Cerebral gas embolism in a case of Influenza A-associated acute respiratory distress syndrome treated with high-frequency oscillatory ventilation
A 22-year-old obese (BMI, 46 kg/m2) asthmatic woman developed ARDS from influenza A subtype H1N1. Her hypoxemia was refractory to 100% oxygen delivered at 6 cc/kg ideal body weight tidal volumes with mean airway pressures (mPaw) of 25-30 cm of H2O on conventional pressure control mechanical ventilation despite the use of neuromuscular blockade and inhaled nitric oxide []. Extracorporeal membrane oxygenation was considered but the patient's morbidly obese body mass index and evolving acute kidney injury proved prohibitive of this strategy. An echocardiogram demonstrated normal cardiac function without intracardiac shunt seen on saline bubble contrast study. Her hospital course was complicated by pneumomediastinum with subcutaneous emphysema []. On hospital day 5, an FIO2 of 0.9 was required to maintain arterial PaO2 of > 50 torr.\nOn hospital day 6, the mode of mechanical ventilation was changed to HFOV targeting mPaw of 35-40 cm H2O, Power of 90 cm H2O, Frequency of 5 Hz, Inspiratory time of 33% and FiO2 of 0.8. The FiO2 was decreased to 0.60 when the arterial PaO2 improved to 50-60 torr [].\nForty-two hours after HFOV initiation (hospital day 8), physical examination revealed bilateral non-reactive pupillary dilation in the patient. Emergent bedside computed tomography of her head revealed diffuse cerebral edema, bi-cortical infarcts, brainstem herniation, and multiple right-sided cortical gas emboli []. Patient expired after institution of comfort measures and withdrawal of mechanical ventilation.