Fig. 2

Association between quantiles of cumulatively infused ketamine and maximal bilirubin levels during mechanical ventilation. a Box plots presenting the distribution of maximal bilirubin levels during mechanical ventilation at different quantiles of cumulatively infused ketamine. b Unadjusted B-spline regression between maximal bilirubin levels and quantiles of cumulative ketamine. c Multivariable adjusted B-spline regression between maximal bilirubin levels and quantiles of cumulative ketamine. Worst values during the mechanical ventilation period were employed for all covariates in the model. Red lines represent regression estimates and the blue-shaded area 95% confidence intervals