Tourniquet Safety

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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Lower tourniquet cuff pressure reduces postoperative wound complications after total knee arthroplasty

Posted on March 4, 2013. Filed under: Lower Tourniquet Cuff Pressures, Tourniquet Safety | Tags: , , , |

An interesting paper from the Södersjukhuset Karolinska Institutet, in Stockholm Sweden evaluating the benefit of measuring limb occlusion pressure before surgery was recently published in the December 2012 issue of the Journal of Bone and Joint Surgery [1].

This randomized controlled study of 164 patients demonstrated a significant reduction in tourniquet pressure and more individual cuff pressures among patients when LOP was measured using 140 mm wide contour cuffs.  Although the study method demonstrated no difference in postoperative pain between the LOP and control groups, the authors note that patients with cuff pressures below 225 mmHg had fewer postoperative complications.

The full abstract of the publication in the Journal of Bone and Joint Surgery is given below. [1]

Background: Measurement of limb occlusion pressure before surgery might lead to the use of a lower tourniquet cuff pressure during surgery and thereby reduce the risk of postoperative pain and complications. The primary aim of this study was to investigate whether the limb-occlusion-pressure method reduces the tourniquet cuff pressure used during total knee arthroplasty and if this leads to less postoperative pain compared with that experienced by patients on whom this method is not used. The secondary aim was to investigate whether there were any differences regarding the quality of the bloodless field, range of motion, and postoperative wound complications.

Methods: One hundred and sixty-four patients scheduled to be treated with a total knee arthroplasty were randomized to a control group or to undergo the intervention under study (the limb-occlusion-pressure [LOP] group). In the control group, the tourniquet cuff pressure was based on the patient’s systolic blood pressure and a margin decided by the surgeon (the routine method). In the LOP group, the tourniquet cuff pressure was based on the measurement of the limb occlusion pressure. The primary outcome measure was postoperative pain, and the secondary outcome measures were the quality of the bloodless field, knee motion, and wound-related complications at discharge and two months after surgery.

Results: The tourniquet cuff pressure was significantly lower in the LOP group than in the control group (p < 0.001). We could not demonstrate any differences between the groups regarding postoperative pain or complications, although the number of postoperative complications was relatively high in both groups. However, at discharge forty of the forty-seven patients with a wound complication had had a cuff pressure above 225 mm Hg and at the two-month follow-up evaluation fourteen of the sixteen patients with a wound complication had had a cuff pressure above 225 mm Hg.

Conclusions: The limb-occlusion-pressure method reduces the cuff pressure without reducing the quality of the bloodless field, but there were no differences in outcomes between the groups. An important secondary finding was that patients with a cuff pressure of 225 mm Hg had no postoperative infections and a lower rate of wound complications.

Level of Evidence: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

References

[1] Olivecrona C, Ponzer S, Hamberg P, Blomfeldt R (2012) Lower tourniquet cuff pressure reduces postoperative wound complications after total knee arthroplasty: a randomized controlled study of 164 patients. J Bone Joint Surg Am 94:2216–2221

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Evidence of safety: matching limb protection sleeves with tourniquet cuffs

Posted on March 4, 2013. Filed under: Matching Limb Protection Sleeves, Tourniquet Safety | Tags: , , , , , |

What evidence exists to show the extent to which the use of limb protection sleeves underlying tourniquet cuffs improves patient safety?  It is known that 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 including petechiae, blistering, bruising, and pinching.  To reduce the nature and extent of such injuries, studies have been published to determine the relative effectiveness of underlying padding, underlying stockinette, and underlying limb protection sleeves that are matched to specific limb sizes and cuff sizes.

Olivecrona et al. [1] compared the use of elastic stockinette, cast padding, and no protective material underneath a pneumatic tourniquet in 92 patients who underwent a primary total knee arthroplasty and confirmed that an elastic stockinette provided the most effective skin protection during tourniquet use, of the three that were studied.  McEwen et al. [2] compared five different tourniquet cuff sleeve and padding configurations in healthy adult volunteers, and Tredwell et al. [3] tested four different tourniquet cuff sleeve and padding configurations on healthy child volunteers.  Both studies found that stretched sleeves made of two-layer tubular elastic material and matched to specific tourniquet cuff sizes, and thus to limb sizes, produced significantly fewer, less severe pinches and wrinkles in the skin surface than other types of underlying limb protection that were tested, including cast padding, single-layer stockinette, and stockinette not matched to the cuff and limb size.

These studies 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 matching limb protection sleeves consisting of two-layer tubular stockinette specifically matched to the limb size and cuff size.  Detailed information about matching limb protection sleeve products is available elsewhere [4].

References

[1]      J. A. McEwen and K. Inkpen, “Tourniquet Safety: Preventing Skin Injuries,” The Surgical Technologist, no. August 2002, pp. 7–15, 2002.

