Trend Correlation Between End-Tidal and Arterial Carbon Dioxide During Laparoscopic Surgery in Trendelenburg Position
Trial statusNot yet recruiting
Trial phaseNot listed
Trial typeObservational
Biological sexAll
Age18+
SponsorKoç University
About this trial
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.
Eligibility criteria
This trial does not accept healthy volunteersQualifiers
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)
Disqualifiers
Chronic obstructive pulmonary disease
Pulmonary hypertension
Active systemic infection
Trial 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.
Trial design
Design model
Case-only
Time perspective
Prospective
Treatments tested in this trial
Not listed
Trial groups
No trial groups listed
Trial outcomes
Primary outcomes
1
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.
Time frame
During the surgery of the patient, arterial blood gas samples will be drawn at the anesthesiologist's discretion whenever clinically indicated.2
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.
Time frame
During the surgery of the patient, arterial blood gas samples will be drawn at the anesthesiologist's discretion whenever clinically indicated.3
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.
Time frame
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
A Bland-Altman plot will be used to assess agreement between ETCO₂ and PaCO₂. For each paired measurement, the difference between ETCO₂ and PaCO₂, and the average of ETCO₂ and PaCO₂ will be calculated. Each point will be plotted with the difference on the vertical axis against the average on the horizontal axis. The mean difference (bias) and 95% limits of agreement (mean difference ± 1.96 × SD of the difference) will then be calculated. Limits of aggreement between ±4 mmHg will be considered as good aggreement.
Time frame
During the surgery of the patient, arterial blood gas samples will be drawn at the anesthesiologist's discretion whenever clinically indicated.Locations
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Source ClinicalTrials.gov
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