Using GapCO2 to distinguish congestive versus non-congestive acute dyspnea

How to Differentiate Congestive and Non-congestive Dyspnea in the Emergency Department? Proof-of-concept Study on Microperfusion Analysis Via GapCO2

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
• Enrollment: 45 (estimated)
• Ages: 18 Years and up
• Sex: All
• Sponsor: Assistance Publique - Hôpitaux de Paris (other)
• Locations: 1 site (Bobigny)
• Trial ID: NCT06556797 on ClinicalTrials.gov

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.

Who should consider this trial

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.

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.

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 performed: 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.

Eligibility 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 this trial is running

Bobigny

• Emergency Department Hospital Avicenne — Bobigny, France (RECRUITING)

Study contacts

• Principal investigator: Judith GORLICKI, MD — Assistance Publique - Hôpitaux de Paris
• Study coordinator: Judith GORLICKI, MD

Conditions: Acute Dyspnea, Dyspnea, Acute dyspnea, Emergency department, Congestion, Proof-of-concept study, GapCO2