[2]      S. J. Tredwell, M. Wilmink, K. Inkpen, and J. a McEwen, “Pediatric tourniquets: analysis of cuff and limb interface, current practice, and guidelines for use.,” Journal of Pediatric Orthopedics, vol. 21, no. 5, pp. 671–6, 2001.

[1]      C. Olivecrona, J. Tidermark, P. Hamberg, S. Ponzer, and C. Cederfjäll, “Skin protection underneath the pneumatic tourniquet during total knee arthroplasty: a randomized controlled trial of 92 patients.,” Acta Orthopaedica, vol. 77, no. 3, pp. 519–23, Jun. 2006.

[4]        http://www.delfimedical.com/pts-ii/limb-sleeves

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Hazards of Hemaclear Elastic Ring Tourniquets

Posted on September 18, 2012. Filed under: Silicone Ring Tourniquets, Tourniquet Safety | Tags: , , , , , , , , , , , |

This article discusses hazards and limitations associated with the use of a Hemaclear elastic ring as a tourniquet.

The Hemaclear elastic ring has been shown to apply high pressure levels and high pressure gradients to the underlying limb and soft tissues [1, 2].  Such high pressure levels and high pressure gradients produced by this elastic ring have resulted in reports of high levels of pain [3, 4, 5].  In addition to pain, evidence in the published literature has shown that higher pressure gradients and higher pressure levels in tourniquets are associated with higher probabilities of injuries to underlying nerves and soft tissues [2,6].

Elastic tourniquets were used as tourniquets in the nineteenth century.  However, their use was abandoned early in the twentieth century because of many recurring reports of serious nerve and soft tissue injuries resulting from elastic tourniquets, including permanent limb paralysis.  They were replaced by pneumatic tourniquet systems which safely and reliably stop arterial blood flow at much lower tourniquet pressures and lower tourniquet pressure gradients [2,6].

Related hazards and limitations associated with recent efforts to re-introduce a non-pneumatic elastic ring as a tourniquet include the following.

1. The Hemaclear elastic ring does not measure the actual tourniquet pressure applied to the limb, nor does it measure the pressure gradient applied to the patient’s limb.

2. Thus a Hemaclear ring cannot provide the user with an accurate indication of the actual tourniquet pressure and pressure gradient applied to the patient’s limb.

3. There is no documented evidence of the actual pressure levels and pressure gradients applied to limbs by each size of Hemaclear elastic rings.

4. It is not possible to control the pressure applied by the Hemaclear elastic ring to the patient’s limb during a surgical procedure.

5. The surgical user is left with no practical contingency plan in the event of arterial bleeding in the limb distal to the Hemaclear ring during surgery, other than finding and cutting off the ring, and then using a pneumatic tourniquet.

6. Use of a Hemaclear elastic ring is impractical if there is a need for reperfusion of the limb during a long procedure that is typical of revision surgery.

7. Although the Hemaclear elastic ring has had very limited usage in the US to date, problems and hazards associated with this limited usage have already been reported to the FDA. For example: Report of Severe Pain and Report of Skin Tearing.

References (VIEW DETAILS)

[1] McEwen JA, Casey V. “Measurement of hazardous pressure levels and gradients produced on human limbs by non-pneumatic tourniquets.”  Proc 32nd Can Med Biol Eng Conf. 2009, pp 1-4.

[2] Noordin S, McEwen JA, Kragh JF Jr, Eisen A, Masri BA. “Current Concepts Review: Surgical Tourniquets in Orthopaedics.” J Bone Joint Surg Am. 2009; 91:2958-67.

[3] Smith OJ, Heasley R, Eastwood G, Royle SG. “Comparison of pain perceived when using pneumatic or silicone ring tourniquets for local anaesthetic procedures in the upper limb.” J Hand Surg Eur. 19 June 2012. DOI: 10.1177/1753193412449116

[4] FDA Report 1, FDA Report 2

[5] Report to FDA MedWatch on the Hemaclear elastic ring tourniquet, 2009

[6] McEwen JA. “Complications of and improvements in pneumatic tourniquets used in surgery.” Medical Instrumentation. 1981;14(4):253-7.

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Tourniquet Safety and Design: How can hazardously high tourniquet pressure gradients be minimized?

Posted on July 4, 2011. Filed under: Tourniquet Safety |

It is well established in the medical literature that the probability of tourniquet-related injuries increases as tourniquet pressure increases, and as the pressure gradients near the edges of tourniquet cuffs increase, eg [1-7]. Unnecessarily high tourniquet pressure gradients represent a serious and recognized hazard associated with unnecessarily high probabilities of patient injuries. Hazardously high pressure gradients can be minimized by the design of improved pneumatic tourniquet cuffs and by design of improved pneumatic tourniquet instruments.


