Assessment of Tidal Volume in Patients Undergoing Noninvasive Ventilation: Systematic Review and Meta-Analysis

Objectives: Noninvasive ventilation (NIV) is widely used in acute respiratory failure (ARF), yet the association between high tidal volume (V t ) and clinical outcomes remains incompletely defined. We evaluated the association between V t and NIV failure overall and by ARF type, and its relationship with respiratory and clinical outcomes. Data Sources: MEDLINE, Cochrane Central Register of Controlled Trials, Web of Science, and Latin American and Caribbean Health Science Literature (1976 to September 2025). Study Selection: Observational studies of adults with ARF treated with NIV reporting V t or V t normalized to predicted body weight (V t /PBW) in NIV success and failure groups. Data Extraction: Three pairs of reviewers identified studies and extracted data independently. Random-effects meta-analysis was performed. Risk of bias and certainty of evidence were assessed using Risk of Bias In Nonrandomized Studies of Interventions and Grading of Recommendations Assessment, Development, and Evaluation. Data Synthesis: Eleven studies (1136 patients) were included. V t /PBW was higher in NIV failure vs. success (mean difference [MD], 1.02 mL/kg [95% CI, 0.60–1.45 mL/kg]), whereas absolute V t did not differ (MD, 1.30 [–33.31 to 35.91]). In hypoxemic ARF, V t /PBW remained higher in NIV failure (MD, 0.89 mL/kg [95% CI, 0.04–1.73 mL/kg]); no data were available for hypercapnic ARF. Post hoc analyses showed that higher V t /PBW was associated with increased mortality (odds ratio, 9.11; 95% CI, 3.88–21.37), higher respiratory rate (RR; MD, 3.14 breaths/min [95% CI, 1.36–4.92 breaths/min]), and lower Pa co 2 (MD, –2.38 mm Hg [95% CI, –4.16 to –0.5938 mm Hg]), but no with pressure support (PS) level (MD, 0.24 [95% CI, –0.81 to 1.29]). Certainty of evidence ranged from very low to moderate. Conclusions: In adults with ARF treated with NIV, higher V t /PBW was associated with NIV failure and worse outcomes. These findings reflect prognostic associations rather than causality, and interventional studies with systematic V t monitoring are needed. Importantly, elevated V t /PBW, higher RR, lower Pa co 2 , and increased mortality, without differences in PS, collectively implicate elevated respiratory drive as a driver of increased mortality (PROSPERO [CRD42024584977]). Findings: Higher V t /PBW was associated with NIV failure, particularly in hypoxemic respiratory failure; post hoc analyses showed associations with increased mortality, higher respiratory rate, and lower Pa co 2 .