Oxygen uptake and cardiac output in graded arm exercise in paraplegics with low level spinal lesions

Oxygen uptake (V32), heart rate (fH) and cardiac output (Q, CO2-rebreathing method) were measured in 8 paraplegics with complete low level (Th6-Th12) lesions and in 1 paraplegic with a Th2 lesion during graded exercise performed on an arm ergometer. The submaximal work rates taxed about 50, 70 and 90% of the estimated functional capacity of the subjects. A linear relationship between the work rate and VO2 were assessed in the three tests. The increase of Q with increasing VO2 was accomplished by a considerable increase in fH accompanied by a slight increase in stroke volume (SV, calculated). Markedly low values of Q were found in 6 of the 9 subjects. The resulting high arterial-mixed venous blood oxygen content differences (calculated) as well as the high blood lactate concentrations (3.5-4.5 mM/l at 20-30 W and 8-11 mM/l after maximal exertion) indicate that the blood flow in the arm muscles was not adequate.