Serratus anterior plane block for pain management in thoracic surgery

Thoracoscopic lung surgeries, such as video- and robotic-assisted procedures, have reduced the complications and recovery times compared to open thoracotomy. However, postoperative pain remains a significant challenge. A multimodal approach to pain management is often adopted, which may include regional nerve blocks like the serratus anterior plane (SAP) block. This study examines whether adding an SAP block to standard pain management protocols enhances pain control and reduces opioid consumption after thoracoscopic lung resection.

Study objective and methods

The primary goal of this randomized, double-blind, placebo-controlled trial was to evaluate the effectiveness of SAP blocks in reducing opioid use and enhancing recovery after thoracoscopic lung surgery. A total of 99 patients undergoing minimally invasive thoracic surgery were randomized into two groups:

SAP block group: 46 patients received an SAP block. A 22-gauge needle was guided via ultrasound into the fascial plane beneath the serratus anterior muscle, targeting the fifth and eighth ribs. After surgery, 40 mL of injectate (bupivacaine 0.25%, dexamethasone 4 mg, clonidine 100 μg) was administered in two equal injections, with aspiration checks to avoid vascular injection.

• Placebo group: 46 patients received 40 mL of normal saline injected at the same anatomical locations.

The primary outcome measure was the 24-hour cumulative intravenous morphine equivalents, evaluating opioid consumption within the first day post-surgery. Secondary outcomes included 48-hour opioid use, pain scores assessed both at rest and during coughing, spirometry volumes to measure respiratory function, the incidence of nausea, and patient-reported recovery quality using the Quality of Recovery-15 (QoR-15) scores. 

Key findings

• Opioid use: The SAP group showed a 32% reduction in 24-hour median morphine equivalents compared to the placebo group (10.6 mg vs. 18.8 mg; P = 0.085). While not statistically significant, sensitivity analysis showed a significant 36% reduction (P = 0.048). At 48 hours, opioid use decreased by 40% in the SAP group (P = 0.036).

• Pain scores: No significant differences in composite pain scores at rest, but the SAP group reported significantly lower pain with coughing (P = 0.044).

• Secondary outcomes: Spirometry volumes, nausea, and QoR-15 scores showed no significant differences between groups. Hospital stay was 25% shorter in the SAP group, though the difference was not statistically significant.

• Safety: No block-related complications were observed, confirming the SAP block as a safe procedure.

Conclusion

The SAP block, when integrated into a multimodal analgesic regimen, modestly reduced opioid consumption and improved coughing-related pain following thoracoscopic lung surgery. These findings, though limited, highlight its potential role in enhancing recovery protocols for thoracic surgery.

Future research

Future research should focus on validating these findings in larger, more diverse patient populations to ensure generalizability. Additionally, studies exploring optimized SAP block techniques, including variations in dosage and injection methods, could refine its efficacy. Investigating combinations with other analgesic modalities may also enhance pain management protocols. Finally, evaluating long-term outcomes such as chronic pain prevention, patient satisfaction, and functional recovery will provide a comprehensive understanding of the block’s benefits in thoracic surgery recovery.

For more detailed information, refer to the full article in Anesthesiology.

Jackson JC, Tan KS, Pedoto A, et al. Effects of Serratus Anterior Plane Block on Early Recovery from Thoracoscopic Lung Resection: A Randomized, Blinded, Placebo-controlled Trial. Anesthesiology. 2024;141(6):1065-1074.

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