Blood oxygenation and disturbances of the acid-base equilibrium in myocardial infarction.

In order to trace the changes in blood oxygenation and disturbances of the acid-base equilibrium in myocardial infarction, investigations were carried out in 136 patients aged 39-83 years. The values of blood oxygenation and the acid-base status were determined on the 1st, 2nd and 3rd day of the disease, and then after one, two and three to four weeks. Besides this, in 38 patients determinations were performed 3, 6, 9 and 12 months after the onset of the disease. The determinations were careied out with a micro-Astrup unit "Radiometer". It was demonstrated that hypoxaemia is very frequent complication of myocardial infarction since it appears in about 60% of cases of uncomplicated infarction. The intensity of hypoxaemia is greatest after 2-3 days. The intensity and duration of hypoxaemia depend on the clinical course of myocardial infarction. The most intense and longest persisting hypoxaemia was seen in patients with shock and/or acute left-ventricular failure. In nearly 25% of cases hypoxaemia was present even six months after the onset of the disease. Slight metabolic acidosis was observed on the 1st day of the disease in 37% of the cases, while severe metabolic acidosis was present in patients with shock and pulmonary oedema. Compensated metabolic acidosis was found in 50-60% of the cases during one year after myocardial infarction.