Wrist and Forearm Amputations Periprocedural Care

Clinical presentation

Patients with vascular compromise or occlusion present very differently, depending on the etiology. For example, patients with vascular occlusion secondary to acute embolic phenomena from a more proximal arterial graft typically present with a cold, pale, initially painful portion of the upper extremity with absent capillary refill. Because of collateral circulation, the location of embolic occlusion is often difficult to determine on the basis of clinical appearance. In such individuals, arteriography or magnetic resonance angiography (MRA) confirms the location of the occlusion and assists in determining the level of intervention.

In persons with acute occlusion, medical or surgical thrombolytic recanalization or vascular bypass efforts should be pursued. However, if these efforts fail or if the devascularized tissue has undergone irreversible injury, then amputation is indicated. ^[8]

Incidents of chronic ischemia, such as occur in persons with diabetes or peripheral vascular disease, are less common in the upper extremity than in the lower. However, revascularization efforts in this situation are less successful, and frequently the decision is made to proceed to amputation. Chronic ischemic injury begins distally and usually progresses proximally to more viable tissue. For this reason, the extent of ischemic injury may not be appreciated fully soon after the initiation of clinical changes.

In individuals with chronic vascular insufficiency, patients remain quite functional for many years despite intermittent reports of mild pain with activity or cold intolerance. The only skin changes, if any, may be those of atrophy (shiny hairless skin). For example, patients may present with acute onset of pain in the ipsilateral index and long digits with no or minimal skin discoloration acutely. Over the course of 24-72 hours, skin usually turns cyanotic, and pain is replaced with decreased sensation. Provided the patient is not acutely ill from sepsis, amputation at this time is discouraged. Patients with severe chronic vascular insufficiency may experience constant symptoms and may be more susceptible to irreversible ischemia.

In persons with chronic ischemia, allowing the extent of the ischemia to declare itself clinically is far preferable. Cyanotic fingers may turn black with time, and more proximal tissue that had been assumed to be viable may follow, with cyanosis observed in the fingers. Once the progression of ischemia has stabilized, plans for definitive amputation may commence. If the level of amputation is in question, specific tests may be performed to assess the viability and healing potential of the tissue.

Thermal burns and frostbite rarely result in amputation more proximal to the hand. However, with extensive injury, amputation may be required. In general, both thermal burns and frostbite injuries should be managed nonoperatively until the extent of the damage can be assessed accurately and the amputation can be performed at the most distal level consistent with good healing. Pyrophosphate nuclear scanning has been demonstrated to be useful in predicting the need for amputation in these situations.

Even in the setting of trauma, the level of amputation may be difficult to determine. Most cases of trauma involve significant avulsion and crush components that leave obvious devitalized tissue exposed. ^[20] The complete extent of the injury zone may not be apparent on initial presentation. When in doubt, especially for grossly contaminated wounds, it is wise to proceed with open amputation to allow the wound to declare itself prior to closure over a definitive stump length.

Neglected compartment syndromes in the upper extremities with resulting global ischemia often necessitate amputation. Provided that the patient is not in a septic state or otherwise medically compromised, it is preferable to avoid acute amputation for the status of the tissues to be better assessed. Initially, fasciotomies are performed, and if the patient remains systemically stable, the role of initial debridement should be to remove tissue that is obviously dead. Tissue that is neither contractile nor bleeding should be removed at this time. Tissue that is noncontractile but bleeding and otherwise healthy appearing should be left intact, and fasciotomies should be left open with a sterile dressing that prevents desiccation.

The patient should then return to the operating room within 24-48 hours for a second observation of the tissues, and the tissues should be debrided as described above. This conservative process continues until the tissues have stabilized and the surgeon is convinced that all remaining tissue is viable.

This step-by-step conservative debridement, though labor-intensive, ensures that tissue removal is minimal and that the patient is left with maximal function. Even in severe cases where amputation is indicated, this stepwise process dictates the level of amputation and ensures maximum length rather than arbitrarily guessing at the level, which may be inappropriately long (resulting in failure of healing) or inappropriately short (resulting in decreased functional potential). However, the step-by-step process is contraindicated in patients with systemic sepsis, renal compromise secondary to disseminated myoglobin, or another critical illness in which the patient cannot sustain multiple surgeries.

Laboratory studies

Hematocrit and hemoglobin levels should be monitored. In trauma situations, acute blood loss is a concern. Even with elective amputations, postoperative bleeding and hematoma formation require careful assessment. Acceptable levels are individualized according to age, associated medical problems and injuries, and baseline values. In general, a young, otherwise healthy patient should maintain a hematocrit/hemoglobin level greater than 20/6. Elderly patients or patients with underlying cardiovascular disease should be maintained at higher levels (30/10).

