Use of 'ideal' alveolar air equations and corrected end-tidal PCO2 to estimate arterial PCO2 and physiological dead space during exercise in patients with heart failure

INTERNATIONAL JOURNAL OF CARDIOLOGY

卷:250

Article

Van Iterson, Erik H.¹  Olson, Thomas P.¹ 

[1] Mayo Clin, Dept Cardiovasc Med, 200 First St SW, Rochester, MN 55905 USA

关键词: HFrEF;    Reduced ejection fraction heart failure;    Arterial carbon dioxide partial pressure;    End-tidal carbon dioxide partial pressure;    PETCO2;    Exercise intolerance;   

DOI  :  10.1016/j.ijcard.2017.10.021

来源: Elsevier

【 摘 要 】

Background: Arterial CO2 tension (PaCO2) and physiological dead space (V-D) are not routinely measured during clinical cardiopulmonary exercise testing (CPET). Abnormal changes in PaCO2 accompanied by increased V-D directly contribute to impaired exercise ventilatory function in heart failure (HF). Because arterial catheterization is not standard practice during CPET, this study tested the construct validity of PaCO2 and V-D prediction models using 'ideal' alveolar air equations and basic ventilation and gas-exchangegas exchange measurements during CPET in HF. Methods: Forty-seven NYHA class II/III HF (LVEF=21 +/- 7%; age=55 +/- 9 years; male=89%; BMI=28 +/- 5 kg/m(2)) performed step-wise cycle ergometry CPET to volitional fatigue. Breath-by-breath ventilation and gas exchange were measured continuously. Steady-state PaCO2 was measured at rest and peak exercise via radial arterial catheterization. Criterion V-D was calculated via 'ideal' alveolar equations, whereas PaCO2 or V-D models were based on end-tidal CO2 tension (PETCO2), tidal volume (V-T), and/or weight. Results: Criterion measurements of PaCO2 (38 +/- 5vs. 33 +/- 5 mm Hg, P < 0.01) and V-D (0.26 +/- 0.07 vs. 0.41 +/- 0.15 L, P < 0.01) differed at rest vs. peak exercise, respectively. The equation, 5.5+0.90 x PETCO2-0.0021 x V-T, was the strongest predictor of PaCO2 at rest and peak exercise (bias +/- 95% LOA = - 3.24 +/- 6.63 and - 0.98 +/- 5.76 mm Hg; R-2 = 0.57 and 0.75, P < 0.001, respectively). This equation closely predicted V-D at rest and peak exercise (bias +/- 95% LOA= - 0.03 +/- 0.06 and - 0.02 +/- 0.13 L; R-2=0.86 and 0.83, P < 0.001, respectively). Conclusions: These data suggest predicted PaCO2 and V-D based on breath-by-breath gas exchange and ventilatory responses demonstrate acceptable agreement with criterion measurements at peak exercise in HF patients. Routine assessment of PaCO2 and V-D can be used to improve interpretability of exercise ventilatory responses in HF. (C) 2017 Elsevier B.V. All rights reserved.

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