A comparative study of the influences of pulmonary arterial pressure and pulmonary capillary wedge pressure on impedance rheopneumogram in patients with three different diseases.

In the present study right heart catheterization and impedance rheopneumogram examinations were performed simultaneously on 21 patients suffering from congenital cardiovascular diseases with atrial or ventricular septal defect accompanied by the left to right shunt (CCD) and 17 patients suffering from rheumatic valvular disease with mitral stenosis (MS) in order to investigate the differences in the impedance rheopneumogram parameters between CCD patients and patients with chronic obstructive pulmonary disease (COPD) as well as between MS and COPD patients. The results showed that when patients with different diseases had the same level of pulmonary arterial pressure, CCD patients had significantly higher Hs than COPD patients, while MS patients had significantly higher Hd/Hs ratio than COPD patients and CCD patients. The linear regressional equation between Hd/Hs ratio and pulmonary capillary wedge pressure (PCWP) was as follows: PCWP (kPa) = 0.17 + 0.98 x Hd/Hs (kappa = 155, gamma = 0.422, p < 0.001). These results suggest that: (1) impedance rheopneumographic regressional equations with Hs as one of the major variables suitable for predicting secondary pulmonary hypertension in COPD patients are not suitable for use on CCD patients; (2) Hd/Hs ratio is useful in clinical work as an index for differential diagnosis between MS and Cor Pulmonale; and (3) PCWP can be roughly and noninvasively measured based on the measurement of impedance rheopneumogram parameter Hd/Hs.