Physiological predictors of survival during high-frequency oscillatory ventilation in adults with acute respiratory distress syndrome

INTRODUCTION: Data that provide clinical criteria for the identification of patients likely to respond to high-frequency oscillatory ventilation (HFOV) are scarce. Our aim was to describe physiological predictors of survival during HFOV in adults with severe acute respiratory distress syndrome (ARDS) admitted to a respiratory failure center in the United Kingdom. METHODS: Electronic records of 102 adults treated with HFOV were reviewed retrospectively. We used logistic regression and receiving-operator characteristics curve to test associations with oxygenation and mortality. RESULTS: Patients had severe ARDS with a mean (SD) Murray's score of 2.98 (0.7). Partial pressure of oxygen in arterial blood to fraction of inspired oxygen (PaO(2)/FiO(2)) ratio and oxygenation index improved only in survivors. The earliest time point at which the two groups differed was at three hours after commencing HFOV. An improvement of >38% in PaO(2)/FiO(2 )occurring at any time within the first 72 hours, was the best predictor of survival at 30 days (area under the curve (AUC) of 0.83, sensitivity 93%, specificity 78% and a positive likelihood ratio (LR) of 4.3). These patients also had a 3.5 fold greater reduction in partial pressure of carbon dioxide in arterial blood (PaCO(2)). Multivariate analysis showed that HFOV was more effective in younger patients, when instituted early, and in patients with milder respiratory acidosis. CONCLUSIONS: HFOV is effective in improving oxygenation in adults with ARDS, particularly when instituted early. Changes in PaO(2)/FiO(2 )during the first three hours of HFOV can identify those patients more likely to survive.