Evaluation of end-tidal CO2 pressure at the anaerobic threshold for detecting and assessing pulmonary hypertension.

Higashi A, Dohi Y, Yamabe S, Kinoshita H, Sada Y, Kitagawa T,
Hidaka T, Kurisu S, Yamamoto H, Yasunobu Y, Kihara Y

Heart Vessels. 2017 Nov;32(11):1350-1357. doi: 10.1007/s00380-017-0999-y. Epub
2017 May 30.

Cardiopulmonary exercise testing (CPET) is useful for the evaluation of patients
with suspected or confirmed pulmonary hypertension (PH). End-tidal carbon dioxide
pressure (PETCO2) during exercise is reduced with elevated pulmonary artery
pressure. However, the utility of ventilatory parameters such as CPET for
detecting PH remains unclear. We conducted a review in 155 patients who underwent
right heart catheterization and CPET. Fifty-nine patients had PH [mean pulmonary
arterial pressure (mPAP) ≥25 mmHg]. There was an inverse correlation between
PETCO2 at the anaerobic threshold (AT) and mPAP (r = -0.66; P < 0.01). Multiple
regression analysis showed that PETCO2 at the AT was independently associated
with an elevated mPAP (P = 0.04). The sensitivity and specificity of CPET for PH
were 80 and 86%, respectively, when the cut-off value identified by receiver
operating characteristic curve analysis for PETCO2 at the AT was ≤34.7 mmHg. A
combination of echocardiography and CPET improved the sensitivity in detecting PH
without markedly reducing specificity (sensitivity 87%, specificity 85%).
Evaluation of PETCO2 at the AT is useful for estimating pulmonary pressure. A
combination of CPET and previous screening algorithms for PH may enhance the
diagnostic ability of PH.