Respiratory Distress Treatment Studies Conflict

By Ed Edelson
HealthDay Reporter
Tuesday, February 12, 2008; 5:00 PM

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TUESDAY, Feb. 12 (HealthDay News) -- Two new studies try to answer one of the most pressing questions in critical care medicine: How much pressure should be applied to keep open the partially collapsed lungs of people being treated for the deadly condition called acute respiratory distress syndrome?

Unfortunately, that question has not been definitively answered. Two experts have differing views on what the outcomes, which were not clear-cut, might mean. To one, the answer from the studies being published in the Feb. 13 issue of the Journal of the American Medical Association is that higher positive end-expiratory pressure (PEEP) is better, but the exact amount of pressure must be adapted to each person. Yet another contended there was no proof of the value of higher PEEP.

The results should have some impact on medical practice, pushing intensive care units toward use of higher PEEP levels, based on a patient's needs, said Dr. Derek C. Angus, chairman of the department of critical care medicine at the University of Pittsburgh, and author of an accompanying editorial.

The two research teams, from Canada and France, used different techniques to determine those needs. "The Canadian study titrated PEEP based on the reading of how oxygenated the lung tissue was," explained Angus. "The French relied on more sophisticated measures. One was slightly simpler than the other, but both were trying to convert a set of principles into a recipe to titrate PEEP, so you end with a different measure for each person."

Neither formula had a major effect on the death rate. In the French study of 767 people treated for acute respiratory distress syndrome (ARDS), the hospital mortality was 39 percent among those who got conventional treatment using relatively low PEEP, and 35.4 percent among those who got higher PEEP based on individual calculations. The comparable figures for the 983 people treated for ARDS in the Canadian study was 40.4 percent for those getting conventional treatment, and 36.4 percent for receiving higher PEEP based on individual characteristics.