[Non-invasive ventilation in acute or chronic respiratory failure: a comparison of volumetric ventilation]

Although experience acquired with non-invasive ventilation is recent, it is often proposed in selected patients with acute respiratory failure occurring in a background of chronic airflow obstruction. Barometric or volumetric techniques can be used.

We compared tolerance and efficacy of inspiration assist (IA) using a preset pressure and volume-controlled ventilation (VC). Twelve patients with chronic airflow obstruction were randomized to IA (n = 7) or VC (n = 9) mode and ventilated with the appropriate mask.

Tolerance was equivalent for the two groups although hypercapnia fell more in the IA group, particularly after 24 h ventilation (p < 0.03), after three days (p < 0.05), and at complete weaning (p < 0.03). Correction of pH was significantly more rapid in the IA group than in the VC group (p < 0.05 at 24 h). There was no difference in the number of days of ventilation, total ventilation time, or length of hospital stay. Success of non-invasive ventilation, defined as the control of acute respiratory failure without recourse to endotracheal ventilation, was similar in the two groups (86% in group IA and 60% in group VC). Two of the 5 patients in the VC group and one of the 7 in the IA group required intubation.