Rapid reduction of oxygenation index by employment of a recruitment technique in patients with severe ARDS

Background

Mechanical ventilation of patients with ARDS may contribute to pulmonary injury and systemic inflammation. The objective of this study was to examine the safety and efficacy of a recruitment maneuver which, if successful, would rapidly improve atelectasis and oxygenation and in so doing reduce the potential for ventilator induced lung injury.

Methods

Nineteen patients with severe ARDS (defined as PaO₂/FiO₂ ≤ 150) from diverse etiologies were turned prone and a positive pressure of 40 cmH₂O was applied for a period of 90 s. This pressure was increased in 5 cmH₂O increments in subsequent maneuvers to a maximum of 50 cmH₂O if there was an inadequate initial response. Subsequently, pressure limited mechanical ventilation with a PEEP of 15 cmH₂O was instituted to preventderecruitment. Peak pressures were maintained at ≤ 35 cmH₂O. Outcome measures were oxygenation index, PaO₂/FiO₂ ratio and alveolar-arterial oxygen difference.

Results

The oxygenation index decreased from a median of 31 cmH₂O to 14 cmH₂O/mmHg immediately post recruitment and to 11 cmH₂O/mmHg (P < 0.0001) 24 hours later. The A-aDO₂ improved from 454 mmHg to 128 mmHg (P < 0.0001) and the PaO₂/FiO₂ ratio from 75 to 218 (P < 0.0001) 24 hours later. 25% of patients had PaO₂/FiO₂ ratio of 300 mmHg at 24 hours. Mean airway pressure increased by 3 cmH₂O initially, from 23 cmH₂O to 26 cmH₂O (NS) as a consequence of the increase of PEEP but his had decreased to 25 cmH₂O after 24 hours. There were no significant complications.

Conclusion

Rapid reductions in FiO₂ can be achieved safely by the implementation of a relatively simple recruitment technique.