Blood Flow Restriction Therapy

Where We Are and Where We Are Going

Bryan G. Vopat, MD; Lisa M. Vopat, MD; Megan M. Bechtold, DPT; Kevin A. Hodge, MD

Disclosures

J Am Acad Orthop Surg. 2020;28(12):e493-e500. 

In This Article

Safety Concerns

Regardless of the reported benefits of BFRT, the safety of its use is often questioned. The idea of physically restricting blood flow to an extremity may raise red flags, especially in regard to the cardiovascular system. Despite the potential dangers, a 2006 Japanese national survey (N = 13,000) found that the most common adverse effects are temporary including subcutaneous hemorrhage (13%), sensory paresthesias (1.3%), and lightheadedness (0.3%).[31] However, there are sparse case reports of rhabdomyolysis and thrombolytic events in the literature. A recent survey noted that of 115 practitioners using BFRT, 3% had an incident of rhabdomyolysis and 0.8% had a thrombolytic event in their practice.[32] Overall, the risk associated with BFRT appears to not be greater than traditional high-load resistance exercise; however, long-term studies on the effect on the cardiovascular system are needed.

One potential concern raised by cardiologists is in regard to BFRT's effect on the exercise pressor reflex (EPR). The EPR is the body's physiologic autonomic response to exercise. During exercise, elevated levels of metabolites, including lactate and hydrogen ions, and mechanical pressure stimulate the EPR. This ultimately increases sympathetic activity, leading to increases in carbon monoxide, heart rate, contractility, and ultimately mean arterial pressure. BFRT has been shown to cause an exaggerated response of the EPR and thus theoretically has the potential to cause adverse cardiac events including arrhythmias, stroke, myocardial infarction, or sudden cardiac death. This is especially true in patients with cardiovascular comorbidities due to their enhanced EPR at baseline. Data on the short- or long-term effects of this reflex in relation to BFRT are insufficient, but practitioners need to be aware of the potential risk, especially in patients with cardiovascular comorbidities.[11]

Another concern is the long-term effect of elevated venous pressures on chronic venous insufficiency. It is not uncommon for individuals performing high-intensity training routines to reach systolic and diastolic pressures over 300 mm Hg. The addition of BFRT with the restriction of venous outflow in theory has the potential to damage the valves in veins, leading to venous insufficiency; however, this has not been reported in investigations to date.[11] This is important to note during the chronic use of BFRT and in patients with venous insufficiency at baseline.

The risk of muscle damage while using BFRT has been analyzed by several investigations. Creatinine kinase, myoglobin, and interleukin 6 have not been shown to be elevated after BFRT. There are case reports where rhabdomyolysis has developed after training; however, it is not known whether BFRT is the causing factor in the thrombus formation. A previous survey out of Japan reported a rhabdomyolysis rate of 1 of 12,642 patients.[31] Overall, it appears that muscle damage is a minor risk with BFRT.

In regard to thrombolytic events, in theory, blood flow occlusion and endothelial damage could promote coagulation pathways via Virchow's triad. However, this appears infrequent in the literature. In the largest study of its kind, 7 of 12,642 patients (0.06%) were found to develop a deep vein thrombosis (DVT) after using BFRT, although it is unknown whether the relationship between DVT and BFRT is associated or causal.[31] In addition, studies have not found elevated markers for coagulation in association with BFRT including fibrinogen and D-dimer. In fact, BFRT actually has been shown to activate the fibrinolytic system, which in theory would inhibit thrombus formation.[32] Due to the paucity of data, BFRT should be avoided in patients at risk for DVT which includes those with a history of DVT or a genetic condition that puts them at increased risk.

In conclusion, evidence to date has not shown BFRT to be more risky than high-load resistance training, although patient selection and professional supervision are essential to decrease the risk of adverse events. The long-term effects of BFRT on the cardiovascular system require further investigation.

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