Design improvements in some new tourniquet instruments and cuffs

Some tourniquet cuffs allow the automatic measurement of Limb Occlusion Pressure (LOP) [8].  It is well established in the medical literature that the optimal guideline for setting the pressure of a constant-pressure tourniquet is based on LOP [9].  LOP can be defined as the minimum pressure required, at a specific time in a specific tourniquet cuff applied to a specific patient’s limb at a specific location, to stop the flow of arterial blood into the limb distal to the cuff.   The use of LOP to set tourniquet pressure for individual patients is an important factor that allows tourniquet pressure gradients to be reduced, eg [10-14].

Tourniquet pressure gradients can also be reduced by improved design of tourniquet cuffs so that the pressure beneath the cuff decreases smoothly and gradually near the cuff edges and yet is sufficient near the center of the cuff to stop underlying arterial bloodflow at low tourniquet pressures.  Three key improvements in the design of some types of tourniquet cuffs have facilitated this:

(1) the advent of wider, low-pressure tourniquet cuffs, and especially variable-contour low-pressure tourniquet cuffs to match tapered limb shapes;

(2) the incorporation of new materials into certain new cuffs having cylindrical shapes and contour shapes, to reduce cuff thicknesses, to reduce pressure variations underlying the cuff circumferentially around the limb, and to achieve desired pressure gradients from proximal to distal cuff edges; and

(3) advances in the design of stiffeners overlying inflatable bladders in certain cylindrical and variable contour cuffs, improving their effectiveness in selectively  controlling bladder pressurization inwardly toward the encircled limb.

Examples of improved tourniquet cuff safety arising from improved tourniquet cuff designs and technologies are given in [15-22] below.


Tourniquet safety and pressure gradients

An excellent and comprehensive review of the published medical  literature on how and why high pressure gradients lead to tourniquet-induced nerve injuries, including electron micrographs of injured nerves, is given in included in reference [7] below (“Current concepts:  surgical tourniquets in orthopaedics”).  The three key conclusions in that review are:

(1) Higher levels of tourniquet pressure and higher pressure gradients beneath tourniquet cuffs are associated with a higher risk of nerve-related injury.

(2) Measurement of Limb Occlusion Pressure (LOP) can help to minimize tourniquet pressure levels and pressure gradients for individual patients and individual surgical procedures.

(3) Selective use of pneumatic, wider, and contoured tourniquet cuffs reduces tourniquet pressure levels and the applied pressure gradients.

The history and pathogenesis of tourniquet-related nerve injuries is well summarized in [7] as excerpted below:

“The risk of tourniquet-related nerve injury remains a particular concern.  In an early study, before the introduction of automatic tourniquet systems and before the routine use of lower tourniquet pressures, electromyographic evidence of peripheral nerve injury was found in a high percentage of limbs after tourniquet use. In prospective randomized studies conducted in the 1980s, when mechanical tourniquets and higher tourniquet pressures were in common use, there was evidence of denervation in 71% (seventeen) of twenty-four patients after lower-extremity tourniquet use and in 77% (twenty-four) of thirty-one patients after upper-extremity tourniquet use. The prevalence of electromyographic abnormalities was reported to increase with tourniquet time, and evidence of denervation typically lasted from two to six months. Electromyographic abnormalities correlated with impaired postoperative function and delayed recovery, suggesting that tourniquet-induced neuropathy played a causal role in impaired rehabilitation.

“On the basis of a questionnaire survey in Norway, the incidence of neurological complications associated with tourniquet use was estimated to be one per 6155 applications to the upper limb and one per 3752 applications to the lower limb. Other estimates have varied, and it has been suggested that the actual incidence of so-called tourniquet paresis may be underreported . Such nerve injuries range from a mild transient loss of function to permanent, irreversible damage and are a potential source of litigation. To minimize risk and potential litigation, an understanding of both the mechanism of injuries and possible preventive measures is important. Ochoa et al. showed that most cases of nerve damage were limited to the portion of the nerve beneath and near the edges of the cuff. They found that compressive neurapraxia rather than ischemic neuropathy or muscle damage was the underlying cause of tourniquet paralysis and demonstrated that compression of the large myelinated fibers involves a displacement of the node of Ranvier from its usual position under the Schwann-cell junction. This was accompanied by stretching of the paranodal myelin on one side of the node and invagination of the paranodal myelin on the other. The nodal axolemma was sometimes identified as far as 300 mm from its original position under the Schwann-cell junction, causing partial or complete rupture of the stretched paranodal myelin (Fig. 3). The nodal displacement was maximal under the edges of the cuff, wherethe applied pressure gradient was greatest. There was relative or complete sparing under the center of the cuff, and the direction of displacement was away from the cuff toward the uncompressed tissue.”

