Feasibility of Continuous Noninvasive 24-h Ambulatory Finger Blood Pressure Measurement with Portapres: Comparison with Intrabrachial Pressure

To date, the great majority of ambulatory blood pressure recordings are made with noninvasive intermittent devices (O’Brien et al. 1989). For several years, however, continuous noninvasive measurement of blood pressure has been possible in the finger with Finapres, based on the volume-clamp (vascular unloading) method of Penaz (Penaz 1973; Penaz et al. 1976) and the physiocal criteria of Wesseling (Wesseling and de Wit 1983; Wesseling 1983, 1990). Several studies have shown that Finapres is an accurate alternative for intra-arterial blood pressure measurements (Smith et al. 1985; Molhoek et al. 1984; Imholz et al. 1988, 1990 a, 1991; Parati et al. 1989). In 1984 TNO raised the following question: Is it possible to develop a portable version of Finapres? Recently, the project aiming to develop such a device, called Portapres, resulted in a clinically acceptable prototype Portapres model 1 (Langewouters et al. 1990). The objective of this paper is to present the major characteristics of the device and to show some intermediate results of the field study in which 24-h Portapres finger blood pressure is compared to simultaneously measured intrabrachial pressure (IBP; see also Imholz et al. 1990 b). The results of the complete study in 24 subjects are described in the MD-thesis of Imholz (1991).