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 F1O2 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.