Original Articles

The Addition of a Membrane Oxygenator to a Ventricular Assist Device in a Patient with Acute Respiratory Distress Syndrome

Address correspondence to: Peter Betit, RRT-NPS, Respiratory Care/ECMO, Children’s Hospital Boston, Respiratory Care MA 883, 300 Longwood Avenue, Boston, MA 02115. E-mail: peter.betit@childrens.harvard.edu

Abstract

A 12-year-old boy with Marfan’s syndrome required a biventricular assist device (VAD) after an aortic root replacement. The patient developed acute respiratory distress syndrome and required escalating ventilator support. We hypothesized that the addition of a membrane oxygenator in series with the assist device would improve gas exchange and allow for a more lung-protective ventilator approach. A membrane oxygenator was placed in series with the right VAD resulting in a blood path of right atrium to VAD to oxygenator to pulmonary artery. Circuit function was gauged by monitoring flow and oxygenator pressures and periodic circuit inspections and oxygenator blood gases. Heparin was titrated to maintain unfractionated antifactor Xa levels of .3–.7 IU/mL and partial thromboplastin time of 60–80 seconds. The initial sweep gas supplying the oxygenator was 5 L/min at an F_IO₂ of 1.0, which achieved a pH >7.40 and a PF ratio >250. The pre- and post-oxygenator pressures were 55–60 mmHg and 45–50 mmHg, respectively, and the measured flow at the oxygenator outlet was 2.0–2.2 L/min. The patient was changed from high-frequency oscillatory ventilation to pressure-controlled synchronized intermittent ventilation with pH maintained at 7.35–7.40 and PF ratio >250. Paralytics were discontinued and the patient’s neurologic condition was deemed intact. The patient hemorrhaged after a sternal closure and required transfusions and antifibrinolytics that led to thrombus in the membrane and membrane circuitry, which were replaced without incident. The patient’s respiratory status remained stable; however, his overall condition worsened as a result of additional organ dysfunction and septicemia, and he did not survive. The addition of a membrane oxygenator to a VAD is feasible and supplements gas exchange permitting the use of more lung protective ventilation.