By Ruwan Laknath Jayakody
A strategy is required in order to address high tension electrocution taking place in workplaces and to prevent casualties resulting from such, a recent local study noted.
Workplace high tension electrocution takes place due to direct contact with the power source or arcing, the latter which has both high temperature (thermal) and explosive effects. The resultant injuries include electric shock, burns as a result of the current passing through the body, arc and flash burns (due to thermal radiation and intense heat), contact burns (through heated objects), flame burns, thermal injuries, and burns due to secondary fire effects such as the conflagration of clothing. In turn, the clinical outcomes include the amputation of the upper limbs, instant death, or delayed death with multiple neurological complications.
Injuries caused by high voltage electricity current, are usually self-evident with the history and examination findings; the latter includes scene investigations whenever possible, and therefore, injury interpretation by the treating doctor (familiarity with the mechanisms of injury is needed in order to be able to substantially lessen morbidity and mortality) would be useful in the injury management plan while injury interpretation by the forensic pathologist (whose duty it is to also help the authorities ascertain the manner and cause of death [accidental, homicidal, or suicide] when compensation issues arise in the occupational setting) would be useful in order to reconstruct the incident or to advice the general public and all stakeholders accordingly, so that prevention can be the treatment of choice for electrical injuries.
These proposals were put forward by H.T.D.W. Ariyarathna (attached to the Department of Forensic Medicine of the Faculty of Medical Sciences of the University of Sri Jayewardenepura) in a case report titled “High tension electric trauma at workplaces in Sri Lanka” which was published recently in the Sri Lanka Journal of Forensic Medicine, Science, and Law.
A voltage of over 1,000 volts is considered as high voltage. According to Ariyarathna, occupational fatalities due to high tension electric current are reported occasionally. Although it was not specified as to whether the fatalities were due to high or low voltage electricity, in 2019, the Public Utilities Commission recorded 103 fatalities due to electrocution.
As explained by Ariyarathna, since 2017, regulations to minimise the effects caused by high tension electrocution stipulate a minimum gap between the power lines and the buildings or the construction sites and furthermore, a certificate of safety clearance is required to be obtained, indicating that there is a safe range both in vertical and horizontal gaps when constructing buildings near power lines. For power lines up to 1,000 volts, the minimum vertical gap is 2.4 metres and the horizontal gap of 1.5 metres, with the distance increasing up to 5.18 metres in the case of high voltage lines up to 2,220,000 volts.
Case 1
A young male was carrying several metal pipes up a staircase from the second to the third floor in a building which was situated close to high tension electric lines. The staircase also faced the power lines.
While carrying the pipes, he suddenly felt as if someone was pulling hard on the metal pipes. He was unable to drop them from his grip and he was jerked by the electricity current gushing through the pipes along with electric sparks and a sudden burst followed by flames. The electrical engineer involved in the scene investigation found that the metal pipes had trespassed the minimum power line clearance safety region, thereby causing arcing and flashing.
He sustained multiple burn injuries including third degree burns, and multiple superficial burns on the lower limbs and a patterned burn on the right armpit, suggestive of contact with a heated object.
Both his hands were amputated from the mid forearm level due to gangrene, following compartment syndrome (increased pressure within an anatomical compartment results in insufficient blood supply to tissue
within that space). During his stay in the ward, he developed rhabdomyolysis (the death of muscle fibres and the release of their contents into the bloodstream). He experienced coagulopathy (impairment of the blood clotting ability) due to the extreme tissue damage. He suffered vascular injury too.
“In this case, the burns are due to the effects of flash by secondary conflagration and by arcing. The victim had experienced a tetanic effect (sustained muscle contraction evoked when the motor nerve that innervates a skeletal muscle emits action potentials at a very high rate). The indefinite refractory state of the neuromuscular junction causes tetanic contractions, resulting in a ‘locking on phenomenon’, thereby preventing the victim from voluntary muscle function. This phenomenon is mostly applicable to low voltage current though its occurrence is not impossible due to high voltage current. In high voltages, the throwing down effect is the one that is typically described (‘Electrical Injuries’ by M.R. Zemaitis, L.A. Foris, R.A. Lopez, and M.R. Huecker),” Ariyarathna explained.