Creatinine levels should be monitored. In individuals with muscle injury and necrosis, myoglobin enters the systemic circulation and can lead to renal insufficiency and failure. This is especially true in individuals with thermal and electrical burns. If creatinine levels continue to rise more than 0.4 over baseline, preoperative, or preinjury levels, more aggressive surgical intervention and fluid hydration should be considered.

Potassium and calcium levels should be monitored. As dead tissue is metabolized, destroyed cells release intracellular stores of potassium and calcium into the extracellular space. Elevated levels of these electrolytes may lead to cardiac arrhythmias and seizures.

White blood cell count, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) values should be monitored in persons with infection. Observe that these values normalize following amputation, thus suggesting resolution of the infection. Expect CRP to be the first laboratory value to respond to treatment; the two others may take several days to weeks to normalize despite eradication of the infection. If these values remain elevated or rise further, treatment should be reassessed by considering changing to a more appropriate antibiotic, searching for an unrelated occult infection or hidden abscess, and possibly revising the amputation at a more proximal level.

Platelets should be monitored periodically if subcutaneous heparin is administered postoperatively. Heparin-induced thrombocytopenia may occur even in small subcutaneous doses.

Imaging studies

With few exceptions, plain radiography should be included in preoperative planning. The presence of hardware or occult pathology in an extremity to be amputated is an embarrassing intraoperative discovery.

In oncology cases, preoperative computed tomography (CT) and magnetic resonance imaging (MRI) have proved invaluable in assessing the extent of tumor involvement and level of amputation. Occasionally, preoperative CT or MRI is helpful to evaluate the extent of infection and abscess in these particular settings.

Arteriography remains the criterion standard for the definitive analysis of vascular status. However, because this is an invasive procedure, arteriography carries increased risks for pseudoaneurysm, hematoma, and vascular embolism.

MRA remains a noninvasive alternative to arteriography. The complications of arterial puncture are avoided, the risk of contrast-related renal failure is eliminated, and sensitivity is higher than in contrast angiography in the identification of severe peripheral arterial occlusive disease. Because of the expense and expertise involved, many medical centers cannot offer this alternative.

Pyrophosphate nuclear scanning has been introduced as another noninvasive method of evaluating tissue viability. ^[21] It has been demonstrated to be a useful adjunct in predicting the need for amputation in persons with extremities damaged by electrical injury, frostbite, or invasive infection. Pyrophosphate nuclear scanning has a sensitivity of 94%, a specificity of 100%, and an accuracy rate of 96%.

Doppler ultrasonography (US) detects blood flow, and, when used in conjunction with blood pressure cuffs, can measure arterial pressure at different levels in the upper extremity.

Other studies

Transcutaneous oxygen tensions reflect tissue perfusion. Significant occlusive disease causes these measurements to fall below 35 mm Hg. When considering the level of amputation, it is imperative that transcutaneous oxygen tensions at the level of incision are at least 35 mm Hg because measurements below this are associated with decreased healing and wound problems. Measurement of tissue oxygen tension is not affected by incompressible calcified vessels and appears to be very sensitive in evaluating arterial occlusive disease during exercise.

The time for prosthetic fitting in the person with upper-extremity amputation has been debated. Traditionally, fitting commences once stump shrinkage has subsided, usually at 8-12 weeks. However, many have advocated immediate or early prosthetic fitting to improve outcome, particularly improvement in early bimanual activities and increased user rates.

Malone et al ^[22] describe a "golden period" of fitting within the first month following amputation of the upper extremity in order to maximize acceptance rates and user patterns, regardless of the type of prosthesis initially provided. They also observed that if the fitting occurred within this time, patients demonstrated decreased edema, decreased postoperative pain, decreased phantom pain, accelerated wound healing, improved rehabilitation, and decreased hospital stays compared to those with later fittings. These benefits were less pronounced at amputation levels above the elbow.

Unlike persons with lower-extremity amputations, most persons with upper-extremity amputations have excellent vascularity in their stumps and are much less prone to wound-related problems. It would appear that in the upper extremity, particularly for below-elbow amputations, the advantages of immediate or early prosthetic fitting far outweigh the disadvantages.

A patient's preamputation attitude, motivation, and desire strongly influence the overall outcome. Grunert et al ^[23] strongly recommended a psychological consultation within the first 3 days of injury. Psychological testing has proved useful not only for predicting outcome but also for assisting in the patient's return to gainful employment.