End Tidal CO 2 Tension

Abstract

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 (E TCO 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 E TCO 2 values. Methods: We performed E TCO 2 measurements for fi ve breaths at rest and after a 6-min walk test (6MWT) in patients seen at our pulmonary vascular center. Mean E TCO 2 values were correlated with 6-min walk distance and right-sided heart catheterization data. Results: We enrolled 84 patients with PAH, 17 with PVH without left ventricular systolic dysfunction, and seven with no PH and no severe alterations in pulmonary function testing. E TCO 2 was signifi cantly lower in patients with PAH than in those with no PH and PVH ( P , .0001 PAH vs both groups). E TCO 2 correlated with the pulmonary artery diastolic pressure-to-pulmonary artery occlusion pressure gradient ( r 5 2 0.50, P 5 .0002) and pulmonary vascular resistance ( r 5 2 0.44, P 5 .002). E TCO 2 after 6MWT correlated with walk distance ( r 5 0.34, P 5 .003). In patients with prostaglandin therapy escalation, E TCO 2 increased in those who had clinical improvement, whereas in patients who did not improve clinically, E TCO 2 failed to rise ( P 5 .04). Conclusions: E TCO 2 is a promising tool to differentiate patients with PAH from those with PVH or no PH, correlates with diagnostic and prognostic hemodynamic indicators, and may increase with successful treatment of PAH. CHEST 2011; 140(5):1267-1273Abbreviations: 6MWT 5 6-min walk test; E tco 2 5 end tidal CO 2 ; mPAP 5 mean pulmonary artery pressure; PAd 5 diastolic pulmonary artery pressure; PAH 5 pulmonary arterial hypertension; PAOP 5 pulmonary artery occlusion pressure; PH 5 pulmonary hypertension; PVH 5 pulmonary venous hypertension; PVR 5 pulmonary vascular resistance; RHC 5 right-sided heart catheterization

Saudi Guidelines on the Diagnosis and Treatment of Pulmonary Hypertension: Pulmonary hypertension due to left heart disease

“…[ 58 ] End-tidal CO 2 has been found to be significantly lower in patients with PAH than in patients with PH due to HFpEF and may be used to help differentiate between the two conditions. [ 59 ]…”

Predictors of Diastolic-To-Wedge Gradient in Patients Evaluated for Pulmonary Hypertension

“…The composition of the study population has been previously reported [2]. For this analysis, we included 85 patients with PAH, 16 with PVH and 7 patients with no evidence of pulmonary hypertension and only mild or moderate pulmonary function testing abnormalities (NoPH).…”

“…Fluid challenge was performed over five minutes in all patients unless right atrial pressure or PWP was > 15mmHg. Exclusion criteria [2] were ≥ 5 L/min nasal cannula oxygen, portopulmonary hypertension (due to cirrhosis-associated hyperventilation), serum bicarbonate level of > 34 mmol/L, pregnancy, known neuromuscular disease, moderate or severe mitral stenosis, mitral or aortic regurgitation, left ventricular ejection fraction <55% by echocardiography, known hypercarbic respiratory failure, untreated hypothyroidism or hyperthyroidism, hereditary hemorrhagic telangiectasia, uncertain diagnosis because of incomplete testing, diagnosis of World Health Organization group 3 or 4 PH, or mixed PH phenotype after thorough evaluation according to published guidelines [12]. …”

Pathophysiology and Diagnosis of Pulmonary Hypertension Due to Left Heart Disease

“…Gas transfer factor for carbon monoxide (TLco) is reduced in this population compared to controls ( 25 ). In addition, TLco and end-tidal CO 2 have been found to be lower in PAH patients compared to PH-LHD ( 26 , 27 ). In the ASPIRE registry, mean TLco in the PAH group was 55 vs. 62% predicted in the PH-LHD one ( 26 ).…”