Fig. 3.
Relationship between lung recruitability, maximal superimposed pressure, and computed tomography (CT)–derived positive end-expiratory pressure (PEEP). (A) Presents the relationship between lung recruitability and maximal superimposed pressure. Lung recruitability (% of total lung weight) = −3.2 + 1.54 × Maximal superimposed pressure (cm H2O), r2 = 0.11, P = 0.02. Lung recruitability was computed as the fraction of lung tissue which regains inflation going from PEEP 5 to 45 cm H2O end-inspiration. (B) Presents the relationship between lung recruitability and CT-derived PEEP. Lung recruitability (% of lung weight) = 14.7 + 0.037 × CT-derived PEEP (cm H2O), r2 = 0.0003, P = 0.91. CT-derived PEEP was available in 50 patients. As the figure presented one outlier, we tested the relationship between the two variables also with the Spearman correlation coefficient which was not statistically significant (ρ = −0.02, P = 0.90).