Effects of alveolar recruitment in patients after cardiac surgery: a prospective, randomized, controlled clinical trial

Introduction

Pulmonary atelectasis and hypoxemia are significant events after cardiac surgery. The aim of the present study was to determine the efficacy of alveolar recruitment in different ventilation modes after cardiac surgery.

Methods

We evaluated 480 patients submitted to cardiac surgery after arrival in the ICU. Groups were randomly allocated to one of eight groups: group 1 – volume controlled (8 ml/kg), respiratory rate if 12/min, PEEP = 5 cmH₂O with no recruitment, FiO₂ = 0.6; group 2 – volume controlled (8 ml/kg), respiratory rate if 12/min, PEEP = 5 cmH₂O, FiO₂ = 0.6 and recruitment with three maneuvers (PEEP 30 cmH₂O for 30 seconds); group 3 – volume controlled (8 ml/kg), respiratory rate if 12/min, PEEP = 10 cmH₂O, with no recruitment, FiO₂ = 0.6; group 4 – volume controlled (8 ml/kg), respiratory rate if 12/min, PEEP = 10 cmH₂O, FiO₂ = 0.6 and recruitment with three maneuvers (PEEP 30 cmH₂O for 30 seconds); group 5 – pressure controlled (to achieve 8 ml/kg), respiratory rate if 12/min, PEEP = 5 cmH₂O with no recruitment, = FiO₂ 0.6; group 6 – pressure controlled, respiratory rate if 12/min, PEEP = 5 cmH₂O, FiO₂ = 0.6 and recruitment with three maneuvers (PEEP 30 cmH₂O for 30 seconds); group 7 – pressure controlled, respiratory rate if 12/min, PEEP = 10 cmH₂O, with no recruitment, FiO₂ = 0.6; and group 8 – pressure controlled, respiratory rate if 12/min, PEEP = 10 cmH₂O, FiO₂ = 0.6 and recruitment with three maneuvers (PEEP 30 cmH₂O for 30 seconds). The primary outcome was the ratio of arterial tension to inspired oxygen fraction measured after 4 hours of ventilation and the time for extubation.

Results

Oxygenation was higher in recruitment groups (P < 0.01), and pressure-controlled ventilation resulted in better oxygenation than volume-controlled ventilation (P < 0.05). Patients of groups 6 and 8 (pressure controlled with recruitment maneuvers) presented a lower time for extubation than the other modes (280 min vs 476 min, P < 0.01).

Conclusion

After cardiac surgery, pressure-controlled ventilation with recruitment is an effective method to reduce hypoxemia, and results in a reduction of length in mechanical ventilation.