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Current concepts in tourniquet uses
BASIC SKILLS
Current concepts in tourniquet uses
operative blood loss. Tourniquets can, however, lead to permanent patient morbidity when used inappropriately.
Applications Tourniquets are most frequently placed on the upper arm or thigh, therefore lending themselves to a broad spectrum of elective and emergency surgery of the upper and lower limbs. They can also be utilized for intravenous anaesthesia (Biers block) and in isolated limb infiltration of toxic agents in the management of localized malignancy. Nowadays, tourniquets are electronically controlled pneumatic devices with accurate pressure control, timing and incorporated user alarms in an attempt to improve their safety. The production of more simplistic elasticated devices has also enabled the application of tourniquets to individual fingers or toes.
Tristan E McMillan Timothy Gardner Alan J Johnstone
Abstract Tourniquets have been around for many years, providing surgeons with a bloodless operative field and saving lives in the pre-hospital care of major limb trauma. However, their use does come with risk. It is therefore extremely important that we, as surgeons, fully understand the physiological influence they impose on patients, the complications associated with their use and, moreover, how to minimize the incidence of these complications. Most tourniquets are now electronically controlled pneumatic devices with built-in pressure sensors and timers. Classically, inflation to 250 mmHg in the upper limb and 300 mmHg in the lower limb is used, but a move towards patientspecific limb occlusion pressures is suggested, although it is more difficult due to the requirement of more time-consuming set-up. Complications from tourniquets can occur, such as nerve injury, pain, venous thromboembolism or even cardiac overload and reperfusion injury. Limiting use to key parts of an operation or using alternatives such as adrenaline infiltration and tranexamic acid can be of benefit. As such, any use of a tourniquet during an operation must be treated with caution and be deployed taking into account the specific characteristics of that particular patient.
Contraindications There are no absolute contraindications to tourniquet use; however, there are number of relative contraindications that surgical teams should be aware of. Tourniquet use within these patient groups should be selective, upon a patient and procedural specific basis. Relative contraindications to tourniquet Peripheral vascular disease. A limb with an arteriovenous fistula or previous vascular surgery. Sickle cell disease. Severe limb infections. Reamed intra-medullary nailing. Previous thromboembolic event. Patients with severe peripheral vascular disease have decreased vessel wall compliance and already compromised tissue perfusion, making tourniquets less effective and also predisposing to further ischaemic damage. Additionally, they are predisposed to thromboembolic events post tourniquet use. Tourniquets cause haemostasis, acidity and hypoxia in limb tissues. These conditions are thought to be the mechanism to provoke sickling of red blood cells in individuals carrying the sickle cell gene. The use of tourniquets in patients with sickle cell disease is debated within the literature, with no absolute contraindication. In general, they should be avoided where possible, and in those cases where they are necessary appropriate measures should be taken to minimize risk, including adequate hydration, optimal exsanguinations (with consideration of elevation only) and minimizing inflation time. The use of tourniquets during reaming of an intra-medullary canal prior to insertion of an intra-medullary nail is contraindicated due to the risk of thermal necrosis.2 It may also predispose patients to an ‘embolic hit’ with tourniquet deflation post-reaming.
Keywords Complications; limb surgery; orthopaedics; tourniquets; trauma
Introduction The term tourniquet describes an instrument or device used to stop or reduce venous and arterial blood flow to an extremity. The known history of tourniquets goes back to the Middle Ages, when Morel first used a tourniquet on the battlefield at Flanders in 1674.1 Since then tourniquets have been broadly utilized within pre-hospital management of injured patients and during surgery. The prospect of a bloodless field within surgery has led to the diverse application of tourniquets and their evolution. To a surgeon, this can greatly improve the operate field permitting better visualization of anatomical structures and can limit intra-
Tristan E McMillan MBChB MRCS is an ST7 in Trauma and Orthopaedics at Aberdeen Royal Infirmary, NHS Grampian, UK. Conflicts of interest: none declared.
Cuff selection and preparation
Timothy Gardner MBChB MSc MRCS is an ST2 in Trauma and Orthopaedics at Aberdeen Royal Infirmary, NHS Grampian, UK. Conflicts of interest: none declared.
A broad range of pneumatic machines and tourniquet cuffs are available in today’s market. Choice of cuff is largely dictated by those available to a surgeon within their hospital. The surgical team should consider the region of application and the patient size when choosing cuff width and length. Generally, the cuff
Alan J Johnstone MBChB FRCS (Tr & Orth) is Professor of Trauma and Orthopaedics at Aberdeen Royal Infirmary, NHS Grampian, UK. Conflicts of interest: none declared.
