Suprazygomatic maxillary nerve block: an ultrasound and cadaveric study to identify correct sonoanatomical landmarks.

​PURPOSE: Suprazygomatic maxillary nerve blocks (SMB) are used in adult and pediatric patients to provide analgesia for midface surgery and chronic maxillofacial pain syndromes. The ultrasound-guided SMB technique ensures visualisation of the needle tip, avoidance of the maxillary artery and confirmation of local anesthetic spread. The goal of this study was to correctly identify SMB sonoanatomical landmarks to ensure the nerve block is performed safely and effectively. METHODS: Following an ultrasound-guided SMB with dye injection on 2 embalmed cadavers, pre-tragal face-lift style incision with a full thickness flap dissection was performed allowing accurate visualization of the bony landmarks being used for sonography and identification of the location of the injected dye. RESULTS: This study identifies the correct sonoanatomic landmarks as the maxilla and the coronoid process of the mandible which suggests that the block needle tip and local anesthetic injection are within the infratemporal fossa as opposed to the previously reported pterygopalatine fossa. CONCLUSION: An improved understanding of the sonoanatomy will aid clinicians who are learning, performing and teaching the ultrasound-guided suprazygomatic approach to the maxillary nerve block.

Uterine Exteriorization Compared With In Situ Repair of Hysterotomy After Cesarean Delivery: A Randomized Controlled Trial.

OBJECTIVE: To compare the effect of exteriorized with in situ uterine repair on intraoperative nausea and vomiting during elective cesarean delivery under spinal anesthesia using a phenylephrine infusion. METHODS: This study was a randomized double-blinded controlled trial of 180 women undergoing elective cesarean delivery using a standardized anesthetic protocol. Patients were randomized to exteriorization (n=90) or in situ uterine repair (n=90). The spinal anesthetic, phenylephrine infusion, and blood pressure management were all standardized. The primary outcome was postdelivery intraoperative nausea and vomiting using a 4-point scale (0-3). A sample size of 80 patients per group was needed to demonstrate a 50% reduction in intraoperative nausea and vomiting with in situ repair. RESULTS: From November 2015 through July 2018, 180 patients were enrolled. Incidence of postdelivery intraoperative nausea and vomiting was 39% in the exteriorization group compared with 22% in the in situ group (P=.01). Incidence of hypotension (80% vs 50%; P<.001) and tachycardia (33% vs 17%; P=.02) was significantly higher in the exteriorization group, and more phenylephrine boluses were administered to this group (median 4 boluses [first and third quartiles 1.25-7] vs 2 [0-4]; P<.001). The duration of surgery, blood loss, and postoperative hemoglobin decline were similar between groups. CONCLUSION: In situ uterine repair for elective cesarean delivery under spinal anesthesia with a phenylephrine infusion is associated with less postdelivery intraoperative nausea and vomiting. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, NCT02587013.