Apnea testing on extracorporeal membrane oxygenation: Case report and literature review.

INTRODUCTION

Extracorporeal membrane oxygenation (ECMO) is used to resuscitate patients with cardiovascular collapse or refractory respiratory failure. Determination of death by neurologic criteria requires the performance of an apnea test. Few data exist describing performance of an apnea test in this setting. Understanding of ECMO physiology and mechanics is critical in the efficient and proper delivery of apnea testing.

METHODS

We report the case of a young woman on venovenous ECMO post-cardiac arrest in whom we performed an apnea test to determine death by neurologic criteria. Decreasing sweep gas flow rate to 0 L/min led to a Paco2 increase of 3 to 5 mm Hg/min of apnea. Stable oxygen saturation was maintained with supplemental oxygen via the endotracheal tube. We further review all reported to date cases of apnea testing in the setting of ECMO.

RESULTS

A total of 8 adult and 3 pediatric cases have been reported in the literature. Decreasing sweep rate is necessary to achieve hypercapnia. Oxygenation is maintained through oxygen circuit delivery with or without supplemental diffusion oxygenation via the endotracheal tube. Hemodynamics can be managed with circuit pump flow in addition to vasoactive medication support. Continuous positive airway pressure is recommended during the test.

CONCLUSION

According to current guidelines, apnea testing has to be performed after prerequisites have been met and in a fashion where hypercapnia is achieved in the face of stable oxygenation and hemodynamics. Performance of the test during ECMO is feasible.