EFFECT OF PERIPHERAL RESISTANCE ON THE KOROTKOFF SOUND: MODELLING.

A recently developed theory for the origin of the Korotkoff sound (Drzewiecki et al. , in press) was employed to study whether the Korotkoff sound is dependent on peripheral resistance. The model incorporates pressure-flow characteristics for pulsatile flow in a collapsing vessel. We have developed a series of computer programs that allow computation of Korotkoff sounds under conditions of variable peripheral resistance. A standard pressure pulse of 120/80 mmHg was assumed proximal to the cuff. For a given peripheral resistance we computed the Korotkoff sound at several cuff pressures in the range 120 to 75 mmHg. Each computer run yielded a graph of brachial arterial pressure immediately distal to the cuff, together with the corresponding sound intensity. For each cuff pressure the maximum and minimum sound intensities were noted and plotted versus cuff pressure. The Korotkoff sound intensity curves so obtained are similar to the sound intensity variations heard by an observer through a stethoscope while the pneumatic cuff deflates.