A Case of Pneumomediastinum in a Patient With Acute Respiratory Distress Syndrome on Pressure Support Ventilation

Abstract

During mechanical ventilation for acute respiratory distress syndrome, tidal volume (V_T) must be reduced. Once switched to pressure-support ventilation, there is a risk that uncontrolled large V_T may be delivered. A 63-year-old man with community-acquired pneumonia required tracheal intubation and mechanical ventilation, with a V_T of 6 mL/kg predicted body weight, PEEP of 10 cm H₂O, a respiratory rate of 30 breaths/min, and F_IO2 of 0.60. Plateau pressure was 22 cm H₂O. He improved and received pressure-support. Twelve days later a chest radiograph showed suspected air leaks, confirmed via computed tomogram (CT), which showed anterior pneumomediastinum. V_T received over the previous 3 days had averaged 14 mL/kg predicted body weight. The patient was put back onto volume-controlled mode, and 2 days later there were no air leaks. In pressure-support ventilation, V_T must be closely monitored to ensure lung-protective mechanical ventilation.