Electric shock
Electric shock: Excerpt from Handbook of Diseases
When an electric current passes through the body, the damage it does depends on the intensity of the current (amperes, milliamperes, or microamperes), the resistance of the tissues it passes through, the kind of current (alternating current, direct current, or mixed), and the frequency and duration of current flow.
Electric shock may cause ventricular fibrillation, respiratory paralysis, burns, and death. The prognosis depends on the site and extent of damage, the patient’s state of health, and the speed and adequacy of treatment.
Causes
Electric shock usually follows accidental contact with exposed parts of electrical appliances or wiring, but it may also result from lightning or the flash of electric arcs from high-voltage power lines or machines.
The increased use of electrical medical devices in the hospital, many of which are connected directly to the patient, has raised serious concern for electrical safety and has led to the development of electrical safety standards. However, even well-designed equipment with reliable safety features can cause electric shock if it’s mishandled. (See Preventing electric shock, page 292.)
CLINICAL TIP: Electric current can cause injury in three ways: true electrical injury as the current passes through the body, arc or flash burns from current that doesn’t pass through the body, and thermal surface burns caused by associated heat and flames.
Signs and symptoms
Severe electric shock usually causes muscle contraction, followed by unconsciousness and loss of reflex control, sometimes with respiratory paralysis (by way of prolonged contraction of respiratory muscles or a direct effect on the respiratory nerve center).
After momentary shock, hyperventilation may follow muscle contraction. Passage of even the smallest electric current — if it passes through the heart — may induce ventricular fibrillation or another arrhythmia that progresses to fibrillation or myocardial infarction.
Electric shock from a high-frequency current (which generates more heat in tissues than a low-frequency current) usually causes burns as well as local tissue coagulation and necrosis. Low-frequency currents can also cause serious burns if contact with the current is concentrated in a small area — for example, when a toddler bites into an electrical cord.
Contusions, fractures, and other injuries can result from violent muscle contractions or falls during the shock; later, the patient may develop renal shutdown. Residual hearing impairment, cataracts, and vision loss may persist after severe electric shock.
Diagnosis
Usually, the cause of electrical injuries is either obvious or suspected. An accurate history can define the voltage and length of contact.
Treatment
Immediate emergency treatment includes carefully separating the victim from the current source, quickly assessing vital functions, and instituting emergency measures, such as cardiopulmonary resuscitation (CPR) and defibrillation.
To separate the victim from the current source, immediately turn it off or unplug it. If this isn’t possible, pull the victim free with a nonconductive device, such as a loop of dry cloth or rubber, a dry rope, or a leather belt.
Emergency measures
After separating the victim from the current source, begin emergency treatment as follows:
❑ Quickly assess vital functions. If you don’t detect a pulse or breathing, start CPR at once. Continue until vital signs return or emergency help arrives with a defibrillator and other life-support equipment. Then monitor the patient’s cardiac rhythm continuously and obtain a 12-lead electrocardiogram.
❑ Because internal tissue destruction may be much greater than indicated by skin damage, give lactated Ringer’s solution I.V. to maintain a urine output of 50 to 100 ml/hour. Insert an indwelling urinary catheter, and send the first specimen to the laboratory.
❑ Measure intake and output hourly, and watch for tea- or port wine–colored urine, which occurs when coagulation necrosis and tissue ischemia liberate myoglobin and hemoglobin. These proteins can precipitate in the renal tubules, causing tubular necrosis and renal shutdown. To prevent this, give mannitol and furosemide.
Special considerations
❑ Assess the patient’s neurologic status frequently because central nervous system damage may result from ischemia or demyelination.
❑ Watch for sensorimotor deficits because a spinal cord injury may follow cord ischemia or a compression fracture.
❑ Check for neurovascular damage in the extremities by assessing peripheral pulses and capillary refill and by asking about numbness, tingling, and pain. Elevate injured extremities.
❑ Apply a temporary sterile dressing, and admit the patient for surgical debridement and observation as needed. Frequent debridement and the use of topical and systemic antibiotics can help reduce the risk of infection.
❑ Prepare the patient for grafting or, if his injuries are extreme, amputation.
❑ Protect patients from electric shock in the hospital.
❑ Tell patients how to avoid electrical hazards at home and at work. Advise parents of young children to put safety guards on all electrical outlets and keep children away from electrical devices. Warn all patients not to use electrical appliances while showering or wet.
❑ Warn patients never to touch electrical appliances while touching faucets or cold water pipes in the kitchen because these pipes commonly provide the ground for all circuits in the house.
Pictures
Book Source Details
- Book Title: Handbook of Diseases
- Author(s): Springhouse
- Year of Publication: 2003
- Copyright Details: Handbook of Diseases, Copyright © 2003 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: Handbook of Diseases
Authors: Springhouse
Publisher: Lippincott Williams & Wilkins
Copyright: 2003
ISBN: 1-58255-266-5
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