title: Introduction of a continual RIII reflex threshold tracking algorithm.
abstract: BACKGROUND
  The RIII reflex is used in fundamental and clinical pain research. Here we introduce a continual reflex threshold tracking algorithm to facilitate investigations of the time courses of influences on the threshold.
  
  
  METHODS
  First we investigated the probability of reflex occurrence at the threshold estimated by the continual algorithm and the changes of the threshold over the time during continual recordings of 100 min duration in 10 subjects. Secondly we compared the threshold estimates of the continual algorithm with those of a standard algorithm of threshold estimation in 52 subjects and compared the differences between the two methods with the test-retest-variability of each method.
  
  
  RESULTS
  The average probability of reflex occurrence at the threshold estimated by the continual algorithm was 48.7% (SD = 3.2%). Changes of the RIII reflex threshold over the time were not significant (Friedman test, p>0.05). The variability between the thresholds determined by the different algorithms (test: SD = 2.50 mA, retest: SD = 1.80 mA) was lower than the variability between test and retest (standard algorithm: SD = 4.32 mA, continual algorithm: SD = 4.44 mA).
  
  
  CONCLUSIONS
  The continual algorithm can be used for a continuous estimation of the reflex threshold at the 50% probability of reflex-occurrence. No evidence of habituation was detected. This allows for investigations of the time courses of pharmacological and physiological influences on the reflex threshold by using this algorithm. The lower variability between the continual algorithm and the standard algorithm compared to the variability between tests and retests of the methods allows for interchangeable conclusions drawn from data obtained with both methods.
authors.affiliation: Charité-Universitätsmedizin Berlin-Department of Anesthesiology, Germany. falk.von-dincklage@charite.de
authors.forename: Falk
authors.initials: F
authors.lastname: von Dincklage
authors.forename: Mark
authors.initials: M
authors.lastname: Hackbarth
authors.forename: Martin
authors.initials: M
authors.lastname: Schneider
authors.forename: Jan Harald
authors.initials: JH
authors.lastname: Baars
authors.forename: Benno
authors.initials: B
authors.lastname: Rehberg
mesh_terms: D000328:Adult; D000465:Algorithms; D004558:Electric Stimulation; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D011336:Probability; D012018:Reflex; D055815:Young Adult