ABSTRACT
Systolic blood pressure (BP) is primarily influenced by stroke volume and compliance. This explains why elderly patients have a higher systolic pressure due to a reduced vascular compliance secondary to atherosclerosis while neonates have a lower systolic pressure because of a very compliant arterial tree. When non-invasive BP measurements are inaccurate – in obese patients, arrhythmias and during ambulance transfers. Diastolic BP is primarily influenced by arterial recoil. In presence of vasodilatation, there is a downward shift of the dicrotic notch. Characteristic features of vasodilatation of the arterial wave form include a low systolic pressure, low diastolic pressure, wide pulse pressure and delayed dicrotic notch. Arterial lines undergo a one-point calibration by zeroing the transducer to atmospheric pressure. Natural frequency is directly related to resonance.
