Complications and Preventive Measures

Nerve Injury Post - Tourniquet Syndrome Intraoperative Bleeding Compartment Pressure Syndrome Pressure Sores and Chemical Burns Digital Necrosis Toxic Reactions Thrombosis Other Complications Summary

Pneumatic tourniquets are used in over 1 million surgical cases annually in North America. The potential for injury assumes startling proportions. Injuries resulting from pneumatic tourniquet use are commonly pressure—related, and can also be caused by excessive tourniquet time. While the majority of these problems may be transient, and perhaps even unnoticeable, some are permanent or reversible only over extended time periods with prolonged disability being experienced by the afflicted person. This section of the self - study considers the most common complications of tourniquet use, their causes, and preventive measures.

Nerve Injury

Nerve injury is the most common complication from the use of tourniquets during upper - extremity surgery, and can also occur in thigh and lower leg cuff applications. It was first recognized more than 100 years ago. The extent of nerve injury can range from a mild transient loss of function to permanent, irreversible damage. Symptoms of nerve injury include an inability to detect pain, heat, cold, or pressure over the skin along the source of the nerve; and a sluggishness or inability to move large or small muscles upon command.

Limb paralysis is also referred to as nerve paralysis or tourniquet paralysis syndrome. When this occurs, all motor nerves distal to the cuff are affected, resulting in a temporary or permanent inability to move the extremity. The radial nerve is the most common nerve affected. Symptoms of tourniquet paralysis are: motor paralysis and loss of the sense of touch, pressure, and proprioceptive responses.

Paralysis can produce considerable disability and psychological stress in affected persons. Medical personnel may be subject to legal action from the injured party.

Causes

The two most common causes of these nerve injuries are: mechanical stress on the nerves under the cuff or at its edges and anoxia or ischemia of nerves under or distal to the cuff, which leads to a slowing or cessation of both sensory and motor nerve conduction. Research has demonstrated that mechanical pressure directly under the cuff leads to irreversible nerve damage much sooner than ischemia or anoxia does. Tourniquet paralysis may result from either excessive or insufficient pressure, but the latter is considered more dangerous, resulting in passive congestion with possible irreversible functional loss.

Persons with flaccid, loose skin (e.g., the elderly), or persons with large amounts of subcutaneous tissue on cone - shaped limbs are subject to nerve and tissue injury from a shearing force mechanically created by an improperly fitting cuff. Most often, shearing occurs at the proximal edge of the cuff. Risk of shearing - related injury may be reduced by selecting a contoured cuff (which fits the limb taper) and a matching limb protection sleeve.

Preventive Measures

Because tourniquet - related neural injury has been linked to mechanical rather than ischemic factors, mechanical stress merits the most focus for preventing nerve injury. It is recommended that the minimum tourniquet pressure that is necessary to obtain a stable, bloodless field be employed in all circumstances. Safety measures to prevent nerve injury and pressure - induced complications can be summarized as follows:

• Never use a tourniquet for more than the recommended period of time.
• Make sure that the pressure display accurately reflects the pressure within the cuff bladder. Some nerve palsies may be secondary to faulty pressure gauges causing excessive tourniquet inflation pressures.
• Use only the minimal effective pressure required to reliably maintain arterial occlusion throughout the procedure. This is best achieved by the Limb Occlusion Pressure technique outlined in Section 3.
• Use a cuff that properly fits the extremity and has the maximum bladder width possible, as outlined in Section 1.
• Use a limb protection sleeve that matches the selected cuff.
• Apply the cuff to the limb with care and attention, according to the manufacturer's instructions.
• Apply the cuff at the proper location on the limb. Application of the cuff over the peroneal nerve (the knee or ankle) or the ulnar nerve (the elbow) may produce nerve/bone impingement resulting in nerve damage or paralysis.

In addition, do not permit the tourniquet to slip or twist during limb manipulation. Do not pinch or kink the connecting tubing. Avoid wrinkling of loose, flaccid tissue and/or padding under the cuff by using the proper limb protection sleeve for the cuff, or 2 layer tubular stockinette which is stretched and applies light compression to the limb when applied.

