End-tidal CO₂ response to passive leg raise for fluid management in lung resections: A randomized controlled trial

To evaluate whether changes in end-tidal carbon dioxide (EtCO₂) following passive leg raise (PLR) can predict fluid responsiveness and guide fluid therapy in patients undergoing Lung Resection Surgery (LRS).

This prospective randomized controlled trial was conducted at Istanbul University-Cerrahpasa Medical Faculty Hospital, Istanbul, Turkey, between August 2020 and March 2021. Fifty patients undergoing elective LRS were enrolled. After anesthesia induction, EtCO₂ was measured before and one minute after PLR. A ≥2 mmHg increase was considered responsive. Responders were randomized into a study group (fluid bolus) and a control group (maintenance fluid only); non-responders formed a third group. Hemodynamic parameters, fluid balance, urea, creatinine and lactate levels were recorded perioperatively.

The proportion of fluid responders was 62%. The study group received significantly more intravenous fluid and showed no cases of acute kidney injury (AKI), while AKI was observed in the control and unresponsive groups. Postoperative urea levels increased significantly only in the control group. Lactate levels rose intraoperatively in all groups but normalized within 24 hours. A positive correlation was found between surgical duration and lactate levels. EtCO₂ and heart rate did not differ significantly between groups.

EtCO₂ changes in response to PLR may provide a simple, non-invasive indicator of fluid responsiveness in thoracic surgery. Targeted fluid supplementation in responsive patients appears to improve renal outcomes. Further studies are needed to validate these findings.Registration No. ClinicalTrials.gov (Identifier: NCT06855966).