AUTO-PEEP AND DYNAMIC HYPERINFLATION IN COPD PATIENTS DURING CONTROLLED MECHANICAL VENTILATION AND HIGH-FREQUENCY JET VENTILATION

We investigated the levels of auto-PEEP and dynamic hyperinflation during high frequency jet ventilation (HFJV) and controlled mechanical ventilation (CMV) in six patients with chronic obstructive pulmonary disease within the first 36 h of acute exacerbation. The comparative evaluation was performed at similar conditions of gas exchange in HFJV and CMV: PaO2 77.6±11 mmHg vs 80.8±12 mmHg; PaCO2 46.8±2.5 mmHg vs 47±2.8 mmHg; pH 7.38 vs 7.38. In this situation, the values of auto-PEEP and dynamic hyperinflation, expressed as Δ over the apneic functional residual capacity (FRC) did not differ: (auto-PEEPHFJV 8.9±3.8 cmH2O; auto-PEEPCMV 8.8±4.7 cmH2O; ΔFRCHFJV 0.56±0.19 l; ΔFRCCMV 0.54±0.2 l). This result suggests that, with a suitable machine setting and similar gas exchanges, HFJV produces the same level of auto-PEEP and dynamic hyperinflation as CMV in patients with chronic obstructive pulmonary disease. © 1990 Springer-Verlag.