Exercise desaturation as a marker of disease severity in pulmonary arterial hypertension

Introduction Pulmonary hypertension patients develop hemodynamic changes that contribute to the symptoms, especially during exertion. The inability of the heart to increase cardiac output and the ventilation/perfusion mismatch, may explain the presence of exercise oxygen desaturation. Rationale The rational is to study the relation of exercise oxygen desaturation with the severity of pulmonary arterial hypertension (PAH) group I. Patients and methods Thirty-nine patients diagnosed as having PAH group I were included in the study; 30 (76.9%) female patients and nine (23.1%) male patients. Six-minute walk distance (6MWD) was performed as a marker for the risk of mortality. The degree of desaturation was calculated. The disease severity is assessed in terms of right atrial pressure (RAP), oxygen saturation of the mixed venous blood, cardiac output, mean pulmonary artery pressure, and peripheral vascular resistance. Results The mean age was 37.74 +/- 10.58; the patients were presented within functional classes II and III. The mean 6MWD (264.95 +/- 87.32), RAP (10.87 +/- 6.22), and oxygen saturation of the mixed venous blood (58.67 +/- 8.13) denote moderate risk of mortality in 1 year of 5-10%. The mean degree of desaturation is 3.72%, and the basal oxygen saturation is 94.44%. There was a statistically significant negative correlation between the 6MWD and RAP, and positive correlation between 6MWD and arterial oxygen saturation, as well as between the mean pulmonary artery pressure and degree of desaturation. Conclusion Exercise desaturation is an important factor in the development and deterioration of PAH, yet it has no significant correlation with the parameters of the disease severity used.