Manmade Electric Current

Both V-Tach and ventricular ectopy can be the result of low and high current electrical shocks. Lower current is more likely to lead to VF, while higher current is more likely to cause asystole. Additionally, patients may develop spasms of the coronary arteries and subsequently decreased perfusion, myocardial cell rupture, and muscular tetany. These injuries can lead to longer-lasting cardiac dysfunction.   

Electric injury to the brain can lead to respiratory arrest secondary to respiratory muscle contraction, paralysis, and brain ischemia secondary to cardiac arrest. Patients can present with altered consciousness and coma due to peripheral nerve injury. This respiratory dysfunction can continue following ROSC. 

There are additional complications secondary to damage to internal organs, muscles, and joints. Patients can present with fractures or joint dislocation due to intense muscle contractions and falls. Renal failure secondary to muscle injury induced rhabdomyolysis can also occur. Perfusion complications from vascular injury and hypovolemia can lead to ischemic injury. 

The effect of electrical shock on the cell is less clear. Research from molecular biology gives some insight as the process of electroporation shows that when electrical energy is applied to cell membranes, there is a transient increase in permeability and conductivity. This allows certain molecules to enter the cell; however, the cell will reseal soon after that with no significant long-term injury if the right conditions are met. 

Lightning

Death from lightning is usually secondary to cardiac arrest. Cardiac arrest may be secondary to either asystole or to VF. The high current of lightning causes sudden and simultaneous depolarization of all of the myocardium. Sometimes, automaticity occurs spontaneously, and a perfusing and organized rhythm restarts. This is a common cause of survival following this event. Lightning energy can lead to widespread catecholamine release that can cause tachycardia, hypertension, and ECG abnormalities (i.e., inverted T waves, prolonged QT interval), if cardiac arrest does not occur. Additionally, necrosis of the myocardium can occur with an associated increase in cardiac biomarkers. There may be direct alterations to the nodal centers of the heart and conduction pathways that cause further damage. 

Patients are also at risk for sudden respiratory arrest that can lead to secondary cardiac arrest secondary to hypoxia. The etiology might be to damage the respiratory center of the medulla or prolonged tetany or paralysis of the respiratory muscles. Neurologic injury can be caused by direct damage to the brain or secondary effects of hypoxia or hypoperfusion. Direct injury may lead to cerebral hemorrhage, edema as well as neuron or small vessel disease.  Types of lightning injuries:

• Direct strike: this occurs in under 10% of cases
• Side flash: The patient is next to a directly hit object, and some of the current jumps to the patient. This occurs in 25-40% of cases. 
• Contact voltage: The patient is in contact with a directly hit object and absorbs some of the current. This occurs in 3-10% of cases.
• Ground current: the patient absorbs the current that extends radially from an object on the ground that is directly hit. This occurs in 30-60% of cases.
• Upward streamer: the thundercloud’s electrical field produces opposite charges that can pass through the patient, causing harm. This occurs in 10-25% of cases.

Types of Lightning Injuries

Importantly no one type of injury is more likely to cause serious morbidity or mortality. As lightning is a complex natural phenomenon and is a source of current (not voltage as with manmade electricity), the outcomes are not as easy to predict.