Combining high-frequency oscillatory ventilation and recruitment maneuvers in adults with early acute respiratory distress syndrome: The Treatment with Oscillation and an Open Lung Strategy (TOOLS) Trial pilot study*

Abstract

To determine the safety, feasibility, and lung-recruitment efficacy of an explicit ventilation protocol combining high-frequency oscillatory ventilation and recruitment maneuvers. Prospective, multiple-center, single-intervention pilot study. Four university-affiliated intensive care units. Twenty-five patients with early acute respiratory distress syndrome and severe oxygenation failure. Patients were transitioned from standardized conventional ventilation to high-frequency oscillatory ventilation beginning with an initial cycle of up to three sustained inflation recruitment maneuvers (40 cm H2O x 40 secs), followed by a decremental titration of Fio2 and then mean airway pressure. Recruitment maneuvers were repeated for hypoxemia and routinely at least twice daily if the Fio2 was >0.4. A specific protocol was used for weaning high-frequency oscillatory ventilation, for transitioning to conventional ventilation, and for judging intolerance of conventional ventilation whereby patients should be put back on high-frequency oscillatory ventilation. Patients (median [interquartile range] Acute Physiology and Chronic Health Evaluation II, 24 [19-32]; age, 50 [41-64]) were enrolled after 13 (range, 6-51) hrs of conventional ventilation. Following the initial cycle of recruitment, the mean (+/-sd) Pao2/Fio2 increased significantly compared with standardized conventional ventilation (200 +/- 117 vs. 92 +/- 36 mm Hg, p < .001). After a mean of 12 hrs of high-frequency oscillatory ventilation, the mean Fio2 was significantly reduced compared with prestudy levels (0.5 +/- 0.2 vs. 0.9 +/- 0.1, p < .001). A median of seven (four to 11) recruitment maneuvers was performed per patient over the study period, with only eight of 244 (3.3%) being aborted. Six of 19 patients transitioned to conventional ventilation (32%) were deemed intolerant and were switched back to high-frequency oscillatory ventilation. Protocol adherence was excellent with documented rates >90%. The combination of high-frequency oscillatory ventilation and recruitment maneuvers resulted in rapid and sustained improvement in oxygenation, likely through lung recruitment. This explicit high-frequency oscillatory ventilation protocol appears well tolerated, feasible, and physiologically sound.