The Efficacy of AVAPS Versus BiPAP in Prevention of Morbidity and Mortality

Introduction: Non-invasive ventilation (NIV) is cornerstone support in chronic hypercapnic respiratory failure, but it remains unclear whether Average Volume Assured Pressure Support (AVAPS) reduces intubation more than conventional BiPAP. This systematic review and meta-analysis compares intubation rates, mortality, and length of stay (LOS) between AVAPS and BiPAP.


Methods: This systematic was conducted according to PRISMA 2020 guidelines. Included studies RCTs and prospective cohort studies of adults (≥18 years) with hypercapnic respiratory failure diagnosed on blood gas and were treated with AVAPS or BiPAP. Patients admitted to the ICU for alternative primary diagnosis were excluded from the study. Studies must have reported rate of intubation, mortality, Length of Stay (LOS), and morbidity. Data was extracted from 14 studies and analyzed using R Programming language. Statistical analyses included random-effects and fixed-effect meta-analyses on binary outcomes (intubation and mortality), forest and funnel plots to visualize pooled effects and publication bias, one-way ANOVAs on continuous physiological outcomes (arterial blood pH, pO₂, pCO₂, and hospital length of stay), chi-squared tests on pooled event counts for intubation and mortality, and calculation of the number needed to treat (NNT) for mortality.


Results: There was a 57% relative reduction in intubation with AVAPS compared with BiPAP. Egger testing concluded no detectable publication bias or selective reporting. No survival advantage is demonstrable (RR 0.89 [0.59–1.34]; p = 0.59). Mortality benefit cannot be definitively ruled on (RR=0.87 [0.38–2.00]; p = 0.62, τ² = 0.09). There was a meaningful reduction in intubations (-4.7%). AVAPS does not affect systemic acid-base balance relative to BiPAP (F = 0.152, p = 0.70). Mean LOS differs by < 0.3 d, confirming no LOS benefit. With pooled risks of 9.5% (AVAPS) vs 11.7% (BiPAP), the absolute risk reduction is 2.1%. Because the underlying risk difference is non-significant, this NNT is exploratory not determinant.


Conclusions: AVAPS substantially lowers intubation risk without compromising gas exchange or LOS, with very low heterogeneity and no evidence of publication risk. Larger, adequately powered RCTs should determine whether this advantage translates into improved survival or economic benefits.