Blood Flow Restriction

Personalized BFR Rehabilitation for Patients with Possible Prior Nerve Injury

Posted on May 23, 2017. Filed under: Blood Flow Restriction, Tourniquet Safety |

A question was raised recently as to whether it is safe and reasonable to conduct personalized BFR rehabilitation on a patient who may have a prior nerve injury.  After consideration of the evidence-based clinical literature, and in consultation with experts in neurology and orthopedic/arthroscopic surgery, the following information is provided in response:

  1. There is no evidence in the clinical literature to suggest that prior nerve injury is a contraindication for use of a surgical-grade tourniquet instrument and surgical-grade tourniquet cuff in BFR rehabilitation. (Confirmed by recent PubMed search)
  2. Prior nerve injury is not listed as a contraindication or precaution in the ‘Instructions for Use’ of the personalized tourniquet system that is most commonly used for BFR.
  3. Any risk of nerve injury in BFR rehabilitation, whether or not the patient has a prior nerve injury, is mitigated by the use of a surgical-grade tourniquet instrument in which the lowest and safest tourniquet pressure can be determined based on Limb Occlusion Pressure (LOP), and by the use of personalized tourniquet cuffs which deliver lower pressures and lower pressure gradients to the underlying limb (see Background below).
  4. The existing clinical literature clearly shows that higher tourniquet pressure levels and higher cuff pressure gradients are associated with higher probability of nerve-related injuries (see Background below). Thus the use of non-personalized BFR cuffs and instruments, which may apply substantially higher pressures and higher pressure gradients to the underlying limb is not recommended. Non-personalized cuffs include narrow pneumatic cuffs and non-pneumatic elastic bands.  Non-personalized instruments are those that cannot determine LOP and thus cannot recommend a patient’s restriction pressure based on LOP.
  5. In the absence of any evidence or contraindications, it is safe and reasonable to carry out personalized BFR rehabilitation on patients with possible prior nerve injury, using proven surgical-grade equipment and protocols.
  6. In treating such patients, standard protocols may be modified, for example by using a lower percentage of LOP or by using shorter periods of time, but this is not considered necessary and may affect outcomes in comparison with published data.
  7. For all patients, whether or not there may be a prior nerve injury, it is recommended that the patient’s condition prior to treatment be well documented, as well as the treatment protocol, specific instrument and cuff used, and patient outcome. The specific nature of any prior nerve injury should be documented, e.g. whether such injury may have been related to prior trauma, prior surgery or prior tourniquet use.  Also, the extent of any prior nerve injury should be documented, e.g. whether it can be localized to a specific region.  Such documentation will develop additional evidence of the value and safety of this rehabilitation modality for others in future.

 

Background:

In the literature, it has been shown that tourniquet-related nerve injuries may arise from two basic mechanisms.  The first mechanism is the application of a high pressure gradient along the length of the nerve underlying a tourniquet cuff [1-5].  A high pressure gradient results in an axial force being applied along the nerve, effectively “stretching” and disrupting the nodes of Ranvier which surround the nerve, and injuring the underlying nerve cells.  The location of such tourniquet-related nerve injuries is typically beneath the cuff location, and often near the distal edge of the cuff location.  One cause of high pressure gradients is the application of high tourniquet pressures over a short distance, such as when narrow tourniquet cuffs are used, which require higher pressures for blood flow restriction compared to wider cuffs [6, 7].

The hazard of high pressure gradients is mitigated in some modern tourniquet systems by (1) use of personalized tourniquet pressures, optimized to identify the lowest pressure needed for individual patients, and (2) use of personalized tourniquet cuffs, designed to match the limb shape and optimally apply cuff pressure circumferentially and from one cuff edge to the other, thereby producing the lowest pressure gradients beneath the cuff when used in conjunction with personalized tourniquet pressures [7, 8].

A second reported cause of tourniquet-related nerve injury is general ischemia of the limb distal to the cuff for an extended period of time, but this risk is mitigated by the use of short tourniquet times [8].

References:

[1] Ochoa J, Fowler TJ, Gilliatt RW. Anatomical changes in peripheral nerves compressed by a pneumatic tourniquet. Journal of Anatomy. 1972 Dec;113(Pt 3):433.

[2] Ochoa J, Danta G, Fowler TJ, Gilliatt RW. Nature of the nerve lesion caused by a pneumatic tourniquet.

