title: Experimental study of the relationship between the base impedance and its time derivative in impedance plethysmography.
abstract: Transthoracic electrical impedance Z consists of a constant baseline component Z0 and the time variable component delta Z such that Z = Z0 + delta Z. The first time derivative of Z has a negative peak, the magnitude of which is (dZ/dt)min. Measurements of 170 volunteers show that (dZ/dt)min is a function of the constant baseline component Z0. This implies that at least a part of the difference of the magnitudes of (dZ/dt)min on Z0 must be taken into account in order to avoid erroneous conclusions or inaccurate calculations.
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002307:Cardiography, Impedance / Q000379:methods; D002648:Child; D005069:Evaluation Studies as Topic; D005260:Female; D006321:Heart / Q000502:physiology; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D010992:Plethysmography, Impedance / Q000379:methods; D013997:Time Factors