Experimental human endotoxemia increases cardiac regularity: Results from a prospective, randomized, crossover trial

Paul J. Godin, Lee A. Fleisher, Alec Eidsath, R. William Vandivier, Hugh L. Preas, Steven M. Banks, Timothy G. Buchman, Anthony F. Suffredini

Research output: Contribution to journalReview articlepeer-review

193 Scopus citations


Objective: To determine whether human endotoxemia is associated with a loss of the physiologic heat-to-beat variability of heart rate. Design: Prospective, randomized, crossover, single-blind study. Setting: Clinical research center in a federal, nonuniversity hospital. Subjects: Healthy volunteers. Interventions: intravenous administration of reference (Escherichia coli) endotoxin or saline placebo, with or without previous administration of oral ibuprofen. Measurements and Main Results: Electrocardiograms were continuously recorded and digitized using series of 1000 beat epochs of R-R intervals over 8 hrs. Analyses included measures in the time domain (standard deviation), frequency domain (power spectra), and a measure of regularity (approximate entropy), Endotoxin administration was associated with loss of variability by all measures. This loss of variability remained significant even with administration of ibuprofen, which blocked the development of fever and endotoxin-related symptoms. Conclusions: Infusion of endotoxin into human volunteers causes loss of heart rate variability, as measured by standard deviation and power spectra, as well as an increase in head rate regularity, as measured by approximate entropy. Changes in approximate entropy occurred earlier than changes in other heart rate variability measures and may be a useful means of detecting early sepsis. This reduction in regularity is consistent with a model in which the pathogenesis of multiple organ system dysfunction syndrome involves the physiologic uncoupling of vital organ systems.

Original languageEnglish (US)
Pages (from-to)1117-1124
Number of pages8
JournalCritical care medicine
Issue number7
StatePublished - Jul 1996
Externally publishedYes


  • approximate entropy
  • critical illness
  • electrocardiography
  • endotoxemia
  • endotoxin
  • heart rate
  • infection
  • lipopolysaccharide
  • multiple organ dysfunction syndrome
  • sepsis

ASJC Scopus subject areas

  • Critical Care and Intensive Care Medicine


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