[3] Gilliatt RW, Ochoa J, Rudge P, Neary D. The cause of nerve damage in acute compression. Trans Am Neurol Assoc. 1974;99: 71-74.

[4] Yates SK, Hurst LN, Brown WF. The pathogenesis of pneumatic tourniquet paralysis in man. Journal of Neurology, Neurosurgery & Psychiatry. 1981 Sep 1;44(9):759-67.

[5] McEwen JA. Complications of and improvements in pneumatic tourniquets used in surgery. Med Instrum. 1981 Jul;15(4):253-7.

[6] Loenneke JP, Fahs CA, Rossow LM, Sherk VD, Thiebaud RS, Abe T, Bemben DA, Bemben MG. Effects of cuff width on arterial occlusion: implications for blood flow restricted exercise. European journal of applied physiology. 2012 Aug 1;112(8):2903-12.

[7] McEwen J, Casey V. Measurement of hazardous pressure levels and gradients produced on human limbs by non-pneumatic tourniquets. In Proceedings of the 32nd Conference of the Canadian Medical and Biological Engineering Society 2009 (pp. 20-22).

[8] Noordin S, McEwen JA, Kragh Jr CJ, Eisen A, Masri BA. Surgical tourniquets in orthopaedics. JBJS. 2010 May 1;92(5):1322-3.

 

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Personalized blood flow restriction training: A new method to rehabilitate injured athletes

Posted on March 6, 2015. Filed under: Blood Flow Restriction | Tags: , , |

Personalized Blood flow restriction (BFR) training is being evaluated by the Houston Texans NFL football team to rehabilitate their injured athletes, including their 2014 top draft pick Jadeveon Clowney and quarterback Ryan Fitzpatrick1. Personalized BFR training involves exercising while restricting arterial inflow into the muscle at an individual level, and while occluding venous return from the muscle using a pneumatic tourniquet cuff2. Studies have shown that such BFR therapy results in beneficial effects on skeletal and muscle form, and function3,4. Furthermore, studies have also shown that BFR training at low resistance can increase both muscle mass and strength, while reducing the risk of injury associated with the traditional muscle gain method of heavy resistance training3,4.

Personalized BFR training was first researched at the Brooke Army Medical Center (BAMC) to help wounded warriors recover from their injuries. The researchers at the BAMC have been using tourniquet systems from Delfi Medical Innovations to apply the personalized BFR training for each individual. They have observed an average increase of 50%-80% strength gains in as little as a few weeks5.

Since November 2014 when the BAMC researchers shared how their use of personalized BFR training helped wounded warriors return to health, personalized BFR training has garnered the attention of the professional sports realm1. The ability to minimize early muscular strength deficits while protecting healing tissues is of key interest to professional sport teams for rehabilitating their injured athletes1. After collaborating with the BAMC researchers, the Houston Texans’ head team physician began evaluating personalized BFR training on some of the team’s players using a tourniquet system from Delfi Medical Innovations. Several Houston Texans’ players currently undergoing personalized BFR training as part of their rehabilitation are saying they feel better and their legs are getting stronger1. The Texans’ medical staff observed that players undergoing personalized BFR training exhibit better muscle control and progress faster than they normally see1. As reported, other NFL teams are considering investigating personalized BFR training1.

[1] Bell, Stephania. “Houston Texans using BFR training.” ESPN. ESPN Internet Ventures, 20 Feb 20 2015. Web. 20 Feb 2015. <http://m.espn.go.com/nfl/story?storyId=12352707&src=desktop&wjb&gt;

[2] Loenneke JP, Thiebaud RS, Abe T, Remben MG. “Blood flow restriction pressure recommendations: the hormesis hypothesis.” Med Hypothesis. 2014 May; 82(5): 623-6.

[3] Loenneke JP, Abe T, Wilson JM, Thiebaud RS, Fahs CA, Rossow LM, Bemben MG. “Blood flow restriction: an evidence based progressive model (Review).” Acta Physiologica Hungarica. 2012 Sep; 99(3): 235-250.

