High-Frequency Oscillatory Ventilation in Adults: HFOV Combined With Other Therapies
The observed pneumothorax rate (21.8%) is higher than the rates observed in studies evaluating conventional treatment strategies in adults with ARDS, in which barotrauma rates ranged from 7 to 14%. Derdak and colleagues reported pneumothorax rates of 9% and 12%, respectively, in the HFOV and CV groups. The higher rate in the current study was likely due to the patients’ severity of illness. Another possible explanation relates to differences in HFOV utilization and settings. However, this explanation is not likely, since the applied mPaw was not higher in the current study than those used in previous studies evaluating HFOV, and there was no difference in the pneumothorax rate among the three ICUs.
In the current study, 66.7% of patients were treated with inhaled NO, steroids, or prone positioning during HFOV. One small randomized trial found that methylprednisolone given to patients with unresolving ARDS was associated with reduced mortality. However, prospective trials’ have failed to show any mortality benefit of NO or prone positioning in patients with ARDS. Nonetheless, clinicians continue to use these latter measures in desperation, since individual patients may show improvements in oxygenation. read more
The physiologic rationale for the combined use of HFOV and NO is sound. Alveolar recruitment during HFOV may increase the amount of alveolar/ capillary interface available for inhaled NO (INO) to act on, potentially resulting in greater improvements in ventilation-perfusion matching than those achieved with each individual therapy. In a prospective study evaluating the combined use of HFOV and NO, 83% of patients demonstrated at least a 20% improvement in Pa02/Fl02 ratio, with an average improvement of 38%. In addition, the use of INO allowed significant reductions in Fio2 within 8 to 12 h. Despite physiologic benefit, there is no evidence that therapy with HFOV, INO, or both in combination reduces mortality in adults with ARDS.