Paralysis of respiratory muscles and hypoxic ventilatory chemoreflex.

We investigated the hypothesis that if the chest and abdominal respiratory muscles are paralyzed, the stimulatory hypoxic ventilatory response (HVR) would be less. We compared the HVR in low cervical cord-transected tetraplegics and in normal subjects during unloaded and mechanically loaded breathing. The results demonstrated that the tetraplegics' HVR was unsuppressed, although they displayed a disturbance in load compensation. We conclude that the descending drive to respiratory muscle motoneurons is not germane for the proper operation of the hypoxic chemoreflex.