Amputations and High-Tension Electrical Injuries
JOHN P. REMENSNYDER, M.D.
High-tension electrical injuries produce devastating destruction of limbs, frequently leading to amputation at not necessarily desirable sites. The purpose of this paper is to:
- Review the pathophysiology and types of high-tension electrical injuries
- Review the experience with high-tension electrical injuries at the Shriner's
- Burns Institute, Boston Unit, particularly as it relates to amputation
- Discuss the management of these extensive wounds, specifically focussing on those leading to major amputation.
For the purposes of this analysis a line should be drawn between low-tension and high-tension current at approximately 1,000 volts, Injuries caused by lower voltages, as when a child bites into an electrical cord, are largely surface burns caused by arc and flash. Injuries produced by high tension also produce injury by arc and flash, but in addition show the devastating effects of conductive injury well away from the initial site. It is in this group that we see a high incidence of major amputations.
There are four different types of injuries occurring with high-tension electrical contact:
1. Direct conductive injury
Direct conductive injuries result from the heat generated in the tissues by the flow of current against resistance of various tissue conductors. Joule's Law states that the rate at which heat is produced by a steady current in any part of an electrical circuit is directly proportional to resistance, square of the current, and duration of the current. In the clinical situation other variables occur, such as voltage fluctuations, type of current, firmness of contact with the power source, and whether the skin is dry or wet. Dry skin has a moderately high resistance, but when its resistance is overcome, current can flow along various tissues, each with differing conductivity. Bone, tendon, and fat have the highest resistance of all the body tissues, while nerves, blood vessels, and muscle have the lowest resistance. Even though these latter tissues are very conductive: they still have a finite resistance to current flow and hence will show effects from the generated heat. This fact helps to explain some of the patterns of injury.
2. Arc injury
Arc injuries are best understood as a result of a discharge of ionized particles between two poles of different electrical charge. Arc burns are commonly seen in high-tension injuries across flexion areas, such as wrist, elbow, axilla, and groin, with an actual arc being formed across these points. Once an arc is formed, a sharp drop in differential voltage occurs; but if the power source continues, the arc is sustained, even though the distance between the two poles is considerably increased. The heat of such arcs may reach 3,000 degrees C and be diveried in many directions, producing a seemingly random pattern of injury.
3. Thermal burns
Patients with high-tension injuries may sustain straightforward surface thermal burns from clothing ignition. Either the arc of the initial contact or secondary arcs across flexion creases may ignite clothing, causing extensive surface burns. Such burns may affect the proximal parts of limbs, requiring amputation, and produce scars and unstable skin is areas of future prosthetic application.
Many times patients with high-tension injuries suffer associated injuries. When the individual contacts the high-tension wire, frequently he is rendered unconscious and falls from a height, such as a tree or a utility pole. The victim may sustain significant skeletal, central nervous system, or visceral damage, requiring separate operative intervention.
High-tension injuries of the direct conductive type have three special characteristics. Since the patient sustains injury by completing and becoming part of a high-tension electrical circuit, there will be wounds at the entrance and exit of the circuit. The thermal effects in tissue destruction are the most extensive at the point of contact with the source, and at the point of exit of the current from the body on the way to grounding. Between the entry and exit sites the thermal effects are considerably reduced, when tissue volume in cross section becomes very large as in the trunk and chest. However, depending on the path of the current, profound myocardial and central-nervous-system effects may be seen despite the absence of thermal damage. Cardiac arrest and temporary respiratory paralysis remain the most likely causes of death at the scene of the accident.
One further special characteristic of high-tension conductive damage is major-vessel injury. Since major vessels are also damaged by the initial passage of current, further progress of ischemic change or late hemorrhage may occur if they become thrombosed or degenerate, further complicating the clinical situation.
More heat is dissipated by the larger arteries than the smaller nutrient muscular branches, which are more prone to thrombosis and progressive ischemic muscular damage days after injury4.
Literature and Present Series
Several series in the past 10 years have reported data concerning high-tension injury. While the authors vary considerably in their experience, because of such factors as the nature of their institutions and patient populations, the figures give some guidelines.
