Cardiac output measured by the injection method with the use of radioactive material and continuous recording. II. Comparison with the Fick method.

Abstract

Abstract The pip interval method for determining cardiac output by a continuous sampling and recording method was compared with the Fick method for cardiac output. This report shows that the average difference between the Fick output and the RISA output was -1.9 per cent (S.D. ±9.3) in a group of 9 patients in which the injection was made into an antecubital vein, the average difference between the Fick output and RISA output was 1.8 per cent (S.D. ±10.3) in a group of 17 patients in which the injection was made into the main pulmonary artery. Consecutive determinations of cardiac output in the same subject by the authors' method in 22 patients shows an average per cent difference between the first and second cardiac output of +0.7 per cent (S.D. ±7.1). In addition, characteristic left-to-right and right-to-left shunt patterns are presented and discussed.