Continuous monitoring of right atrial oxygen tension in patients with myocardial infarction

Abstract

Right atrial oxygen tension ($RAP\bar vO_2$) was measured continuously in 26 patients admitted to a coronary care unit with acute myocardial infarction. A catheter incorporating a Clark type oxygen sensor at its tip was inserted percutaneously into the right atrium. Insertion was simple, safe and comparable to the introduction of a standard central venous pressure line.$RAP\bar vO_2$ correlated well with the patients' clinical condition and reflected both cardiac and pulmonary function. When breathing air 11 of the patients had sustained$RAP\bar vO_2$ levels of less than 34 mmHg (4.53 kPa). In this group there were eight deaths. Fifteen patients had an$RAP\bar vO_2$ greater than 34 mmHg (4.53 kPa) except for transient falls related to movement and in this group there were no deaths (p<0.002). The correction of arterial hypoxaemia by oxygen therapy raised$RAP\bar vO_2$ and lowered the heart rate. In some patients Dopamine and transvenous pacing raised$RAP\bar vO_2$ and could be adjusted with reference to the continuous recording. Movement often caused marked falls in$RAP\bar vO_2$ especially in the seriously ill. Evidence relating$RAP\bar vO_2$ to mixed venous oxygen and tissue oxygen is reviewed.