ABSTRACT
A new method and apparatus for non-disruptive blood pressure (BP) recording in the finger based on the vascular unloading technique is introduced. The instrument, in contrast to intermittent set point readjustments of the conventional vascular unloading technique, delivers BP without interruptions, thus refining the Penáz' principle. The method is based on concentrically interlocking control loops for correct long-term tracing of finger BP, including automatic set point adaptation, light control and separate inlet and outlet valves for electro-pneumatic control. Examples of long-term BP recordings at rest and during autonomic function tests illustrate the potential of the new instrument.
Subject(s)
Blood Pressure Monitors , Blood Volume/physiology , Carotid Sinus/physiology , Electronics, Medical/instrumentation , Equipment Design , Femoral Artery/physiology , Fingers/blood supply , Fuzzy Logic , Humans , Plethysmography/instrumentation , Pulsatile Flow/physiology , Radial Artery/physiology , Respiration , Transducers, Pressure , Transillumination/instrumentation , Valsalva Maneuver/physiologyABSTRACT
The report describes a method of impedance cardiography using an improved estimate of thoracic volume. The formulas and their implementation in hardware and software are explained and new shortband electrodes are described which generate a good homogeneous thoracic field. Examples of stroke volume and cardiac output curves underline the capabilities of the monitoring system "Task Force Monitor". In several experiments, results are compared to thermodilution as well as to BioZ measurements: the new method excels in comparison with thermodilution and is comparable to the BioZ device. Compared to traditional electrodes, the new shortband electrodes are shown to provide better reproducibility.
