Minimally invasive parathyroidectomy using cervical block: Reasons for conversion to general anesthesia

Hypothesis: We investigated the frequency and reasons for conversion from cervical block anesthesia to general anesthesia (GA) in patients undergoing minimally invasive parathyroidectomy for primary hyperparathyroidism. Design: Prospective case series. Setting: Tertiary university hospital. Patients: A total of 441 consecutive patients with primary hyperparathyroidism undergoing minimally invasive parathyroidectomy under cervical block and monitored anesthesia care using midazolam and narcotics were included. Patients with known multiglandular, familial, or secondary hyperparathyroidism or noninformative preoperative localization or those electing minimally invasive parathyroidectomy under GA were excluded. Intervention: All patients underwent cervical block anesthesia and focused exploration using minimally invasive techniques. Main Outcome Measure: Intraoperative need for conversion from cervical block anesthesia to general endotracheal anesthesia. Results: Of the 441 patients, 47 (10.6%) required conversion to GA. In all instances, conversion was performed in a controlled fashion using neuromuscular blockade, endotracheal intubation, and maintenance of the original surgical field preparation. Sixteen procedures were converted to accomplish simultaneous thyroid resections. An additional 15 were converted because the intraoperative parathyroid hormone level failed to decrease by at least 50% from the baseline after resection of the incident parathyroid tumor and extensive exploration was required. Eight procedures were converted because of technical difficulties related to ensuring adequate protection of the recurrent laryngeal nerve. Five procedures were converted to optimize patient comfort, and 2 were converted because of the intraoperative recognition of parathyroid carcinoma. One patient experienced a toxic reaction to lidocaine, causing a seizure. Conclusions: The vast majority of minimally invasive parathyroidectomies can be performed using cervical block anesthesia. However, conversion to GA is appropriate when unexpected intraoperative findings are encountered or for patient comfort.