Mean arterial pressure (MAP) is defined as the average pressure throughout the cardiac cycle.1 It has physiologic and clinical importance since it represents the perfusion pressure and it is a factor utilised in the calculation of haemodynamic variables. Based on the normal blood pressure curve configuration, the functional MAP is lower than the arithmetic one (pulse pressure/2). For many years, MAP has been calculated by blood pressure cuff measurements using an empiric formula, which states that the MAP equals one third of the distance between the systolic pressure (SP) and the diastolic pressure (DP).2 ,3 Since the true mean pressure is the time–weight average of a series of instantaneous pressures, the above formula has substantial limitations.4 This article proposes a more precise formula for the estimation of mean arterial pressure. A nomogram for the calculation of MAP is also provided.

The blood pressure tracings and haemodynamic data of 150 patients who underwent cardiac catheterisation were analysed. Eighty six were male and 64 were female. Ischaemic heart disease was …