Relationship between Oxygen Uptake and Oxygen Delivery in Patients with Pulmonary Hypertension

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Abstract
Dependency of oxygen consumption (O2) on oxygen delivery (ḊO2) in patients with adult respiratory distress syndrome and with congestive heart failure has been reported previously. We evaluated this relationship in 11 patients with pulmonary hypertension, 8 with primary pulmonary hypertension (PPH), and 3 with pulmonary hypertension secondary to chronic obstructive lung disease (SPH) at baseline and during treatment with vasodilating calcium channel antagonists. The mean baseline ḊO2 and O2 were 11.0 ± 4.2 and 3.9 ± 1.1 ml/min/kg, respectively. After increasing cardiac output via vasodilators, we obtained an average of 3 additional data points per patient. We found a significant relationship between changes in O2 and changes in ḊO2 (ΔO2 = −0.19 + 0.27 × ΔḊO2; r = 0.88, n = 37). In 4 patients, O2 was determined both by respired gas analysis and by calculation from thermodilution cardiac output and measured arteriovenous oxygen gradient; results by the 2 methods were virtually identical. There was no signifi...