Ultrasound-Guided Superficial Versus Deep Continuous Serratus Anterior Plane Block in Patients Undergoing Thoracotomy for Lung Surgery: A Randomized Controlled Trial

BACKGROUND: Thoracic surgery is considered to be one of the most painful surgical procedures; therefore, providing adequate analgesia in the perioperative period is crucial. Inadequate pain control impedes deep breathing, which further leads to atelectasis and pneumonia. The optimal analgesic protocol that allows adequate postoperative pain control and facilitates fast recovery of this population has yet to be determined. The serratus anterior plane (SAP) block is a new procedure that is relatively easier to perform and safer, compared with other modalities. MATERIALS AND METHODS: Patients undergoing lung resection surgery via thoracotomy at a single center were randomized to undergo either superficial or deep SAP block with 0.4 mL/kg of bupivacaine 0.25%, following which 20-gauge peripheral nerve block catheter was placed above or below the serratus anterior muscle plane and continuous bupivacaine 0.125% infusion at the rate of 5-7 mL/h was initiated up to 24 hours in intensive care unit (ICU). The primary outcome was the total opioid consumption during the first 24 h in the ICU. Secondary outcomes were the severity of pain in the visual analog scale (VAS) score, patient satisfaction score, ICU stay duration, and the incidence of postoperative nausea and vomiting (PONV). RESULTS: A total of 36 participants were randomized to each group, and the baseline characteristics were comparable between the groups. The total postoperative opioid consumption during the first 24 h in ICU was lower in deep SAP block (60.00 ± 68.22) compared to superficial SAP block (85.31 ± 68.40), but it was not statistically significant (P > 0.303). The VAS score, time to first rescue analgesia, patient satisfaction score, incidence of PONV, and the length of ICU stay were comparable between the two groups (P > 0.05). CONCLUSION: There was lower opioid consumption in the continuous deep SAP block compared to the superficial SAP block at 24 hours; however, the difference was not statistically significant. Continuous analgesia through an indwelling catheter is safe and an effective method for the management of postoperative pain in lung resection surgery.