Use of non‐invasive finger blood pressure monitoring in the estimation of aortic pressure at rest and during the Mueller manoeuvre

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Abstract
The aim of this investigation was to evaluate whether reliable estimates of aortic pressure can be derived using non-invasive finger blood pressure monitoring. Finger blood pressure (Ohmeda 2300 Finapres device; Finapres, Englewood, CO) was compared with simultaneous ascending aortic pressure measured with a catheter-transducer system both at rest and during acute negative intrathoracic pressure (the Mueller manoeuvre). Thirty-eight patients aged 17-73 years were studied. All were undergoing routine diagnostic or therapeutic cardiac catheterization. Beat-to-beat values of systolic, diastolic and mean non-invasive finger and invasive aortic blood pressure were measured at rest and factors which might have an influence on the difference between methods were examined. The mean finger-aortic difference was +5 +/- 14 mmHg for systolic, -2 +/- 7 mmHg for diastolic, -5 +/- 8 mmHg for mean and +6 +/- 13 mmHg for pulse pressure. In multivariate linear regression analysis, the difference in systolic pressure was related to aortic systolic pressure (standardized coefficient beta = -0.33, P = 0.01), heart rate (beta = 0.49, P < 0.000), age (beta = -0.29, P < 0.025) and height (beta = 0.40, P < 0.005). The linear regression equations to derive resting aortic pressures from the non-invasive finger pressure readings had correlation coefficients between 0.83 and 0.87 and standard errors of estimate between 6 and 14 mmHg. During the Mueller manoeuvre, Finapres reproduced average pressure changes reliably compared with intra-aortic pressure. Due to moderate inter-individual variation in the finger-aortic differences the correlation coefficients ranged from 0.83 to 0.93 and the standard errors of estimate from 3 to 6 mmHg. Non-invasive finger blood pressure monitoring could be used to estimate central aortic mean and diastolic blood pressure fairly reliably at rest, but with respect to systolic pressure the variance in finger-aortic difference was marked. The average intra-aortic pressure changes caused by the Mueller manoeuvre were reliably reproduced by the Finapres device.