Case 2
The deceased was a work assistant installing a transformer. At the time of his death, he was holding onto the side mirror of a crane, whilst the crane operator was lifting a transformer with the arm of the crane. A sudden large explosion like noise was heard with sparks and flames and the victim was thrown on the ground. The crane operator too was thrown out of the crane onto the ground, sustaining minor injuries due to the fall. The driver too claimed to have felt an electric shock. There were electric energy entry wounds on the assistant’s right hand due to contact with the crane (the palm and fingers of the right hand had multiple contact wounds [Joule burns] depicting the shape of the object he was holding at the time) and multiple exit wounds on his lower limbs despite safety shoes (on the soles of the feet).
“In this case, the arm of the crane had accidently come into contact with the overhead high tension line. The helper who was standing on the floor suffered fatal electrocution as the current was earthed through him. Due to the high voltage current, the shoes were not effective in order to prevent electrocution. The tires of the crane were made of rubber and that probably explains the circuit not having completed through the driver. As G. Parvathy, C.V. Shaji, K.A. Kabeer, and S.R. Prasanth noted in ‘High voltage electrocution causing bulbar dysfunction’, low voltage current usually passes through the path of lowest resistance while high voltage current passes through the shortest path, irrespective of the tissue type, through the body. Usually, in low voltage electrocution, as noted by G. Manigandan, S. Peranantham, and K. Shanmugam in ‘Fatal High Voltage Accidental Electrocution – Two Case Reports’, ventricular fibrillation (abnormal heart rhythm in which the ventricles of the heart quiver instead of pumping normally) is the result, whereas in high voltage electrocution, the mechanism is likely to be ventricular arrest, resulting in sudden death. Poor knowledge and negligence on the part of the driver of the crane caused the death of his assistant,” Ariyarathna elaborated.
Case 3
A plumber climbed onto the roof of a three-storey building to inspect a water tank. Suddenly, a huge noise and a ball of fire appeared from the overhead high tension lines and instantly set his clothes on fire. The plumber was thrown away and sustained significant burns. Considerable flame burns and thermal damage were found. It was evident that the electricity current had entered his body. Exit wounds were seen on both soles. He was found unconscious and remained so for 36 hours. He was managed in a ward for 60 days since he had 26% deep burns involving the face, the back of the chest, and upper and lower limbs. He was quadriplegic thereafter. He had infected burns which needed to be managed. He was discharged two months after in-ward treatment. However, he had been re-admitted five days later with complaints of high fever and sudden onset total blindness. On this second admission, he was diagnosed with bilateral occipital lobe (visual processing centre of the brain containing the majority of the anatomical region of the visual cortex) infarction (necrosis), frontal lobe infarct, moderate global ischemia (blood flow to brain reduced), and sepsis. The patient died two days after the second admission. The post mortem examination revealed few decubitus ulcers (open skin wounds which are pressure ulcers) on the back and bilateral pneumonic changes and gangrene of the right toes. The cause of death was concluded as sepsis. The arc effect was the cause of the injuries sustained. Upon the site visit by engineers of the Ceylon Electricity Board, the cause of death was concluded as accidental.
“The loss of consciousness and quadriplegia indicated the immediate involvement of the central nervous system. The instant quadriplegia was due to the electro thermal effects on the spinal cord. ‘An Unusual Cervical Injury Caused by Accidental Electrical Burns’ by A. Mosbahi, W. Majdoub, B. Sriha, and E. Turki, ‘Cerebral Corticospinal (motor pathway that carries information from the cerebral cortex to the spinal cord) Tract Injury Resulting from High Voltage Electrical Shock’ by C.K. Johansen, K.M. Welker, E.P. Lindell, and G.W. Petty, and ‘Cervical myelopathy (injury to the spinal cord due to severe compression) after high voltage electrical burn of the head: Report of an unusual case’ by S.R. Sharma, M. Hussain, and H. Hibong state that there could be delayed onset diaphragm nerve paralysis, electrical cataract, and quadriplegia upon high tension electrocution. Blindness may be explained by occipital infarctions due to thrombosis (blood clot forming) of already damaged blood vessels with embolisation (the passage and lodging of an embolus [an unattached mass travelling through the bloodstream and capable of creating blockages] within the bloodstream due to high tension electrocution. The deceased had not thought of the immediate danger of arcing from the high tension electric line above, while climbing up to the water tank. If he was educated about the danger, he could have made some alternative arrangements,” Ariyarathna pointed out.
