Background and design: In order to evaluate the accuracy of continuous, non-invasive blood pressure measurements in the finger during stress, blood pressure was measured in six patients with a Portapres Model 2 during increasing levels of bicycle exercise, using simultaneously registered intra-aortic (aortic arch) pressure as a reference.
Methods: Blood pressure was measured continuously and non-invasively in the left middle finger using the Portapres Model 2 device, at the same time invasively using a pigtail catheter situated in the aortic arch at rest and during and after standardized bicycle exercise. At the end of each stress level, in accordance with the protocol of the Association for the Advancement of Medical Instrumentation, systolic and diastolic blood pressure and pulse values were determined from the non-invasive (Portapres Model 2) and invasive measurements for 15 s each, and the mean values and standard deviations were calculated.
Results: Compared with simultaneous invasive blood pressure measurement in the aortic arch, the difference in measured blood pressure value (the value determined by the device minus the value determined invasively) at rest fell within the authorized normal range for German and European blood pressure measurement devices: systolic +1.7 +/- 1.8 mmHg and diastolic -3.7 +/- 6.2 mmHg. The difference in measured value increased with the stress level.
Conclusion: Blood pressure and pulse can be determined reliably and accurately using the Portapres Model 2, non-invasively, both at rest and at low-to-moderate levels of stress.