Haemodynamic changes during the apnoea test in patients with brain death.

Objective: in France, an apnoea test is compulsory to confirm brain death. This test results in a major hypercarbia and respiratory acidosis. This study aimed to assess haemodynamic changes elicited by the apnoea test. Study design: Prospective clinical study. Patients: Fifteen patients with brain death. Methods: Before the apnoea test, the lungs were ventilated with pure oxygen for 20 minutes. Thereafter, the test was conducted with continuous oxygen flow through the endotracheal tube, and SpO(2) monitoring. Blood gases and haemodynamic parameters, including systemic arterial pressure, pulmonary artery pressure, pulmonary artery occlusion pressure, cardiac index and right Ventricular function parameters were assessed before, during and 20 minutes after the apnoea test. Mean Values at the Various times were compared. Results: Hypercarbia and acidosis induced a major pulmonary hypertension and an increase in cardiac output, associated with a decrease in systemic vascular resistances. Despite pulmonary hypertension and acidosis, right ventricular function was maintained. All haemodynamic modifications were reversed by reventilation. Conclusion: Apnoea test induces a reversible pulmonary hypertension that is seemingly not deleterious for right ventricular function. Apnoea test probably does not alter viability of the donor's organs.