Operation time, blood loss, and anaesthesia time and their effects on the need for postoperative ventilation and major surgical complications. A and B. The multiple logistic regression model describes the need for postoperative respiratory assistance (vertical axis: 0 = no assistance, 1 = assistance needed) depending on operation time (minutes) and blood loss (ml). The longer the operation (P <0.01) and the higher the blood loss (P <0.05), the higher the need was for postoperative ventilation. C and D. Major complications (≥3b according to the Clavien-Dindo classification) on the vertical axis (0 for complications <3b, 1 for ≥3b) are plotted against operation time (minutes) or anaesthesia time (minutes) on the horizontal axis. The longer the operation (P <0.01) and the longer anaesthesia time (P <0.01), the higher the incidence of major complication was. Data are corrected for BMI and age.