Invasive V. Non-Invasive Measurement of Arterial Pressure

Abstract

Two indirect arterial pressure monitors, the Finapres and the Accutorr, were investigated and compared with the direct measurement of intra-arterial pressure. Pressures in patients in a variety of circulatory states were measured and analysed in relation to two types of random error: first, the "intra-individual standard error" (within one session of measurement) and second, the "inter-individual standard error" (between sessions). (This distinction is important, since in routine monitoring of arterial pressure one is usually dealing with the first type of error only.) This study showed that sudden changes in pressure were closely followed by the Finapres. A pressure reading of the Accutorr takes about 15-20 s, meaning that, within this period, variations will not be observed. The accuracy or reproducibility of each method, as expressed in intra-individual variance, diminished in the order Intra-Arterial-Line, Finapres, Accutorr. The inter-individual variation decreased in the order Intra-Arterial-Line, Accutorr, Finapres. Most of the inter-individual variance of the Finapres is probably real because of the more peripheral position of its cuff. A correlation between malfunctioning of the Finapres and vasoconstriction or hypothermia of the finger could not be demonstrated.

The effects of exercise duration on post-exercise hypotension

“…Ourselves and others have previously validated this method for baseline and postexercise measurements. [11][12][13] In our hands, steady- …”

Accuracy and precision of blood pressure determination with the Finapres: an overview using re-sampling statistics

“…This is surprising as it is generally accepted that amplification of the systolic BP occurs distally, due to a combination of physiological events including waveform dispersion and reflection. 11,12,33 We have previously noted 23 that the bulk of validation studies on the Finapres suggested that the systolic and diastolic pressures were underrecorded compared with that directly assessed; 3,14,18,24,26,28 physiologically one would expect an accurate peripheral device to record a higher systolic but a lower diastolic pressure compared with that recorded at a more proximal recording site. However, the extent to which the systolic pressure is amplified may be variable, depending both on biological (age and extent of arterial pathology) and technical factors.…”

“…12 Therefore any periheral BP method such as the Finapres requires rigorous validation to understand its strengths and limitations. The accuracy of the Finapres compared with intra-arterial reference pressure has now been assessed in many studies [3][4][5][6][7][8][9][10][13][14][15][16][17][18][19][20][21][22][23] without any clear consensus emerging on the average performance of the method; precision data has been infrequently reported. 20,24 This paper is a synthesis of these literature data; a novel statistical method of re-sampling allowed a global overview of the performance of the system to be derived.…”

The effects of exercise intensity on post exercise hypotension

“…Although numerous researchers (eg, Parati et al 13 and Van Egmond et al 14 ) have previously validated the Finapres, we also performed comparisons with simultaneous intra-arterial measurements. In our experience, resting Finapres measurements slightly but consistently under-estimated intra-arterial recordings (Ͻ10%) but tracked the pressure waveform remarkably well.…”