The investigators aimed to examine the effect of goal-directed fluid therapy (GDFT) compared to conventional fluid therapy in thoracoscopic lobectomy surgery with ERAS protocol on intraoperative pulmonary oxygenation and 30-day patient outcomes including postoperative morbidity and mortality. The primary outcome measure of the study was the PaO2/FiO2 ratio (change in pulmonary oxygenation) during one-lung ventilation, and the secondary outcomes were postoperative morbidity, quality of recovery, 30-day re-admission, and mortality rate.

This randomized controlled study analyzed 80 adult patients who underwent thoracoscopic lobectomy surgery with the ERAS protocol. In addition to standard monitoring in the operating room, all participants underwent Pressure Recording Analytical Method (PRAM) monitoring with the help of intra-arterial pressure monitoring method. Participants were randomly assigned to GDFT and conventional fluid therapy groups. In the GDFT group, fluid, inotropic agent and/or vasopressor therapy was administered by targeting stroke volume variation (SVV) and cardiac index (CI). In the control group, fluid and/or vasopressor therapy was administered with the guidance of MAP 65-95 mmHg and urine output at least 0.5 mL/kg/hr. Intraoperative hemodynamic data, amount and types of fluid administered, inotropic and vasopressor agents were recorded. Vital signs, pulmonary, cardiac and other system morbidity, quality of recovery on days 1, 3 and 5 in the postoperative care unit and in the ward, and re-admission to hospital and mortality within 30 days were recorded.

Inclusion Criteria:

• Age 18-65 years.
• ASA Physical Status Classification I-II.
• Undergoing elective thoracoscopic lobectomy with the ERAS protocol.
• Provided informed consent.

Exclusion Criteria:

• Age < 18 or > 65 years.
• ASA Physical Status Classification III or higher.
• Patients not in sinus rhythm, and with recent oral beta-blocker use.
• Patients with cardiac/renal/hepatic insufficiency, valvular heart disease (aortic or mitral valve insufficiency or stenosis)
• Patients with abnormal preoperative lung function (forced expiratory volume in 1 second less than 50% of predicted values)
• Patients with severe obesity (BMI>35 kg/m2)
• Patients who cannot be applied to the ERAS protocol
• Emergency surgery.
• Refusal to provide informed consent.

The anesthesiologist responsible for intraoperative management was aware of the group assignments, but other members of the research team, other healthcare providers, and patients were unaware. Confidentiality of randomization to the investigators was maintained until the end of the study for statistical data analysis.