Intermittent positive pressure ventilation with either positive end-expiratory pressure or high frequency jet ventilation (HFJV), or HFJV alone in human acute respiratory failure

Abstract

Continuous Positive Pressure Ventilation (CPPV), High-Frequency Jet Ventilation (HFJV), and a combination of HFJV with Intermittent Positive Pressure Ventilation (CV) were randomly compared in 13 critically ill patients with severe acute respiratory failure. Ventilatory settings were chosen in order to apply the same mean airway pressure (Paw) during the three modes. Respiratory frequencies were adjusted during CPPV (16 +/- 2 breaths/min) and HFJV (235 +/- 32 breaths/min) to achieve the same level of PaCO2 and were then combined during CV. All patients were heavily sedated during the study and had had peripheral and balloon-tipped pulmonary arterial catheters previously inserted. After a steady state at FIO2 1 in each mode of ventilation, hemodynamic and respiratory parameters were measured. A Paw of 13.8 +/- 2.9 mm Hg was applied to each patient by using a PEEP of 7.4 mm Hg during CPPV; a driving pressure of 2.9 +/- 0.2 bars and an I/E ratio of 0.43 during HFJV; and by combining HFJV, using a driving pressure of 1.2 +/- 0.3 bars with intermittent positive pressure ventilation during CV. There were no significant differences in any of the hemodynamic or respiratory parameters measured, except for a significant decrease in PaCO2 during CV when compared to CPPV or HFJV. We concluded that 1) arterial oxygenation and cardiac output depend mainly on Paw independent of the method used to increase Paw and 2) CV can improve CO2 elimination without increasing Paw.(ABSTRACT TRUNCATED AT 250 WORDS)