title: Blinded observer evaluation of distal skin temperature for predicting lateral infraclavicular block success.
abstract: BACKGROUND
  Changes in digit skin temperature may be used to predict and determine upper limb nerve block success. We investigated whether a temperature difference between the blocked and the nonblocked hands, simply registered by touching the skin of the 5th and 2nd digit was valid and reliable as a diagnostic test for predicting a successful lateral infraclavicular block.
  
  
  METHODS
  Blinded observers investigated temperature difference between the blocked and the nonblocked hands of 40 patients. Sensitivity, specificity, and predictive values of a positive and a negative test were estimated for evaluating the validity of a temperature difference for predicting a successful lateral infraclavicular block defined by sensory and motor block of all 4 major nerves (musculocutaneous, radial, ulnar, and median nerves). κ statistics of interobserver agreement were used for evaluating the reliability of the test.
  
  
  RESULTS
  As a stand-alone test, a temperature difference between the corresponding 2nd and 5th digits of the blocked and the nonblocked hands predicted a successful block with a sensitivity of 92% (95 % confidence interval (CI), 83%-97%) and with a predictive value of a positive test of 95% (CI, 86%-98%). Fleiss κ for multiple observers was 0.74, (CI, 0.61-0.87) for the 5th digit and 0.87 (CI, 0.73-0.998) for the 2nd digit, respectively.
  
  
  CONCLUSIONS
  We found that a qualitative difference in skin temperature between the blocked and nonblocked hands, measured distally on the 2nd and 5th digits, was a valid and reliable diagnostic test for predicting successful lateral infraclavicular block.
authors.affiliation: From the Department of Anaesthesiology and Intensive Care, Nordsjællands Hospital, Copenhagen University, Hillerød, Denmark.
authors.forename: Semera
authors.initials: S
authors.lastname: Asghar
authors.forename: Kai H W
authors.initials: KHW
authors.lastname: Lange
authors.forename: Lars H
authors.initials: LH
authors.lastname: Lundstrøm
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001917:Brachial Plexus; D005260:Female; D005385:Fingers / Q000502:physiology; D005542:Forearm / Q000601:surgery; D006225:Hand / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D009407:Nerve Block / Q000379:methods*; D015588:Observer Variation; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D012881:Skin Temperature / Q000502:physiology*; D055815:Young Adult