ABSTRACT
Ideally, the arterial pressure waveform should be measured in the ascending aorta. As this is impractical, several alternative peripheral sites have been used for arterial cannulation, including the radial, dorsalis pedis, femoral, axillary, brachial, and ulnar arteries. Nevertheless, the pressure measured in peripheral arteries does not usually correspond exactly with the aortic pressure; the more distal the site for measuring arterial pressure, the greater the systolic pressure and the lower the diastolic pressure (Figure 74.1). The mean arterial blood pressure remains nearly constant at all sites. Waveform distortion by the addition of reflected waves as the arterial waveform travels distally in the arterial tree causes the changing arterial pressure. With ageing, reflected waves occur at progressively more proximal cannulation sites.