Distinguishing injuries
High tension electric energy, as mentioned by Ariyarathna, causes many hazardous effects depending on the circumstance, including electrocution, electric shock, arc flash and arc blast, flame and explosions, and burn injuries caused by flame, flash, arc, heat, or a combination thereof. “The effects of high tension current may be immediate or delayed, and transient or permanent. The resultant damage may be due to true or direct electrical injuries or indirect electrical injuries. In true electrical injuries, the victims themselves become a part of the electrical circuit along with entry and exit. However, such injuries may not be recognisable at times because of overwhelming burns,” Ariyarathna further explained.
Whereas, in indirect electrical injuries, as noted by A. Patel and R. Lo in “Electric injury with cerebral venous (vein) thrombosis. Case report and review of the literature”, a direct contact is not required as the generated current is delivered to the person from the source, through an electrical arc, before actual physical contact is made. “When a body becomes a part of the electrical circuit, it makes a reflex response with an entry or exit point and it is loosely named as shock. If such an entry brings about the death of a person it is termed as electrocution. When high voltage current ionises the surrounding gases, the current passes through this medium which was previously non-conductive. Such current has the highest current density and is often luminous, forming an electrical arc. When an electric conductor is in close proximity to a human being, such a current can enter the body, resulting in electrocution. Such arcs have the potential of causing electro thermal flash or flame burns and arching electrical burns. Flash injuries only occur when electrical energy travels through the skin. Such arcs and flashes give rise to thermal radiation (heat) and intense light, causing burns. The temperature as noted by Zemaitis et al., may rise to as high as 50,000 Celsius and the rapidly heating air causes pressure waves and in turn creates a blast as well. By catching on clothes, it gives rise to flame burns as a secondary flame and burn,” Ariyarathna elaborated.
The nervous system, Ariyarathna noted, is the most vulnerable to damage by electric current because of its least resistance, resulting in a high frequency of neurological findings. “The passage of electricity through the nervous system facilitates the degeneration of myelin (insulating layer or sheath that forms around nerves) and also causes endothelial (cells which form the barrier between vessels and tissue and control the flow of substances and fluid into and out of a tissue) damage of vessels which favour microvascular thrombosis, thus impairing the arterial blood supply,” Ariyarathna explained further. The delayed onset neurological damage is, according to A.D. Reisner’s “Possible mechanisms for delayed neurological damage in lightning and electrical injury”, due to the combined effects of gradual nerve ischemia (restriction in the blood supply to tissues, thus causing a shortage of oxygen that is needed for cellular metabolism, to keep tissue alive) secondary to vascular damage and due to the effects of the hyper-stimulation of neurons.
Although the pattern of injuries sustained were different in each of the cases, they shared a few points in common such as the fact that all the victims were male and were the breadwinners of their respective families and died or sustained injuries as a result of their occupations.
A significant amount of workplace accidents are theoretically assumed to be preventable if the workers are provided with proper guidance by using risk indicators such as minimal vertical and horizontal distances from high tension electric wires at least in urban areas, Ariyarathna emphasised. A significant influence towards minimising such incidents can therefore be made, Ariyarathna observed, if awareness is raised among workers and they are made to understand the dangers of and the injuries that they could sustain from working in such high-risk environments, sans adequate protection.
Strategy needed to prevent workplace high tension electrocution: Study
01 Jun 2021
Strategy needed to prevent workplace high tension electrocution: Study
01 Jun 2021