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Tourniquet safety in lower leg applications
James A McEwen1, Deborah L Kelly, Theda Jardanowski
1UBC Department of Orthopaedics, Vancouver, British Colombia, Canada.
Purpose:
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.
Sample:
16 adult volunteers were tested in a controlled laboratory setting, and 53 clinical cases were reviewed at two centers.
Design:
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.