Pathophysiological disturbance of the respiratory rhythm

Any reflex or direct perturbation of the primary oscillator or its interaction with the network has pathophysiological consequences.

1. Activation of inspiration phase activity by afferents from the larynx or pulmonary C fibers results in respiratory arrest (reflex postinspiratory apnea).

2. Prolonged inspiratory phases (apneusis) result whenever synaptic inhibition is reduced.

3. When synaptic inhibition is blocked (e.g. under hypoxia or ischemia), respiration stops during expiration, i.e. 'expiratory apnea'.

Cheyne-Stokes periodic breathing is a slow oscillation between hyper- and hypoventilation which occurs every 45 s to 3 min ( Fig 1). It may be caused by a delay in blood transport from the lungs to the brain as well as by a change in feedback gain of the respiratory center, resulting in a phase shift and an inadequate response to the respiratory stimulus. Its occurrence in severe brain damage or acute cerebral edema is an unfavorable sign.

Fig. 1 Abnormal respiratory patterns associated with pathological lesions (shaded areas) at various levels of the brain (tracings by chest-abdomen pneumograph; inspiration reads up): (a) Cheyne-Stokes respiration; (b) central neurogenic hyperventilation; (c) apneusis; (d) cluster breathing; (e) ataxic breathing. (Reproduced with permission from Plum and... E°s.n..e.L (1.9.8.0))

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