Can simulators evaluate systematic differences between oscillometric non-invasive blood-pressure monitors?

BACKGROUND

Oscillometric non-invasive blood-pressure (NIBP) monitors estimate the arterial pressure using model-specific signal processing and algorithms. Hence each model's accuracy must be clinically evaluated. Simulators may assist the evaluation, but their ability to do so has not been verified.

OBJECTIVE

To investigate whether simulators can detect systematic differences between NIBP monitors.

METHODS

We tested whether a simulator can distinguish between the two different algorithms available in a particular monitor, detect calibration errors and detect systematic differences between monitors that are observed clinically.

RESULTS

Simulator evaluation correctly detected 1.8 and 4.2 mmHg systolic and diastolic differences between the two Nellcor N-3100 algorithms (with specified 2 and 5 mmHg differences) but found no difference between their mean arterial pressures (as expected from the specification). Simulator evaluations detected calibration adjustments at 80/50, 120/80 and 200/150 mmHg. Simulator and clinical comparisons of two devices of the same type recording slightly different blood pressures were in close agreement, but simulator and clinical comparisons of three different models (Propaq, Critikon DINAMAP and Datex Cardiocap) were not consistently in agreement. The simulators generated oscillometric pulse shapes different from physiological recordings.

CONCLUSION

The results suggest that, although simulators can reveal systematic differences between devices of the same model, they cannot be used to detect systematic differences between different NIBP models. This could be at least partly because the oscillometric pulses generated by the simulators are dissimilar to physiologically recorded pulses.