Rhythmic bursts in the medullary reticular formation and their connection with agonal respiration during hypoxia and the post-hypoxic period

Abstract

1. 1. Rhythmic bursts that appear in the medulla oblongata during the later stages of dying and during the early stages of reanimation consist of oscillations at 7–24 c/sec; they are controlled by the respiratory centre (inspiration) and determined by the rhythm of its activity. 2. 2. Bursts appear only during agonal respiration when the relationship between the activities of inspiratory and expiratory muscles is disturbed. 3. 3. Together with the isolation of the medullary respiratory centre from central influences, the appearance of bursts requires additional hypoxic suppression of the brain-stem mechanisms. 4. 4. These bursts are accompanied by clonic changes in contraction of the respiratory and auxiliary muscles, the rhythm of clonic excitation being the same in all muscles and identical to that of the bursts. 5. 5. Bursts and alteration of muscle contraction may be a result of excitation of a phylogenetically ancient mechanism of the brain-stem reticular formation coordinating generalized tremor movements. Excitation of this mechanism is determined by the impulses from the respiratory centre. 6. 6. Association of bursts with a relatively profound hypoxic alteration of the brain-stem allows use of the former to estimate the brain damage during both agony and recovery.