title: Tourniquet-induced hypertension correlates with autonomic nervous system changes detected by power spectral heart rate analysis.
abstract: OBJECTIVE
  To determine the autonomic changes associated with pneumatic tourniquet-induced hypertension as measured by power spectral heart rate analysis (PSHR).
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  Tertiary teaching hospital.
  
  
  METHODS
  21 healthy-patients scheduled for lower extremity surgery, during which pneumatic tourniquet inflation was expected to exceed 90 minutes.
  
  
  METHODS
  Hemodynamic and PSHR data collected at 5 minute intervals during inflation of the pneumatic tourniquet. Tourniquet-induced hypertension (T-HTN) defined at 30% increase above baseline.
  
  
  RESULTS
  Blood pressure, heart rate, maximum changes in low frequency variability (LFa), high frequency variability (HFa), and their ratio (LFa/HFa) were measured. Of the 21 patients, 11 had T-HTN. A significantly greater increase in LFa and LFa/HFa ratio was seen in the T-HTN group, where patients were greater in age. LFa, HFa, and ratio were not significantly different with T-HTN until 60 minutes or greater. Best correlation with T-HTN occurred with maximum increase in LFa/HFa ratio compared with increase in LFa or decrease in HFa.
  
  
  CONCLUSIONS
  Tourniquet hypertension correlated with activation of the sympathetic nervous systems, as measured by PSHR variables.
authors.affiliation: Department of General Anesthesiology, Cleveland Clinic Foundation, OH 44195, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Tetzlaff
authors.forename: J
authors.initials: J
authors.lastname: O'Hara
authors.forename: H J
authors.initials: HJ
authors.lastname: Yoon
authors.forename: A
authors.initials: A
authors.lastname: Schubert
mesh_terms: D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology*; D001794:Blood Pressure / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D007866:Leg / Q000601:surgery; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D003473:Neuromuscular Nondepolarizing Agents; D011446:Prospective Studies; D014111:Tourniquets; D014403:Tubocurarine
chemical_list: D003473:Neuromuscular Nondepolarizing Agents; D014403:Tubocurarine