Some of the effects of tourniquet cuff design on tourniquet pressure gradients are also well summarized in reference [7] as excerpted below:

“The actual levels of pressure applied by a pneumatic tourniquet cuff to the underlying limb and soft tissues vary widely in comparison with the pneumatic inflation pressure within the tourniquet cuff. McLaren and Rorabeck measured the distribution of tissue pressures under pneumatic tourniquets in canine limbs. The peak pressure, which was 97% of the cuff inflation pressure, was in the subcutaneous tissue just proximal to the midposition along the tourniquet width. Tissue pressures decreased progressively as they became closer to the cuff edges, with a decrease of about 90% from the midpoint of the cuff width to the cuff edge. Pressures were lower in deeper tissues as well, but the decrease from the limb surface to the center was only about 2%. At the midpoint of the cuff width, surface tissue pressure was 95% of the cuff inflation pressure.

“Shaw and Murray also showed a decrease in tissue pressure with increasing depth, midway along the width of a cylindrical pneumatic tourniquet cuff on the lower extremities of human cadavers. They noted that the pressure measured in the soft tissue was consistently lower than the pneumatic pressure in the tourniquet cuff and that the level of tissue pressure varied inversely with the thigh circumference. All such studies suggest that higher tourniquet inflation pressures and higher applied pressure gradients on the limb surface correspond to higher pressures and higher pressure gradients in the underlying soft tissues. The distribution of perineural pressures under the cuff is described by a parabolic curve (Fig. 4), with peak levels at the midpoint of the cuff and much lower pressures at the proximal and distal edges. The difference between soft-tissue pressures at the cuff midpoint and those at the cuff edges increases at higher levels of cuff inflation, establishing a direct relationship between the level of the cuff inflation pressure and the pressure gradient in the underlying soft tissue.

“There is an inverse relationship between limb occlusion pressure and the ratio of the cuff width to the limb circumference. This relationship is shown in Figure 4, indicating that, for a given limb circumference, a narrower cuff requires a much higher tourniquet pressure to stop blood flow (higher limb occlusion pressure). This is associated with higher applied pressure gradients and a greater risk of neurological injury. Conversely, for the same limb circumference, a wider cuff requires a lower tourniquet pressure to stop blood flow. Additionally, a contoured tourniquet cuff occludes blood flow at a lower inflation pressure than does a straight (cylindrical) cuff of equivalent width24,25. This may be attributable to a better fit of the cuff to the limb and thus more efficient transmission of pressure to the underlying tissue. These facts have motivated the development and increasing use of wider, variable-contour cuffs that conform to a wide range of limb shapes, stopping blood flow at pressures that are lower than are necessary with narrower, cylindrical cuffs.”


Ratio of Cuff Width to Circumference Chart

(Excerpted From [7]) Fig. 4   Limb occlusion pressure (LOP) versus the ratio of tourniquet cuff width to limb circumference. For any given limb circumference, the tourniquet pressure required to stop arterial blood flow decreases inversely as the width of the tourniquet cuff increases. (Reproduced, with modification, from: Graham B, Breault MJ, McEwen JA, McGraw RW. Occlusion of arterial flow in the extremities at subsystolic pressures through the use of wide tourniquet cuffs. Clin Orthop Relat Res. 1993;286:257-61.)

A comparison of applied pressures and pressure gradients

(Excerpted From [7])   Fig 5.  A comparison of applied pressures and pressure gradients typically produced by a modern pneumatic surgical tourniquet cuff (A); a nonpneumatic,non-elastic, belt-type military tourniquet designed for self-application on the battlefield (B); and a non-pneumatic ring made of elastic material, designed to be rolled from a distal location to a proximal location on a limb and to remain there for surgery, thereby combining exsanguination and tourniquet functions (C). Each tourniquet was selected and applied as recommended by the respective manufacturer to stop arterial blood flow in an upper limb. Higher levels of pressure and higher pressure gradients are associated with higher probabilities of patient injuries6.

References and Citations

1.   Ochoa J, et al. “Anatomical changes in peripheral nerves compressed by a pneumatic tourniquet”. Journal of Anatomy. 113 (1972): 433-455.

2.   Ochoa J, et al. “Nature of the nerve lesion caused by a pneumatic tourniquet”. Nature. 233 (1971): 265-266.

3.   Gilliatt R and Ochoa J. The cause of nerve damage in acute compression. Trans Am Neurol Ass 1974: 99: 71-4.

4.   Shaw J and Murray D. The relationship between tourniquet pressure and underlying soft tissue pressure in the thigh. J Bone Joint Surg 1982: 64A(8):1148-52.

5.   Graham B et al. Perineural pressures under the pneumatic tourniquet in the upper and lower extremity. J Hand Surg 1992: 17B: 262-6.

