Variable Ventilation During Acute Respiratory Failure

In variable ventilation, the tidal volume on the Puritan-Bennett 840 ventilator will be randomly varied by 40% on a breath-by-breath basis around a pre-set mean, using the variable ventilation software developed by Dr. Bela Suki and Dr. Arnab Majumdar. In conventional ventilation, the tidal volume on the Puritan-Bennett 840 ventilator will be set to equal the mean tidal volume used in variable ventilation and does not vary.

tidal volume will be set as the patient's baseline tidal volume prior to study entry and will not vary.