Statistical analyses
SD
Continuous data are presented as median with interquartile range [IQR], or as a mean ± SD when applicable. Normality of distribution was assessed visually using histograms and To test whether increasing MAP improves dynamic CA, we used a stepwise constructed linear mixed effect model. A base-model of CA in different MAP stages was constructed, with fixed intercept (mean). A random intercept, fixed slope and random slope were consecutively added in additional models. These nested models were compared using the −2 restricted log-likelihood (−2RLL) goodness-of-fit test. The model with the smallest number of parameters explaining most variance was selected. Both anaesthetic techniques were added to this model as a grouping factor, to analyse the base difference in CA with increasing blood pressure, between anaesthetic techniques. Finally, the relationship between increasing MAP and anaesthetic technique on change in CA was analysed by adding this interaction to the model. Other relevant transfer function variables, as well as haemodynamic, respiratory, and intra-operative medication variables were then added to the model in order to analyse potential systematic differences between anaesthetic techniques. Statistical analyses were performed using R, version 3.5.1,