Serratus Plane Versus Paravertebral Nerve Blocks for Breast Surgery

Following painful surgical procedures of the breast, postoperative analgesia is often provided with a paravertebral nerve block (PVB). For intense, but shorter-duration acute pain, a single-injection of local anesthetic is used with a duration of approximately 12 hours. Recently an alternative block has been reported: the serratus plane block.2 The theoretical benefits include ease of administration since it is a plane superficial to the PVB and therefore easier to identify and target with ultrasound (therefore increasing success rate); and an increased safety margin as there are fewer anatomic structures in the immediate area which could be injured with the needle; and, the target plane is much further from the intrathecal/epidural space relative to the PVB, therefore leakage of cerebrospinal fluid or injury to the spinal cord are less likely with the serratus compared to the PVB.3 There are, therefore, multiple theoretical reasons to prefer the serratus over the PVB. Unfortunately, it remains unknown if the analgesia provided by this new technique is comparable to that provided with the PVB.4 The investigators therefore propose to compare these two techniques with a randomized, subject-masked, active-controlled, parallel-arm clinical trial.