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1
Ó 2020 Published by Elsevier Ltd.
Please cite this article as: McMillan TE et al., Current concepts in tourniquet uses, Surgery, https://doi.org/10.1016/j.mpsur.2020.01.005
BASIC SKILLS
recommend a safety margin of 40 mmHg for LOPs <130 mmHg, 60 mmHg for those 131e190 mmHg, 80 mmHg for those >190 mmHg and 50 mmHg in paediatric patients.7 For example, a tourniquet pressure of 140 mmHg should be selected for a patient with a measured LOP of 100 mmHg. The main limitation of this technique is the requirement for Doppler ultrasound measurement, which is time consuming and can be unreliable in people with vascular disease, with cool, poorly perfused peripheries. Additionally, maintaining sterility during procedures while simultaneously doing Doppler measurements adds another layer of challenge. There has been work done to develop alternative methods of measuring LOP, using dedicated tourniquets with built in sensors. A randomized crossover multicentre trial of 143 patients found that there were no statistically significant differences between this new technique and Doppler ultrasound, which is the current gold-standard method of measuring LOP.
should overlap by a minimum of six inches and be at least half as wide as the limb. Wider cuffs offer better distribution of pressure, reducing the risk of underlying soft tissue, muscle and nerve injury. Additionally, for any given limb circumference, the tourniquet pressure required to stop arterial blood flow decreases inversely as the width of the tourniquet cuff increases. Interestingly, when the cuff width is around half of the limb circumference, occlusion pressure has been shown to be within the subsystolic blood pressure range, and if the cuff width is equal to limb circumference, occlusion pressure is around diastolic blood pressure.3 Contoured cuffs further reduce the required limb occlusion pressure (LOP). Upon application of the cuff, a protective layer should be applied to minimize skin wrinkling and trauma. A barrier should also be applied to prevent surgical cleaning solution soaking beneath the tourniquet, leading to skin burns. Within our unit we use a double layer of under-cast padding and a circumferential layer of adhesive op tape. Prior to tourniquet inflation, appropriate limb exsanguination is required. This can be achieved using a number of devices such as an Esmarch bandage or a Rhys-Davies exsanguinator, or by simply elevating the limb. While mechanical devices are generally felt to achieve optimal exsanguination they can lead to dissemination of tumour, infection and emboli, and some of the devices can cause soft tissue trauma, particularly in those patients with thin or friable skin. Limb elevation can generally avoid the risks associated with mechanical exsanguination and may potentially reduce the non-operative tourniquet application time. The limb angle at elevation and period of elevation continues to be debated. Warren et al. recommend elevation of the limb at 90 degrees for a period of 2 minutes.4 Contrary to this, Blond and Madsen showed no benefit in vertically elevating the upper limb for greater than 5 seconds and the lower limb for greater than 30 seconds.5 An incorrectly applied or inflated tourniquet can cause complete venous occlusion and incomplete arterial occlusion, leading to venous congestion within the extremity, which most commonly manifests as pain.
Physiological implications Tourniquet use causes local changes mainly due to ischaemia or direct mechanical pressure. These local changes, particularly if prolonged, can go on to cause systemic upset, most notably upon tourniquet deflation and subsequent reperfusion. As a result of ischaemia and with the switch to anaerobic respiration, creatine phosphate, adenosine triphosphate and glycogen reserves become depleted and concentrations of lactic acid and carbon dioxide increase. Research within our unit has shown a linear pattern of pH decline following tourniquet inflation, with a significant change in muscle pH after just 5 minutes of muscle tourniquet ischaemia. After 50 minutes of tourniquet time in total knee arthroplasty muscle, pH can drop below 6.4. This degree of acidity has been associated with cellular injury. Furthermore, it took 20e30 minutes for pH to return to baseline after tourniquet deflation. With exsanguination and inflation there is an increase in circulating volume of up to 15% that may lead to a transient increase in central venous pressure (CVP). Upon its deflation there can be a reciprocal drop in CVP. Tourniquet deflation is also associated with a transient increase in end-tidal CO2 tension, an increase in cerebral blood flow and intracranial pressure and a decrease in core temperature. The insult associated with reperfusion may be reduced through ischaemic pre-conditioning attenuating the oxidative stress response following reperfusion.8 This is performed by three cycles of 5 minutes of ischaemia and 5 minutes of reperfusion prior to final inflation of the tourniquet. The effects have been measured with tourniquet times up to 87 minutes. This is quite a timeconsuming method that may prove difficult to incorporate into a busy surgical schedule, furthermore, the long-term effects and clinical benefits of this technique are not yet fully understood.
