Myocardial oxygen supply-demand ratio: a validation of peripherally vs centrally determined values

We sought to validate that the supply-demand ratio for myocardial oxygen could be accurately measured from tracings of peripheral as well as central arterial pressure. This ratio was the ratio of the diastolic pressure-time-index (DPTI) over the systolic pressure-time index (SPTI). Sixteen patients had the peripheral DPTI/SPTI determined at cardiac catheterization by the following two different methods: (1) P1, using the mean diastolic and systolic peripheral arterial pressure and the ratio of the duration of diastole and systole; and (2) (P2, where the peak systolic and diastolic peripheral arterial pressures are used, eliminating the need for planimetric data. The results of P1 and P2 correlated closely with the central value (r = 0.96 and 0.92, respectively). We conclude that DPTI/SPTI can reliably be measured from a tracing of peripheral arterial pressure, enabling reliable continuous monitoring of this ratio.