Combined figures from several series indicate the overall mortality of high-tension injuries to be about 7 per cent, with reports varying from 0 per cent to 18 per cent mortality. With respect to major amputations (see Table 1. ), it is possible to extract data from several series which indicate that the crude rate for major amputation (excluding digits) runs around 43 per cent average for all series. Of 118 patients who had either arm or leg amputation out of 272 reported injuries, there were 130 amputations. The majority of these were in the upper extremities--69 per cent versus 31 per cent lower extremity--probably reflecting the manner in which the patients were injured and the intensity of the wounds of entrance, which were predominantly in the upper extremity. In those series where the data were separately reported, about 85 per cent of the wounds of entrance were in the upper extremity, while about 85 per cent of the wounds of exit were in the lower extremity and other sites1,9. Table 2. gives the data from the literature on upper-extremity amputations and high-tension injuries. About half of the reported cases required amputation somewhere in the forearm while the other half were either the hand or above the elbow, with a substantial majority requiring shoulder disarticulation as a result of the injury.
Our experience derives from treating 34 children at the Shriner's Burns Institute in Boston from 1969 through April 1979. These children ranged in age from 7 to 16 years and were almost exclusively males (33 males and one female). Fourteen of these children had only thermal or ignition burns, while 20 children
had deep conductive injuries of the type described above. There were two deaths, both from uncontrolled sepsis, for a mortality rate of 6 per cent. The 14 children with only surface burns had fairly large average body surface area burns of 35 per cent (varying from 3 per cent to 80 per cent) and no amputations at all. By contrast, the 20 children with deep conductive injuries sustained much more limited average body surface area burns of 17 per cent, and this group included four children with major associated ignition injuries from 30 per cent to 60 per cent body surface area. In addition, 14 of these children were rendered unconscious by their injuries and sustained falls, producing four major associated injuries
(epidural hematoma, ruptured spleen, pneumothorax, and fractured pelvis). With respect to major amputations, 12 of our children (60 per cent) had 16 major limb amputations. The distribution between upper and lower extremity is much as reported in other series, with the majority being somewhere in the upper limb (75 per cent upper-limb amputations versus 25 per cent lower-limb amputations). In addition, we have had four other major incisions involving the skull, chest wall, and in two cases, the genitalia.
In summarizing the data from other series, as well as our own, one can arrive at a reasonable characterization of the electrically burned patient. In general he is male and is a young person, usually around the age of 30 years. He will be a competent or working individual, as opposed to the experience in surface thermal burn injury where the patients tend to be either incompetent and elderly or very young children unable to fend for themselves. In addition he will have a major conductive injury to the upper extremity with a limited body surface thermal component, and may very well come to one or more major amputations.
With regard to the clinical management of patients, there are a variety of general and resuscitative problems which are obviously important and complicated but which are beyond the scope of this discussion. Once the patient's wound has been assessed, the operative management of these injuries falls into two parts: the primary operation and subsequent operations.
Following stabilization of the patient and general resuscitation, the primary operation is carried out. The objective of this procedure in managing the high-tension wound is early removal of the dead and necrotic tissue, with prompt closure of the wound by direct suture, graft, or flap. This is a straightforward objective which applies to most burns, but timing is all important in its attainment. Any areas of constricting full-thickness injury should be released immediately by escharotomy, using longitudinal excisions through the insensate destroyed tissue. Rapid swelling, impaired circulation, and excessive resuscitative fluid requirement are indications for early exploration, fasciotomy of all muscle compartments, and wide debridement of all devitalized tissue. When debridement is initially complete, major vessels, tendons, and nerves should be covered with viable tissue.
Following the initial operation, several further debridements may be necessary because of progressive ischemic necrosis and muscle loss. The object of the subsequent operations is the continued removal of dead tissue until a completely viable wound is obtained. Frozen sections are helpful in deciding as to marginal tissue, since the gross appearance at operation may be deceptive because the blood in devitalized muscle becomes oxygenated upon exposure to air and changes the cyanotic appearance to a fairly normal color5. Amputations are carried out when necessary during these subsequent debridements, and the wounds are gradually closed by appropriate means.
