Are Pneumatic Tourniquets Necessary for Optimum Benefits from Knee Surgery - Essay Example

Are Pneumatic Tourniquets Necessary for Optimum Benefits from Knee Surgery Are Pneumatic Tourniquets Necessary for Optimum Benefits from Knee Surgery Introduction A pneumatic tourniquet can generally be described as an item designed to control blood pressure during limb surgery and specifically to provide a bloodless field for surgical procedures. The earliest documented usage dates back to 199 BCE where Romans used it to manage bleeding during amputation. However, they are also reported to have caused shearing forces and high pressures that often resulted in fatal complications such as pulmonary embolism. More modern use of pneumatic tourniquet for open extremity surgery, developed from the early 20th century, has shown less drastically adverse results with working in conditions of limited blood loss being the most obvious benefit but with numerous disadvantages (Tang, Olesnicky & Heiskell 2013, p. 32). On the other hand, modern day knee surgery, employing pneumatic tourniquets in more than one million surgical cases in North America alone per year, is prone to risks presented by intra-operative and post-operative complications as well as operation-specific complications. Several studies have identified the pneumatic tourniquet as a significant factor for the increased risk of complications with regards to knee surgery (Krushell & Fingeroth 2007, p. 78). Although there are some advantages such as confining anaesthetics to an extremity, the most common risks are in the form of nerve injury, post-tourniquet syndrome, blood clots, infections and osteolysis (Walsh 2006, p. 711). Because of the risks that patients are exposed to during the use of pneumatic tourniquets in knee surgery, this paper will argue in support that pneumatic tourniquets are not necessary for optimum benefits from knee surgery by discussing their complications. The use of tourniquets, even the older, non-pneumatic versions, has been riddled with complications, sometimes fatal ones (Shemshaki, Laripiur & Jalalian 2010, p 683). Pneumatic tourniquets are used in knee surgery to primarily occlude the flow of blood in an extremity so as to establish a bloodless field in which surgery may be conducted. However, their increased use is also accompanied by the growing risk of incidents related to complications with pronounced physiological changes such as the base-acid imbalance caused by the application of pneumatic tourniquets and may result in pulmonary oedema. The physiological changes also induce transendothelial movement of polymorphonuclears. Most of the injuries that result from the application of pneumatic tourniquets are often pressure-related but may also be consequences of prolonged tourniquet time (Wen, Wu & Lin 2009, p. 1264). Some injuries are also transient and will only be noticed after time while other can only be reversed over extensive periods through which the afflicted individuals will experience prolonged disability. The key benefit achieved when the leg is exsanguinated using a pneumatic tourniquet is that a clear operating area is established and the overall loss of blood is reduced. However, at the same time, the occluded leg’s cells undergo progressive acidosis, hypoxia and cooling as the muscles are rendered susceptible to ischemic changes. These changes are reported in more than 65% of cases just one hour after the tourniquet is inflated (Rama, Apsingi & Poovali 2007, p. 699). The complications discussed are evidence that even though pneumatic tourniquets were meant for the realisation of optimum benefit from knee surgery, they are in fact more detrimental. Summarising the general disadvantages of pneumatic tourniquets, it is seen that when excessive pressure is applied over a narrow area for too long, the nerves to the limb will be injured, causing a paresis (McEwen, Kelly & Jardanowski 2007, p. 57). Transient nerve palsy cannot be ruled out even in cases where the pneumatic tourniquet is applied correctly. Then, prolonged tourniquet time of up to six or more hours will most probably be followed by gangrene, myoglobinaemia or Volkmann’s ischemic contracture especially in patients with arterial disease. A common cause of prolonged tourniquet time is the lack of careful application in which the application time is not recorded and in some cases, the tourniquet is even forgotten about especially when it is under drapes (Gavriely 2010, p. 1321). The deflation of pneumatic tourniquets is also known to have its own effects in knee surgery that partly arise when metabolites are released from the ischemic limb and into circulation and partly the reduction in peripheral vascular resistance. Essentially, the mean arterial blood pressure will reduce significantly following deflation of the pneumatic tourniquet. There are also transient tensions in central venous oxygen and temperature. The blood flow re-established by deflating the tourniquet will induce paradoxical extension of ischemic harm with the possibility of undesired systemic effects. They include cardiac injuries, renal injuries and Acute Respiratory Distress Syndrome that often lead to further and possibly fatal complications (Wen, Wu & Lin 2009, p. 1267). Pneumatic Tourniquet-Related Complications Nerve injury. Ranging from mild momentary functional loss to permanent and irreversible damage, this is the commonest of all complications casued by pneumatic tourniquet application in extremity knee surgery and was recognised over a century ago. Nerve injury often manifests itself in the inability of a patient to detect pressure, cold, heat or pain over the skin that runs along the nerve’s source. Cases of