Assessment of Inferior Vena Cava Dynamics as a Backup Strategy for Intraoperative Fluid Management in Robotic-Assisted Off-Pump Coronary Bypass Surgery

The inferior vena cava distensibility index (dIVC) has been proposed as an alternative dynamic parameter for predicting fluid responsiveness (FR) in mechanically ventilated patients. This study explored the correlation between dIVC and commonly used FR indicators in patients undergoing robotic-assisted off-pump coronary artery bypass (OPCAB) surgery. Thirty-two patients were prospectively enrolled, and hemodynamic parameters, including stroke volume variation (SVV), pulse pressure variation (PPV), central venous pressure (CVP), pulmonary capillary wedge pressure (PCWP), and the right ventricular end-diastolic volume index (RVEDVI), were recorded at four intraoperative time points. These time points were selected to represent distinct physiological phases during surgery: two-lung ventilation (TLV), one-lung ventilation (OLV), capnothorax, and mini-thoracotomy. dIVC showed a weak but significant positive correlation with SVV (r = 0.28, p < 0.001) and PPV (r = 0.28, p < 0.001), whereas no significant correlation was observed with static preload indicators (CVP, PCWP, and RVEDVI). Given that transesophageal echocardiography (TEE) is routinely employed in OPCAB surgery, dIVC measured via TEE may serve as a valuable adjunct for FR assessment when the SVV and PPV are unreliable, such as in patients with irregular heartbeats. However, using dIVC to predict intraoperative FR should be approached with caution, considering factors such as ventilator settings, inspiratory efforts, cardiopulmonary conditions, and intraabdominal hypertension.