Cuff pressures Classically, surgeons tend to use 250 mmHg for upper limb surgery and 300 mmHg for lower limb surgery. An alternative pressure is based on the patient’s systolic pressure, aiming for a cuff pressure of 100 mmHg above this. There is great controversy within the literature as to ideal pressures that minimize tourniquet complications while maintaining cuff efficacy. In 2016, Sarfani et al. found there to be no noticeable difference to the surgeon during carpal tunnel release surgery using tourniquet pressures ranging from 125 to 250 mmHg.6 Although not a new concept, the use of limb occlusion pressures (LOP) has evolved within the last decade and is now recommended by the Association of peri-Operative Registered Nurses (AORN). LOP is the minimum pressure required to stop arterial blood flow into the limb distal to the cuff. It can be established using arterial Doppler while gradually increasing cuff pressure. This is a patient-specific measurement and takes into consideration the patient’s blood pressure, limb circumference and shape, tissue characteristics, cuff design and application. AORN
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When to deflate Tourniquet time should always be minimized where possible as tourniquet-related complications are directly related to increased tourniquet time and increased tourniquet pressure. Within the literature there is considerable inconsistencies as to a ‘safe’ tourniquet time. Most authors, on the basis of animal and human studies, tend to advise a maximum tourniquet time of 2 hours, and if longer than this a deflation interval should be utilized.
2
Ó 2020 Published by Elsevier Ltd.
Please cite this article as: McMillan TE et al., Current concepts in tourniquet uses, Surgery, https://doi.org/10.1016/j.mpsur.2020.01.005
BASIC SKILLS
Various drugs can help reduce blood loss during surgery. Tranexamic acid has been shown to decrease the overall blood loss in knee arthroplasty, and can be given in a variety of regimens, with single or multiple doses intravenously in additional to topical preparation if required.19 Tranexamic acid has been used successfully both with and without tourniquets. Local anaesthetic agents containing adrenaline have shown promising results when used in hand surgery. In carpal tunnel surgery, it is the favoured option for patients compared with using tourniquets as there is less reported pain, although the operation time is slightly longer.20 The age-old concerns of digital necrosis with the use of peripheral local anaesthetics containing adrenaline has been questioned, especially when they are used in otherwise healthy patients who have no risk factors for peripheral vascular disease. In this patient group, using local anaesthetics containing adrenaline is now accepted.
These intervals allow limb reperfusion and correction of metabolic abnormalities, with hourly release of the tourniquet for 10 minutes ensuring maintenance of adenosine triphosphate and rapid metabolic recovery.9 The timing of final deflation is generally pre- or post-wound closure. The senior author, within his upper limb practice, prefers final deflation prior to wound closure as this decreases overall tourniquet time and facilitates meticulous haemostasis with diathermy. In lower limb surgery, specifically total knee arthroplasty, time to release is controversial. The worry with early release of a tourniquet is excessive blood loss and increased symptomatic anaemia requiring transfusion; however, this is often weighed up against the decreased overall risk of complications by releasing the tourniquet prior to wound closure.10,11 Indeed, some work has been done on having the tourniquet inflated only during implantation where a bloodless field is considered crucial, or not using a tourniquet at all.12,13
Conclusion Complications
As our understanding of the physiological effects of tourniquets improves and tourniquet devices continue to evolve, so too does their safety. More importantly, surgeons are continuing to question the traditional teaching that includes the use of set upper and lower limb pressures, blanket use for upper and lower limb procedures, and deflation post dressing application, etc. A particular area where tourniquet use is continuing to be modified and questioned is in total knee arthroplasty, with some surgeons now opting against tourniquet use altogether. A surgeon’s decision to use a tourniquet must, above all else, be patient specific. Complications and detrimental effects can hopefully be avoided through careful cuff choice and application, exsanguination and pressure selection. Tourniquet inflation time should be minimized, and where not possible a suitable reperfusion regimen should be utilized during the procedure. A
Nerve injuries are the most common complication associated with tourniquet use. This can result in varying degrees of functional impairment that is most commonly temporary with full functional recovery in most cases. The reported incidence of upper limb paralysis is 1:11,000 and lower limb paralysis is 1:250,000.14 Nerve injuries are attributed to both ischaemia and direct compression causing microvascular congestion, inadequate perfusion and subsequent axonal degeneration. Additionally, direct mechanical compression can lead to skin, vascular and muscle injury beneath the cuff. Intraoperatively, the anaesthetist may report signs suggestive of tourniquet pain with increasing heart rate and blood pressure. Patients may also report pain and bruising postoperatively, localized to the tourniquet site. Muscle damage can also occur, Arciero et al. showed increased quadriceps and hamstring atrophy 1-month postsurgery in patients who had undergone anterior cruciate ligament reconstruction with a tourniquet.15 In addition, it has been shown that postoperative wound complications are associated more with higher pressures of tourniquet inflation rather than when the LOP method is used.16 Systemic complications include coagulopathy, cardiac overload upon inflation and myocardial depression upon deflation, dangerous increase in intracranial pressure and ischaemiareperfusion injury. Venous thromboembolism is also listed within the literature as a potential complication of tourniquet use; however, the direct correlation remains argued.
