Cardiorespiratory and Sympathoadrenal Responses to Weaning with Synchronized Intermittent Mandatory Ventilation from Mechanical Vrntilatory Support

The autor studied the cardiopulmonary effects of synchronized intermittent mandatory ventilation (SIMV) used for weaning in the patients with acute respiratory failure. Weaning from assisted ventilation by means of SIMV was attempted in 22 patients, who had been ventilated with a Servo 900 C ventilator for at least 48 hours before entering the trial. Fourteen of the 22 patients ware weaned successfully, but eught were not weaned. The non-weaners had a significantly higher PaCO2 and cardiac index both before and during SIMV than the weaners. Non-weaners showed significantly higher rigt ventricular stroke work index before weanig, and significantly lower mean arterial pressure during SIMV in comparsion with weaners. Hence, the changes in systemic vascular resistance were opposite in the two groups. There was no significant difference in arterial oxygenation and oxygen delivery between weaners and nonweaners before and during weaning. These results suggest that SIMV may be better than conventional methods for weaning patients with acute respiratory failure from the point of view of the cardiorespiratory and sympathoadrenal responses.

Respiration

weaning

acute respiratory failure

Circulation

catecholamine