Data acquisition and analysis of hemodynamic signals using a standard microcomputer.

Hemodynamic drug-effect studies require repetitive measurements and time-consuming calculations, particularly for the indices of left ventricular (LV) contractility and relaxation. To save time, we have created a system of acquisition, calculation, storage, and report of hemodynamic data processing E.K.G, peripheral arterial pressure, and LV pressure signals using a standard microcomputer (Apple II+) and simple accessory devices. The master program is written in BASIC Applesoft, with Mem/Dos as the disk operating system. A suite of utility routines, written in machine language, are used to program the A/D converter and to perform the vectorial calculations on the data. The software, written to process single-dose drug-effect studies, performs 1) data acquisition and storage as vectorial arrays accessible using BASIC, 2) monitor display, 3) calculations of the peripheral pressure and of the LV contractility and relaxation indices, 4) storage of the calculated indices, and 5) print-out of a report (curves and tables) at the end of each experiment and cumulated results of all the animals included in a protocol. The drawback of such a low-cost system is essentially the lack of available memory and the relatively slow speed of the microprocessor, which hinders simultaneous processing of indices needing nonlinear curve fitting and adequate print-out of protocols that are not single dose.