Proportional modes versus pressure support ventilation: a systematic review and meta-analysis

Proportional modes (proportional assist ventilation, PAV, and neurally adjusted ventilatory assist, NAVA) could improve patient-ventilator interaction and consequently may be efficient as a weaning mode. The purpose of this systematic review is to examine whether proportional modes improved patient-ventilator interaction and whether they had an impact on the weaning success and length of mechanical ventilation, in comparison with PSV.

We searched PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials from inception through May 13, 2018. We included both parallel-group and crossover randomized studies that examined the efficacy of proportional modes in comparison with PSV in mechanically ventilated adults. The primary outcomes were (1) asynchrony index (AI), (2) weaning failure, and (3) duration of mechanical ventilation.

We included 15 studies (four evaluated PAV, ten evaluated NAVA, and one evaluated both modes). Although the use of proportional modes was not associated with a reduction in AI (WMD - 1.43; 95% CI - 3.11 to 0.25; p = 0.096; PAV-one study, and NAVA-seven studies), the use of proportional modes was associated with a reduction in patients with AI > 10% (RR 0.15; 95% CI 0.04-0.58; p = 0.006; PAV-two studies, and NAVA-five studies), compared with PSV. There was a significant heterogeneity among studies for AI, especially with NAVA. Compared with PSV, use of proportional modes was associated with a reduction in weaning failure (RR 0.44; 95% CI 0.26-0.75; p = 0.003; PAV-three studies) and duration of mechanical ventilation (WMD - 1.78 days; 95% CI - 3.24 to - 0.32; p = 0.017; PAV-three studies, and NAVA-two studies). Reduced duration of mechanical ventilation was found with PAV but not with NAVA.

The use of proportional modes was associated with a reduction in the incidence with AI > 10%, weaning failure and duration of mechanical ventilation, compared with PSV. However, reduced weaning failure and duration of mechanical ventilation were found with only PAV. Due to a significant heterogeneity among studies and an insufficient number of studies, further investigation seems warranted to better understand the impact of proportional modes. Clinical trial registration PROSPERO registration number, CRD42017059791. Registered 20 March 2017.