[Changes in cardiac rhythm in humans during breathing compressed air under pressure up to 1.1 MPa (results of the rhythmo-cardiographic study)].

Dynamics of cardiac rhythm has been considered according to rhythmocardiographic characteristics of heart rate under orthostatic test and one-stage step-test in four altitude chamber experiments where air under pressure of 0.4-1.1 MPa is used as a breathing mixture. It is shown that these characteristics linearly depend on the partial nitrogen and oxygen pressure and hyperbaric bradycardia essentially decreases in the final period of isopression due to toxic oxygen effect. Cytochrome C decreases hyperbaric bradycardia. Under hyperbaric conditions the regulation of cardiac rhythm proceeds with altered central vegetative effects provided a direct effect of higher nitrogen and oxygen pressure on the sinusal node cells.