Superficial vs. deep serratus anterior plane block for analgesia in patients undergoing mastectomy: A randomized prospective trial.

STUDY OBJECTIVE

In the initial description of the serratus anterior plane block (SAPB), both superficial and deep SAPB provided effective blockade. The purpose of this study was to investigate the difference in opioid consumption and postoperative analgesia between superficial and deep SAPB for patients undergoing mastectomy.

DESIGN

Randomized prospective trial.

SETTING

Academic hospital.

PATIENTS

64 women, >18 years of age, ASA I-III, undergoing single or bilateral mastectomy, with and without lymph node biopsy, with and without tissue expander reconstruction.

INTERVENTION

Either superficial or deep SAPB by an ultrasound-guided technique in addition to multimodal analgesia.

MEASUREMENTS

The primary outcome was opioid consumption in the first 24 h. Secondary outcomes were pain scores, satisfaction scores, incidence of PONV, length of stay and block performance time.

RESULTS

Subjects who received a deep SAPB required 30% less oral morphine equivalents (OME) (113.5 mg vs. 147 mg, p = 0.009) and reported lower pain scores. There were no significant differences in satisfaction scores, incidence of PONV, LOS, or block performance time between the two groups.

CONCLUSION

There was a significant difference in opioid consumption between the deep and superficial SAPB groups. Subjects in the deep SAPB group had lower pain scores at 12 h; however, the difference was not statistically significant at other time points. While both the superficial and the deep SAPB can be used for post-operative analgesia in patients undergoing mastectomy, our study suggests that the deep SAPB may improve analgesia to a greater degree than the superficial SAPB as shown through decreased opioid consumption of 30% over a 24-h period post-block. CLINICAL TRIAL NUMBER AND REGISTRY URL: clinicaltrials.gov: NCT03154658.