Evidence and recommendations for tourniquet re-inflation/deflation cycles

Posted on February 21, 2014. Filed under: Tourniquet Re-inflation/Deflation Cycles, Tourniquet Safety | Tags: , , , , , , , |

A hospital recently asked about the existence of evidence and recommendations regarding tourniquet inflation/deflation cycles, after a complicated knee surgery in that hospital lasted 7 hours with three separate inflations of 2 hours, 1 hour 15min. and 40 min. with 30 min. deflation between the first and second inflation and approximately 1 hour deflation between the second and third inflation.

The following excerpts from the existing literature provide information on recommended tourniquet inflation times and re-inflation practices. The excerpts demonstrate that there are no established, evidence-based recommendations for tourniquet re-inflation times and durations. Also evident from these excerpts is any mention of tourniquet pressures, yet there is convincing and well established evidence that higher tourniquet pressure levels and higher tourniquet pressure gradients beneath the cuff are associated with higher probabilities of nerve and soft-tissue injuries [1]. There is also good evidence that lower and safer personalized tourniquet pressure levels and pressure gradients can be achieved through the measurement of the Limb Occlusion Pressures (LOPs) of individual patients [2]. Thus to develop evidence for a best practice, a future study might be warranted in which tourniquet pressure levels and pressure gradients are studied in conjunction with different inflation/deflation/reinflation periods.

     “One way of avoiding ischemic injury to muscle cells may be to employ a so-called tourniquet downtime technique, in which the tourniquet is released for a short period and then is reinflated. However, there is no evidence to support use of this technique, the suggested reperfusion time between successive ischemic periods has ranged from three to twenty minutes47, and time limits for subsequent ischemia are unknown. Furthermore, some authors have questioned the benefit of any tourniquet release and reinflation if the total tourniquet time does not exceed three hours48. In view of this controversy and in the absence of convincing evidence otherwise, we do not recommend a routine tourniquet inflation time of more than two hours. Accurate monitoring and minimization of tourniquet time are recommended.” [1]

     “There is no clearcut rule as to how long a tourniquet may be inflated safely, although various investigators have addressed effects of ischemia on muscle and nerve to define a relatively “safe” period of tourniquet hemostasis. In practice, safe tourniquet inflation time depends greatly on the patient’s anatomy, age, physical status, and the vascular supply to the extremity. Unless instructed otherwise, report to the surgeon when 60 minutes of tourniquet time has elapsed. There is general agreement that for reasonably healthy adults, 90 minutes should not be exceeded without releasing the tourniquet for a short time.

Releasing the tourniquet allows for removal of metabolic waste products from the limb and nourishment of the tissue with oxygenated blood. During this time, elevate the limb 60 degrees to encourage venous return and apply steady pressure to the incision with a sterile dressing. Tissue aeration periods should last at least 10 and preferably 15 minutes the first time and 15 – 20 minutes subsequently. To proceed with the surgery, re – exsanguinate the limb before reinflating the cuff. Take care during this procedure to maintain the sterility of the operative field. No known safe limit to the number of aeration intervals during prolonged tourniquet time has been established.”[3]

     “Even with relatively short tourniquet inflation times (ie, 26 minutes ± eight minutes), researchers have found significant markers of systemic inflammatory response when they were measured 15 minutes after tourniquet deflation.106 Inflation times of 60 minutes for an upper extremity and 90 minutes for a lower extremity have been identified as a general guideline for inflation duration.17 However, some sources indicate that two hours is a safe time limit for tourniquet inflation.20,31 In pediatric patients, inflation times of less than 75 minutes for lower extremities has been recommended.114

Irreversible skeletal muscle damage is thought to begin after three hours of ischemia and is extensive at six hours.115 Allowing intermittent reperfusion restores oxygenation and releases toxins.31 Deflating the tourniquet every two hours with at least a 10-minute reperfusion time has been identified as a strategy to consider to decrease the risk for tissue damage.28 Another approach is to release the tourniquet after 90 minutes for at least 10 to 15 minutes for the first reperfusion period, then 15 to 20 minutes for each subsequent reperfusion period.17 However, it has also been reported that implementing reperfusion periods after 60 to 90 minutes of ischemia can contribute to muscle injury. 23 ”[4]

     “The practice of using breathing periods represents an attempt to reduce ischaemic injury. This involves releasing the tourniquet after a set period of ischaemia to allow reperfusion, with the aim of returning tissue to its pre-ischaemic state, before subjecting the limb to a further period of ischaemia. Several studies have defined the appropriate breathing periods for the time ischaemia is required.

