Lightning is a massive electrostatic discharge caused by an imbalance of electrical charge in the atmosphere.  Lightning strikes though rare are believed to be the second leading cause of weather related deaths in the developed world with a mortality rate of between 10 and 30 percent.  See Casualty Care in Mountain Rescue for further details.

A lightning storm is a dangerous, fast moving and unpredicatble event, remember that team safety is always paramount, there are no safe locations outdoors during a thunderstorm.  Being crude Faraday cages vehicles offer the best protection.

If no vehicle is available to shelter in, try to minimise the risk of being struck by avoiding:

• Summits and ridges

• Single trees

• Sheltering under overhangs

• Stream beds

• Power lines

• Walls

• Groups of people should spread out if outside during a thunderstorm.

According to the Mountaineering Council of Scotland: A walking party sitting out a lightning storm should ideally crouch or sit upright on top of insulating material such as rucksacks and sleeping mats. Hands should be kept on knees rather than touching the ground.

Metal items of equipment do not significantly increase the risk of attracting a strike, but if they start to hum and spark, it would be wise to accept the hint and lay them to one side until the storm passes.

A projection such as a pinnacle or post acts as a lightning conductor that services an area with a radius corresponding approximately to its own height. This means that the area within this circumference is a relatively safe place to wait because the projection will deflect lightning strikes onto itself. However do not shelter below trees, they can channel the strike into the area below as happened to these cows.

Lightning Can Strike In Several Ways

People can be struck in different types of ways, how they are struck affects the location and type of injuries they suffer.

The types are:

• Direct strikes

• Contact injury

• Current spread

Direct strikes are where the lightning hits the person directly and discharges it’s current through them into the earth. Though rare accounting for 3-5% of lightning strike injuries, direct strikes are extremely violent events and often prove fatal.

Contact injury is where the casualty was touching an object when it was hit and the object transfers some of the current it receives to the casualty.  An example the team has come across previously is someone who was touching a fence when it was hit by lightning.  Contact injury is even rarer than direct strikes accounting for just 1-2% of lightning strike injuries and tend to involve serious or fatal injury. The picture on the right shows cows killed when a fence was hit by lightning.

Current spread or splash is the most common way for people to be injured by a lightning strike. It accounts for around 90% of injuries and is where the current either jumps from a nearby object or passes through the ground from a nearby strike into the casualty. The picture on the right shows how the energy from a strike has spread out through the ground.

People who are close to the location of a strike, can also receive blast injuries from the shock wave which can cause hearing damage and blunt trauma if the casualty is thrown to the ground.

Most indirect strikes are not fatal, people who are stunned or lose consciousness without experiencing a cardiorespiratory arrest are unlikely to die (unless they suffer significant concomitant blunt trauma), but are likely to suffer serious injuries.

18 seconds into the the video below lightning strikes the pitch off camera and the current transfers through the wet grass causing several players to collapse even though they were not hit directly.

Lightning Causes Injuries In Several Ways

Depending upon how the casualty was struck, injuries can be caused by:

• High voltage delivered in a few milliseconds

• Heat production

• Explosive force (the shock wave from the strike)

Which can lead to:

• Cardiac arrest

• Respiratory arrest

• Burns

• Neurological problems

• Temporary paralysis of the lower limbs

• Ruptured ear drums

• Organ damage (longer term)

• Injuries from blunt trauma including, fractures, head and spinal injuries.

Triage

If people stay in groups it is relatively common for a single strike to affect two or more people simultaneously.  Contrary to our normal triage priorities, in the case of lightning strikes we reverse the order of priority and attempt to resuscitate the apparently dead first.  This is because almost all people with signs of life will recover without intervention and there is a substantial chance the apparently dead will recover if given immediate cardiorespiratory support so contrary to normal triage rules, resuscitate the apparently dead first.  

