METHODS: This prospective, double-blind, randomized study enrolled 60 female patients scheduled for unilateral mastectomy and axillary clearance. The patients received either a superficial serratus plane block or deep serratus plane block. Dermatomal spread was recorded 30 minutes after block administration. Postoperatively, pain visual analog scale (VAS) scores were documented at recovery (time 0), at 30 minutes; and in the ward hourly for 4 hours, and 4-hourly until 24 hours postoperatively. The time to first analgesic rescue and cumulative morphine consumption using patient-controlled analgesia morphine (PCAM) were recorded.

RESULTS: The results showed lower VAS scores at rest (at 1, 2, 3, and 4 hours postoperatively), and during movement (at 1, 2, 3, 4, 8, and 24 hours postoperatively) in the superficial serratus plane block group, P < .005. Similarly, cumulative morphine usage was lower in the superficial serratus plane group, P < .005. The time to the first rescue analgesic was also significantly longer in the superficial group, P < .001. More patients in the superficial serratus plane group achieved greater dermatomal spread at T2 and T7 than those in the deep group.