Basic oscillating mechanism of Cheyne-Stokes breathing.

Cheyne-Stokes breathing has been induced in 30 dogs by inserting a circulatory delay system between the heart and the brain to prolong the transit time of blood from the lungs to the brain. The duration of each cycle of Cheyne-Stokes breathing increased proportionately with the volume of the delay system and decreased as the perfusion pressure to the brain was increased. Periodic variations in oxygen and carbon dioxide concentrations in the blood were found to be in appropriate phase to stimulate the respiratory centers at the time of maximal ventilation. This supports the theory that Cheyne-Stokes breathing is due to oscillation of the respiratory control system. T HE PHYSICAL CHARACTERISTICS Of Cheyne-Stokes breathing suggest that it might be due to oscillation of the basic regulatory mechanism of respiration. One theory of its cause is the following: the patient overventilates for a few seconds, and this changes the blood gas concentrations until the respiratory center loses its stimulation; as a result, he underventilates, and the blood gases change again; consequently, he overventilates once more, and the cycle continues (1-6). The present study has been designed to help answer whether or not this theoretical oscillating mechanism is the actual basis of CheyneStokes breathing. The results to be reported are based on periodic respiration established in dogs by inserting a circulatory delay system between the lungs and brain. Also, additional studies have been carried out to establish phase relationships between blood gas concentrations and the cycles of periodic breathing.