End-Tidal Carbon Dioxide as a Prognostic Feature in Pulmonary Arterial Hypertension.

Rationale: Pulmonary arterial hypertension (PAH) is characterized in part by increased dead space ventilation, which can be estimated noninvasively at the bedside by measurement of end-tidal CO (ETco).

Objectives: Prior work has demonstrated that ETco is lower in patients with PAH than in control patients, but whether ETco has prognostic value is unknown. We hypothesized that lower measurements of ETco in patients with PAH correlate with worse long-term outcomes.

End tidal CO(2) tension: pulmonary arterial hypertension vs pulmonary venous hypertension and response to treatment.

Background: CO(2) excretion is impaired in pulmonary arterial hypertension (PAH) due to underlying vascular obstruction and increased dead space. Our aim was to determine whether resting end tidal CO(2) (Etco(2)) could differentiate patients with PAH from those with pulmonary venous hypertension (PVH) or patients without pulmonary hypertension (PH) and whether successful treatment of PAH resulted in higher Etco(2) values.

Methods: We performed Etco(2) measurements for five breaths at rest and after a 6-min walk test (6MWT) in patients seen at our pulmonary vascular center.