Periodic breathing at high altitude

Periodic breathing is often associated with heart disease or stroke, and commonly Cheyne-Stokes breathing has a period of about a minute. Periodic breathing also commonly occurs in healthy subjects at high altitude, and here the periods may be much shorter, of the order of 15-20 s. In this paper we study such periodic breathing using the classical model of Grodins et al. (1967, J. Appl. Physiol. 22, 260-276), together with a prescription for the dependence of ventilation on the blood CO<inf>2</inf> concentration, modulated by the reduced oxygen pressure (the 'Oxford fan'). The model focusses on the fast dynamics of the arterial blood CO<inf>2</inf>, and differs in this respect from our previous work which emphasised the brain CO<inf>2</inf> concentration; in this sense our model is in fact a generalization of the conceptually simpler Mackey-Glass model.