[4] Hylden C, Burns T, Stinner D, Owens J. “Blood flow restriction rehabilitation for extremity weakness: a case series.” JSOM. JSOM Online, 15 Jul 2014. Web. 20 Feb 2015. <https://www.jsomonline.org/Newsletter/140715.html#2&gt&gt;

[5] Bell, Stephania. “New method may benefit athletes.” ESPN. ESPN Internet Ventures, 11 Nov 2014. Web. 20 Feb 2015. <http://espn.go.com/nfl/story/_/id/11858977/tourniquet-training-change-way-athletes-recover-injuries&gt;&gt;

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Innovative blood flow restriction (BFR) training based on LOP

Posted on December 1, 2014. Filed under: Blood Flow Restriction, Newest Developments | Tags: , , , |

Blood flow restriction (BFR) training involves exercising while restricting arterial inflow into the muscle, and occluding venous return from the muscle1. Although the exact mechanism is not fully understood, many studies have shown that BFR therapy results in beneficial effects on skeletal muscle form and function, and preliminary evidence suggests it may also promote bone formation 2, 3. Researchers have found that the low oxygen state caused by BFR makes the body use muscle fibers typically reserved for the most strenuous tasks, such as sprinting and heavy lifting4. This causes the brain to release anabolic substances such as human growth hormone (HGH), as much as 290 times greater than baseline4.

Typically, a person needs to lift weights at around 70% of their one repetition maximum to have noticeable increase in muscular strength and size2. However, heavy resistance training has risk of injuries and may not be used for many at risk population such as the elderly, and patients undergoing rehabilitation. Studies have shown that BFR training at low resistance can increase both muscle mass and strength, and is beneficial for the recovery of wounded soldiers, injured athletes and patients requiring muscle gain 2,4,5,6.

For an example, at the Centre for the Intrepid (CFI) in San Antonio, low-resistance BFR training was introduced to help rehabilitate wounded soldiers4. Many of these patients have severely damaged limbs which prevent them from participating in traditional weight training. BFR training has allowed them to gain muscle strength and function without compromising vulnerable soft tissues and joints. Researchers at CFI have observed an average increase of 50%-80% strength gains in a little as a few weeks.

While BFR training appears to hold promise in increasing muscle strength and size, it must be done in a controlled, supervised environment with trained staff, and with specialized surgical tourniquet systems adapted for BFR training4. Furthermore, since the applied pressure should be high enough to stop venous return but low enough to allow for consistently restricted arterial flow, the optimal pressure applied will be different for each individual, and should be personalized to maximize the safety, consistency, and effectiveness of the BFR training. Personalization of the BFR training can be achieved by applying a specialized pneumatic tourniquet cuff and setting a cuff pressure based on the individual’s limb occlusion pressure (LOP) [http://www.tourniquets.org/lop.php]. It has been suggested that applying a cuff pressure at a predetermined percentage of the LOP can maximize the anabolic response to skeletal muscle without increasing the possible negative consequences of higher pressures1. The use of a specialized surgical tourniquet system adapted for BFR training improves BFR training by maintaining, controlling and applying evenly distributed pressure, based on personalized limb occlusion pressure, through an adapted surgical tourniquet cuff, applied around the limb proximal to the targeted muscle group.

References:

[1] Loenneke JP, Thiebaud RS, Abe T, Remben MG. “Blood flow restriction pressure recommendations: the hormesis hypothesis.” Med Hypothesis. 2014 May; 82(5): 623-6.

[2] Loenneke JP, Abe T, Wilson JM, Thiebaud RS, Fahs CA, Rossow LM, Bemben MG. “Blood flow restriction: an evidence based progressive model (Review).” Acta Physiologica Hungarica. 2012 Sep; 99(3): 235-250.

[3] Loenneke JP, Young KC, Wilson JM, Andersen JC. “Rehabilitation of an osteochondral fracture using blood flow restricted exercise: a Case review.” J of Bodywork and Movement Therapies. 2013 Jan; 17(1): 42-45.

[4] Bell, Stephanie. “New method may benefit athletes.” ESPN. ESPN Internet Ventures, 11 Nov 2014. Web. 26 Nov 2014. <http://espn.go.com/nfl/story/_/id/11858977/tourniquet-training-change-way-athletes-recover-injuries&gt;.

[5] Martin-Hernandez J, Marin PJ, Menendez H, Ferrero C, Loenneke JP, Herrero AJ. “Muscular adaptations from two different volumes of blood flow-restricted training.” Scand J Med Sci Sports. 2013 Mar; 23(2): e114-20.

[6] Hylden C, Burns T, Stinner D, Owens J. “Blood flow restriction rehabilitation for extremity weakness: a case series.” JSOM. JSOM Online, 15 Jul 2014. Web. 28 Nov 2014. <https://www.jsomonline.org/Newsletter/140715.html#2&gt;.

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