threshold
[thresh´old] 1. the level that must be reached for an effect to be produced, as the degree of intensity of stimulus that just produces a sensation.
2. that value at which a stimulus just produces a sensation, is just appreciable, or comes just within the limits of perception.
auditory threshold the slightest perceptible sound.
threshold of consciousness the lowest limit of
sensibility; the point of
consciousness at which a stimulus is barely perceived.
defibrillation threshold DFT; the minimum amount of energy in joules that will consistently terminate
ventricular fibrillation.
fibrillation threshold the least intensity of an electrical impulse that will cause cardiac tissue to begin
fibrillation.
pacing threshold the minimal electrical stimulus required to produce consistent cardiac depolarization.
renal threshold that concentration of a substance (
threshold substance) in plasma at which it begins to be excreted in the urine.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.