A tale of three cuffs: the hemodynamics of blood flow restriction

Introduction The blood flow response to relative levels of blood flow restriction (BFR) across varying cuff widths is not well documented. With the variety of cuff widths and pressures reported in the literature, the effects of different cuffs and pressures on blood flow require investigation. Purpose To measure blood pressure using three commonly used BFR cuffs, examine possible venous/arterial restriction pressures, and measure hemodynamic responses to relative levels of BFR using these same cuffs. Methods 43 participants (Experiment 1, brachial artery blood pressure assessed) and 38 participants (Experiment 2, brachial artery blood flow assessed using ultrasound, cuff placed at proximal portion of arm) volunteered for this study. Results Blood pressure measurement was higher in the 5 cm cuff than in the 10 and 12 cm cuffs. Sub-diastolic relative pressures appear to occur predominantly at <60% of arterial occlusion pressure (AOP). Blood flow under relative levels of restriction decreases in a non-linear fashion, with minimal differences between cuffs [resting: 50.3 (44.2) ml min(-1); 10% AOP: 42.0 (36.8); 20%: 33.6 (28.6); 30%: 23.6 (20.4); 40%: 17.1 (15.9); 50%: 12.5 (9.4); 60%: 11.5 (8.1); 70%: 11.4 (7.0); 80%: 10.3 (6.3); 90%: 7.9 (4.8); 100%: 1.5 (2.9)]. Peak blood velocity remains relatively constant until higher levels (>70% of AOP) are surpassed. Calculated mean shear rate decreases in a similar fashion as blood flow. Conclusions Under relative levels of restriction, pressures from 40 to 90% of AOP appear to decrease blood flow to a similar degree in these three cuffs. Relative pressures appear to elicit a similar blood flow stimulus when accounting for cuff width and participant characteristics.