Aims: There is a significant demand especially in anesthesiology and intensive care for a reliable continuous non-invasive blood pressure monitor which could be used to detect fatal changes in blood pressure for example during and after surgical operations. Thus, this study aimed to find out if two continuous non-invasive blood pressure monitors, Finapres Nova and Caretaker 4, react similarly to fast changes in blood pressure. In addition, these two continuous monitors were compared with a traditional oscillometric device (Microlife BP B6 Connect).
Methods: 21 subjects were recruited for measurements which included four rest phases and three laboratory intervention tests intended to induce fast changes in blood pressure. The tests were hand grip test, cold pressor test, and Valsalva maneuver.
Results: There was a clear agreement between the devices during the rest phases. Mean discrepancies and standard deviations for systolic and diastolic blood pressures measured with Finapres and Caretaker were -1.6 ± 8.4 mmHg and -2.3 ± 5.3 mmHg during rest. However, Caretaker reacted to the blood pressure changes caused by the interventions significantly less than Finapres (P=0.004 for systolic and P=0.006 for diastolic blood pressure during cold test and P<0.001 for systolic and diastolic pressures during hand grip test) and on some occasions, there were no visible changes in the blood pressure readings of Caretaker during the intervention. This might be caused by Caretaker's model-based approach for estimating blood pressure values in brachial artery.
Conclusion: Finapres and Caretaker work equally well in rest but their reactions to fast changes in blood pressure differ significantly. Probably Caretaker is not able to react fast enough, and it underestimates the magnitudes of the chances. On the contrary, Finapres seems to overestimate the changes sometimes.