Correction of respiratory acidosis and transient hypomagnesemia.

Four elderly patients with established chronic obstructive airways disease were admitted with a days' to weeks' history of increasing dyspnea. Acute respiratory acidosis was diagnosed and mechanical ventilation instituted. A few hours after initiation of treatment, arterial pH was normal in all patients, but serum magnesium concentrations decreased over the next 1-3 days. Thereafter, a spontaneous normalization was seen. It is suggested that the transient hypomagnesemia is due to correction of the acidosis per se.