Pedowitz, using technetium uptake, found in a rabbit model that with a tourniquet time of four hours, skeletal muscle injury beneath the cuff was reduced significantly by hourly ten minute reperfusion intervals.11 He noted that a ten-minute reperfusion period after a two-hour tourniquet tended to exacerbate muscle injury. Reperfusion intervals could prolong the duration of anaesthesia, increase blood loss, or produce haemorrhagic staining and oedema.12 Nevertheless, Sapega and colleagues recommended on the basis of studies on dogs that ischaemic injury to muscle can be minimised by limiting the initial period of tourniquet time to 1.5 hours.13 Release of the tourniquet for five minutes permitted a further period of 1.5 hours. With knowledge of the ischaemia–reperfusion syndrome, the use of breathing periods is not logical, as reperfusion is now recognised as a major cause of damage to limbs after ischaemia. Further damage by free-radical-mediated mechanisms is likely even after the biochemistry of the venous blood returns to normal equilibrium. Work in animals has suggested that allowing reperfusion may actually increase the amount of damage to the ischaemic limb in certain structures.14  ”[5]

 

References:

A PDF containing selected excerpts from the references below can be found here

[1] Noordin S, McEwen JA, Kragh JF Jr, Eisen A, Masri BA. Surgical tourniquets in orthopaedics. J Bone Joint Surg Am. 2009;91(12):2958-2967.

[2] Younger AS, McEwen JA, Inkpen K. Wide contoured thigh cuffs and automated limb occlusion measurement allow lower tourniquet pressures. Clin Orthop Relat Res. 2004 Nov;(428):286-93.

[3] McEwen JA. Tourniquet use and care. http://www.tourniquets.org/use_care.php

[4] Recommended practices for care of patients undergoing pneumatic tourniquet-assisted procedures. In: Perioperative Standards and Recommended Practices. Denver, CO: AORN, Inc; 2013; p. e25-e50.

[5] Klenerman L. The Tourniquet Manual Principles and Practice. London: Springer; 2003.

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Survey of Tourniquet Use in Upper and Lower Limb Surgery

Posted on January 16, 2014. Filed under: Survey of Tourniquet Use, Tourniquet Safety | Tags: , , , , , , |

A recent publication in the Irish Journal of Medical Science [1] surveyed upper and lower limb tourniquet use among Irish orthopaedic surgeons.

Ninety-two Irish orthopaedic consultants were sent a 15-survey question on tourniquet use.  Sixty respondents returned a completed survey of which 49 used both upper arm and thigh tourniquets.

The survey showed that few surgeons use contoured tourniquet cuffs on patient limbs and a wide range of “most commonly used cuff pressures” was reported with few surgeons taking limb occlusion pressure (LOP) or systolic blood pressure into consideration when selecting tourniquet pressure.

Accordingly, tourniquet-related problems and concerns were focused on cuff fit and nerve injury: Thigh cuff users reported higher rates of poor cuff fit when compared with upper arm cuff users (Table 4). The two respondents who used a contoured cuff for both upper arm and thigh reported that they rarely or never experienced poor cuff fit. Eighty-five percent of respondents were concerned with a tourniquet-related complication during tourniquet use. Nerve injury was the most common concern, with 41 % of respondents ranking nerve injury as their primary concern when using a tourniquet.”

Based on the results of the survey, the recently published study concluded that “there is a wide variation in tourniquet practice by Irish orthopaedic surgeons.  Based on published studies of LOPs, this study suggests that some of the tourniquet cuff inflation pressures used may be higher than necessary.  Guidelines for optimising cuff pressure and technique should be established to minimise the risk of complications.”

The full abstract of the publication in the Irish Journal of Medical Science is given below. [1]

 

Background:  Tourniquet use in orthopaedic surgery is common practice. However, the technique varies among Irish orthopaedic surgeons and there are no standard guidelines. 

Aim: To analyse trends in tourniquet use among Irish orthopaedic surgeons. 

Methods:  Ninety-two Irish orthopaedic consultants were sent a 15-survey question about tourniquet use by post. 

