PURPOSE: Blood flow restriction (BFR) in physical therapy settings requires personalized restriction pressures in order to remain a safe rehabilitation modality. Measuring limb occlusion pressure (LOP) is one method of setting the pressure relative to each patient and is performed with a vascular doppler and inflatable cuff. Several dopplers are available, but have not been compared. This study was performed to compare the Hokanson MD6 and the Edan SonoTrax vascular dopplers in measuring LOP.
METHODS: In a randomized crossover design, 20 participants (women=10, men=10) visited the laboratory once. Arm and thigh circumferences were measured. After 10min of rest, LOP was measured in the arm and leg with 5cm and 10cm wide inelastic cuffs, respectively. Measurements were repeated every 5min until LOP was measured in both limbs with both dopplers. Bland-Altman analyses (MD6 - SonoTrax) were performed and limits of agreement (LOA) calculated. Two one-sided tests of equivalence with lower and upper equivalence bounds of -5 mmHg to 5 mmHg were calculated. Results are reported as mean (95%CI) for Bland-Altman analyses and mean (90%CI) for equivalence testing.
RESULTS: Arm LOP measurement showed a mean bias of 0.6 (-1.3 - 2.4) mmHg, with upper and lower LOA of 8.4 (5.1 - 11.7) mmHg and -7.3 (-10.6 - -4.0) mmHg, respectively. Thigh LOP measurements showed a mean bias of -1.5 (-4.4 - 1.4) mmHg with upper and lower LOA of 10.5 (5.5 - 15.5) mmHg and -13.5 (-18.5 - -8.5) mmHg, respectively. Equivalence testing determined that both doppler measurements were equivalent in the arm (0.55 (-0.99 - 2.1) mmHg, p = .547) and leg (-1.5 (-3.87 - 0.87) mmHg, p = .288).
CONCLUSIONS: The SonoTrax measured LOP equivalently to the MD6. Physical therapists wanting to use BFR therapy should feel comfortable using either vascular doppler in their clinic.