Tourniquet Cuff Pressure During Blood Flow Restriction Exercise

Patrick Swain¹James McEwen^2,3Tom Lai²Luke Hughes^1*

• ¹Northumbria University, Newcastle upon Tyne, United Kingdom
• ²Western Clinical Engineering Ltd., Vancouver British Columbia, Canada
• ³School of Biomedical Engineering and Departments of Orthopedics and Electrical and Computer Engineering, University of British Columbia, Vancouver British Columbia, Canada

Background: The present study examined how well different blood flow restriction (BFR) devices deliver the prescribed tourniquet cuff pressure. Methods: Fifteen participants completed four BFR exercise sessions, each with a different BFR device (Delfi Personalized Tourniquet System [PTS] for BFR, Saga, SmartCuffs, and Suji), comprising four sets of unilateral leg press (30-15-15-15 repetitions) against resistance bands with 30-second rest periods. The tourniquet cuff was secured proximally on the exercising leg, and the target pressure was set to 80% limb occlusion pressure (LOP), as measured by the device, applied continuously throughout the exercise/rest periods. Tourniquet cuff pressure was sampled at 100Hz via a pressure transducer. Results: Despite prescribing tourniquet cuff pressure at 80% LOP, the actual pressure can vary substantially and be inconsistent between individuals depending on the BFR device used. During the exercise periods, the median percentage of time pressure was within ±10% the target pressure was 95% (Delfi PTS for BFR), 25% (Saga), 26% (SmartCuffs), and 34% (Suji). During the rest periods, the median percentage of time pressure was within ±5% the target pressure was 99% (Delfi PTS for BFR) and 0% for the Saga, SmartCuffs, and Suji BFR devices. Tourniquet cuff pressure during BFR exercise behaves in a wave-like manner characterised by cyclical pressure peaks and valleys. The magnitude of pressure peaks and valleys was: Delfi PTS for BFR (89±2% and 72±3% LOP), Saga (79±9 and 58±7% LOP), SmartCuffs (79±9% and 61±7% LOP), and Suji (90±15 and 65±10% LOP). In several cases, participants experienced tourniquet pressures >100% LOP using the Saga, SmartCuffs, and Suji BFR devices, for up to ~30-55% of the exercise set duration. A progressive loss of pressure occurred throughout the BFR application period by an average of 2-4mmHg•min-1 (~1-2% LOP•min-1 ) in the Saga, SmartCuffs, and Suji BFR devices, whilst the Delfi PTS for BFR exhibited trivial pressure drifts. Conclusion: Differences between the actual and prescribed tourniquet cuff pressure can highly depend on the BFR device employed. The selection of the BFR apparatus is thus important to delivering the prescribed tourniquet cuff pressure to allow for standardisation of the relative occlusion pressure between users.