IngentaConnect Automatic System for Noninvasive Blood Pressure Determination in ...

Authors: Heinrich Schima; Herbert Boehm¹; Leopold Huber²; Helmut Schmallegger²; Michael Vollkron²; Michael Hiesmayr³; Robert Noisser⁴; Georg Wieselthaler²

Source: Artificial Organs, Volume 28, Number 5, May 2004 , pp. 451-457(7)

Publisher: Blackwell Publishing

Abstract:

In patients with implanted rotary pumps, the arterial pressure pulsatility is usually far lower than in normal individuals. Depending on the remaining degree of pulsatility, cuff-based systems such as the classical Riva–Rocci-determination of arterial blood pressure and correlated sounds or pressure measurements based on cuffpressure oscillations become inaccurate or even impossible. Therefore, a system was developed which evaluates the flow in the radial artery using an ultrasound wristwatch sensor, and this additional information is used for pressure determination. A computerized data acquisition and cuff-control system based on a PC using Matlab software, a wristwatch ultrasound device, and a compressor-driven pressure cuff was set up. The cuff was controlled for automatic inflation and deflation cycles. Cuff pressure and arterial flow was recorded. Several algorithm strategies were developed, which gave data for systolic blood pressure and heart rate together with a reliability index for data quality. Finally, the new algorithms were implemented in a microcontroller system. Comparisons with invasive measurements showed excellent correlation with systolic blood pressure (mean Delta

P -0.3 mm Hg, n = 28). During exercise of rotary pump patients and therefore enhanced pulsatility the difference from manual evaluation was -2.1 mm Hg (n = 18). In conclusion, adaptation of the classical cuff-pressure method with ultrasound evaluation of peripheral flow allows reliable determination of blood pressure in patients with low pulsatility resulting from implanted rotary cardiac assist pumps. By development of a wristwatch sensor and an automatic control system a robust method for daily use could be developed.

Keywords: Rotary pump; Cardiac assist; Noninvasive blood pressure determination; Riva–Rocci; Ultrasound

Document Type: Research article

DOI: 10.1111/j.1525-1594.2004.07095.x

Affiliations: 1: Department of Biomedical Engineering and Physics 2: Department of Cardiothoracic Surgery and LBI of Cardiosurgical Research 3: Department of Cardiovascular Anesthesiology, University of Vienna 4: Institute of Automation and Control, Technical University of Vienna, Austria

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Automatic System for Noninvasive Blood Pressure Determination in Rotary Pump Recipients