A simulation study of the consistency of oscillometric blood pressure measurements with and without artefacts.

BACKGROUND

Oscillometric pressure is measured by analysing, in relation to the cuff pressure, low-amplitude cuff-pressure pulsations generated by each arterial pulse. The cuff pressure is sampled at the pulse rate, introducing measurement variations, which are compounded by artefactual pulses.

OBJECTIVE

To study the consistency of measurements with and without artefacts using simulated waveforms.

METHODS

The Propaq Smartcuf (with and without electrocardiographic synchronization), the Welch Allyn 52 000 (before and after its software had been upgraded), the Critikon DINAMAP 8100 and Compact TS and the Criticare 507 NJC were evaluated. Each monitor recorded 15 determinations at 120/80 (93) mmHg without and with either low-frequency or high-frequency artefacts generated by the Bio-Tek BP-Pump simulator. Consistency of measurements was defined as SD of less than 2 mmHg for at least two of the systolic, diastolic and mean arterial pressures with all less than 3 mmHg.

RESULTS

All monitors except the Critikon 8100 satisfied the consistency criteria without artefacts with most SD less than 1 mmHg. Several satisfied the criteria with a severe low-frequency artefact (all recorded SD were less than 6 mmHg). None satisfied the criteria with a severe high-frequency artefact. High systolic blood pressures were typically recorded with a severe tremor artefact, though the Criticare device, which measures during cuff inflation, recorded lower systolic blood pressures. The Propaq device with electrocardiographic synchronization had the lowest variability, with synchronization increasing determination time.

CONCLUSION

Oscillometric monitors are more sensitive to a high-frequency artefact than they are to a low-frequency artefact. Signal-processing techniques can improve consistency of measurements. Simulators can evaluate a monitor's consistency with and without artefacts.