Comparison of high frequency jet ventilation to conventional ventilation during severe acute respiratory failure in humans.

High frequency jet ventilation (HFJV) was compared to conventional (high tidal volume, low frequency) ventilation in 9 patients with acute respiratory failure (ARF). Alveolar ventilation was comparable or lower with HFJV in all but one case. When comparisons were made at the same concentration of oxygen and level of PEEP, no consistent change in arterial oxygenation (PaO2) was found. In one case, it was possible to increase PaO2 during HFJV by additional increases in PEEP without elevation in peak airway pressure (AWP) compared to conventional ventilation (CV). At the same level of PEEP, peak AWP was lower during HFJV, except in 1 patient with bronchospasm. Cardiac output did not differ significantly between the 2 ventilation systems, except in the same patient with bronchospasm. HFJV may be useful in acute respiratory failure when peak AWP during CV limits effective use of mechanical ventilation for gas exchange. Patients with significantly elevated airway resistance may be an exception. Improvement in PaO2 will usually depend on increases in PEEP.