The oxygen cost of breathing in tetraplegic patients

Abstract

The oxygen consumption of the respiratory muscles of II complete tetraplegic patients was measured using the method of Campbell et al. (1957), the principle of which is to measure the oxygen consumption of a subject at rest and at several levels of ventilation. The oxygen consumption was measured by recording the disappearance of oxygen from a closed-circuit spirometer incorporating a motor blower and carbon dioxide absorber. Ventilation was increased by making the subject breathe through varying amounts of dead space provided by thick-walled rubber tubing. It was found that the tetraplegics could not increase their ventilation above 32 litres per minute due to the paralysis of their expiratory muscles. At these levels the average oxygen consumption in all ii patients was 16 ml. per litre of excess ventilation with a range of 0 85 ml.-2'7 ml. in the individual patients. This was higher than the findings of Cournand and Richards (1954) and Campbell et al. (1957) on normal subjects but much lower than their findings in patients with cardio-pulmonary disease. In all the tetraplegic patients the resting oxygen consumption was not above 230 ml. per minute. It was concluded that while the ventilatory capacity in tetraplegic patients was severely reduced the oxygen consumption of the respiratory muscles was not excessive. © 1963, International Spinal Cord Society. All rights reserved.