Practice Points C
C
Alternatives/adjuncts during surgery Tourniquets convey many advantages to the surgeon; this does, however, come at a cost of potential complications. As such, many strategies have been developed to minimize the risk as much as possible. Silicon ring tourniquets rather than conventional pneumatic tourniquets have been shown to have comparable blood loss and lower skin complication rates in knee arthroplasty,17 and equally comparable results in carpal tunnel surgery,18 but their downfall is often increased cost. Other theoretical advantages include better exsanguination and being able to place the ring further proximally, although these are yet to be proven.
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C
C
3
Tourniquets are frequently useful to the surgeons, both in the immediate management of critical haemorrhage from trauma and also during limb surgery where anatomical complexity exists. Tourniquet use should be patient specific. The appropriate cuff size should be used, and inflation pressure should, where possible, be specific to the patient. Limb occlusion pressure (LOP) can be calculated as the minimum pressure to occlude arterial blood flow. With an additional safety margin on top of this, LOP can result in much lower pressures being used, therefore limiting the risk of iatrogenic injury, especially nerve injury. Timing of release of a tourniquet is controversial, and needs to be carefully considered. Inflating the tourniquet at specific points during an operation, or indeed not using one at all, must be weighed up against the risks of bleeding and postoperative anaemia. Adjuncts and alternatives to tourniquet use are encouraged. Common ones include the use of adrenaline infiltration and tranexamic acid administration in both trauma and elective orthopaedic operations.
Ó 2020 Published by Elsevier Ltd.
Please cite this article as: McMillan TE et al., Current concepts in tourniquet uses, Surgery, https://doi.org/10.1016/j.mpsur.2020.01.005
BASIC SKILLS
REFERENCES 1 Welling D, McKay P, Rasmussen T, Rich N. A brief history of the tourniquet. J Vasc Surg 2012; 55: 286e90. 2 Leunig M, Hertel R. Thermal necrosis after tibial reaming for intramedullary nail fixation. A report of three cases. J Bone Jt Surg Br 1996; 78: 584e7. https://doi.org/10.1302/0301-620X.78B4. 0780584. 3 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: 257e61. 4 Warren PJ, Hardiman PJ, Woolf VJ. Limb exsanguination. I. The arm: effect of angle of elevation and arterial compression. Ann R Coll Surg Engl 1992; 74: 320e2. 5 Blond L, Madsen JL. Exsanguination of the upper limb in healthy young volunteers. J Bone Joint Surg Br 2002; 84-B: 489e91. 6 Sarfani S, Cantwell S, Shin AY, Kakar S. Challenging the dogma of tourniquet pressure requirements for upper extremity surgery. J Wrist Surg 2016; 5: 120e3. 7 AORN. Recommended practices for use of the pneumatic tourniquet. In: Peri- operative standards and recommended practices. 2009. Denver, CO: AORN Inc, 2009; 373e85. 8 Halladin NL, Zahle FV, Rosenberg J, Gogenur I. Interventions to reduce tourniquet-related ischaemic damage in orthopaedic surgery: a qualitative systematic review of randomised trials. Anaesthesia 2014; 69: 1033e50. 9 Newman RJ. Metabolic effects of tourniquet ischaemia studied by nuclear magnetic resonance spectroscopy. J Bone Joint Surg Br 1984; 66: 434e40. 10 Rama KR, Apsingi S, Poovali S, Jetti A. Timing of tourniquet release in knee arthroplasty. Meta-analysis of randomized, controlled trials. J Bone Jt Surg Am 2007; 89: 699e705. 11 Zhang W, Liu A, Hu D, Tan Y, Al-Aidaros M, Pan Z. Effects of the timing of tourniquet release in cemented total knee arthroplasty: a
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12
13
14 15
16
17
18
19
20
4
systematic review and meta-analysis of randomized controlled trials. J Orthopaedic Surg Res 2014; 9: 125. Zhang W, Li N, Chen S, Tan Y, Al-Aidaros M, Chen L. The effects of a tourniquet used in total knee arthroplasty: a meta-analysis. J Orthopaedic Surg Res 2014; 9: 13. Tarwala R, Dorr L, Gilbert PK, Wan Z, Long WT. Tourniquet use during cementation only during total knee arthroplasty: a randomized trial. Clin Orthop Relat Res 2014; 472: 169e74. Middleton R, Varian J. Tourniquet paralysis. Australian and New Zealand. J Surg 1974; 104: 190e2. Arciero RA, Scoville CR, Hayda RA, et al. The effect of tourniquet use in anterior cruciate ligament reconstruction. A prospective, randomized study. Am J Sports Med 1996; 24: 758e64. Olivecrona C, Ponzer S, Hamberg P, Blomfeldt R. Lower tourniquet cuff pressure reduces postoperative wound complications after total knee arthroplasty: a randomized controlled study of 164 patients. J Bone Joint Surg Am 2012; 94: 2216e21. Jenny JY, Bahlau D, Wisniewski S. Silicone ring