Assist control versus synchronized intermittent mandatory ventilation during acute respiratory failure.

Overview

Controversy persists as to the relative advantages and disadvantages of synchronized intermittent mandatory ventilation (SIMV) vs. assist/control ventilation (A/C) in the management of acute respiratory failure. In an effort to resolve these differences, we evaluated differences in hemodynamic, metabolic, ventilatory, and oxygenation variables during ventilation with both SIMV and A/C using a crossover protocol in critically ill patients without chronic obstructive pulmonary disease. Despite differences in ventilation, resting energy expenditure, and oxygen delivery in specific subgroups of patients, we found no evidence to support any clear-cut advantage of SIMV or A/C in the acute management of respiratory failure. Careful assessment of individual patients may indicate which patient might benefit from each modality of support.