Post - Tourniquet Syndrome

Post - tourniquet syndrome (PTS) is manifested by pronounced and, at times, prolonged postoperative swelling of the extremity. Approximately half of all post - tourniquet swelling is caused by blood returning to the limb after the release of the tourniquet (hyperemia). The remainder is the result of postischemic reactive hyperemia, an additional increase of blood to restore normal acid - base balance in tissue. Postischemic reactive hyperemia reflects the body's attempt to cleanse the limb of the metabolic products of anoxia. Later, additional swelling due to edema or a postoperative hematoma may occur. Prolonged bleeding from the surgical wound also significantly affects swelling. Post - tourniquet syndrome is characterized by edema, stiffness, pallor, weakness without paralysis, and subjective numbness without objective anesthesia.

Causes

Unlike nerve palsies, PTS is thought to be due primarily to prolonged ischemia rather than the direct mechanical effect of the tourniquet on the muscle. The tourniquet induces neuromuscular injury by causing ischemia in the tissues distal to the tourniquet, and by compression and ischemia in tissues beneath the cuff.

Postoperative weakness, edema, stiffness, dysesthesia, and pain may be falsely attributed to surgical trauma or to lack of patient motivation if the clinician does not have an adequate index of suspicion of tourniquet - related neuromuscular injury. Randomized, prospective studies have demonstrated EMG abnormalities in extremities treated with a routine pneumatic tourniquet. These neurophysiologic changes may be associated with weakness of the involved extremity and a longer clinical recovery time; in fact, postoperative EMG abnormalities persist as long as 5 months in some cases.

Recent experimental studies suggest that the magnitude of skeletal muscle injury beneath the tourniquet is related to a complex interaction of the cuff pressure and duration.

The complication occurs in patients who have had tourniquets applied for a prolonged time and also in patients whose tourniquet cuff pressures were insufficient to prevent arterial inflow while preventing venous outflow. Under inflation of the tourniquet cuff is a particular risk for elderly patients who frequently have extensive calcification of the major arteries, which renders the vessels noncompliant to tourniquet pressure. Rheumatoid arthritis patients on steroid treatment experience the same problem in which a bloodless field cannot be obtained because of steroid - induced vascular calcification. Because of the significance of postoperative bleeding, patients with prolonged clotting times also are at risk for post - tourniquet syndrome.

Preventive Measures

Preventive measures for PTS are similar to those for nerve injury complications. During the preoperative assessment, review the patient's physiological status, including:

• Medication history. A patient's drug history should detect the routine ingestion of any drug that will influence clotting time or promote development of atherosclerotic vascular disease. Among these are steroids, aspirin, and birth control substances.
• History of hypertension.
• Clotting time.
• History of past thromboembolic occurrences.
• Evidence of arterial calcification.

Comply strictly with the recommended tourniquet time limit. A higher than normal pressure may be required, particularly in larger limbs, and it is particularly important with these at - risk patients to use arterial occlusion pressure (see LOP section above) rather than systolic blood pressure to determine the most appropriate tourniquet cuff pressure and if possible to avoid exceeding the recommended maximum cuff pressure limits (typically recommended to be 300 - 350 mmHg for the thigh and 250 - 300 mmHg for the arm and lower leg).

Intraoperative Bleeding

Intraoperative bleeding may be caused by:

• An underpressurized cuff. Underinflation of the tourniquet cuff can result in venous pooling, leading to passive venous congestion of the limb, hemorrhagic infiltration of the nerve, and oozing of blood into the field.
• Blood remaining in the limb because of insufficient exsanguination.
• Too - slow inflation and deflation, both of which allow arterial flow to enter while preventing venous return.
• Improper selection of the cuff, resulting in a poor or loose fit.
• Excessive padding between the cuff and the limb, which prevents a snug fit.
• A cuff that is applied too loosely.
• Blood entering through the intramedullary nutrient vessels of the long bones (such as the humerus). Theoretically, if breakthrough arterial bleeding does occur, it does so less often than the venous ooze due to medullary cavity bypass of venous blood.

Preventive Measures

To prevent intraoperative bleeding, take care to select the proper style and size of tourniquet cuff, if limb protection is to be used then use the matching limb protection sleeve or similar stretched tubular stockinette rather than a thick buildup of padding, apply the cuff snugly, and inflate it to the optimal pressure. If the tourniquet cuff pressure selected is insufficient to control bleeding into the operative field, increase pressure in 25 mmHg increments until a satisfactory bloodless field is achieved. Some surgeons may prefer to deflate the cuff, re - exsanguinate the limb, and reinflate to a higher pressure in order to prevent the blood from being trapped in the distal part of the extremity.

