THE DIAGNOSTIC USE OF AN EAR OXIMETER IN CONGENITAL HEART DISEASE

Abstract

A standard exercise test was performed by 40 subjects with congenital heart disease and changes of arterial O2 saturation with the patient first breathing air and then pure O2 were recorded by an ear oximeter. This was followed by dye dilution curves of the central circulation. Patients with congenital heart disease with a right-to-left shunt (14 cases) showed a fall of O2 saturation on exercise while breathing air and an equal or greater fall when the test was repeated while breathing O2. The dye curve showed the characteristic short circulation time and double hump pattern. The group with non-cyanotic congenital heart disease (12 cases) showed varying O2 desaturation breathing air and no fall breathing O2. In the presence of a left-to-right shunt, the dye curves showed a normal appearance time, a normal steep ascent but prolongation of descent and absence of a recirculation peak. Patients with acquired heart disease (10 cases) had similar results in their O2 desaturation patterns. The patients with pulmonary disease (20 cases) all showed a significant fall in O2 saturation on exercise breathing air but in only one case was there a slight fall breathing O2.