One-dimensional (1D) models are useful to study pressure and flow waves in large arteries in cases where clinical measurements are not available. Using a simplified 1D model (1) we have modelled the pressure waveform in the brachial artery with and without occlusion, which is relevant to non-invasive measurement of blood pressure with cuff-based devices. The results show that occlusion of the brachial artery leads to superposed high frequency oscillations in local brachial blood pressure of up to 10mmHg (Fig.). A modelling study of brachial occlusion done independently by a group from Swansea University (2) has also shown similar results.

Preliminary data made with a fluid-filled catheter by collaborators in New Zealand (unpublished data) show much smaller pressure fluctuations during cuff occlusion, but the use of a fluid-filled catheter may have damped out the relatively high frequency waves that are predicted. Therefore, measurements of blood pressure using a high-fidelity catheter are being made in patients undergoing routine cardiac catheterization. Pressure waveforms recorded in the brachial, subclavian arteries and the ascending aorta with and without brachial artery occlusion are compared to the predictions of the 1D models.

Figure 1

Predicted pressure waveforms for an occluded and non-occluded brachial artery.