Hypokalaemia and respiratory acidosis following partial obstruction of the airway.

An 87-year-old female, with a history of hypertension controlled with hydrochlorothiazide, was scheduled for excision of a cystic mass of the left lobe of the thyroid. In the course of the anaesthetic, she developed partial airway obstruction that resulted in respiratory acidosis (PaCO2 108 mmHg, pH 7.06), developed premature ventricular contractions and experienced a reduction in plasma potassium concentration from 3.9 to 2.9 mmole X L-1. We interpret this hypokalaemia as a consequence of the epinephrine discharge due to hypercapnia. The case is reported to emphasize the importance of minimizing the sympathetic response to induction of anaesthesia, intubation and surgery in patients with marginal potassium stores.