Compartment Pressure Syndrome

Compartment syndrome is a condition in which external and internal pressures on a confined space result in swelling of the extremity. It is a relatively rare complication of tourniquet use. The compartment is the area between the two tough fascia layers of a muscle group. An infinitesimal amount of fluid in the space normally allows contraction and relaxation of the muscle group within its covering fascia. There is no room for additional fluid. The first symptom of compartment syndrome is usually pain that increases in severity and cannot be alleviated by narcotics. Other symptoms include muscle weakness, paresthesia, decreased or absent pulses, tense skin over the limb and, in some cases, irreversible paralysis.

Causes

The combination of external compression and an increase in compartment contents due to either trauma or surgery may cause a compartment syndrome. Like PTS, this complication is due to tourniquet ischemia time. Prolonged tourniquet times lead to a fall in tissue pH, an increase in capillary permeability, and a prolongation of clotting, all of which promote the development of a compartment syndrome.

Patients at risk for tourniquet - related compartment syndrome are those with a previous history of compartment syndrome symptoms. Patients with McArdle's disease (a muscle phosphorylase deficiency disease) exhibit compartment - like syndromes after about 20 minutes of vigorous exercise. Use of a pneumatic tourniquet on these patients, even for a short time, may lead to compartment syndrome.

Also at risk are patients who must have a cast placed on a limb prior to tourniquet release. Post - tourniquet swelling, if inhibited by a cast, can lead to compartment syndrome.

Preventive Measures

The following are preventive measures for compartment syndrome:

• Preoperative evaluation of the patient's personal and family history for any previous compartment syndrome - like symptoms; patients with McArdle's disease are contraindicated.
• Limit tourniquet time to under 90 minutes before allowing an aeration interval as outlined in Section 3.
• Avoid solid cast placement prior to tourniquet cuff release.

Pressure Sores and Chemical Burns

Pressure sores, skin blisters, and chemical burns are uncommon consequences of pneumatic tourniquet use; however, when they do occur, they cause considerable patient discomfort. Although occasionally seen in adults, chemical burns beneath the cuff occur most frequently in the sensitive skin of children. Tourniquets can also cause skin damage due to shearing stresses. These stresses tend to occur at the time of inflation and may be a particular problem in older patients with delicate skin. Surveys of clinicians show that skin injuries occur with and without fluid accumulation under the cuff and can be attributed to fluid leakage, excess pressure, excess tourniquet duration or a combination of these factors. In one case report severe friction burns were caused by a thigh cuff sliding distally off the underlying padding during the procedure.

Causes

Pressure sores and skin blisters are the result of skin breakdown, friction, or soft tissue folding under the tourniquet. Pressure necrosis or shearing may be due to inadequate padding or faulty cuff application in patients with loose or thin skin, such as obese patients or elderly patients with loose, flabby skin. Patients with compromised circulation, such as those who are elderly or diabetic, are also at higher risk for pressure sores.
Chemical burns may be caused by antimicrobial prep solutions seeping under the tourniquet cuff. When the cuff is inflated, the solution is held tightly against the patient's skin. Chemical burns are most likely to occur when prep solutions come in contact with the rather delicate skin of young children.

Preventive Measures

The following measures will help prevent pressures sores and chemical burns:

• Use adhesive tape or an adhesive edged drape between the distal edge of the cuff and limb to prevent prep solution from leaking under the tourniquet; this also keeps the cuff free from stains.
• Position the cuff properly on the limb. Apply the cuff high on the limb and away from the joints; bony joints prevent compression of blood vessels and proper fit.
• Use the correct limb protection technique as recommended for the selected cuff. If available, use a limb protection sleeve specifically designed for the cuff. This will provide light compression and give a toning effect to loose skin, reducing the tendency of the cuff to gather up the skin into a wrinkle or pinch, and is more likely to be smooth and wrinkle - free than loose, wrapped padding. Use sufficient length of material to extend distally beyond the cuff, and fold this material back over the cuff to help prevent the cuff from sliding distally off the material.
• For better cuff placement on the obese patient, draw the subcutaneous tissue and skin distally before applying the tourniquet. After the tissue is released, it will help hold the cuff in place.
• Do not readjust an already positioned tourniquet cuff using rotation. Rotation produces shearing forces which may damage the underlying tissues.

Digital Necrosis

Digital necrosis is the gangrenous destruction of a finger or toe as a result of prolonged ischemia/anoxia.

