Koller J, OrsAg M, GrOinger L, KvaMni K, Ondrias'ovA E.

SUMMARY. Twenty-one patients with electrical burns due to railway overhead cables were treated at the Bratislava Bums Department over a period of three years. All the injuries occurred with the same mechanism - climbing on top of railway carriages and approaching the 25,000 V a.c. overhead cables. The cutaneous bums, ranging from 18 to 79% BSA, were mostly deep partial- to full-thickness injuries. Exceptionally, deep structures were involved in small areas of electrocution. The age range of the patients was from 9 to 41 years. Six of' the patients were adults and the remaining 18 were under 18 years of age. Two patients, a 14-year-old boy and an 18-year-old man, died respectively on days 5 and 9 post-burn. No amputations were necessary. ne pathophysiology and possible preventive measures are discussed. It must be stressed that arcing can be induced by an earthed moving object simply by approaching, and not necessarily touching, a cable carrying high voltage.

Electrical injury occurs infrequently and presents many unique and complex problems to the physician. It constitutes about 5% of all burn admission to our Burns Department.
Electrical injuries can be categorized into flash burns, are burns, and true or direct electrical burns. Flash burns result from the effect of heat from electrical flash on uncovered parts of the body, and may also ignite the victim's clothes. Arc burns are produced by short circuiting of high currents which pass externally to the body. True or direct electrical injuries occur when the body becomes part of the electrical circuit. Characteristic features of these injuries are the entrance and exit wounds. The degree of tissue damage is proportional to the intensity of current, as stated in Ohm's Law.

During the last three years 24 patients who suffered injuries from railway overhead cables were treated at the Bratislava Burns Department.
Throughout the Bratislava region the railway is supplied by overhead cables carrying 25,000 V a.c. All 24 victims tried to climb on top of railway carriages (Fig. 1). Close approach to the live overhead cables caused arcing to occur, thereby causing severe burn injuries. All the victims but two fell to the ground from heights ranging from 2.5 to 4 in. Two victims remained lying on the roofs of carriages. In eight cases the victims' clothing caught fire and burned off.
All the victims but one were males (Tab. 1). The sole female in the series was a 15-year-old high-school student. Fourteen of the 24 patients were boys between 9 and 15 years old (Tab. 2).
Only two of the accidents were work-related. Sixteen accidents occurred during play within the station area and five in connection with alcohol abuse.
Sixteen patients were treated primarily at our department, while the remaining eight were initially treated at local hospitals and transferred on days I to 4 post-burn to our department. All the patients received the standard resuscitation treatment regimen according to the Parkland formula. Early excision of deep anaesthefic bums was carried out on days 2 or 3 post-bum, and the excised areas were covered with auto
grafts, when available, and allografts, which were later replaced by autografts. In extensive burns several excision and transplantation procedures were performed 3 to 5 days apart until complete coverage of the wounds was achieved. The extent of cutaneous burns varied between 24 and 79% BSA, while the extent of full-thickness burns was between 2 and 70% BSA. The mean BSA burned was 53.08%, the mean full-thickness loss representing 27.28%.

Pt. = patient; BSA = body surface area; Adm. = admission; pbd. = post-burn day; inj. = injury; Oper. = operations; Complic. = complications; Heal. = healing; RD,' = respiratory distress syndrome; GI = gastrointestinal; cel.im.d. = cellular immunity deficiency; inf. = infection; Cont.cer. = cerebral contusion; SAB = subarachnoi dal bleeding; lac. = laceration; Fx = fracture; pr. = processus; tr. = transversus; surv. = survived.

Two patients died as a cQnsequence of their injuries. One of these was a 14-year-old boy with 79% BSA burns and 70% full-thickness loss, with inhalation injury, who died 5 days after the accident owing to respiratory failure. The other fatal case was a 20-year-old male with 54.5% BSA burns and 47.5% full-thickness loss, with associated cerebral contusion, subarachnoidal haematoma and frontal laceration, who died on day 7 post-burn from ARDS and resulting respiratory failure.

The depth of the burns varied from deep partial-thickness to full-thickness injuries, reaching down to the deep fascia in some patients.

In five patients other concomitant injuries were observed (Tab. 4). The most severe injury was a subarachnoidal haematoma.
The complication rate was appropriate to the type of the injury (Tab. 5). The most frequent complication was delayed healing (7 cases) and local infection and sepsis (4 cases). In one patient complete unilateral blindness with atrophy of the optical nerve occurred, without any apparent direct damage to the globe or face. Delayed spinal cord damage developed in a 17-year-old boy with a 24% BSA burn. This condition presented itself as a T4-6 level motor paraparesis with no sensory loss beginning 3 weeks post-bum. Recovery from the paresis was very slow, taking several months.