6.   Crenshaw AG et al. Wide tourniquet cuffs more effective at lower inflation pressures. Acta Orthopaedica 1988,59:4,447-451.

7.  Noordin et al. “Surgical Tourniquets in Orthopaedics” Journal of Bone and Joint Surgery, 91 (2009): 2958-2967. http://www.jbjs.org/

8.  McEwen JA et al. “Surgical tourniquet apparatus for measuring limb occlusion pressure.” US Pat No. 7,479,154, Jan 2009. http://patft.uspto.gov/

9.  www.tourniquets.org/lop.php – McEwen JA, Educational website focused on surgical tourniquets, and related tourniquets for military and emergency applications, including tourniquet safety and usage.

10.     McEwen JA. “Complications of and improvements in pneumatic tourniquets used in surgery.” Medical Instrumentation, 15(4) (1981): 253-7.

11.  Younger, SE et al. “Automated Cuff Occlusion Pressure Effect on Quality of Operative Fields in Foot and Ankle Surgery: A Randomized Prospective Study.” Foot and Ankle international, 32(3)(2011): 239-243.

12.  Reilly et al. “Minimizing Tourniquet Pressure in Pediatric Anterior Cruciate Ligament Reconstructive Surgery. A Blinded, Prospective Randomized Controlled Trial.” Journal of Pediatric Orthopaedics, 29 (2009): 275-280.

13.  Younger A et al. “Wide contoured thigh cuffs and automated limb occlusion measurement allow lower tourniquet pressures.” Clinical Orthopaedics and Related Research, 428 (2004): 286-93.

14.  Tredwell SJ, Wilmink M, Inkpen K, McEwen JA. “Pediatric tourniquets: Analysis of cuff/limb interface and guidelines for use.” Journal of Pediatric Orthopaedics, 21(5) (2001): 671-6.

15.  McEwen JA, Auchinleck GF. “Advances in surgical tourniquets.” AORN Journal, 36(5) (1982): 889-96.

16. McEwen JA, Kelly DL, Jardanowski T, Inkpen K. “Tourniquet safety in lower leg applications.” Orthopaedic Nursing, 21(5) (2002): 55-62.

17.  McEwen JA, Inkpen K. “Tourniquet safety: Preventing skin injuries.” The Surgical Technologist, 24(8) (2002): 6-15.

18.  McEwen JA, Inkpen K, Younger A.”Thigh tourniquet safety.” The Surgical Technologist, 24(7) (2002): 9-18.

19. McEwen JA et al. “Adaptive tourniquet cuff system.” US Pat No. 7,331,977, Feb 2008. http://patft.uspto.gov/

20. McEwen JA. “Occlusive cuff.” US Pat No. 5,312,431, May 1994. http://patft.uspto.gov/

21. McEwen JA et al. “Low-cost contour cuff for surgical tourniquet systems.” US Pat App No. 20100268267, Oct 2010. http://patft.uspto.gov/

22. McEwen JA et al. “Low-cost disposable tourniquet cuff.” US Pat App No. 20100004676, Jan 2010. http://patft.uspto.gov/


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Tourniquet Safety: Which tourniquet cuffs can be reused safely, and how?

Posted on June 24, 2011. Filed under: Disposable Cuffs, Reprocessing, Reusable Cuffs, Tourniquet Safety |

Some tourniquet cuffs are designed and manufactured to be reusable in multiple surgeries and their reuse is authorized by the manufacturer. Limited guidance on cleaning, reprocessing, testing and evaluation of reusable cuffs may be provided by the manufacturer, but there is a general need for improvement and more guidance for users.

Other types of tourniquet cuffs are designed manufactured to be safely used as single-use, sterile disposable tourniquet cuffs, and their reprocessing and reuse is not authorized by the manufacturer.

Some general recommendations about tourniquet cuff safety are given in the AORN Recommended Practices for Use of the Pneumatic Tourniquet. [1] Published literature provides still further guidance, eg [2-9].

The current (2009) AORN Recommended Practices (RPs) are in need of updating regarding tourniquet cuff safety, tourniquet cuff reuse and tourniquet cuff reprocessing. For example:

1. For single-use disposable tourniquet cuffs, the RPs do not indicate the hazards to the patient that may be associated with unauthorized reprocessing and inadequate testing of disposable cuffs after reprocessing and prior to any reuse.

2. For reusable tourniquet cuffs, the RPs do not provide recommendations on what type of testing of reusable cuffs should be performed after cleaning and before reuse.

3. For both reusable and single-use disposable tourniquet cuffs, the RPs do not recommend how the results of cuff testing and inspection should be documented and evaluated after cleaning and before any reuse.

4. In current RPs such as those excerpted below, it is not clear which recommendations are meant to include tourniquet cuffs as well as tourniquet instruments.

