Abstract
Eight patients with clinically stable chronic respiratory failure, hypoxemia (PaO2⩽60 mmHg) and pulmonary hypertension (mean pulmonary arterial pressure⩾20 mmHg) were allocated to long-term domiciliary oxygen therapy, and were followed for three months. Oxygen was supplied for from 15 to 18 hours daily from an oxygen concentrator at a flow rate sufficient to raise the PaO2 to 60 to 80 mmHg. We examined the effects of this therapy on right ventricular performance both at rest and during exercise in these patients. Homodynamic data were obtained by right heart catheterization. Right ventricular ejection fractions (RVEF) were ascertained using first-pass quantitative radionuclide 81mKr angiocardiography. Thirty minutes of oxygen inhalation at rest had no significant effect on cardiac function, both before therapy (T0) and after 3 months of therapy (T1). The mean pulmonary arterial pressure and the pulmonary vascular resistance during exercise were not significantly different between T0 and T1. On the other hand, at T0, the RVEF tended to decrease from 51.6±4.9% (during oxygen inhalation at rest) to 48.7±7.9% (during exercise), whereas at T1 it significantly (p<0.05) increased from 48.8±6.8% (during oxygen inhalation at rest) to 54.2±8.2% (during exercise). Thus, while 3 months of long-term domiciliary oxygen therapy did not reduce the right ventricular after load either at rest or during exercise, it was found to improve the right ventricular systolic performance during exercise. This suggested that long-term oxygen therapy could be useful in improving the quality of daily life of patients with chronic respiratory failure.