Results:  Sixty respondents returned a completed survey, of which 49 (81% of respondents) used both upper arm and thigh tourniquets. A variation in tourniquet pressure settings and techniques used was reported. Thirty-nine surgeons (65% of respondents) use a tourniquet pressure range of 201-250 mmHg for the upper arm and 30 surgeons (50% of respondents) use a range of 251-300 mmHg for the thigh. Thirty-six surgeons (60 % of respondents) experienced a complication secondary to tourniquet use, the most common complications being nerve and skin injury. 

Conclusions:  Based on published studies of limb occlusion pressures, this study suggests that some of the tourniquet cuff inflation pressures used may be higher than necessary. Guidelines for optimising cuff pressure and technique should be established to minimise the risk of complications. This study may help determine direction for future research on tourniquet use.

 

References

[1] Cunningham L, McCarthy T, O’Byrne J. A survey of upper and lower limb tourniquet use among Irish orthopaedic surgeons. Ir J Med Sci. 2013 Sep;182(3):325-30.

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Safety and Efficacy Advances in Surgical Tourniquets

Posted on November 22, 2013. Filed under: Safety and Efficacy Advances | Tags: , , , , , , , , , , , , |

Jim McEwen PhD

 

New AORN Recommended Practices for Surgical Tourniquets

All surgical tourniquet users should be aware that on June 15, 2013 the AORN (Association of periOperative Registered Nurses) published a major update of its recommended practices on pneumatic tourniquet used in surgery.   These guidelines are widely used and followed, especially in accreditation of surgical facilities.  Many changes in recommended practices have been made, and new topics have been added, as outlined below and as given at http://www.tourniquets.org .   The RP is available for purchase at http://aornstandards.org/.

 

Comparative Effectiveness  

Outpatient surgical staff and facilities are paying increased attention to ‘comparative effectiveness’.   Comparative effectiveness research (CER) is a method of comparing different devices and treatments to determine which is the most effective.  The growth of CER highlights the value of research and published evidence quantifying the benefits of medical devices, and a growing body of evidence supports recent advances seen in surgical tourniquet instruments, cuffs and accessories.  Updated information on recent publications and evidence can be found at www.tourniquets.org and in the 2013 AORN Recommended Practices.

Two disturbing developments related to comparative effectiveness have occurred recently.  First, counterfeit tourniquet products have been seen. These counterfeit products have markings and appearances that mimic existing, proven and authentic products, but their quality, performance and safety are suspect or unknown.  Second, cloned tourniquet products have been seen in some countries.  While cloned products do not bear counterfeit markings, the fact that their physical appearance is similar to authentic products may lead users to mistakenly believe that their safety, quality and effectiveness will be equivalent.  This is not the case.  In considering comparative effectiveness, it is critical that surgical facilities and staff verify the origin and authenticity of tourniquet products.

 

Personalized Tourniquet Pressure Settings

It is well established by evidence in the clinical literature that higher tourniquet pressures are associated with higher probabilities of tourniquet-related injuries.  As a result, modern tourniquet systems aim to use the minimum pressure required to stop blood flow in a limb over the duration of a surgical procedure.  A new method based on Limb Occlusion Pressure (LOP) has been shown to allow individualized, optimal tourniquet pressure settings to be achieved.  LOP  can be defined as the minimum pressure required, at a specific time in a selected tourniquet cuff applied to an individual  patient’s limb at a desired location, to stop the flow of arterial blood into the limb distal to the cuff.   Some advanced surgical tourniquet systems include means to measure LOP automatically, although LOP can also be measured non-automatically by users.   Further information can be found at http://tourniquets.org/lop.php.

 

Personalized Tourniquet Cuffs

A recent introduction of personalized tourniquet cuffs has also resulted in safer and more effective tourniquet use.  Personalized cuffs are designed to better match patient limb size and shape and thus provide more efficient application of cuff pressure to the limb, allowing lower and safer tourniquet pressures to be used.  The improved fit is a result of the advent of new types of tourniquet cuff designs, in addition to the traditional tourniquet cuff design.  The traditional ‘straight’ tourniquet cuffs are best suited to cylindrical limb shapes.   New types of cuffs are ‘variable contour cuffs’ and allow the user to adapt the shape of the tourniquet cuff to any of a wide range of non-cylindrical (or tapered) limb shapes.  In addition the advent of new cuffs that allow better matching of cuff shapes to individual limb shapes, other advances in tourniquet cuff design have been made for pediatric and bariatric patient populations.  Tourniquet cuffs are now available that are matched specifically to pediatric and bariatric limb sizes and shapes, with comparative effectiveness established in published literature.

