High-Frequency Oscillatory Ventilation in Adults: Materials and Methods
In adults with ARDS, the experience with HFOV is limited to five observational studies and one randomized controlled trial. The observational studies reported significant improvements in oxygenation using an aggressive open lung strategy during HFOV, and the two larger studies suggested better outcomes when HFOV is applied early in the course of ARDS. Derdak and colleagues conducted a multicenter randomized, controlled trial comparing HFOV with conventional pressure control ventilation strategy in 148 adults with early-phase ARDS. Applying a significantly higher mPaw in the HFOV group, there was an early improvement in the Pa02/fraction of inspired oxygen (Fio2) ratio compared with the conventional group. However, this difference did not persist beyond 24 h. the mortality rate in the HFO group was 37%, compared with 52% in the CV group, but this difference was not statistically significant. They concluded that HFOV is a safe and effective mode of ventilation for the treatment of ARDS in adults.
HFOV is increasingly employed in ICUs for patients with ARDS who remain hypoxemic during conventional therapy. Our goal was to review the experience with HFOV in three academic university-affiliated medical surgical ICUs in Toronto, Canada, and to describe patient characteristics, HFO ventilator strategies, the safety of the technique, patient outcomes, and potential predictors of outcome.
Three University of Toronto-affiliated medical centers with extensive experience using HFOV in adults participated in this retrospective descriptive study of their practice patterns and outcomes. The three centers were Mount Sinai Hospital, University Health Network, and Sunnybrook & Women’s College Health Sciences Center. All of the ICUs use an adult high-frequency oscillatory ventilator (model 3100B; SensorMedics; Yorba Linda, CA). In general, HFOV is used in these centers as rescue therapy for patients who remain hypoxemic and require high levels of inspired oxygen during CV. There was no standard protocol in place for the initiation, titration, or weaning of HFOV. The recorded data included patient demographics, etiology of respiratory failure, comorbidities, ventilator settings, and blood gas and cardiovascular data from baseline to 72 h of treatment. The study was approved by the institutional review board of each hospital. Data from 33 of these patients have been included in previous reports. We have included them in the current study to report on the largest clinical experience possible, and to capitalize on the higher statistical power of the larger population to identify small but potentially important clinical effects.