All the patients but one underwent surgery - excision of deep burns and grafting procedures. The mean number of operating procedures was 2.9 per patient. The patients' hospital stay ranged from 13 to 175 days, with a mean stay of 62 days.

Electric-arc induced thermal burns on railway lines continue to be a serious problem. Artursson (1984) reported 19 patients admitted to the Uppsala Burn Center in a period of 13 years. Reichl (1985) reported a series of nine cases occurring in the southern part of the north-west region of the UK over a period of 6 years. Our first report (Koller, 1991) included I I patients. The observations of Artursson and Reichl were very similar to ours (Tab. 6).

In the analysis of the pattern of the injuries, several factors had to be taken into account (Tab. 7). It was obvious that all the injuries were caused by high-tension electrical arc exposure to high temperatures and in some cases by ignition of clothing.
An electric are is formed between two bodies of sufficiently different potential (Nichter, 1984). In our cases the power source was the overhead cable carrying 25,000 V a.c. towards the metal parts of the carriages grounded by the rails. The temperature generated by an electrical arc can be in the range of 3,000-20,000 'C (Bingham, 1986). An important fact is that arcing will cross 2-3 cm for every 10,000 V (Skoog, 1970) so that no direct contact is necessary to trigger arcing at 25,000 V. In addition, once an electrical arc is established, it may extend over several metres (Skoog, 1970). The so-called critical distance is the distance between the power source and another grounded subject which may trigger arcing. In moving subjects, such as in our victims, the arcing can be triggered over a longer distance than in static ones.
The appearance of the cutaneous burns was variable. The burns were mostly found to be more superficial than expected in high-voltage accidents. Only in patients whose clothing was ignited were the lesions similar to other flame-type deep burns. This finding could be partially explained by the fact that in burns caused by high-tension electric arc the current travels externally to the body from the point nearest the power source to the ground by the shortest way (Lee, 1987). Circumscribed burns occur where portions of the arc contact the patient's body surface. These contact points may be multiple, single, or diffuse, and they vary in depth. The picture is somewhat different when clothing is set on fire by the intense heat of the arc. We believe that the current did not pass through the body to any significant extent because:

1. there appeared to be no direct contact between the patient and the live cable; and
2. the duration of an arc is extremely short.

At very high temperatures, extremely short thermal exposures do not transmit all their energy into the skin because of the skin's reflectance and thermal resistance (Ripple, 1990). in this context it also seems important that the victims were rapidly thrown away from the power source, thus interrupting the flow of the current before the resistance of the skin to the current could be broken down.
The explanation for the delayed spinal cord damage observed in one patient is not apparent (Koller, 1989). This may have been associated with deep burns involving a few per cent of the lower angle of the left scapula. Initially it was believed that this injury was caused solely by areinduced ignition of the clothes covering this area. The later development of paraparesis suggested the possibility of the passage of some current through the tissues adjacent to the spine. However, no current exit point could be found anywhere else on the body and surgical excision of the necrotic eschar over the lower angle of the scapula did not reveal any macroscopic damage in the deeper subcutaneous layers of tissue.
In conclusion, electrical-arc induced thermal burns from railway overhead cables continue to be a problem of considerable importance. All the injuries reported in this review were preventable.

RESUME. Pendant une période de trois ans nous avons traité chez le Centre des Brûlés de Bratislava 21 patients atteints de brûlures électriques causées par les câbles aériens ferroviaires. Toutes les lésions ont été produites par le même mécanisme - la victime est montée sur le haut d'une voiture ferroviaire et s'est approchée des câbles aériens à 25000 volts courant alternatif. Les brûlures cutanées (18 - 79% de la superficie corporelle) étaient pour la plupart des lésions profondes à épaisseur partielle ou totale. Exceptionellement, les structures profondes étaient atteintes dans des zones limitées d'électrocution. L'âge des patients variait de 9 à 41 ans. Six patients étaient des adultes et les autres 18 étaient âgés de moins de 18 ans. Deux patients, un garçon de 14 ans et un jeune homme de 18 ans, sont morts respectivement le jour 5 et le jour 8 après l'accident. Nous discutons la pathophysiologie et les mesures de prévention possibles. Nous soulignons que le phénomène de l'arc électrique peut être causé par un objet mis à la masse en mouvement qui simplement s'approche d'un câble à haute tension, même sans le toucher.

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