Effect of high-frequency oscillatory ventilation on esophageal and transpulmonary pressures in moderate-to-severe acute respiratory distress syndrome

BACKGROUND: High-frequency oscillatory ventilation (HFOV) has not been shown to be beneficial in the management of moderate-to-severe acute respiratory distress syndrome (ARDS). There is uncertainty about the actual pressure applied into the lung during HFOV. We therefore performed a study to compare the transpulmonary pressure (P(L)) during conventional mechanical ventilation (CMV) and different levels of mean airway pressure (mPaw) during HFOV. METHODS: This is a prospective randomized crossover study in a university teaching hospital. An esophageal balloon catheter was used to measure esophageal pressures (Pes) at end inspiration and end expiration and to calculate P(L). Measurements were taken during ventilation with CMV (CMVpre) after which patients were switched to HFOV with three 1-h different levels of mPaw set at +5, +10 and +15 cm H(2)O above the mean airway pressure measured during CMV. Patients were thereafter switched back to CMV (CMVpost). RESULTS: Ten patients with moderate-to-severe ARDS were included. We demonstrated a linear increase in Pes and P(L) with the increase in mPaw during HFOV. Contrary to CMV, P(L) was always positive during HFOV whatever the level of mPaw applied but not associated with improvement in oxygenation. We found significant correlations between mPaw and Pes. CONCLUSION: HFOV with high level of mPaw increases transpulmonary pressures without improvement in oxygenation.