The Value of Partial Arterial Carbon Dioxide Pressure - End-Tidal Carbon Dioxide Gradient Courses in Predicting Acute Renal Injury in Critically Ill Patients on Mechanical Ventilation: A Novel Hemodynamic Marker?

June 13, 2026 updated by: Leman Acun Delen, Malatya Egitim Ve Arastirma Hastanesi
End-tidal carbon dioxide (EtCO₂) refers to the level of carbon dioxide in the air exhaled during expiration and is measured using capnography. EtCO₂ is an important monitoring parameter in the management of critically ill patients on mechanical ventilation, providing indirect information about the patient's cardiac output, pulmonary perfusion-ventilation (V/Q) status, and metabolic activity. The Pa-EtCO₂ gradient, the difference between EtCO₂ and arterial CO₂ partial pressure (PaCO₂), changes significantly, especially in cases of hemodynamic deterioration, microcirculatory failure, and increased dead space. Therefore, the gradient is considered a potential indicator of perfusion in critically ill patients. In critically ill patients on mechanical ventilation, the usability of changes (courses) of the Pa-EtCO₂ gradient over time is being evaluated not only as an indicator of ventilation but also as a dynamic and indirect predictor of hemodynamic status and renal perfusion. Therefore, it should be investigated whether the Pa-EtCO2 gradient is a suitable parameter for early detection of AKI (acute kidney injury) development in patients with renal perfusion impairment.

Study Overview

Status

Completed

Conditions

Study Type

Observational

Enrollment (Actual)

155

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Turkey (Türkiye)
    • Osmaniye
      • Malatya, Osmaniye, Turkey (Türkiye), +90(505)620-3888
        • Malatya Training and Research Hospital

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

patients being monitored with mechanical ventilators in intensive care

Description

Inclusion Criteria:

  • Patients over 18 years of age
  • patients under mechanical ventilation
  • initiation of EtCO₂ monitoring within the first hour of admission to the ICU
  • patients monitored in the ICU for at least 24 hours
  • having undergone arterial blood gas analysis (for PaCO₂ measurement) within the first 24 hours.

Exclusion Criteria:

  • Patients under 18 years of age
  • intensive care unit monitoring shorter than 24 hours
  • missing or inaccessible clinical data
  • chronic renal failure
  • acute renal failure present at admission to intensive care unit
  • advanced pulmonary diseases affecting EtCO₂ measurement (e.g., severe obstruction, giant bulla, advanced emphysema)
  • patients in whom PaCO₂ measurement cannot be performed

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change From Baseline in PaCO₂-EtCO₂ Gradient at 6, 12, and 24 Hours After ICU Admission
Time Frame: Baseline, 6 hours, 12 hours, and 24 hours after ICU admission
The PaCO₂-EtCO₂ gradient will be calculated as arterial carbon dioxide pressure minus end-tidal carbon dioxide pressure at baseline and at 6, 12, and 24 hours after ICU admission. Change from baseline will be reported for each follow-up time point in mmHg.
Baseline, 6 hours, 12 hours, and 24 hours after ICU admission

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Malatya Egitim Ve Arastirma Hastanesi

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

March 15, 2026

Primary Completion (Actual)

May 15, 2026

Study Completion (Actual)

June 5, 2026

Study Registration Dates

First Submitted

April 9, 2026

First Submitted That Met QC Criteria

June 13, 2026

First Posted (Actual)

June 17, 2026

Study Record Updates

Last Update Posted (Actual)

June 17, 2026

Last Update Submitted That Met QC Criteria

June 13, 2026

Last Verified

January 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • MEAH-AKI-ICU-2026-01

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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