End tidal PCO(2) for evaluation of severity of disease in idiopathic pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension

Objective To explore the difference in end tidal PCO2 (PETCO2) between idiopathic pulmonary arterial hypertension (IPAH) and chronic thromboembolic pulmonary hypertension (CTEPH), and to analyze the correlation between PETCO2 and the indexes of disease severity in IPAH and CTEPH patients. Methods Data were retrieved from 68 IPAH patients and 52 CTEPH patients who all had received right-heart catheterization, pulmonary function test and cardiopulmonary exercise testing at Shanghai Pulmonary Hospital from October 2011 to October 2014. In addition, other clinical parameters were also collected. Results The IPAH group had a significantly higher mPAP, PVR [(60±16) mmHg (1 mmHg=0.133 kPa), (13±6) Wood U ] than the CTEPH group [(46±12) mmHg, (9±4) Wood U, t=4.90, 4.83, all P 0.05). A moderately inverse correlation was found between PETCO2 at AT and NT-proBNP in the IPAH group (r=-0.58, P<0.01), meanwhile PETCO2 at AT in the CTEPH group was weakly correlated with NT-proBNP (r=-0.34, P<0.05). Conclusions Compared with the CTEPH patients, the IPAH patients had significantly decreased exercise capacity and increased PETCO2. PETCO2 could reflect the disease severity in both IPAH and CTEPH patients, being superior in IPAH than in CTEPH. Furthermore, PETCO2 at AT might be better than PETCO2 at peak in reflecting the ventilatory efficiency. Key words: Hypertension, pulmonary; Chronic thromboembolic pulmonary hypertension; Cardiopulmonary exercise testing; End tidal PCO2