The effect of different lung-protective strategies in patients during cardiopulmonary bypass: a meta-analysis and semiquantitative review of randomized trials.

OBJECTIVES

A variety of lung-protective techniques, including continuous positive airway pressure and vital capacity maneuvers, have been suggested as beneficial when applied during cardiopulmonary bypass (CPB). To better define the efficacy of these techniques, a systematic review of different ventilation strategies during and after CPB was performed.

DESIGN

A systematic review and meta-analysis according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses recommendations.

SETTING

Hospitals.

PARTICIPANTS

Eight hundred fourteen participants of 16 randomized controlled trials.

INTERVENTIONS

Continuous positive airway pressure (CPAP), low-volume ventilation, or vital capacity maneuvers (VCMs) during CPB.

MEASUREMENTS AND MAIN RESULTS

The methodologic validity of the included trials was scored according to the Oxford scale. Included trials had to report on at least 1 of the following parameters: oxygenation, oxygenation index, alveolar-arterial oxygen difference, or shunt fraction. The average quality of the included trials was as low as 2 on a scale from 1 to 5. The use of CPAP or VCM during CPB led to a significant increase in oxygenation parameters immediately after weaning from CPB, but this effect was not sustainable and did not improve patient outcome.

CONCLUSIONS

This meta-analysis showed that the positive effects of the designated techniques are probably short-lived with a questionable impact on the long-term clinical outcome of the treated patients. Based on the available data, it might be impossible to advise an optimal or best-evidence strategy of lung preservation during CPB.