Trending Ability of End-Tidal Capnography to Reflect Arterial Carbon Dioxide Changes in One-Lung Ventilation
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 if measuring carbon dioxide from a patient's breath (end-tidal CO₂ or ETCO₂) can reliably reflect changes in blood carbon dioxide levels (arterial CO₂ or PaCO₂) during lung surgery. Instead of just looking at individual values, we are specifically investigating whether ETCO₂ and PaCO₂ rise and fall in the same direction over time.
During lung surgery, patients often need "one-lung ventilation," where only one lung is used for breathing while the other is deflated to help the surgeon. This can cause carbon dioxide levels in the blood to change, which are typically monitored by taking blood samples. If ETCO₂ trends closely follow PaCO₂ trends, doctors may not need to take as many blood samples.
Patients in this study will already have a small tube in an artery for monitoring blood pressure. Whenever a blood test is taken, we will compare the blood CO₂ level with the ETCO₂ reading at that moment. We will also track heart rate, blood pressure, and body temperature.
By comparing these measurements, we hope to learn whether ETCO₂ reliably follows the same trends as PaCO₂, making it a useful tool for monitoring carbon dioxide levels in lung surgery with fewer blood tests.
Eligibility criteria
This trial does not accept healthy volunteersQualifiers
Patients undergoing thoracoscopic lung surgery with one-lung ventilation
Patients requiring invasive arterial blood pressure monitoring
Disqualifiers
Chronic obstructive pulmonary disease (COPD)
Pulmonary hypertension
Systemic infection
Trial population
Participants will be drawn from the adult patient population (≥18 years) scheduled for thoracoscopic lung surgery with one-lung ventilation 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 relative to the 45-degree line 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 × Standard deviation 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
Sponsors and contacts
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Source ClinicalTrials.gov
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