Introduction: The relationship between preoperative VE/VCO<inf>2</inf> slope and mortality in adults undergoing major surgery is not well-established.
Evidence acquisition: PubMed and Embase were queried until November 2023 to identify studies exploring the link between preoperative VE/VCO<inf>2</inf> slope and postoperative mortality in adults undergoing major surgery. The primary outcome was all-cause mortality at the longest follow-up. A random-effects model was used to calculate the pooled odds ratio (OR) and 95% CI.
Evidence synthesis: Fourteen observational studies, involving 7637 patients, were included. Higher preoperative VE/VCO<inf>2</inf> slope on a continuous scale was associated with increased mortality after major surgery (eight studies; 2872 participants; OR, 1.11; 95% CI, 1.07-1.16). On a dichotomous scale, elevated preoperative VE/VCO<inf>2</inf> slope was associated with a greater risk of mortality following major surgery (seven studies; 4889 participants; OR, 2.77; 95% CI, 1.89-4.06). The findings were consistent in subgroup analyses according to surgical type. Further analyses suggested that elevated preoperative VE/VCO<inf>2</inf> slope is associated with an increasing risk of postoperative short-term mortality (30-day and 90-day) and long-term mortality (1-year, 2-year, 3-year, and 5-year).
Conclusions: Elevated preoperative VE/V CO<inf>2</inf> slope is associated with an increased risk of postoperative short- and long-term mortality in adults undergoing major surgery.