tourniquet or pneumatic cuff tourniquet for total knee arthroplasty. Int Orthop 2016; 40: 1803e6. Pereira A, Hendriks S, Facca S, Bodin F, Gay A, Liverneaux P. Evaluation of a new tourniquet for hand surgery: comparison of 76 carpal tunnel syndrome cases operated using a Hemaclear(Ò) Model-F tourniquet versus a pneumatic tourniquet. Chir Main 2015; 34: 73e8. Xiong H, Liu Y, Zeng Y, Wu Y, Shen B. The efficacy and safety of combined administration of intravenous and topical tranexamic acid in primary total knee arthroplasty: a meta-analysis of randomized controlled trials. BMC Muscoskel Disord 2018; 19: 321. Braithwaite BD, Robinson GJ, Burge PD. Haemostasis during carpal tunnel release under local anaesthesia: a controlled comparison of a tourniquet and adrenaline infiltration. J Hand Surg Br 1993; 18: 184e6.
Ó 2020 Published by Elsevier Ltd.
Please cite this article as: McMillan TE et al., Current concepts in tourniquet uses, Surgery, https://doi.org/10.1016/j.mpsur.2020.01.005
Current concepts in tourniquet uses
operative blood loss. Tourniquets can, however, lead to permanent patient morbidity when used inappropriately.
Applications Tourniquets are most frequently placed on the upper arm or thigh, therefore lending themselves to a broad spectrum of elective and emergency surgery of the upper and lower limbs. They can also be utilized for intravenous anaesthesia (Biers block) and in isolated limb infiltration of toxic agents in the management of localized malignancy. Nowadays, tourniquets are electronically controlled pneumatic devices with accurate pressure control, timing and incorporated user alarms in an attempt to improve their safety. The production of more simplistic elasticated devices has also enabled the application of tourniquets to individual fingers or toes.
Tristan E McMillan Timothy Gardner Alan J Johnstone
Abstract Tourniquets have been around for many years, providing surgeons with a bloodless operative field and saving lives in the pre-hospital care of major limb trauma. However, their use does come with risk. It is therefore extremely important that we, as surgeons, fully understand the physiological influence they impose on patients, the complications associated with their use and, moreover, how to minimize the incidence of these complications. Most tourniquets are now electronically controlled pneumatic devices with built-in pressure sensors and timers. Classically, inflation to 250 mmHg in the upper limb and 300 mmHg in the lower limb is used, but a move towards patientspecific limb occlusion pressures is suggested, although it is more difficult due to the requirement of more time-consuming set-up. Complications from tourniquets can occur, such as nerve injury, pain, venous thromboembolism or even cardiac overload and reperfusion injury. Limiting use to key parts of an operation or using alternatives such as adrenaline infiltration and tranexamic acid can be of benefit. As such, any use of a tourniquet during an operation must be treated with caution and be deployed taking into account the specific characteristics of that particular patient.
Contraindications There are no absolute contraindications to tourniquet use; however, there are number of relative contraindications that surgical teams should be aware of. Tourniquet use within these patient groups should be selective, upon a patient and procedural specific basis. Relative contraindications to tourniquet Peripheral vascular disease. A limb with an arteriovenous fistula or previous vascular surgery. Sickle cell disease. Severe limb infections. Reamed intra-medullary nailing. Previous thromboembolic event. Patients with severe peripheral vascular disease have decreased vessel wall compliance and already compromised tissue perfusion, making tourniquets less effective and also predisposing to further ischaemic damage. Additionally, they are predisposed to thromboembolic events post tourniquet use. Tourniquets cause haemostasis, acidity and hypoxia in limb tissues. These conditions are thought to be the mechanism to provoke sickling of red blood cells in individuals carrying the sickle cell gene. The use of tourniquets in patients with sickle cell disease is debated within the literature, with no absolute contraindication. In general, they should be avoided where possible, and in those cases where they are necessary appropriate measures should be taken to minimize risk, including adequate hydration, optimal exsanguinations (with consideration of elevation only) and minimizing inflation time. The use of tourniquets during reaming of an intra-medullary canal prior to insertion of an intra-medullary nail is contraindicated due to the risk of thermal necrosis.2 It may also predispose patients to an ‘embolic hit’ with tourniquet deflation post-reaming.
