Study of Cardiac Power Index During Supine, Lateral, and Between Left and Right Positions During Two- and One-Lung Ventilation (OLV): Comparison of Hemodynamic Changes After Lung Recruitment Maneuver and Fluid Challenge Among Responders and Non-Responders (SVI, MAP, CPI Changes).

This study investigates changes in Cardiac Power Index (CPI) in the same patients across different body positions (supine and lateral) during both two-lung ventilation (2LV) and one-lung ventilation (OLV). The primary aim is to assess how these positional and ventilation changes influence CPI values, a dynamic hemodynamic marker of cardiac function. A secondary objective is to evaluate the hemodynamic response to a recruitment maneuver and a fluid challenge, using stroke volume (SV) and mean arterial pressure (MAP) as indicators.

All measurements are performed with the chest closed, prior to surgical incision. Patients will be placed under general anesthesia with thoracic epidural support, and continuous hemodynamic monitoring will be established via a radial artery catheter connected to a HemoSphere monitor (Edwards Lifesciences). Key parameters monitored include CPI, cardiac index (CI), heart rate (HR), stroke volume index (SVI), and MAP.

Hemodynamic data will be collected at various predefined timepoints:

• Baseline in the supine position under 2LV
• Lateral position under OLV
• Before and after a recruitment maneuver
• Before and after a standardized fluid challenge

The recruitment maneuver consists of continuous positive airway pressure at 30 cmH₂O for 30 seconds. The fluid challenge involves administering 250 mL of isotonic saline over 10 minutes. Hemodynamic responses will be used to classify patients as fluid responders or non-responders based on ≥10% changes in SV and/or MAP.

Data analysis will focus on comparing CPI trends across positions and ventilation modes, as well as evaluating the utility of CPI in predicting fluid responsiveness. Hemodynamic parameters will be collected digitally and analyzed for intraoperative trends.

Inclusion criteria

• Age over 18
• Physical status ASA I-III (per the American Society of Anesthesiologists)
• Fluent in Greek or English
• Scheduled for thoracic surgery using a double-lumen endotracheal tube

Exclusion criteria

• Known arrhythmia
• Severe valvular disease
• Severe right or left ventricular dysfunction
• Morbid obesity (BMI ≥ 40 kg/m²)
• Inability to perform spirometry and/or echocardiography
• Patient refusal to participate