Disclosure(s): No relevant financial relationship(s) to disclose.
First Author: Swati Jain, MD – Medical College of Wisconsin Co-Author: Racine Reinoso, MD – MD, Medical College of Wisconsin Co-Author: Kurt Hu, MD – MD, Medical College of Wisconsin
Introduction: Average volume-assured pressure support (AVAPS) is a mode of noninvasive ventilation that automatically adjusts inspiratory pressure to maintain a preset tidal volume. Although widely used in chronic respiratory disorders, its role in acute hypercapnic respiratory failure (AHRF) remains unclear. This systematic review and meta-analysis evaluated whether AVAPS provides clinical or physiologic benefits compared to standard bilevel positive airway pressure in spontaneous/timed mode (BIPAP-ST).
Methods: We systematically searched the following databases: CENTRAL, CINAHL, Cochrane Database of Systematic Reviews, Medline (via Ovid), Scopus Web of Science Core Collection (SCI-EXPANDED, SSCI, AHCI, CPCI-S, CPCI-SSH, BKCI-S, BKCI-SSH, ESCI, CCR-Expanded, and IC) for all published studies till August 2024 that compared AVAPS with BIPAP-ST for AHRF in adults. Eligible studies included RCTs and observational studies reporting outcomes such as changes in CO2 levels, blood pH, intubation rates, mortality, and length of hospital stay. Data were pooled using random-effects meta-analysis, and study quality was assessed using standardized tools
Results: 11 studies met the inclusion criteria, including 4 RCTs and 7 observational studies, enrolling a total of 728 patients. AVAPS resulted in a greater reduction in arterial CO2 (mean difference −4.78 mmHg) and a modest but statistically significant improvement in blood pH (mean difference +0.03) compared to BIPAP-ST. Although there was a trend toward fewer intubations in the AVAPS group, the difference was not statistically significant. No meaningful differences were found in hospital length of stay or mortality. Subgroup analysis suggested that patients with altered mental status, including hypercapnic encephalopathy, experienced more rapid neurologic recovery and gas exchange improvement with AVAPS.
Conclusions: Compared to BIPAP-ST, AVAPS provides more rapid correction of CO2 retention and blood pH in AHRF. These physiologic benefits appear most pronounced in patients with altered consciousness, though the effects on intubation and mortality remain uncertain. Further well-designed trials are needed to determine whether these early improvements translate into better long-term outcomes and to clarify which patient groups may benefit most from this mode of support.
