The oxygen cost of rehabilitation interventions in mechanically ventilated patients: an observational study.

OBJECTIVE

Early rehabilitation is assumed to be a crucial intervention to facilitate weaning from mechanical ventilation in critically ill patients and to limit their long-term functional dependence. However, little is known about the physiological load imposed on patients during such interventions. Without the ability to quantify the exercise intensity of rehabilitation interventions it is impossible to establish a clear separation between usual care and intervention groups in randomised controlled trials. This may explain the lack of definitive benefit of rehabilitation in published trials. We sought to characterise the physiological load, measured as oxygen consumption (V˙O), of the physical activities carried out during rehabilitation interventions in mechanically ventilated participants.

DESIGN

Observational study.

SETTING

Single centre medical-surgical university hospital ICU.

PARTICIPANTS

26 mechanically ventilated participants ventilated >7 days, able to participate in a rehabilitation program.

INTERVENTION

Oxygen consumption (measured by the Medgraphics Ultima breath-by-breath gas exchange analysis system) and heart rate were measured continuously pre-, during and post-standard rehabilitation sessions.

RESULTS

52 sessions were recorded in 26 participants. There was considerable variation in the oxygen cost of the physical activities between participants. The recovery time for 1 in 4 rehabilitation sessions was longer than the rehabilitation activity time.

CONCLUSIONS

Absolute exercise intensity in mechanically ventilated ICU participants, as measured by oxygen consumption, is not activity-dependent.