at 15 min after the end of anesthesia was also evaluated on a five-point pain scale.

Results. The consumption of isoflurane under a fresh gas flow of 6 l·min⁻¹ was 17.3 ± 6.5 ml·kg⁻¹·h⁻¹ (mean ± SD) in the block group and 27.4 ± 9.4 ml·kg⁻¹·h⁻¹ in the nonblock group during surgery (P < 0.001). Nicardipine was required during surgery less frequently in the block group than in the nonblock group (P < 0.01). Postoperative pain intensity was lower in the block group than in the nonblock group (P < 0.01).

Conclusion. General anesthesia combined with infraorbital nerve block is effective in reducing the consumption of isoflurane and postoperative pain intensity in ESS.