Postoperative respiratory depression following excision of carotid body tumours

This report is of two adult patients who were scheduled for excision of carotid body tumours. One of the patients had bilateral tumours, while the second had a unilateral tumour. In the first, anaesthesia was maintained by nitrous oxide:oxygen and halothane 1-2%. Postoperatively, the intramuscular injection of meperidine 75 mg resulted in apnoea, cyanosis, and loss of consciousness. In the second, anaesthesia was maintained by nitrous oxide:oxygen, supplemented by fentanyl 2 micrograms.kg-1 and incremental doses of vecuronium. Following complete reversal of neuromuscular block, the patient became wide awake but spontaneous breathing was resumed at a rate of only two to three breaths per minute, and the oxygen saturation as monitored by pulse oximetry decreased to 50%. Naloxone 0.4 mg iv increased the respiratory rate to 14 per minute and the oxygen saturation to 98%. The report suggests that surgical excision of carotid body tumours, whether unilateral or bilateral, can be followed by severe postoperative respiratory depression. The complication may be attributed to opioid administration in the absence of peripheral chemoreceptor drive.