This report documents the occurrence of lactic acidosis in a subgroup of patients undergoing cardiopulmonary bypass. The pathogenesis of this disorder is uncertain, but it appears to not relate to inadequate oxygen delivery. Systemic vasodilation and reduced oxygen extraction appear to be features of this disorder, which has an excellent prognosis.

The use of epinephrine after cardiopulmonary bypass precipitates the development of lactic acidosis in some patients. This phenomenon is presumably a beta-mediated effect, and is associated with an increase in whole-body and lower limb blood flow and a decrease in whole-body and transfemoral oxygen extraction. The phenomenon does not appear to be related to reduced tissue perfusion and does not have the poor outlook of lactic acidosis associated with shock.

SummaryThe 'cuff-leak' test, which involves demonstrating a leak around a tracheal tube with the cuff deflated, has been advocated to determine the safety of extubation in patients with upper airway obstruction. In 62 such patients we were able safely to extubate all patients with a cuff leak. Two patients extubated without cuff leak required reintubation and in five patients who repeatedly failed the test, tracheostomy was performed. Subsequently, we extubated 10 patients who were stable on spontaneous ventilation and did not have cuff leak; three later required tracheostomy and seven were uneventfully extubated. While the presence of cuff leak demonstrates that extubalion is likely to be successful, a failed cuff-leak test does not preclude uneventful extubation and if used as a criterion for extubafion may lead to unnecessarily prolonged intubation or to unnecessary tracheostomy.