Electric current in human body • heart • muscles • brain • threshold of perception • let-go current • ventricular fibrillation (pacemaker with defibrillaror)
How can we calculate the value of the current flowing through any circuit?
Body resistance • in ohms/cm2 • resistance of dry, well-keratinized, intact skin averages 20,000 to 30,000 ohms/cm2 • for a thickly calloused palm or sole, it may be 2 to 3 million ohms/cm2 • resistance of moist, thin skin is about 500 ohms/cm2 • if the skin is punctured (e.g., from a cut or abrasion or by a needle) or if current is applied to moist mucous membranes (e.g., mouth, rectum, vagina), resistance may be as low as 200 to 300
heat = amperage2 × resistance× time Q = I2 . R. t
Symptoms and signs • depend on the pathway of electric current • from arm to arm • from arm to foot • conduction between legs or leg and the ground • electrical injuries to the head • in Czech republic in half of electric injuries at home children under 5 y are insulted • high voltage vs. low voltage injuries (special category bathtub accidents)
Ligthning injury • Neuropsychologic damage, pain syndromes, and sympathetic nervous system damage are the most common long-term sequelae. • Cardiopulmonary arrest is the most common cause of death.
Hypotension, fluid and electrolyte disturbances, and severe myoglobinuria may cause acute renal failure. Dislocations, vertebral or other fractures, blunt injuries, and loss of consciousness may result from powerful muscle contractions or falls secondary to the electric shock (eg, electricity can startle a person, causing a fall).
Treatment • separating the patient from the current source • rapid cardiopulmonary resuscitation (ABC) • care in hospital
ECG cardiac enzymes urinalysis, especially for myoglobin cardiac monitoring for 12 h CT or MRI scan to rule out intracranial hemorrhage. Baseline assessment for all electric injuries
If myoglobinuria is present, fluid replacement and alkalinization therapy is essential to reduce the risk of renal tubular myoglobin precipitation.Mannitol or furosemide may be indicated to increase renal flow
Victims of lightning injuries Fluid restriction is the rule because of potential brain edema.
Prevention • respect in dealing with electricity • proper design, installation and maintenance of all electric devices • education and care about children