Hyperparathyroidism, hypercalcemia and difficult laryngoscopy: a retrospective review

Background: The incidence of difficulty with intubation in the general population depends upon the definition used but results as high as 37% have been published. Endocrine disorders such as diabetes and hyperthyroidism have been linked to an increased incidence of difficult intubation via laryngoscopy. Hypercalcemia with resulting calcification has been demonstrated to result in neck pain, decreased cervical range of motion, and loss of skin and tendon compliance. We speculated that patients with hyperparathyroidism and resulting hypercalcemia would have anincreased incidence of intubation difficulty via laryngoscopy.Methods: We studied 382 patients presenting for parathyroidectomy in whom direct laryngoscopy was initially attempted compared to 262 patients presenting for abdominal surgery in whom laryngoscopy was initially attempted via retrospective chart review. Difficult laryngoscopy was defined as 3 or greater attempts at direct laryngoscopy or 2 attempts and the use of airway adjunct (Eschmann stylet), flexible fiberoptics, or an indirect laryngoscope (Pentax AWS or Airtraq). Awkward intubation was defined as requiring 1 attempt at laryngoscopy, intubation requiring a change in laryngoscope blade, the use of an airway adjunct (Eschmann stylet), or a Cormack and Lehane’s view on initial laryngoscopy 2. Hypercalcemia was defined as serum [Ca2+] 10.2 mg/ dl. Propensity score matching was done to create 88 matched patient sets. McNemar’s test was used to evaluate intubation difficulties in patients presenting for parathyroidectomy. The relationship between difficult laryngoscopy and hypercalcemia in parathyroidectomy patients was assessed by simple logistic regression (unadjusted) and multiple logistic regression. Results: There is no difference in the rate of difficult or awkward laryngoscopy or the rate at which laryngoscopy was abandoned in favor of another means of intubation between parathryoidectomy and abdominal surgery patients. Hypercalcemia also does not impact laryngoscopy difficulty. Conclusions: To our knowledge, this is the first manuscript evaluating the impact of parathryoidectomy surgery and hypercalcemia on ease of intubation via laryngoscopy. Despite the fact that patients presenting for parathyroidecomy have many potential etiologies of increased difficulty with laryngoscopy, they do not appear to be at increased risk of laryngoscopy problems. The same is true of those patients presenting with hypercalcemia.