Variability of the breathing pattern before and after extubation.

A stable breathing pattern during unassisted ventilation through an endotracheal tube (ETT) prior to extubation is an important factor in determining whether a patient can be successfully extubated. Proper interpretation of changes in the breathing pattern requires knowledge of the normal variability of the breathing pattern in critically ill, intubated patients. To establish these guidelines, 50 spontaneously breathing patients who were being weaned from mechanical ventilation were monitored with respiratory inductive plethysmography for one hour immediately prior to and following successful extubation. Immediately after extubation, respiratory rate (f), tidal volume (VT), minute ventilation, and mean inspiratory flow increased slightly. By 30 minutes postextubation, these parameters were similar to preextubation values. There was no significant change in variability of f or VT. Although the breathing pattern of these relatively stable, intensive care patients differed from values of normal ambulatory subjects, values were similar in the preextubation and postextubation periods.