Effects of neuromuscular blockers on transpulmonary pressures in moderate to severe acute respiratory distress syndrome

Purpose

To investigate whether neuromuscular blocking agents (NMBA) exert beneficial effects in acute respiratory distress syndrome (ARDS) by reason of their action on respiratory mechanics, particularly transpulmonary pressures (P _L).

Methods

A prospective randomised controlled study in patients with moderate to severe ARDS within 48 h of the onset of ARDS. All patients were monitored by means of an oesophageal catheter and followed up for 48 h. Moderate ARDS patients were randomised into two groups according to whether they were given a 48-h continuous infusion of cisatracurium besylate or not (control group). Severe ARDS patients did not undergo randomisation and all received cisatracurium besylate per protocol. The changes during the 48-h study period in oxygenation and in respiratory mechanics, including inspiratory and expiratory P _L and driving pressure, were assessed and compared. Delta P _L (?P _L) was defined as inspiratory P _L minus expiratory P _L.

Results

Thirty patients were included, 24 with moderate ARDS and 6 with severe ARDS. NMBA infusion was associated with an improvement in oxygenation in both moderate and severe ARDS, accompanied by a decrease in both plateau pressure and total positive end-expiratory pressure. The mean inspiratory and expiratory P _L were higher in the moderate ARDS group receiving NMBA than in the control group. In contrast, there was no change in either driving pressure or ?P _L related to NMBA administration.

Conclusions

NMBA could exert beneficial effects in patients with moderate ARDS, at least in part, by limiting expiratory efforts.