title: Tourniquet safety in lower leg applications.
abstract: OBJECTIVE
  To reduce the chance of injury due to pneumatic tourniquet use, the minimum cuff pressure required to maintain a bloodless field should be used. The purpose of this study was to find out if Limb Occlusion Pressure (LOP--the cuff pressure required to occlude arterial flow) is lower with a wide contoured cuff than with a standard width cylindrical cuff at the calf, if cuff pressures based on measured LOP will be lower than the typical 250 mmHg used in lower leg cuffs, and if a new automatic LOP measurement method gives the same results as the standard Doppler stethoscope method.
  
  
  METHODS
  16 adult volunteers were tested in a controlled laboratory setting, and 53 clinical cases were reviewed at two centers.
  
  
  METHODS
  Repeated measures comparison of LOP on volunteers with the two different cuffs and measurement methods, and review of clinical cases.
  
  
  RESULTS
  LOP was lower with the wide cuff on all volunteers (mean reduction 20 mmHg, SD 8.6, range 5-35, p < 0.001). The average difference of 1.2 mmHg between Doppler and automatic LOP readings was not significant (p = 0.43). Based on the volunteer results, using LOP plus a safety margin of 40, 60, or 80 mmHg (for LOP < 130, 131-190, or 190+ respectively) with a standard width cylindrical cuff will lead to an average cuff pressure of 223 mmHg (range 170-299, SD 36), 11% lower than typical practice and up to 80 mmHg (32%) lower on some patients. Using a wide, contoured cuff should further reduce cuff pressures to an average of 195 mmHg (range 160-280, SD 33), 22% lower than typical practice and a reduction of up to 90 mmHg (36%). At two clinics, the wide cuff maintained a bloodless field in 48 out of 53 cases (91%) when used at 200 mmHg.
  
  
  CONCLUSIONS
  Using a wide, contoured cuff at the calf should reduce required cuff pressures compared to a standard cuff. Setting cuff pressure based on LOP should further reduce cuff pressures for most patients compared to typically used pressures. With continued development, the new automatic method may become a viable alternative to the Doppler method and may make LOP measurement more practical in the clinical setting.
authors.affiliation: UBC Department of Orthopaedics, Vancouver, British Colombia, Canada.
authors.forename: James A
authors.initials: JA
authors.lastname: McEwen
authors.forename: Deborah L
authors.initials: DL
authors.lastname: Kelly
authors.forename: Theda
authors.initials: T
authors.lastname: Jardanowski
authors.forename: Kevin
authors.initials: K
authors.lastname: Inkpen
mesh_terms: D000328:Adult; D015400:Clinical Nursing Research; D004867:Equipment Design; D005260:Female; D006801:Humans; D007866:Leg / Q000098:blood supply* / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods* / Q000592:standards*; D011312:Pressure; D017751:Safety Management / Q000379:methods*; D014111:Tourniquets / Q000009:adverse effects* / Q000592:standards*; D018608:Ultrasonography, Doppler