Causes

The common practice of using a Penrose drain, rubber band, or a rolled finger of the surgical glove as a tourniquet is associated with this complication. Causes of digital necrosis are:

• Failure to remove the constricting device. This is more prevalent when rubber bands or Penrose drains are used, since they can be easily overlooked.
• Excessive, uncontrolled pressure. This is a potential problem with all nonpneumatic tourniquets.
• Prolonged tourniquet time.

Patients at risk include those with impaired circulation (i.e., Raynaud's syndrome, peripheral vascular disease, diabetes, etc.), those with small limbs, and the elderly.

Preventive Measures

Digital necrosis can be prevented by taking the following safety measures:

• Adhere strictly to a predetermined tourniquet time.
• Eliminate excessive, uncontrolled pressure from the constricting device.

Toxic Reactions

Toxic reactions to local anesthetic agents are potential complications of IVRA. Hypersensitive patients can exhibit generalized symptoms almost immediately. The greatest danger is an inadvertent bolus of local anesthetic entering the general circulation, which can affect the central nervous system and the heart. Early recognition and prompt treatment of early signs of toxicity such as dizziness, drowsiness, respiratory depression, tinnitus, and bradycardia may prevent progression to more serious complications, like grand mal seizures, coma, cardiorespiratory depression, and even cardiac arrest and death.

Causes

The major cause of adverse effects of IVRA and/or failure of the technique is technical error. A toxic reaction may result from:

• Accidental, sudden deflation of the tourniquet.
• Deflation of the tourniquet too soon after injection of local anesthetic; prior to tourniquet release, approximately 15 - 20 minutes is required to maximize tissue binding of the local anesthetic, thus removing the anesthetic from the circulatory system.
• Single release of tourniquet pressure at the end of IVRA procedures. This results in a sudden infusion of metabolic waste products and local anesthetic into the circulatory system.
• Under inflation of the tourniquet cuff. If complete occlusion is not present, leakage of the anesthetic will occur.

In general, high - risk patients have a hypersensitivity to the anesthetic agent, a condition that makes arterial occlusion difficult (i.e., obesity, hypertension, arterial calcification, etc.), a chronic respiratory disease (e.g., chronic obstructive pulmonary disease); congestive heart failure; or CNS impairments (e.g., seizure disorders). Many of these problems are associated with advanced age; thus, elderly patients with any of these conditions are at high risk.

One study found detectable levels of anesthetic agent in the general circulation even while the tourniquet was properly inflated. The authors suggested that the hemodynamics in the skeleton allowed endosteal (intraosseous, medullary) venous outflow from the extremity, using the bone as a tourniquet bypass while the tourniquet still effectively blocked extraosseous arterial inflow and venous return. Thus, venous blood from the extremity slowly entered the general circulation through this intraosseous skeletal bypass.

Preventive Measures

The following preventive measures will reduce the possibility of toxic reactions:

• Test the tourniquet system before each use.
• Obtain a complete allergy history when IVRA is being contemplated. Of particular note is any allergic reaction to any local anesthetic agent used for dental work or another surgical procedure. Persons who have contact, inhalation, and/or food allergies are also suspect because of their hypersensitivity. Such an immunological hypersensitivity may preclude the use of IVRA unless other physical conditions rule out general anesthesia.
• Obtain a complete medical history to detect the presence of cardiopulmonary or renal disease, seizure disorders, vascular problems, morbid obesity, diabetes, and the like. The severity of such problems may eliminate administration of a general anesthetic and make IVRA the better of two poor choices.
• Ensure proper size and fit of the tourniquet cuff. Use a dual - bladder tourniquet for IVRA.
• Ensure that the limb is occluded at the selected cuff pressure by confirming absence of a distal arterial pulse. Limb Occlusion Pressure (LOP) is particularly useful in setting the cuff pressure in IVRA procedures due to the importance of maintaining occlusion.
• Use of the dual bladder tourniquet cuff provides a measure of safety. If the distal bladder should accidentally deflate, the proximal bladder can be inflated immediately.
• Use intermittent deflation and reinflation of the tourniquet cuff at the end of the procedure; this releases the local anesthesia and waste chemicals into general circulation in small amounts.
• Observe the patient's physiological status at all times for any sign or symptom of a toxic reaction, beginning immediately after injection of the anesthetic.

Thrombosis

Deep venous thrombosis and the associated risk of pulmonary embolism are a major cause of morbidity and mortality in lower extremity orthopaedic surgery and have led to the use of various prevention modalities. Lower extremity deep venous thrombosis has been identified at autopsy as the source of pulmonary embolism in several cases of tourniquet - related cardiac arrest. Less severe episodes of venous embolism during surgery using tourniquets may not be recognized by simple clinical observation.

