Maximal recruitment strategy minimizes tidal recruitment in severe ARDS: a CT scan study

Introduction

The maximal recruitment strategy (MRS) is considered an efficient maneuver to reverse nonaerated lung in ARDS patients. There is no information regarding tidal recruitment during MRS.

Methods

Early and severe ARDS patients were submitted to MRS guided by thoracic CT: A - recruitment phase (PEEP 10 to 45 cmH₂O and constant driving pressure 15 cmH₂O); B - PEEP titration phase (PEEP 25 to 10 cmH₂O). Images were obtained at end expiration and inspiration. Global and regional quantitative CT analyses from each step of PEEP were compared [1].

Results

Analyses of 12 patients showed that MRS reduced significantly the global amount of nonaerated tissue (54 ± 8% to 7 ± 6%, P < 0.01), tidal recruitment (4 ± 4% to 1 ± 1%, P = 0.029) (Figure 1). Most dependent regional tidal recruitment significantly increased from PEEP 10 to 20 cmH₂O (2 ± 3% to 11 ± 7%, P < 0.01), but significantly decreased after MRS (11 ± 7% to 2 ± 2%, P < 0.01). High PEEP (25 cmH₂O) was necessary to sustain recruitment.

Figure 1

Percentage of regional (I to IV) tidal recruitment during all steps of the MRS protocol.

Conclusions

MRS decreased nonaerated areas and tidal recruitment. Increasing PEEP without full recruitment may cause lung injury exacerbation in the severe ARDS population.