Relevant excerpts from the current (2009) AORN RPs are given below:

Recommended Practice II: The pneumatic tourniquet and its accessories should be inspected, tested and maintained according to manufacturers’ written instructions.

6. Before each use, the entire tourniquet system should be checked. The cuff and tubing should be inspected for cracks, leaks, and the security of the closure mechanism. Unintentional pressure loss can result from loose tubing connectors, deteriorated tubing, or cuff bladder leaks, and may result in patient injury.

Recommended Practice XIV: The pneumatic tourniquet and accessories should be cleaned after each use.

4. Single-use cuffs should be discarded in an appropriate receptacle.

Recommended Practice XVII: Policies and procedures for pneumatic tourniquets should be developed, reviewed periodically, revised as necessary, and readily available in the practice setting.

1. Policies and procedures for the pneumatic tourniquet should include, but are not limited to:
– safety features required on pneumatic tourniquets;
– equipment maintenance programs; supplemental safety monitors required;
– equipment checks before initial use;
– reporting and impounding malfunctioning equipment;
– preoperative, intraoperative, and postoperative patient assessments;
– responsibility for cuff application;
– precautions during use;
– reporting of injuries;
– potential adverse events;
– care and cleaning of the tourniquet after use; and
– documentation.

2. The frequency, method, and criteria for pneumatic tourniquet testing should be established according to manufacturers’ written instructions. A pneumatic tourniquet management program assists in identifying equipment problems that may have adverse effects on patient safety.


Recommendations Regarding Future Guidelines

The following recommendations for guidelines, based on published literature (eg [2-9]) and manufacturers’ recommendations as available, as well as the current AORN RPs [1], would better reflect current practices and would improve tourniquet cuff safety and effectiveness.


1. For patient safety and for facility risk management purposes, establishment of a tourniquet cuff testing program is recommended, 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. (Some modern tourniquet instruments allow this to be done automatically.[10])

2. For each reusable tourniquet cuff, it is recommended that the cuff have a unique identifier, that the number of reuse cycles be recorded, and that the cuff be thoroughly tested on a regular basis by qualified personnel, with results documented and evaluated.

3. For reusable cuffs used in certain procedures, eg IVRA or Bier block anesthesia, it is further recommended that consideration be given to replacing the cuff after a maximum number of reuse cycles is reached, to reduce the risk of cuff failure and patient injuries during use.

4. It is recommended that the tourniquet cuff testing protocol be established in accordance with the recommendations of the original manufacturer of the cuff. At a minimum, a 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; discolouration 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.


Rationale

Results of hospital-based inspections and testing of reusable (not disposable) tourniquet cuffs, identifying patient hazards and risks, have been published in the AORN Journal and elsewhere, eg [2-9].

Reusable tourniquet cuffs that are specifically intended by their manufacturers to be used in multiple surgeries generally are accompanied by some instructions on how to inspect, clean and test such cuffs between uses. Often, the instructions are limited and no information is provided on cuff testing programs, on cuff testing protocols and on the documentation and evaluation of cuff testing results.

Disposable tourniquet cuffs are generally supplied as sterile, single-use products by manufacturers. Some facilities and individuals reuse disposable cuffs. However, there are no established guidelines at present to assure patient safety during reuse.

Hazards and risks are associated with unauthorized reprocessing and inadequate testing of reprocessed disposable cuffs. [11] Reprocessing efforts typically involve saving rather than discarding a disposable tourniquet cuff after surgery, visually examining the cuff to identify any obvious deterioration that might suggest reprocessing is not appropriate, attempting to remove any blood and other surgical debris by washing the cuffs with water combined with any of a variety of detergents or other cleaning liquids, disinfecting in some instances with various disinfecting agents, and in some cases conducting functional tests of the cuff, often using non-standard protocols and results that are neither documented nor evaluated relative to established criteria.

Some of these disposable cuffs may be reused as non-sterile cuffs after only cleaning, or after only cleaning and disinfection, with no functional testing and with no attempt to re-sterilize the cuff. In other situations, cleaned cuffs may be re-packaged and then re-sterilized by exposure to a sterilization agent within a sterilization process that may be different from that determined by the original manufacturer to be safe and effective. Reprocessing of disposable tourniquet cuffs, with or without re-sterilization, may be carried out within hospitals or surgery centers or by third-party reprocessors, and the quality and methods of reprocessing are highly variable.

Reprocessing of disposable tourniquet cuffs may result in hazards for the surgical patients on whom such cuffs are subsequently used. One such hazard arises from deterioration of cuff materials due to the use of any of a variety of chemical or physical agents that are attendant with the reprocessing, cleaning, disinfection and possible re-sterilizing processes. For example, exposure of a cuff to liquids during cleaning and disinfection may allow the liquids to enter and partially or completely block the pneumatic passageway within the port and inflatable portion of the cuff. If the cuff is re-sterilized as part of the reprocessing, any water remaining within the pneumatic passageway after cleaning may subsequently react chemically with ethylene oxide, a sterilizing agent commonly used in reprocessing, to form ethylene glycol, a sticky substance that may completely or partially block the pneumatic passageway.

