Is there a safe plateau pressure in ARDS? The right heart only knows

Airway pressure limitation is now a largely accepted strategy in adult respiratory distress syndrome (ARDS) patients; however, some debate persists about the exact level of plateau pressure which can be safely used. The objective of the present study was to examine if the echocardiographic evaluation of right ventricular function performed in ARDS may help to answer to this question.

For more than 20 years, we have regularly monitored right ventricular function by echocardiography in ARDS patients, during two different periods, a first (1980-1992) where airway pressure was not limited, and a second (1993-2006) where airway pressure was limited. By pooling our data, we can observe the effect of a large range of plateau pressure upon mortality rate and incidence of acute cor pulmonale.

In this whole group of 352 ARDS patients, mortality rate and incidence of cor pulmonale were 80 and 56%, respectively, when plateau pressure was > 35 cmH(2)O; 42 and 32%, respectively, when plateau pressure was between 27 and 35 cmH(2)O; and 30 and 13%, respectively, when plateau pressure was < 27 cmH(2)O. Moreover, a clear interaction between plateau pressure and cor pulmonale was evidenced: whereas the odd ratio of dying for an increase in plateau pressure from 18-26 to 27-35 cm H(2)O in patients without cor pulmonale was 1.05 (p = 0.635), it was 3.32 in patients with cor pulmonale (p < 0.034).

We hypothesize that monitoring of right ventricular function by echocardiography at bedside might help to control the safety of plateau pressure used in ARDS.