Investigating hemodynamic parameters in a group of 19 ICU-patients with septic shock, respiratory variation of carotid doppler peak velocity (∆CDPV) has been shown to be able to predict fluid responsiveness. For patients receiving so called lung protective ventilation with a tidal volume of 6ml/kg ∆CDPV was superior for prediction of fluid responsiveness when compared to other well established parameters such as pulse pressure variation (∆PP).~Likewise in another study ∆CDPV has been shown to be superior to stroke volume variation (∆SV) for prediction of fluid responsiveness in patients with septic shock when ventilated with a tidal volume of ≥8ml/ kg.~All in all respiratory variation of carotid doppler peak velocity (∆CDPV) seems to be a promising parameter for prediction of fluid responsiveness (Yao et al., BMC Anesthesiology 2018). However, so far clinical studies have been conducted only under a small number of patients mainly in the intensive care unit and/ or under highly specific conditions (e.g. cardiac surgery).~If ∆CDPV is able to predict fluid responsiveness with high accuracy intraoperatively remains unknown. The investigators are therefore conducting this prospective monocentric observational trial to evaluate the performance of ∆CDPV during major abdominal surgery and compare it to validated fluid responsiveness monitoring parameters ∆PP and corrected flow time (fTc).~Following IRB-approval and written informed consent 84 patients scheduled for major abdominal surgery will be enrolled in the study. Stroke volume will be monitored by Esophageal Doppler Monitoring (CardioQ-ODM®, Deltex Medical Ltd, Chichester, UK). In case of hypovolemia a fluid bolus of 7 ml/kg ideal body weight will be administered at the discretion of the attending anesthesiologist. Respiratory variation of carotid doppler peak velocity (∆CDPV) will be monitored before and 1 minute after completion of each fluid bolus using an ultrasound device with a common linear array transducer (Philips ClearVue 350, Philips Medizin Systeme GmbH, Boeblingen, Germany).
The purpose of this study is to assess respiratory variation of carotid doppler peak velocity (∆CDPV) for prediction of fluid responsiveness during major abdominal surgery.