 

Reducing Soft Tissue Injuries with Matching Limb Protection Sleeves

High pressures, high pressure gradients and shear forces applied to skin and soft tissues underlying a tourniquet cuff can cause injuries to the skin and soft tissues.  To reduce the nature and extent of these injuries, studies have been published to determine the relative effectiveness of no protective material, underlying padding, underlying stockinette, and underlying limb protection sleeves that are matched to specific limb sizes and cuff sizes.  Study results present evidence that limb protection sleeves improve safety by protecting the skin underlying tourniquet cuffs during tourniquet use, and further provide evidence that greatest safety is achieved through the use of limb protection sleeves consisting of two-layer material specifically matched to the limb size and cuff size.  (See further information at www.tourniquets.org)

 

Reprocessing tourniquet cuffs

Outpatient surgical facilities are increasingly facing the question of whether, when, and how to reprocess tourniquet cuffs.  The answer requires consideration of patient safety, risk management, and cost.

For tourniquet cuffs designated as ‘reusable’ by manufacturers, the answers are straightforward because instructions on cleaning, inspecting and testing cuffs between uses are usually provided by the manufacturers.  Some facilities are reprocessing and reusing tourniquet cuffs designated as being ‘disposable’ or ‘single use’ by the manufacturers.  In such cases, no instructions on cleaning, inspecting and testing cuffs between uses are provided by the manufacturers.  For any facility considering the reprocessing and reuse of disposable or single-use cuffs, the following precautions should be taken.

  • A tourniquet cuff testing program should be established so that each cuff is thoroughly tested according to a written protocol after each use, and prior to the next use, with the results thoroughly documented.
  • A unique identifier should be used for each cuff so that the number of reuse cycles can be recorded.
  • Each cuff should be replaced after a maximum number of reuse cycles has been reached, to reduce the risk of cuff failure and patient injuries during use.
  • A tourniquet cuff testing protocol should be established in accordance with the recommendations of the original manufacturer of the cuff. At a minimum, the cuff testing protocol should include:

(a) a leak test, including inflating the cuff to a maximum pressure recommended by the manufacturer for a period of time, with the cuff wrapped around a test mandrel or laid flat,
(b) a fastener integrity test, to assure that the fasteners are not degraded to the point of being unsafe at the maximum pressure specified by the manufacturer,
(c) a physical inspection of the cuff to detect blockages of the pneumatic passageway in any portion of the inflatable bladder or tubing due to reprocessing damage or fluid entry,
(d) a visual inspection of the cuff to detect damage or deterioration, including: any warping of stiffener due to inappropriate reprocessing; discoloration or contamination of the cuff surface; damage or deterioration of the cuff connector or inflatable portion; and
(e) written documentation and evaluation of the test results before a decision is made regarding cuff reuse.

The complexity and cost of implementing an appropriate tourniquet cuff testing program may mean that the safe reprocessing of single-use tourniquet cuffs may not be cost-effective.

  

Emergency and military tourniquets

Some outstanding work by the US Army’s Institute for Surgical Research has led to the introduction and widespread use of tourniquets in combat settings.  It has been proven convincingly that many lives have been saved that would have been lost without the use of tourniquets.   As a result of these successes in combat settings, the same types of tourniquets are now being used increasingly by police, paramedics and other first responders in non-military settings with similar benefits.    Also, based on the proven safety and efficacy of pneumatic tourniquets in surgical settings over many years, new types of compact pneumatic tourniquets are being developed and used in emergency and military settings.  For example, a recent study of comparative effectiveness led to the introduction and use of pneumatic tourniquets by NATO forces. (See http://www.tourniquets.org for more information.)

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Three Considerations When Buying Tourniquet Systems

Posted on October 25, 2013. Filed under: Instrument Selection | Tags: , , , , |

Jim McEwen PhD

Pneumatic tourniquets are used many thousands of times per day in orthopaedic and non-orthopaedic surgical procedures in the United States and elsewhere, facilitating operations by reliably establishing a bloodless surgical field with a high level of safety.

