Democrats vs Republicans, Coke vs Pepsi, Yankees vs Red Sox, and pressure vs volume control. Okay, maybe pressure vs volume shouldn't be on the same list as the others, but for intensivists it might as well. We have talked about if for decades. There are "true believers" in one mode or another and the issue never seems settled. In a paper published online in a May issue of Chest, another group of authors took a stab at providing an evidence-based resolution to this debate.
Their approach to the question was ambitious and novel. Anyone who reads the critical care literature knows that it is difficult to find differences in clinical outcomes when comparing modes of ventilation. The study authors knew that they would have to look at physiologic outcomes as surrogates. In so doing they developed a physiologic quality assessment to screen studies for inclusion in their meta-analysis—a fairly novel idea. Others should look to do the same because it's important that we have an agreed-upon method for combining physiologic data and determining best practices. They also provide a nice, concise review of the nuances to each mode of ventilation, complete with figures of wave forms.
As for their results and conclusions, it would be too much to expect that they would provide a resolution to the debate. They found very little difference between pressure and volume modes of ventilation, regardless of the outcome examined. It seems clear that an insufficient flow rate during volume control can increase work of breathing in comparison with pressure control, in which the patient can control flow. However, if the flow rate is increased in the volume mode, there is no difference in work of breathing between modes. There was little evidence for differences between modes in gas exchange, compliance/elastance, or hemodynamics. ...
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