[Errors in blood pressure measuring with modern automated machines. Effects of errors in non-invasive oscillometric...

Automatic blood pressure measuring devices with digital display are now in common use, both among lay persons and physicians. The oscillometric method is, however, associated with a number of possible sources of error which, among other things, make comparison with the standard Riva-Rocci method difficult. Methodological errors arise from physiological/anatomical variations: circumference of the forearm and wrist, position of the arteries, structure of the surrounding tissue, arterial diameter and also vasomotor function. The latter represents an appreciable uncertainty factor, in particular with measurements obtained from the finger. Technological sources of error play a role in pronounced hypotension or severe hypertension, since the devices are calibrated only for a range extending from 120 to 180 mmHg. The processing by the device of arrhythmic pulses is also critical. Additional sources of error are in handling and interpretation. Overall, these sources of error are such that not all the various types of device available are equally suitable for use by the patient, and it is necessary to place limitations on the application of such devices and to establish rules for their use.