Partial Pressure of End-Tidal Carbon Dioxide Predicts the Complication of Secondary Pulmonary Hypertension in Patients With Advanced Heart Failure

Partial pressure of end-tidal carbon dioxide (PETCO2) monitoring is commonly used for intubated patients receiving mechanical ventilation in the field of anesthesiology and critical care medicine. Recently, both noninvasive and mainstream PETCO2 monitoring technique has become available in several clinical settings and the value of PETCO2 has been reported to be a predictor of prognosis in patients with heart failure (HF). However, the exact mechanisms underlying this association between PETCO2 and HF have not been fully elucidated. Thirty patients (mean age 42.2±13.3 years, 20 males) were prospectively examined simultaneous right heart catheterization and PETCO2 monitoring. Echocardiogram, respiratory function test, and arterial blood gas analysis were also examined. Study participants consisted of 23 patients with HF and 7 heart transplant recipients. Sixteen dilated cardiomyopathy, 3 dilated-phase hypertrophic cardiomyopathy, 8 heart transplant recipients, 2 myocarditis, and 1 ischemic cardiomyopathy were included in this study. The mean PETCO2 of all patients was 31.6±4.5 mmHg. PETCO2 was significantly lower in a stepwise fashion along with patients’ New York Heart Association (NYHA) functional class (class I, 34.3±4.4 mmHg; class II, 31.6±4.2 mmHg; class III or IV, 28.7±2.9 mmHg; p=0.007). Among various clinical parameters that correlated with PETCO2, mean pulmonary arterial pressure (PAP) was most well correlated with PETCO2 (r=0.67, p’0.0001). Receiver operating characteristics analysis revealed that PETCO2 of 28 mmHg could be a cutoff for predicting the presence of pulmonary hypertension (PH, mean PAP ≤25 mmHg) in our patient population. Among various clinical parameters investigated, PAP, a well-known predictor of poor prognosis in HF patients, was most well correlated with PETCO2. Further, PETCO2 not greater than 28 mmHg is a potential surrogate marker of secondary PH in HF patients.