Chronobiological aspects of blood gas composition in 24 patients with COPD were studied. To achieve this goal, the gas composition of the arterialized capillary blood simultaneously with the investigation of respiratory function was studied with an interval of 6 hours over 2 days. In healthy individuals and patients with mild COPD two types of gas composition of blood biorhythm – daytime and nighttime – were found. In patients with moderate, severe and very severe disease 3 types of biorhythm of partial oxygen and carbon dioxide tension – morning time, noontime and evening time were registered. In healthy individuals and patients with mild COPD gas composition of blood was characterized by significant degrees of freedom in relation to functioning of the respiratory system, which indicated the stored processes of adaptation to changing conditions of the external and internal environment. In patients with moderate, severe and very severe COPD at the moment of acrophase of circadian rhythm of lung function maximum partial oxygen pressure in the arterialized capillary blood was observed. During the batiphaze of circadian rhythm of the respiratory system the highest values of the partial carbon dioxide tension were revealed. Thus, it was found out that with the growth of the severity of the disease in patients with COPD abnormal rhythms of blood gas composition are registered; the dependence of circadian rhythm of blood gas composition on the functioning of the respiratory apparatus increases.
II. THE CARBON DIOXIDE ABSORPTION CURVE AND CARBON DIOXIDE TENSION OF THE BLOOD IN CARDIAC DYSPNEA