Relationship between individual values of end-expiratory esophageal pressure at low positive end-expiratory pressure and body mass index (Spearman ρ = 0.69 [95% CI, 0.48 to 0.82]). The dotted line represents the regression line (end-expiratory esophageal pressure = 3.88 + 0.26 × body mass index; R² = 0.45; P < 0.001).