nerve injury, also refered to as limb paralysis or nerve paralysis, not only result in considerable disability but also psychological stress. Further, injured parties can also subject medical personnel to legal action. There are two common causes of nerve injuries. One is the ischemia or anoxia of nerves under the cuff used with the pneumatic tourniquet and the other is the mechanical stress exerted on the nerves at the edges of the cuff or under it (Association of Perioperative Registered Nurses 2010, p. 93). Both these occurrences will lead to the cessation or slowing down of motor and sensory nerve conduction. Physicians have established that nerve damage will result much sooner from the direct mechanical pressure under the cuff than from ischemia. Both insufficient and excessive pressure will cause tourniquet paralysis, but physician have considered insufficient pressure to be more dangerous because it results passive congestion. Further, passive congestion has also been shown to have the potential to lead to irreversible loss of function. Another disadvantage of pneumatic tourniquets in relation to knee surgery is caused by subcutaneous tissue present in large amounts on the leg and flaccid skin as in elderly people (Gavriely 2010, p. 1322). This disadvantage is further pronounced by the fact that such persons form the population that may most likely require knee surgery. In such persons, injury will be caused by the shearing force applied by cuffs that fit improperly. Post-tourniquet syndrome. This is mainly in the form of pronounced and often lengthened, postoperative inflammation of the extremity. Nearly 50% of all cases of post-tourniquet inflammation are as a result of hyperemia, which is basically blood finding its way back to the leg after the tourniquet is released. The other 50% results from the increasing blood to restore normal tissue balance between base and acid (Drosos, Stavropoulos & Kazakos 2013, p. 134). This increase in blood through a process known as post-ischemic reactive hyperemia is a reflection of the attempt to rid the leg of anoxia’s metabolic products. As can be seen, these are all attempts of the body to return the leg that has undergone knee surgery in a bloodless field back to normal as much as possible, but with undesirable results. Experimental studies have shown the interaction between the cuff duration and pressure to be related to the extent of injury to the skeletal muscle beneath the pneumatic tourniquet (Noordin, McEwen & Eisen 2009, p. 2959). It was established that complications are more probable in patients who have been subjected to extended tourniquet time and those whose cuff pressures were not sufficient enough to stop arterial inflow and venous outflow simultaneously. Chemical burns, pressure sores and skin blisters. Inflating of the pneumatic tourniquet cuff tightly holds antimicrobial prep solutions against the skin (Roffman Boiko 2006, p. 185). However, chemical burns are the result of the seeping of the solutions beneath the pneumatic tourniquet cuff. They are more frequent in children because of their sensitive skin but are occasionally also reported among adults and are a result of the pneumatic tourniquet’s shearing stress that normally occurs during inflation. In such cases, even without the accumulation of fluid beneath the cuff, skin injury will still occur due to prolonged tourniquet duration, excess pressure or fluid leakage. A combination of any of these causal factors will also result in skin injury. Skin blisters and pressure sores will mostly be caused by the folding of soft tissue beneath the tourniquet as well as friction and breakdown of the skin (Sharma & Salhotra 2012, p. 379). The improper application of tourniquet cuffs or poor padding especially in patients with loose skin will result in shearing or pressure necrosis. Diabetic or elderly patients, most of who suffer from compromised and poor circulation, are at increased risks of ending up with pressure sores. When these occur, they subject patients to considerable discomfort. Such conditions cannot provide for optimum benefits from knee surgery because the population of the diabetic and elderly are more likely to require knee surgery but are also adversely affected by the use of pneumatic tourniquets. Thrombosis. This is more common in knee replacement surgery. Alongside the associated pulmonary embolism risk, deep vein thrombosis (DVT) is a key cause of mortality or morbidity in lower extremity surgery. Autopsies have identified DVT in lower extremity as the cause of pulmonary embolism in cases of cardiac arrests related to the use of pneumatic tourniquet in knee surgery (Sharma & Salhotra 2012, p. 380). Intraoperative bleeding. This may result from cuffs that are not sufficiently pressurized or exsanguinated. It can also be from too slow deflation or inflation, calcified vessels and loosely applied or improperly applied cuffs (Odinnson & Finsen 2007, p. 1091). When the tourniquet cuff is underinflated, it may lead to venous pooling and venous congestion of the leg. Since this is a chain reaction, there will also be hemorrhagic permeation of the nerve and eventually blood will ooze into the field. Another cause of intraoperative bleeding is the blood that remains in the leg due to the insufficient exsanguination. Then, when the inflation and deflation processes are too slow, they will allow the entry of arterial flow while preventing venous return. This problem also occurs because the size of the cuff is not selected properly and it ends up ill-fitting Effect on muscles. The application of pneumatic tourniquet has the effect of reducing muscular endurance. As a consequence, weakness is intensified which further