In this article we will discuss about the cheyne-stroke breathing in human beings and along with its mechanism.
Cheyne-Stokes Breathing:
In which the period of apnoea is followed by a phase of gradually rising ventilation followed by gradual fall and the cycle is repeated, each phase lasting about 30 seconds. Cheyne-Stokes breathing- sometimes occurs in normal children or adults during sleep or at high altitude.
Diseases in which Cheyne-Stokes breathing occurs are:
i. Elevated intracranial pressure from any cause, e.g. brain tumour, meaningitis, etc.
ii. Anoxia from heart failure or pulmonary disease.
iii. Uraemia and other toxic conditions in which the respiratory centres are depressed.
Mechanism of Cheyne-Stokes Breathing:
Cheyne Stokes breathing is associated with rise of blood pressure sometimes in the apnoic phase and sometimes later. Rise of intracranial pressure causes anoxia of respiratory centre as well as vasomotor centre, the former is depressed and the latter is stimulated, the depression of respiratory centre is followed by apnoea.
Elevation of BP due to stimulation of VMC is followed by relief of anoxia of the brain and so the hyperpnoic phase follows (Fig. 8.40). The hyperpnoea is attended with washing off of the CO2 from the lungs and the relief of anoxia of the brain causes fall in blood pressure with consequent anoxia of brain and the whole cycle starts again.
In Cheyne-Stokes breathing the respiratory centre is less sensitive to CO2. Arterial Pco2 of 40 mm Hg produces augmentation of ventilation to only about 50% of the expected value. Anoxic stimulation of ventilation reflexly through the Sino-aortic zone perhaps plays a role but denervation of the Sino-aortic area does not abolish the Chenye-Stokes type of respiration.
Administration of O2 improves metabolism of nerve cells of the respiratory centre and administration of CO2 stimulates respiratory centre. So both the procedures abolish the abnormal type of breathing.