Newest Developments

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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New Concept: Internal tourniquets for surgery

Posted on July 19, 2011. Filed under: Internal Tourniquets, Newest Developments |

A new US Patent issued on July 19, 2011 for an ‘internal tourniquet for surgery’[1] . The innovation described in this new patent opens the door to extending tourniquet-related concepts to surgical procedures not previously amenable to conventional tourniquets, especially procedures near truncal-extremity junctions, including hip and shoulder regions, and in the deep abdomen. Synergies exist by integrating this internal tourniquet innovation with related new concepts of ‘tourniquet effectors’ and ‘ultrasonic tourniquets’ [1-4].


Limitations of external tourniquets

External tourniquet systems have long been used to establish hemostasis in the upper and lower limb in order to facilitate orthopedic surgical procedures. Such systems typically include a pneumatic tourniquet cuff applied around a patient’s limb proximal to a desired surgical field, and an external tourniquet instrument for supplying the cuff with gas at a pressure above the minimum pressure needed to stop arterial bloodflow past the cuff and into the surgical field for the duration of a surgical procedure. In this way, an external tourniquet system establishes a bloodless and clear surgical field in the limb distal to the cuff, allowing complex orthopedic surgical procedures to be performed with improved accuracy, safety and speed.

However, in addition to establishing a bloodless surgical field, external tourniquet systems also stop bloodflow to non-surgical regions of the limb, resulting in ischemia and a risk of injury to these non-surgical regions that increases as the duration of ischemia increases. Further, external tourniquet systems apply pressure to underlying muscle, blood vessels and nerves proximal to the surgical site, resulting in a risk of injury to these tissues that increases as the level of pressure and duration of pressure application increases.

In addition, anatomical considerations in certain surgical procedures, such as in hip and shoulder surgeries, may limit or completely prevent the use of external tourniquet systems for establishing hemostasis.


Alternatives to external tourniquets in joints, at truncal-extremity junctions and in the deep abdomen

If an external tourniquet system is not used, or cannot be used, then other devices have been used in the past to improve visualization and reduce bleeding, especially for arthroscopic surgical procedures. Some of these devices manage the flow of sterile fluid into and out of a capsule that envelops a joint, thereby to help establish a pressure within the capsule that may reduce bleeding and improve visualization, and to help remove surgical debris and blood that may be present in the capsule. Some of the fluid management systems that have been used for arthroscopies require significant manual intervention, knowledge, skill and attention by the surgeon throughout a surgical procedure in order to balance a number of competing requirements: the control of bleeding in the surgical field, the minimization of extravasation or swelling of tissues surrounding the surgical field and its associated risk of patient injury; the removal of blood and surgical debris from the surgical field; the maintenance of acceptable visualization; and the minimization of fluid loss and its related costs and hazards.


Internal tourniquets, tourniquet effectors and ultrasonic tourniquets

To facilitate new orthopedic surgical procedures that are becoming less invasive, as well as to facilitate arthroscopic surgical procedures that are becoming increasingly complex, the innovation described in the newly issued US patent meets the need for an internal tourniquet that can establish adequate hemostasis and provide a sufficiently bloodless surgical field when conventional external tourniquets cannot be used. The innovation does this without the limitations in performance and without many of the risks of patient injuries associated with prior-art external tourniquet systems and arthroscopic fluid management systems. Meeting this need, as described in the new US patent and in combination with ultrasonic tourniquet innovations and tourniquet effector innovations [1-4], opens the door to extending tourniquet-related concepts to surgical procedures not previously amenable to conventional tourniquets, especially in the abdomen and near truncal-extremity junctions including hip and shoulder regions.


References

[1] JA McEwen, “Internal Tourniquet for Surgery”, US Pat No 7,981,070, Issue date 19 July 2011.

[2] JA McEwen et al, “Tourniquet Effector”, US Pat App Ser No 61/323,486, filed April 13, 2010.

[3] JA McEwen et al, “Tourniquet Apparatus for Controlling Blood Penetration”, PCT Patent Application PCT/CA2010/00106, filed 22 January 2010.

[4] JA McEwen and M Jameson, “Ultrasonic Tourniquet System”, PCT Patent Application No. 60/951,632, filed 23 July 2008.




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