leads to a decline in the postoperative functions of the patient. In recent studies, it was shown that an average of only 3.4% of the knee operations performed without pneumatic tourniquets while those that used pneumatic tourniquets and had complications were 77% (Drosos, Stavropoulos & Kazakos 2013, p. 131). Pneumatic Tourniquets and its Effects on Obese Patients The obese population is one that has been identified as highly likely to require knee surgery at a point in time (Phillips & McEwan 2007, p. 14). Patients who undergo knee operations among this population have a body mass index (BMI) greater than 30 with a considerable percentage having BMI greater than 40, which makes the morbidly obese. When such patients must be operated upon, it presents difficulties that range from achieving and maintaining a bloodless field to the need for wider specialty cuffs. Essentially, the larger and curved cuffs decrease the distance from the incision to the distal edge of the pneumatic tourniquet dangerously. Then, upon inflation, the tourniquets slide distally due to the thigh’s taper. Since occlusion of the arterial flow in obese persons will require significantly higher pressure, there will be corresponding skin damage tissue compression. Unlike persons of the recommended BMI, obese patients are more at risk of infection in case the pneumatic tourniquets are not sterilised (Phillips & McEwan 2007, p. 21). Further, obese persons experience greater inability to drive out blood from the limb operated on prior to inflating the tourniquet. This increased difficulty makes the procedure more tedious and time consuming and usually suboptimal, which leaves considerable blood volumes in the vessel. During the period the tourniquet is in application, this residual blood will clot and, upon deflation of the tourniquet, make its way to the pulmonary circulation. The blood that is left behind will obstruct the visibility of the surgical field, which means that the imperfect field will need more time for homeostasis. From these proven observations, it is evident that even though the pneumatic tourniquet is meant to facilitate the achievement of optimum benefits from knee surgery, it adversely affects obese patients. In such patients, special skills and experience are required to achieve bloodless fields (Hunter, Jayasekera & Altaf 2013, p. 1). Apart from the pneumatic tourniquet requiring to be specially shaped, it must be used alongside other special tools and extra padding. These are intended to suit the obese thigh that is characteristically wide, relatively soft and acutely tapered soft. Apart from the skin being loose, the distance to the groin is also comparatively short relative with regards to the circumference. These geometrical mechanics and the wider thigh dictate that the tourniquet’s cuff must be made wider. Essentially, that translates into inappropriately less area for surgical incision. Consequently, such problems have led researchers to conclude that, in the case of obese patients, it is safer to have knee surgery in non bloodless fields (Hunter, Jayasekera & Altaf 2013, p. 1). The researchers have also pointed out that most knee surgery units only continue the routine use of pneumatic tourniquets with the belief that it is the only way to achieve clear operative views. On the contrary, the researchers have shown that that knee surgery for soft tissue procedures can adequately be carried out with efficient pump systems to maintain pressure above venous pressure (Hunter, Jayasekera & Altaf 2013, p. 1). Conclusion It can be concluded that the use of pneumatic tourniquets is not necessary for optimum benefits from knee surgery. The use of tourniquets has evolved and developed for centuries in surgical procedures. Although most of the procedures were specifically meant to eliminate the adverse effects, modern day pneumatic tourniquets are still facing pressure-related challenges that expose patients of knee surgery to complications. As pneumatic tourniquets are continuously being used to occlude blood flow in extremities in order to provide a bloodless field, there is also an accompanying complications risk. This includes physiological changes such as base-acid imbalances with the possibility of pulmonary oedema. Some of the common complications include nerve injury, post-tourniquet syndrome, chemical burns, pressure sores and skin blisters, thrombosis, intraoperative bleeding and effect on muscles. Nerve injury may range from momentary functional loss to permanent and irreversible damage while post-tourniquet syndrome is in the form of pronounced and often lengthened, postoperative inflammation of the extremity. Chemical burns, pressure sores and skin blisters subject patients to great discomfort and mostly affect children but are also reported among adults while thrombosis is a key cause of mortality or morbidity in lower extremity surgery. Intraoperative bleeding will result from insufficiently inflated cuffs an either too slow inflation or deflation while a reduction in muscle endurance leads to weakening of muscles. Pneumatic tourniquets have also been shown to have adverse effects on obese patients. With all these documented shortcomings, pneumatic tourniquets cannot be said to be necessary for optimum benefits from knee surgery. References Association of Perioperative Registered Nurses 2010, Perioperative standard and recommended practices, Author, Denver. Drosos, G, Stavropoulos, N & Kazakos, K 2013, ‘Silicone ring tourniquet versus pneumatic cuff tourniquet in carpal tunnel release: a randomized comparative study’, Journal of Orthopedic Traumatology, vol. 14, no. 2, pp. 131-135. 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