Cardiovascular Problems

The high voltage delivered in a lightning strike can act as a massive defibrillation.  This can cause immediate death, cardiac arrest, respiratory arrest or ECG changes signifying normal cardiac function has been disrupted or the heart muscle damaged.

The high current can cause respiratory arrest and cardiac arrest.

The treatment of cardiac arrest following a lightning strike is generally the sames as other arrests. Early defibrilation, high quality continuous CPR, good ventilation using an i-gel or bag valve mask and rapid evacuation are the key to survival. See Cardiac Arrest and Resuscitation for details on the assessment and treatment of cardiac arrest.

There are however some special considerations when treating a lightning strike induced cardiac arrest:

• Cardiac function may spontaneously return after asystole if ventilation is maintained.

• Prolonged respiratory support may be required following a cardiac arrest as respiratory arrest often outlasts the period of cardiac arrest.

• Victims of lightning strike can tolerate prolonged periods of resuscitation and still survive with a good outcome.
   

Respiratory Arrest

It is possible for people hit by lightning to have a respiratory arrest only, where they stop breathing, but the heart continues beat. During the respiratory arrest, the brain is starved of oxygen.  Oxygen starvation is the greatest killer.

If the casualty has a cardiac rhythm, but is not breathing they should only require respiratory support to prevent the occurrence of a hypoxic cardiac arrest. If supported using a bag-valve-mask or an i-gel and bag-valve, preferably with high flow oxygen their cardiac function should return spontaneously.

See Breathing for details on assisting breathing.

Neurological Complications

High voltage passing through the body will normally produce complications in the nervous system. These symptoms will present immediate and are often dramatic, but should pass and as such are largely benign.

Immediate transient symptoms include:

• Weakness and paresthesia (pins & needles).  Studies indicate this occurs in 80% of patients

• Brief loss of consciousness (this occurs in 75% of patients)

• Amnesia (memory loss)

• Confusion

• Headache

• Deafness

• Blindness

• A temporary paralysis called keraunoparalysis which only occurs in to lightning strike patients. The paralysis affects lower limbs more than upper limbs and is accompanied by sensory loss, pallor, vasoconstriction, and hypertension

Some other neurological problems can also occur and may be prolonged or permanent. These include:

• Personality changes

• Seizures

• Deafness

• Blindness

• Chronic pain

• Brain haemorrhage

• Blood pressure instability

• Post traumatic stress (will not present on the hill)

• Motor neurons disease (will not present on the hill)

• Movement disorders (will not present on the hill)

Burns

Lightning can cause two types of burns depending upon how it grounds from the body to the earth.

If the bodies resistance is sufficient, a high voltage may build and ‘flash’ around the skin or clothing to the ground. This ruptures small capillaries under the skin leaving Lichtenburg figures or lightning flowers (seen to the right). These may last for days or hours, tend to be superficial and not to be particularly serious.  More conventional superficial burns may also be seen following flash over and are of more concern.

More serious full thickness burns can also be cause by the heat from a lightning bolt itself which can approach 28,000°C or about five times hotter than the surface of the sun for a split second.

Injuries tend to be found where lightning has hit the casualty on or around the head, neck or shoulders.  Injuries can also occur in the lower limbs due to the splash effect from nearby ground strikes or where lightning exits the body.  These entry and exit points can have full thickness burn and should be assessed and treated accordingly. Although the affects usually become apparent too late to be seen on the hill, organs may be damaged at these points.

See burns for details on assessment and treatment.

Concussive Injury

The rapid expansion of air surrounding the path of a lightning bolt causes an explosive shock wave (this is the cause of thunder). At close range this shock wave can cause concussion, damage to the eyes and auditory injury such as burst ear drums.

Traumatic Injuries

A lightning strike can cause object or people (through their muscles involuntarily contracting) to be thrown, potentially causing traumatic blunt force injuries.

Access and treat as any other traumatic injuries using the primary and secondary survey approach. Because of mechanism of injury be vigilant for spine and head injuries.