Trend Correlation Between End-Tidal and Arterial Carbon Dioxide During Laparoscopic Surgery in Trendelenburg Position

In this study, we want to find out whether a person's "end-tidal carbon dioxide" (ETCO₂)-a value measured from the air they breathe out-accurately reflects the amount of carbon dioxide in their blood, called "arterial carbon dioxide" (PaCO₂).

We are focusing on people having laparoscopic (keyhole) surgery in the Trendelenburg position, which involves tilting the patient's head down to help the surgeon see the surgical area better. This position can sometimes affect carbon dioxide levels in the blood. Right now, doctors must draw blood samples to measure the PaCO₂ level. If we can show that ETCO₂ readings are reliable, doctors may not need to draw blood samples as often.

During surgery, patients already need a small tube (catheter) in an artery so doctors can closely monitor their blood pressure. Whenever the anesthesiologist decides a blood sample is needed, we will note the blood's PaCO₂ level and compare it with the ETCO₂ reading taken at the same time. We will also record other measurements like heart rate, blood pressure, and temperature.

By comparing these measurements, we hope to learn if the ETCO₂ readings can reliably match the changes in PaCO₂ over time, making it a useful tool to monitor carbon dioxide levels in this type of surgery without needing as many blood tests. We plan to include 79 patients in this study, which should give us enough measurements to see how closely these two methods match.