Repeated exposure of cuffs containing flexible thermoplastic materials to an elevated temperature during drying after cleaning or disinfection with liquids, or during re-sterilization, may soften thermoplastic materials and components, increasing the likelihood of hazardous deformation of some components, including: substantial deformation of the thermoplastic stiffener included in some cuffs that may impair the application of pressure by such a cuff to an underlying limb upon subsequent use in surgery; partial or complete blockages of the pneumatic passageways within ports or thermoplastic connectors of some cuffs; and weakening of the retention force of typical thermoplastic barb-type port connectors so that such connectors cannot establish or reliably maintain a gas-tight passageway between the tourniquet cuff and tourniquet instrument upon reuse. In general, repeated reuse of a disposable tourniquet cuff beyond the limit of usage specified by the manufacturer, including exposure to cleaning and disinfection agents and processes not anticipated by the manufacturer if reused as non-sterile cuffs, and including exposure to re-sterilization agents and processes if reused as sterile cuffs, may progressively increase the hazards for the surgical patients on whom the cuff is used.


References and Citations

1. http://www.aorn.org/PracticeResources/AORNStandardsAndRecommendedPractices/EDocuments/ AORN, Recommended Practices for the Use of the Pneumatic Tourniquet, 2009.

2. www.tourniquets.org – McEwen JA, Educational website focused on surgical tourniquets, and related tourniquets for military and emergency applications, including tourniquet safety and usage.

3. McEwen JA, Auchinleck GF. “Advances in surgical tourniquets.” AORN Journal, 36(5) (1982): 889-96.

4. McEwen JA, Kelly DL, Jardanowski T, Inkpen K. “Tourniquet safety in lower leg applications.” Orthopaedic Nursing, 21(5) (2002): 55-62.

5. McEwen JA, Inkpen K. “Tourniquet safety: Preventing skin injuries.” The Surgical Technologist, 24(8) (2002): 6-15.

6. McEwen JA, Inkpen K, Younger A.”Thigh tourniquet safety.” The Surgical Technologist, 24(7) (2002): 9-18.

7. Tredwell SJ, Wilmink M, Inkpen K, McEwen JA. “Pediatric tourniquets: Analysis of cuff/limb interface and guidelines for use.” Journal of Pediatric Orthopaedics, 21(5) (2001): 671-6.

8. McEwen JA. “Complications of and improvements in pneumatic tourniquets used in surgery.” Medical Instrumentation, 15(4) (1981): 253-7.

9. Noordin et al. “Surgical Tourniquets in Orthopaedics” Journal of Bone and Joint Surgery, 91 (2009): 2958-2967. http://www.jbjs.org/

10. McEwen JA et al, “Integrated tourniquet system.” US Pat. App. No. 20100211096, Aug 2010. http://patft.uspto.gov/

11. McEwen JA and Jameson M. “Surgical tourniquet cuff for limiting usage to improve safety.” US Pat No. 7,955,352, June 2011. http://patft.uspto.gov/


 

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Tourniquet Safety and Intravenous Regional Anesthesia (IVRA, also called Bier Block Anesthesia): What’s New and Why?

Posted on June 21, 2011. Filed under: Bier Block Anesthesia, IVRA, Tourniquet Safety |

Many tourniquet systems are used for intravenous regional anesthesia (IVRA), also known as Bier block anesthesia.   IVRA is a tourniquet-related alternative to general anesthesia for limb surgery that is inexpensive and widely used with adult and pediatric patients, with the frequency varying by type of surgery and patterns of practice [1].

In IVRA, blood is first exsanguinated from the limb, usually by wrapping it with an elastic bandage, beginning distally and squeezing and wrapping toward the heart.  A dual-bladder tourniquet cuff is then applied proximal to the operative site and pressurized.  The elastic bandage is removed and a local anesthetic agent is injected into the limb through an intravenous cannula.  The local anesthetic remains in the limb as long as the tourniquet is inflated.  About 20 minutes after infusion, most of the anesthetic agent has been absorbed into the limb tissues and deflation of the tourniquet will not result in systemic release of the agent in high concentration.  IVRA may be performed by anaesthesiologists, anesthetists, nurse-anesthetists, surgeons, or occasionally others.