As with any type of medical device there is considerable variation between tourniquet systems currently available in the market in terms of cost, capabilities and safety features.  When considering a tourniquet system for purchase, buyers should take the following factors into consideration:

 

Safety

Within the last thirty years, there have been important improvements in the technology of tourniquet instruments and tourniquet cuffs.  Buyers should be aware of the types of safety features and alarms that may be included in the instruments and cuffs they are considering for purchase and carefully review the specifications of each.

Modern electronic tourniquet instruments include a pressure regulator that maintains cuff pressure at the level set by the user and an automatic timer to provide an accurate record of tourniquet inflation time and alarm if the inflation time exceeds a limit set by the user.  Tourniquet instruments also typically include audiovisual alarms to prompt the operator if hazardously high or low cuff pressures are present in the cuff.  Other safety related features and alarms that may be present in a tourniquet instrument include:

  • Self-test capabilities to provide automatic checks of system operation and calibration at each start-up of the instrument.
  • Self-monitoring capabilities to continuously monitor the operation of the instrument.
  • A backup battery to allow instruments to continue to operate normally during an unanticipated power interruption or during patient transport.
  • Alarms to detect potentially hazardous air leakage from pressurized tourniquet cuffs.
  • Alarms to detect occlusions of the tubing connecting the instrument to the cuff.
  • Alarms to detect failure of a cuff to depressurize when deflation is intended.
  • A cuff hazard interlock to prevent the instrument from being inadvertently powered off while a cuff is still inflated.
  • Interlocks to help prevent inadvertent cuff deflation during intravenous regional anesthesia (Bier Block) procedures.

Additional features that may be found in some of the most modern tourniquet systems include:

  • Automated estimation of Limb Occlusion Pressure, permitting individualized setting of safer tourniquet pressures.
  • Integrated cuff testing, the capability to test cuffs, tubing and connectors for leaks.
  • Interfaces to OR information systems to capture cuff pressures and inflation times.

In addition to the safety features listed above, the user interface of the tourniquet instrument may also include special safety features to help prevent inadvertent and unintended changes in cuff pressure by the user during a procedure.

The tourniquet cuffs that are applied to each patient should also be taken into consideration when selecting a tourniquet system.  Proper cuff selection and application is essential for safe tourniquet use.  Cuffs must provide adequate surgical exposure and properly fit the surgical limb.  Buyers should consider if cuffs are available for the instrument to correctly fit the patient population for which the system is intended.  Manufacturers offer cuffs in various sizes and shapes to fit a wide range of patient limbs, from the smallest pediatric patients to large bariatric patients.  Some manufacturers also provide matching limb protection sleeves to be used between the cuff and the limb to help prevent damage to the skin beneath the cuff.

 

Two tubes or one?

Tourniquet instruments and cuffs are commonly available in dual port (two tubes per cuff) or single port (one tube per cuff) configurations.  Dual port instruments and their corresponding cuffs have two separate tubing connections between the instrument and each attached cuff.  One connection regulates the air pressure in the cuff and the other monitors the pressure in the cuff.  Generally speaking, dual port instruments and cuffs provide the most accurate and reliable indication of pressure within the cuff.  This is especially important when the tourniquet cuff is used to measure Limb Occlusion Pressure as described above.

Single port instruments and their corresponding cuffs have a single tube connecting the instrument to the cuff.  The connection is used for both pressure regulation and monitoring.  Single port instruments and cuffs usually cost less than dual port instruments.

Adaptors should not be used to connect single port cuffs to dual port instruments or to connect dual port cuffs to single port instruments.

 

One cuff or two?

Tourniquet instruments are available in single and dual channel configurations.  Dual channel instruments can control the pressure in two cuffs simultaneously, facilitating bilateral and IVRA (Bier Block) procedures.  Each cuff channel should have independent indicators for cuff pressure and inflation time and independent, well identified controls for cuff inflation and deflation.  The controls, indicators and cuff connecting tubing should be color coded to help identify the cuff connected to each channel.  For additional safety, interlocks are included in some systems to help prevent inadvertent cuff deflation during IVRA procedures.

Single channel instruments control the pressure in only one cuff.  They are generally smaller and less costly than dual channel instruments.  Two single channel instruments may be used together for bilateral and IVRA procedures.  Under no circumstances should adaptors be used to connect two or more cuffs to a tourniquet instrument intended for single channel operation.

When selecting a tourniquet instrument and cuff system buyers should always consider their clinical needs and carefully review the safety features and performance specifications of the systems under consideration.

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