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

NCT06838078 | Not Yet Recruiting

• 1 other identifier: 2024.271.IRB1.035
• Study Type: observational
• Target: 79
• Locations: 0 countries
• Sites: N/A

Brief Summary

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.

Conditions

Laparoscopic Surgery; Trendelenburg Position

Outcome Measures

Primary Outcomes (3)

• Trend correlation between ETCO₂ and PaCO₂ measured by the concordance ratio in the four-quadrant plot

  A four-quadrant plot will be generated by comparing consecutive changes (deltas) in PaCO₂ and ETCO₂. For each patient, every pair of sequential measurements will be used to calculate ΔPaCO₂ (horizontal axis) and ΔETCO₂ (vertical axis). Points in the top-right (Quadrant I) and bottom-left (Quadrant III) indicate concordant changes (both variables increased or both decreased). A "central zone" will be defined to exclude clinically negligible fluctuations (±1mmHg). The percentage of points in Quadrant I and III, relative to those outside the central zone, will be reported as the overall concordance. A concordance ratio above 90% will be considered as good trending ability.

  During the surgery of the patient, arterial blood gas samples will be drawn at the anesthesiologist's discretion whenever clinically indicated.

• Trend correlation between ETCO₂ and PaCO₂ measured by the angular bias in the four-quadrant plot

  In the four-quadrant plot, the angle of each data point relative to the 45-degree line will be calculated. The average of this angles will be reported as angular bias. An angular bias between ±5 degrees will be considered as good trending ability.

  During the surgery of the patient, arterial blood gas samples will be drawn at the anesthesiologist's discretion whenever clinically indicated.

• Trend correlation between ETCO₂ and PaCO₂ measured by radial limits of aggreement in the four-quadrant plot

  In the four-quadrant plot, the angle of each data point relative to the 45-degree line will be calculated. The radial sector that contains 95% of the data points will be reported as radial limits of agreement. Radial limits of agreement between ±30 degrees will be considered as good trending ability.

  During the surgery of the patient, arterial blood gas samples will be drawn at the anesthesiologist's discretion whenever clinically indicated.

Secondary Outcomes (1)

• Aggreement between simultaneous ETCO₂ and PaCO₂ values measured by limits of aggreement in Bland-Altman plot

  During the surgery of the patient, arterial blood gas samples will be drawn at the anesthesiologist's discretion whenever clinically indicated.

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

Participants will be drawn from the adult patient population (≥18 years) scheduled for laparoscopic surgery in the Trendelenburg position at a tertiary care hospital. These individuals are already indicated to receive invasive arterial blood pressure monitoring as part of their routine clinical management. No special outreach or community recruitment methods will be employed; rather, eligible patients will be identified from the hospital's surgical wards and preoperative clinics.

You may qualify if:

• Scheduled to undergo laparoscopic surgery in the Trendelenburg position
• Planned to receive invasive arterial blood pressure monitoring as part of routine clinical care (independent of the study)

You may not qualify if:

• Chronic obstructive pulmonary disease
• Pulmonary hypertension
• Active systemic infection

Sponsors & Collaborators

• Koç University: lead

Central Study Contacts

Muhammet S Söğüt, Anesthesiologist

CONTACT

00905056183219; selmansogut@gmail.com

Kamil Darçın, Anesthesiologist

CONTACT

00905055895099; kdarcin@kuh.ku.edu.tr

Study Design

• Study Type: observational
• Observational Model: CASE ONLY
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Associate Professor

Study Record Dates

• First Submitted: February 12, 2025
• First Posted: February 20, 2025
• Study Start: April 1, 2025
• Primary Completion: June 1, 2025
• Study Completion: June 15, 2025
• Last Updated: February 20, 2025

Record last verified: 2025-02