Surgical tourniquet systems, including tourniquet cuffs and instruments, play a vital role in the safety and success of IVRA.  [2]   Safe and successful IVRA typically requires the use of tourniquet instruments and cuff having advanced capabilities, including: two independent pneumatic channels, additional IVRA hazard suppression features, and special-purpose dual-bladder tourniquet cuffs (although special single-channel cuffs may occasionally be used).  [3-4]   Thorough testing of tourniquet instruments and cuffs prior to use, with results documented and checked, is also necessary to prevent hazards. [5-6]

IVRA has proven to be very simple, safe and effective over many years and large numbers of patients, when performed properly according to established protocols with safe, accurate and reliable tourniquet instruments and cuffs that have been thoroughly tested prior to use.  [3-6] However, IVRA is not without risk.  [1-2]  Risks may be associated with inherent safety limitations of tourniquet instruments and tourniquet cuffs not specifically designed for IVRA, with failures of tourniquet instruments and cuffs during use, and with incomplete testing of instruments and cuffs prior to use.  Those risks increase with non-standard protocols and with staff having limited training and experience with IVRA. [1]   Some reports of IVRA-related injuries, hazards and their causes are given in the reference and citations below [1-7].

In the past, injuries associated with IVRA have been reported, eg [1].  The deaths involved a combination of an agent no longer recommended for IVRA, failure of tourniquet instruments and cuffs and human error.    Hazards associated with IVRA can include failure to establish limb anesthesia, complete or partial loss of limb anesthesia, the sudden release of a bolus of anesthetic agent into systemic circulation, venous congestion and the loss of a clear surgical field.

Safe IVRA requires the use of advanced tourniquet systems, including both tourniquet cuffs and instruments, which are reliable, accurate, safe and effective [3, 4, 6].  Some notable and unique improvements which have added considerable value and safety to modern tourniquet instruments and cuffs for IVRA include:

Tourniquet instruments having two completely independent channels for independent, accurate and reliable control of the tourniquet pressure in each bladder of a tourniquet cuff used for IVRA.  This is especially important when individual bladders are being selectively depressurized, pressurized and regulated during IVRA.

Variable-contour dual-bladder tourniquet cuffs, in which the cuff shape matches patient-specific limb shapes from proximal edge to distal edge beneath each of the dual bladders, improving the uniform and reliable application of tourniquet pressure from each bladder to the underlying limb.  Such cuffs include additional features to improve safety in IVRA, such as dual independent fasteners to help prevent sudden cuff detachment and release, positive locking connectors and improved gas passageways within the cuffs.

Automatic measurement of Limb Occlusion Pressure (LOP) embedded in some tourniquet instruments, so that patient-specific tourniquet pressures can be accurately determined or checked (for each bladder of a dual-bladder cuff), for each surgical procedure, limb location, limb shape, and technique of cuff application.

IVRA safety lockout embedded in some tourniquet instruments, to help prevent staff from inadvertently and unintentionally deflating both bladders of a dual-bladder cuff during a procedure, thereby helping prevent the hazard of a sudden and unanticipated loss of IVRA.

Automatic cuff testing capability embedded in some tourniquet instruments, to allow staff to quickly, automatically and thoroughly test tourniquet cuffs, according to recommended practices, prior to use in IVRA and especially after any cleaning or reprocessing. [8]

Automatic cuff leak detection embedded in some tourniquet instruments, to detect leaking cuffs, connectors and tubing during use and to identify them to users after each procedure, thereby helping to prevent their hazardous use in subsequent IVRA procedures.

 

Further Reading

Advanced safety lockout mechanisms for IVRA tourniquets.

References and Citations

[1]  Henderson CL, Warriner CB, McEwen JA, Merrick PM. “A North American survey of intravenous regional anesthesia.” Anesthesia and Analgesia, 85 (1997): 858-63.

[2]  ECRI, Pneumatic Tourniquets Used for Regional Anesthesia: Hazard. Health Devices Dec 1982;12(2):48-9  www.mdsr.ecri.org/summary/detail.aspx?doc_id=8080

[3]  Noordin et al. “Surgical Tourniquets in Orthopaedics” Journal of Bone and Joint Surgery, 91 (2009): 2958-2967.

[4]  www.tourniquets.org – McEwen JA, Educational website focused on surgical tourniquets, and related tourniquets for military and emergency applications, including tourniquet safety and usage.

[5]  McEwen JA, Auchinleck GF. “Advances in surgical tourniquets.” AORN Journal, 36(5) (1982): 889-96.

[6]  McEwen JA. “Complications of and improvements in pneumatic tourniquets used in surgery.” Medical Instrumentation, 15(4) (1981): 253-7.

[7]  http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/search.cfm – MAUDE – Manufacturer and User Facility Device Experience, US Food and Drug Administration

[8]  http://www.aorn.org/PracticeResources/AORNStandardsAndRecommendedPractices/EDocuments/  AORN, Recommended Practices for the Use of the Pneumatic Tourniquet, 2009.

 

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