Lorenzen U, Pohlmann M, Hansen J, et al. - In morbidly obese patients undergoing laparoscopic bariatric surgery, a high risk of perioperative hemodynamic complications is conferred by the combination of obesity-related comorbidities, pneumoperitoneum and extreme posture changes. Thus an advanced hemodynamic monitoring comprising continuous cardiac index (CI) assessment is desirable. In this study, the non-invasive vascular unloading was compared with a semi-invasive pulse contour analysis reference technique for continuous CI measurements in bariatric surgical patients. They enrolled 60 patients (mean BMI 49.2 kg/m²) who were scheduled for elective, laparoscopic bariatric surgery. The vascular unloading technique (Nexfin) and semi-invasive reference method (FloTrac) were used to perform CI measurements. Overall, interchangeability for absolute CI values from 54 patients that entered in the final analysis, could not be established between the two devices with a correlation coefficient of rs = 0.76, a bias of − 0.164 l/min/m² (limits of agreement: − 1.478 - 1.150 l/min/m²) and a high  percentage error (56.61%). Although there was a high overall concordance rate of 85.12%, the predefined Critchley criterion of 92% was not attained by the trending capability of the vascular unloading technique in the pre- and intraoperative phase.