Acute physiologic effects of a stepwise recruitment maneuver in acute respiratory distress syndrome

Stepwise recruitment maneuvers (RM) applied with high airway pressures may optimize lung recruitment, but this kind of intervention may lead to widely heterogeneous responses with possible side effects. To assess the clinical impact of these maneuvers, we performed a stepwise maximal-recruitment strategy superimposed on routine mechanical ventilation.

We studied 13 adults with early-phase acute lung injury/acute respiratory distress syndrome (ALI/ARDS). We used pressure-control ventilation at an FiO(2) of 1. Starting from a Pplat/positive end-expiratory pressure (PEEP) of 40/25, we sequentially increased airway pressure in 5 cmH(2)O steps until a PaO(2)/FiO(2) of 350 mmHg or a Pplat/PEEP of 60/40 cmH(2)O was reached. The PEEP was then progressively reduced until the PaO(2) decreased by more than 10% of the maximum PaO(2); the PEEP was subsequently set to 2 cmH(2)O above this level. An intra-arterial catheter continuously displayed blood gas measures. The respiratory mechanics and hemodynamics were monitored at each phase and during the two-hour follow-up.

Two hours after the RM, the PaO(2)/FiO(2) was higher than at baseline (187±102 versus 339±136 mmHg, P<0.001). In 8 patients, the PEEP increased from 12±3 cmH(2)O to 15±4 cmH(2)O after the RM (P<0.001). In the other five, it closely mirrored the basal PEEP. Seven patients did not reach the 350-mmHg PaO(2) target. The respiratory system compliance decreased in seven patients. The RM was discontinued due to severe complications in four patients.

Although stepwise-RM improves oxygenation, it has a heterogeneous impact on respiratory mechanics and may cause adverse hemodynamic effects and transient hypoxemia. If the use of this kind of RM is considered, it should be adapted to individual patient needs, applied carefully and closely monitored.