Using GapCO2 to distinguish congestive versus non-congestive acute dyspnea
Official title: How to Differentiate Congestive and Non-congestive Dyspnea in the Emergency Department? Proof-of-concept Study on Microperfusion Analysis Via GapCO2
Run by Assistance Publique - Hôpitaux de Paris · NCT06556797 · Data updated 2026-11-12
This study tries to see if the difference between arterial and transcutaneous pCO2 (GapCO2) can tell whether adults with sudden shortness of breath in the emergency department have a congestive cause or not.
Quick facts
| Study type | Observational |
|---|---|
| Ages | 18 Years and up |
| Sex | All |
| Enrollment | 45 (estimated) |
| Sponsor | Assistance Publique - Hôpitaux de Paris Academic / other |
| Locations | 1 site (Bobigny) |
| Status | Recruiting |
| Started | January 26, 2025 |
| Main results expected | March 26, 2026 |
| Study ends | April 26, 2026 |
| Registry record updated | February 10, 2026 |
| Trial ID | NCT06556797 on ClinicalTrials.gov |
Is this trial a fit for you?
✓Likely a good fit
Adults aged 18 or older who present to the ED within one hour of arrival with acute dyspnea (respiratory rate ≥22 and/or SpO2 <95%), who will have an arterial blood gas as part of care, and who do not object to participation are eligible.
✕Probably not a fit
Patients with fever (≥37.5°C), systolic blood pressure ≤100 mmHg or signs of peripheral hypoperfusion, those already given diuretics or vasodilators before inclusion, or those unable to express non-opposition are not likely to benefit from this protocol.
A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.
What this trial studies
This is an observational proof-of-concept study in which adults who arrive to the emergency department with acute dyspnea receive simultaneous arterial blood gas sampling and continuous transcutaneous capnography using a Radiometer TCM5 monitor. A TC 92 sensor is placed on the earlobe (or forehead if needed) and measurements are recorded after a 5-minute equilibration and throughout ED management, while treating clinicians remain blinded to the PtcCO2 and GapCO2 values. The primary analysis compares GapCO2 (PaCO2 − PtcCO2) with an independent adjudication by two emergency physicians who classify dyspnea as congestive or non-congestive based on full medical records. Standard diagnostic and therapeutic care is provided per attending physicians and the transcutaneous values are not used to guide treatment decisions.
Why it matters
Potential benefit: If successful, GapCO2 could offer a quick, non-invasive bedside signal to help clinicians distinguish congestive from non-congestive dyspnea and speed appropriate treatment in the ED.
How similar studies have gone: Transcutaneous capnography has been shown to track PaCO2 in other clinical settings, but using the GapCO2 specifically to discriminate congestive versus non-congestive dyspnea is a novel, largely untested approach.
Who can join: the full rules
Show full inclusion / exclusion criteria
Inclusion Criteria: * Age ≥ 18 years * Patient presenting with acute dyspnea defined by a sensation of respiratory discomfort with at least one of the following criteria: RR ≥ 22 and/or SpO2 \< 95% * Arterial blood gas sampling performed as part of care * Inclusion less than 1 hour after arrival time to the emergency department * Non-opposition to participation in the study Exclusion Criteria: * Temperature greater than or equal to 37.5°C * Patient who has already received a diuretic or vasodilator treatment in the emergency department or by a prehospital medical team * Systolic blood pressure less than or equal to 100 mmHg and/or signs of peripheral hypoperfusion * Inability to express refusal to participate in the study
Where it's running
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Emergency Department Hospital Avicenne
Bobigny, France Recruiting
Study contacts
- Principal investigator: Judith GORLICKI, MD — Assistance Publique - Hôpitaux de Paris
- Study coordinator: Judith GORLICKI, MD
- Email: judith.gorlicki@aph.fr
- Phone: +33 (0)1 48 95 57 85
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How to take part
- Review the eligibility criteria above with your treating physician.
- Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
- Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.