Keywords Complications; limb surgery; orthopaedics; tourniquets; trauma
Introduction The term tourniquet describes an instrument or device used to stop or reduce venous and arterial blood flow to an extremity. The known history of tourniquets goes back to the Middle Ages, when Morel first used a tourniquet on the battlefield at Flanders in 1674.1 Since then tourniquets have been broadly utilized within pre-hospital management of injured patients and during surgery. The prospect of a bloodless field within surgery has led to the diverse application of tourniquets and their evolution. To a surgeon, this can greatly improve the operate field permitting better visualization of anatomical structures and can limit intra-
Tristan E McMillan MBChB MRCS is an ST7 in Trauma and Orthopaedics at Aberdeen Royal Infirmary, NHS Grampian, UK. Conflicts of interest: none declared.
Cuff selection and preparation
Timothy Gardner MBChB MSc MRCS is an ST2 in Trauma and Orthopaedics at Aberdeen Royal Infirmary, NHS Grampian, UK. Conflicts of interest: none declared.
A broad range of pneumatic machines and tourniquet cuffs are available in today’s market. Choice of cuff is largely dictated by those available to a surgeon within their hospital. The surgical team should consider the region of application and the patient size when choosing cuff width and length. Generally, the cuff
Alan J Johnstone MBChB FRCS (Tr & Orth) is Professor of Trauma and Orthopaedics at Aberdeen Royal Infirmary, NHS Grampian, UK. Conflicts of interest: none declared.
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1
Ó 2020 Published by Elsevier Ltd.
Please cite this article as: McMillan TE et al., Current concepts in tourniquet uses, Surgery, https://doi.org/10.1016/j.mpsur.2020.01.005
BASIC SKILLS
recommend a safety margin of 40 mmHg for LOPs <130 mmHg, 60 mmHg for those 131e190 mmHg, 80 mmHg for those >190 mmHg and 50 mmHg in paediatric patients.7 For example, a tourniquet pressure of 140 mmHg should be selected for a patient with a measured LOP of 100 mmHg. The main limitation of this technique is the requirement for Doppler ultrasound measurement, which is time consuming and can be unreliable in people with vascular disease, with cool, poorly perfused peripheries. Additionally, maintaining sterility during procedures while simultaneously doing Doppler measurements adds another layer of challenge. There has been work done to develop alternative methods of measuring LOP, using dedicated tourniquets with built in sensors. A randomized crossover multicentre trial of 143 patients found that there were no statistically significant differences between this new technique and Doppler ultrasound, which is the current gold-standard method of measuring LOP.
should overlap by a minimum of six inches and be at least half as wide as the limb. Wider cuffs offer better distribution of pressure, reducing the risk of underlying soft tissue, muscle and nerve injury. Additionally, for any given limb circumference, the tourniquet pressure required to stop arterial blood flow decreases inversely as the width of the tourniquet cuff increases. Interestingly, when the cuff width is around half of the limb circumference, occlusion pressure has been shown to be within the subsystolic blood pressure range, and if the cuff width is equal to limb circumference, occlusion pressure is around diastolic blood pressure.3 Contoured cuffs further reduce the required limb occlusion pressure (LOP). Upon application of the cuff, a protective layer should be applied to minimize skin wrinkling and trauma. A barrier should also be applied to prevent surgical cleaning solution soaking beneath the tourniquet, leading to skin burns. Within our unit we use a double layer of under-cast padding and a circumferential layer of adhesive op tape. Prior to tourniquet inflation, appropriate limb exsanguination is required. This can be achieved using a number of devices such as an Esmarch bandage or a Rhys-Davies exsanguinator, or by simply elevating the limb. While mechanical devices are generally felt to achieve optimal exsanguination they can lead to dissemination of tumour, infection and emboli, and some of the devices can cause soft tissue trauma, particularly in those patients with thin or friable skin. Limb elevation can generally avoid the risks associated with mechanical exsanguination and may potentially reduce the non-operative tourniquet application time. The limb angle at elevation and period of elevation continues to be debated. Warren et al. recommend elevation of the limb at 90 degrees for a period of 2 minutes.4 Contrary to this, Blond and Madsen showed no benefit in vertically elevating the upper limb for greater than 5 seconds and the lower limb for greater than 30 seconds.5 An incorrectly applied or inflated tourniquet can cause complete venous occlusion and incomplete arterial occlusion, leading to venous congestion within the extremity, which most commonly manifests as pain.
