Preliminary study of the effects of low flow oxygen on oxygen delivery and right ventricular function in chronic lung...

This study was designed to test the feasibility of using the noninvasive radionuclide measurement of the right ventricular ejection fraction (RVEF) to identify which patients with chronic lung disease objectively benefit from low flow oxygen therapy. Two categories of benefit, pulmonary artery pressure/resistance and peripheral oxygen delivery, were examined in 19 patients. Fourteen subjects returned after at least 3 wk of continuous low flow oxygen therapy for restudy; 12 patients had complete radionuclide and hemodynamic data. The change in RVEF, in response to continuous oxygen, correlated significantly with the change in coefficient of oxygen delivery (r = 0.59, p less than 0.05) and the change in cardiac output (r = 0.62, p less than 0.05). The change in RVEF did not correlate significantly with the change in pulmonary artery pressure (r = 0.06) or the change in total pulmonary resistance (r = -0.35). The change in coefficient of oxygen delivery, representing oxygen delivery corrected for oxygen consumption, correlated positively with change in cardiac output (r = 0.58, p less than 0.05) and negatively with change in oxygen consumption (r = -0.63, p less than 0.05), arterial oxygen content (r = -0.63, p less than 0.05), and arterial oxygen tension (r = -0.61, p less than 0.05). That is, the fall in hemoglobin in these patients more than compensated for any increase in Pao2 so that improved oxygen delivery frequently occurred despite a decrease in arterial oxygen content, and improved oxygen delivery occurred for the most part among patients with smaller improvement in Pao2.(ABSTRACT TRUNCATED AT 250 WORDS)