Pumpless extracorporeal lung assist in a pregnant woman with severe ARDS

Introduction

Acute respiratory distress syndrome is characterized by acute-onset, refractory hypoxemia, bilateral infiltrates on chest radiographs and PAOP <18 mmHg or absence of clinical signs of left atrial hypertension. The protective ventilatory strategy limiting plateau pressure to lower than 28 cmH₂O, driving pressure below 15 cmH₂O and tidal volume between 4 and 6 ml/kg using a PEEP level to sustain the open lung approach usually results in hypercapnia. However, it is the mainstream supportive therapy that can modulate survival in this syndrome.

Methods

We describe a case report where a 31-year-old woman who was admitted to the intensive care unit with fatigue, shortness of breath and hypoxemia. She was 24 weeks pregnant and acute myeloid leukemia, subtype M3 was diagnosed 5 days before admission. Non-invasive ventilatory support, chemotherapy (doxirubicin and all-trans retinoic acid) and blood components (red blood cells, fresh frozen plasma, cryoprecipitate and platelets) were implemented. After 4 days the clinical scenario was out of control and she was intubated. Renal function deteriorated and hemodialysis was required.

Results

Controlled mechanical ventilation using neuromuscular blocking (NMB) agents was set to limit plateau pressure, driving pressure, tidal volume and high level of PEEP (15 cmH₂O). However, oxygenation progressively deteriorated despite the instituted therapy and on the eighth day on mechanical ventilation the intraabdominal pressure (IAP) was 20 mmHg, the driving pressure was 20 cmH₂O and Vt was 5 ml/kg, which resulted in PaO₂/FiO₂ of 90, pH 7.15, PaCO₂ of 115 mmHg. Interventional lung assist (iLA; Novalung, GmbH, Talheim, Germany), a pumpless arterio-venous extracorporeal membrane for CO₂ removal, was connected without systemic anticoagulation. After 20 minutes using iLA with 9 l/minute O₂, a PEEP level of 20 cmH₂O, Vt of 4 ml/kg, driving pressure of 20 cmH₂O, I:E of 1:1 resulted in a PaO₂/FiO₂ of 175, PaCO₂ of 57 mmHg and pH 7.35. Hemodynamics were stable and vasopressor agents were not needed. The blood flow in the circuit was 1.4 l/minute. After 14 hours on iLA the NMB agent was interrupted and assisted ventilatory support with Bivent + PSV (Servo i Maquet, Solna, Sweden) was started, sustaining a driving pressure of 15 cmH₂O. After 48 hours on iLA the baby was born naturally and the IAP decreased to 7 mmHg. Respiratory system mechanics and the PaO₂/FiO₂ ratio improved: 56% and 64%, respectively. CPAP + PSV was started on day 8 after iLA implementation and it was surgically removed on the day after when the PaCO₂ was sustained below 40 mmHg.

Conclusion

We present the first case so far where iLA was safely used during 9 days in a pregnant woman with severe ARDS and multiple organ dysfunction syndrome under continuous hemodialytic support that allowed us to set a protective ventilatory strategy using an assisted ventilation mode.