Physiological implications Tourniquet use causes local changes mainly due to ischaemia or direct mechanical pressure. These local changes, particularly if prolonged, can go on to cause systemic upset, most notably upon tourniquet deflation and subsequent reperfusion. As a result of ischaemia and with the switch to anaerobic respiration, creatine phosphate, adenosine triphosphate and glycogen reserves become depleted and concentrations of lactic acid and carbon dioxide increase. Research within our unit has shown a linear pattern of pH decline following tourniquet inflation, with a significant change in muscle pH after just 5 minutes of muscle tourniquet ischaemia. After 50 minutes of tourniquet time in total knee arthroplasty muscle, pH can drop below 6.4. This degree of acidity has been associated with cellular injury. Furthermore, it took 20e30 minutes for pH to return to baseline after tourniquet deflation. With exsanguination and inflation there is an increase in circulating volume of up to 15% that may lead to a transient increase in central venous pressure (CVP). Upon its deflation there can be a reciprocal drop in CVP. Tourniquet deflation is also associated with a transient increase in end-tidal CO2 tension, an increase in cerebral blood flow and intracranial pressure and a decrease in core temperature. The insult associated with reperfusion may be reduced through ischaemic pre-conditioning attenuating the oxidative stress response following reperfusion.8 This is performed by three cycles of 5 minutes of ischaemia and 5 minutes of reperfusion prior to final inflation of the tourniquet. The effects have been measured with tourniquet times up to 87 minutes. This is quite a timeconsuming method that may prove difficult to incorporate into a busy surgical schedule, furthermore, the long-term effects and clinical benefits of this technique are not yet fully understood.
Cuff pressures Classically, surgeons tend to use 250 mmHg for upper limb surgery and 300 mmHg for lower limb surgery. An alternative pressure is based on the patient’s systolic pressure, aiming for a cuff pressure of 100 mmHg above this. There is great controversy within the literature as to ideal pressures that minimize tourniquet complications while maintaining cuff efficacy. In 2016, Sarfani et al. found there to be no noticeable difference to the surgeon during carpal tunnel release surgery using tourniquet pressures ranging from 125 to 250 mmHg.6 Although not a new concept, the use of limb occlusion pressures (LOP) has evolved within the last decade and is now recommended by the Association of peri-Operative Registered Nurses (AORN). LOP is the minimum pressure required to stop arterial blood flow into the limb distal to the cuff. It can be established using arterial Doppler while gradually increasing cuff pressure. This is a patient-specific measurement and takes into consideration the patient’s blood pressure, limb circumference and shape, tissue characteristics, cuff design and application. AORN
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When to deflate Tourniquet time should always be minimized where possible as tourniquet-related complications are directly related to increased tourniquet time and increased tourniquet pressure. Within the literature there is considerable inconsistencies as to a ‘safe’ tourniquet time. Most authors, on the basis of animal and human studies, tend to advise a maximum tourniquet time of 2 hours, and if longer than this a deflation interval should be utilized.
2
Ó 2020 Published by Elsevier Ltd.
Please cite this article as: McMillan TE et al., Current concepts in tourniquet uses, Surgery, https://doi.org/10.1016/j.mpsur.2020.01.005
BASIC SKILLS
Various drugs can help reduce blood loss during surgery. Tranexamic acid has been shown to decrease the overall blood loss in knee arthroplasty, and can be given in a variety of regimens, with single or multiple doses intravenously in additional to topical preparation if required.19 Tranexamic acid has been used successfully both with and without tourniquets. Local anaesthetic agents containing adrenaline have shown promising results when used in hand surgery. In carpal tunnel surgery, it is the favoured option for patients compared with using tourniquets as there is less reported pain, although the operation time is slightly longer.20 The age-old concerns of digital necrosis with the use of peripheral local anaesthetics containing adrenaline has been questioned, especially when they are used in otherwise healthy patients who have no risk factors for peripheral vascular disease. In this patient group, using local anaesthetics containing adrenaline is now accepted.
