Figure 6.

Pao₂/Fio₂ (P/F) values associated with atelectasis and blood volume redistribution. Effect of atelectasis (A) and intra-tidal normalized blood volume redistribution toward the dependent region (B) upon P/F ratio. P/F ratio was negatively correlated with both measures in a nonlinear fashion (Spearman ρ = –0.93 and –0.77, respectively) and the log-transform of P/F ratio was linearly related to atelectasis (r² = 0.87). Box-and-whisker plots represent median, interquartile range and range for the three different fractional atelectatic mass in expiration (FAM_exp) groups studied (A) and between those conditions that demonstrated either an inspiration-related reduction or increase in blood volume in the dependent region (B).