With specific reference to amputation in children with high-tension injury, there are several considerations: level and decision, healing and coverage, and late problems.
Level of amputation is determined as often as not by the nature and extent of the injury, leaving little choice for maintaining optimal length. Too often in the initial or secondary operation we feel we have maintained excellent length, only to find that subsequently with progressive necrosis the stump length shortens to less than desirable. The decision for amputation is made either preoperatively in the case of obviously destroyed extremities, or intraoperatively when further exploration reveals irreparably damaged muscle and bone requiring removal. Exploration must be carried out in these extremities until normal tissue is found. In our experience, indications for amputation of the upper extremity usually have been clear within two or three days of injury. But in those four children requiring below-knee amputation, 10 to 14 days were required before the extent of ischemic necrosis was sufficiently clear to permit a secure decision about amputation. Occasionally it is necessary to perform double amputations because of bilateral
injury or equally serious entry and exit wounds. DiVencenti reported incidence of 21 per cent bilateral-extremity amputations in the Brooke Army report of 19692. In our own series we have had two of our patients undergo bilateral upper-arm amputations, and two others who had a combination of a near total upper-arm amputation coupled with a below-knee amputation.
As far as healing and coverage are concerned, we try to achieve a closed wound as early as possible to avoid invasive sepsis. This closure is done as simply as possible by either direct suture, local flap, or free grafting. In this series we have used a distant flap for wound closure in only one patient. Not infrequently amputations must be done through limbs with severe proximal damage with large open wounds. These wounds should be gradually closed with simple split-thickness skin grafting as indicated by the condition of the wound and the patient. It is common observation in these wounds that the grafted areas will shrink down considerably by the process of wound contraction in subsequent months. It has been our usual experience that even forbiddingly large wounds associated with arm amputations can be rapidly closed by simple grafting, with a full expectation that with subsequent contraction and narrowing of the wound, normal durable tissue will be brought around into the area of prosthesis bearing. When possible, local flaps are used to cover amputation ends. Usually volar damage is a good deal worse than dorsal injury in high-tension electrical injury, and frequently good viable dorsal flaps can be employed to give good end coverage on the stump.
Late problems may occur in these children, including questions of durability of skin cover, mobility of proximal joints, and peculiarities of prosthesis fitting and acceptance. There have been surprisingly few problems with breakdown of the skin on the stumps of these patients. Only three of our children have developed significant stump sores requiring minor revisions. Such unstable areas are usually at the site of a joint between two skin grafts or in areas that have been permitted to heal secondarily, leaving unstable scar. It is not surprising that some degree of breakdown occurs, considering the amount of proximal thermal damage that is seen in these extremities. Three of our children have developed significant limitation of motion of the joints proximal to amputation. This limitation was undoubtedly caused by partial damage of the joint structures by the initial injury, as well as the effects of prolonged healing and disuse, coupled with the loss of certain muscle groups. In each case, closed manipulation has significantly increased the range of motion of the joint in question.
- Burke, J. F., et al., Patterns of high tension electrical injury in children and adolescents and their management. Amer J Surg, 133:492, 1977.
- DiVencenti, F., et al., Electrical burns: a review of 65 cases. J Trauma, 9:497, 1969.
- Hartford, C. E., and S. E. Zifferen, Electrical injury. J Trauma, 11:331, 1971.
- Hunt, J. L., et al., Vascular lesions in acute electrical injuries. J Trauma, 14:461, 1974.
- Quinby, W. C., et al. The use of microscopy as a guide to primary excision of high tension electrical burns. J. Trauma, 18:423, 1978.
- Rouse, R., and A. R. Dimick. The treatment of electrical injury compared to burn injury. J Trauma, 18:43, 1978.
- Salisbury, R. E., et al., Management of electrical burns of the upper extremity. Plast Reconstr Surg, 51:648, 1973.
- Sinha, J. K., Electrical burns: a review of 80 cases. Burns, 4:261--266, 1978.
- Solem, L., et al., The natural history of electrical injury. J Trauma, 17:487, 1977.