After the end of surgery in ICU the positive end-expiratory pressure (PEEP) test of 15 cm H2O for 300 seconds will be performed. Following PEEP test, the two-step fluid load test of 6 ml/kg balanced crystalloid solution will be performed sharing in two portions: Initial mini FLT (mFLT) of 1.5 ml/kg within 1 min (approximately 100 mL) followed by the registration of continuous CI and traditional fluid responsiveness parameters and the rest of standard FLT (4.5 mL/kg) within 5 minutes (approximately 350 mL) followed by transpulmonary thermodilution, registration of continuous cardiac index (CI) and classic fluid responsiveness parameters.

After the end of surgery in ICU the positive end-expiratory pressure (PEEP) test of 15 cm H2O for 300 seconds will be performed. Following PEEP test, the two-step fluid load test of 6 ml/kg balanced crystalloid solution will be performed sharing in two portions: Initial mini FLT (mFLT) of 1.5 ml/kg within 1 min (approximately 100 mL) followed by the registration of continuous CI and traditional fluid responsiveness parameters and the rest of standard FLT (4.5 mL/kg) within 5 minutes (approximately 350 mL) followed by transpulmonary thermodilution, registration of continuous cardiac index (CI) and classic fluid responsiveness parameters.

Mean bias and standard deviation according to Bland-Altman analysis and angular bias and radial limit of agreement according to polar plot analysis for cardiac output assessed using pulse wave transit time in comparison with transpulmonary thermodilution

Prediction of changes in cardiac output in response to fluid load in early postoperative period of off-pump CABG using the assessment of reaction of cardiac output to an increase in PEEP. Evaluation of correlation and ROC curve.