These intervals allow limb reperfusion and correction of metabolic abnormalities, with hourly release of the tourniquet for 10 minutes ensuring maintenance of adenosine triphosphate and rapid metabolic recovery.9 The timing of final deflation is generally pre- or post-wound closure. The senior author, within his upper limb practice, prefers final deflation prior to wound closure as this decreases overall tourniquet time and facilitates meticulous haemostasis with diathermy. In lower limb surgery, specifically total knee arthroplasty, time to release is controversial. The worry with early release of a tourniquet is excessive blood loss and increased symptomatic anaemia requiring transfusion; however, this is often weighed up against the decreased overall risk of complications by releasing the tourniquet prior to wound closure.10,11 Indeed, some work has been done on having the tourniquet inflated only during implantation where a bloodless field is considered crucial, or not using a tourniquet at all.12,13
Conclusion Complications
As our understanding of the physiological effects of tourniquets improves and tourniquet devices continue to evolve, so too does their safety. More importantly, surgeons are continuing to question the traditional teaching that includes the use of set upper and lower limb pressures, blanket use for upper and lower limb procedures, and deflation post dressing application, etc. A particular area where tourniquet use is continuing to be modified and questioned is in total knee arthroplasty, with some surgeons now opting against tourniquet use altogether. A surgeon’s decision to use a tourniquet must, above all else, be patient specific. Complications and detrimental effects can hopefully be avoided through careful cuff choice and application, exsanguination and pressure selection. Tourniquet inflation time should be minimized, and where not possible a suitable reperfusion regimen should be utilized during the procedure. A
Nerve injuries are the most common complication associated with tourniquet use. This can result in varying degrees of functional impairment that is most commonly temporary with full functional recovery in most cases. The reported incidence of upper limb paralysis is 1:11,000 and lower limb paralysis is 1:250,000.14 Nerve injuries are attributed to both ischaemia and direct compression causing microvascular congestion, inadequate perfusion and subsequent axonal degeneration. Additionally, direct mechanical compression can lead to skin, vascular and muscle injury beneath the cuff. Intraoperatively, the anaesthetist may report signs suggestive of tourniquet pain with increasing heart rate and blood pressure. Patients may also report pain and bruising postoperatively, localized to the tourniquet site. Muscle damage can also occur, Arciero et al. showed increased quadriceps and hamstring atrophy 1-month postsurgery in patients who had undergone anterior cruciate ligament reconstruction with a tourniquet.15 In addition, it has been shown that postoperative wound complications are associated more with higher pressures of tourniquet inflation rather than when the LOP method is used.16 Systemic complications include coagulopathy, cardiac overload upon inflation and myocardial depression upon deflation, dangerous increase in intracranial pressure and ischaemiareperfusion injury. Venous thromboembolism is also listed within the literature as a potential complication of tourniquet use; however, the direct correlation remains argued.
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Alternatives/adjuncts during surgery Tourniquets convey many advantages to the surgeon; this does, however, come at a cost of potential complications. As such, many strategies have been developed to minimize the risk as much as possible. Silicon ring tourniquets rather than conventional pneumatic tourniquets have been shown to have comparable blood loss and lower skin complication rates in knee arthroplasty,17 and equally comparable results in carpal tunnel surgery,18 but their downfall is often increased cost. Other theoretical advantages include better exsanguination and being able to place the ring further proximally, although these are yet to be proven.
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Tourniquets are frequently useful to the surgeons, both in the immediate management of critical haemorrhage from trauma and also during limb surgery where anatomical complexity exists. Tourniquet use should be patient specific. The appropriate cuff size should be used, and inflation pressure should, where possible, be specific to the patient. Limb occlusion pressure (LOP) can be calculated as the minimum pressure to occlude arterial blood flow. With an additional safety margin on top of this, LOP can result in much lower pressures being used, therefore limiting the risk of iatrogenic injury, especially nerve injury. Timing of release of a tourniquet is controversial, and needs to be carefully considered. Inflating the tourniquet at specific points during an operation, or indeed not using one at all, must be weighed up against the risks of bleeding and postoperative anaemia. Adjuncts and alternatives to tourniquet use are encouraged. Common ones include the use of adrenaline infiltration and tranexamic acid administration in both trauma and elective orthopaedic operations.
Ó 2020 Published by Elsevier Ltd.
Please cite this article as: McMillan TE et al., Current concepts in tourniquet uses, Surgery, https://doi.org/10.1016/j.mpsur.2020.01.005
BASIC SKILLS
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Ó 2020 Published by Elsevier Ltd.
Please cite this article as: McMillan TE et al., Current concepts in tourniquet uses, Surgery, https://doi.org/10.1016/j.mpsur.2020.01.005