Preventive Measures

To prevent dislodgement of thrombi, do not use an elastic bandage for exsanguination in a patient with a traumatic injury or in a patient who recently has been in a cast. Some experts recommend subtherapeutic heparinization prior to the inflation of the tourniquet.

Other Complications

Other complications of pneumatic tourniquet use might include:

• Tourniquet Pain.
• Thermal Damage to Tissues.
• Hyperthermia.
• Rhabdomyolysis.
• Metabolic Changes.

Tourniquet Pain

Tourniquet pain is the most common complication seen in clinical practice, Hypertension and a dull, aching pain (tourniquet pain) throughout the limb may develop during and following tourniquet use, despite otherwise adequate anesthesia. The initial sensation of pressure at the tourniquet site is replaced by a progressive numbness and paralysis, progressing to complete paralysis. A severe, aching sensation at the site of the tourniquet or distal extremity progressively develops. After deflation of the tourniquet, a different pain sensation is noted, associated with reperfusion of the limb. This sensation is described as being equal to or greater than the intensity of the discomfort caused by the tourniquet immediately before deflation. The average time of pain tolerance after inflation of the tourniquet seems to be about 30 minutes in unsedated patients.

Thermal Damage

Heat generated by surgical lights or powered surgical instruments is not dissipated in limbs under tourniquet control, and tissue may be subject to drying or trauma. Frequent irrigation, special draping, and low - power surgical lights are recommended to reduce the risk of thermal damage to tissues.

Hyperthermia

Limb tourniquets have been associated with a progressive increase in central body temperature in pediatric patients, and the increase is significantly greater when bilateral tourniquets are used. It has been suggested that pediatric patients requiring intraoperative tourniquets should not be aggressively warmed during surgery.

Rhabdomyolysis

Rhabdomyolysis has been described rarely as a complication of prolonged ischemia time after tourniquet application. It is defined as the release of the cellular contents after damage to skeletal muscle and has a variable clinical presentation. Pyrexia and tachycardia develop, and patients often complain of pain, tenderness, edema, and hemorrhage of the limb. Classically, the urine is dark and oliguria may develop. Prompt recognition and early treatment prevent long term sequelae.

Metabolic Changes

While the tourniquet is inflated, metabolic changes occur in the ischemic limb, changes that include increased PaCO₂, lactic acid, and potassium, and decreased levels of PaO₂ and pH. Pathophysiologic changes due to pressure, hypoxia, hypercarbia, and acidosis of the tissue occur and become significant after about 90 minutes of tourniquet use.

Deflation of the tourniquet results in the release of these products of ischemia into the general circulation. The resultant decreases in arterial pH and PaO₂ and increases in arterial lactic acid, potassium, PaCO₂ and end tidal carbon dioxide are associated with significant decreases in mean arterial and central venous pressures and increases in heart rate. The clinical significance of these changes is not yet clear; in healthy individuals, no significant adverse effects have been observed. However, the rapid increase in PaCO₂ after thigh tourniquet release would be expected to result in a corresponding increase in cerebral blood flow (CBF), which could be dangerous in patients with increased intracranial pressure. It may be prudent to monitor the increase in CO₂ and treat it promptly by hyperventilation.

Metabolic changes are generally more pronounced when bilateral tourniquets are used, and it is also thought that the risk of Fat Embolism Syndrome (FES) upon release of the tourniquet in procedures such as bilateral total knee arthroplasty is reduced if deflation times are separated by 30 - 45 minutes.

Summary

Use of a pneumatic tourniquet to produce a bloodless surgical field places the patient at risk for complications. Certain patients, because of their size, age, or physical condition, are more likely to respond unfavorably to pneumatic tourniquet use than others. Since most complications are pressure - related, institute the following preventive measures:

• Conduct an adequate preoperative patient assessment.
• Assure an accurate pressure display.
• Use a tourniquet cuff that has the proper fit and size and can maintain occlusion of arterial blood flow at the minimum effective pressure.
• Accurately determine systolic blood pressure.
• Pay attention to tourniquet cuff pressure.
• Inform the surgeon regularly of elapsed tourniquet time.

Physicians are responsible for determining the correct cuff pressure and tourniquet time, but nurses share responsibilities for many of these measures. In addition, nurses assume responsibility for maintenance of the cuff and accessories.