High-frequency oscillatory ventilation in adults - The Toronto experience

Study objectives: To review the clinical experience with high-frequency oscillatory ventilation (HFOV) in three medical-surgical ICUs in Toronto, ON, Canada, and to describe patient characteristics, HFOV strategies, and outcomes. Design and patients: Retrospective chart review of all patients treated with HFOV at three academic university-affiliated ICUs since 1998. The data extracted included patient demographics, etiology of respiratory failure, ventilator settings, and gas exchange and cardiovascular data from baseline to 72 h of treatment, as well as at the transition from HFOV to conventional ventilation (CV). Heart rate and BP were recorded at regular intervals in all patients, and hemodynamic data were recorded in 32 patients who had pulmonary artery catheters in place. Cointerventions and ICU mortality were also recorded. Measurements and results: A total of 156 adults (67 women and 89 men; mean [+/- SD] age, 48 +/- 18 years; mean acute physiology and chronic health evaluation [APACHE] 11 score, 23.S +/- 7.5) with severe ARDS (ie, mean PaPO2/fraction of inspired oxygen [FIO2] ratio, 91 +/- 48 mm Hg; mean oxygenation index [01], 31 14) who had received CV for a duration of 5.6 +/- 7.6 days underwent 171 trials of HFOV. HFOV was discontinued within 4 h in 19 patients (12%) because of difficulties with oxygenation, ventilation, or hemodynamics. Pao(2)/FIO2 ratios and 01 ([FIO2 X mean airway pressure X 100]/Pao(2)) improved significantly with the application of HFOV, and this benefit persisted for the 72-h study duration. Significant changes in hemodynamics following HFOV initiation included an increase in central venous pressure and a reduction in cardiac output (throughout the 72 h), and an increase in pulmonary artery occlusion pressure (at 3 and 6 h). Patients were treated with HFOV for 5.1 +/- 6.3 days. The 30-day mortality rate was 61.7%. Pneumothorax occurred in 21.8% of patients, 43.6% of patients were treated with inhaled nitric oxide, and 37.2% of patients were treated with steroids. Independent predictors of mortality on multivariate analysis were older age, higher APACHE 11 score, lower pH at the initiation of HFOV, and a greater number of days receiving CV prior to HFOV. Conclusions: HFOV has beneficial effects on Pao(2)/FIO2 ratios and 01, and may be an effective rescue therapy for adults with severe oxygenation failure. The early institution of HFOV may be advantageous.