Burns: What to Expect When You’re on Fire

March 26, 2013

As an engineer, you may work in the most interesting and dangerous situations in the modern world. Fires, explosions, and high-voltage electricity are tools of the trade. Implementing and refining safety procedures reduced workplace fatalities by more than 90% over the last century, but they do still occur.

What happens when accidents happen? What should you expect when you catch fire?

First things first:  EngineerJobs is not qualified to offer medical advice and we don’t claim to be. Our job is to inform and entertain readers, not to diagnose or treat patients. If you or a colleague are on fire, injured, or otherwise in need of medical attention, please close your browser window and contact emergency medical personnel.


How Bad is It?

The severity of a burn depends on the depth of damage to the skin; the deeper the damage, the worse the burn. We used describe burns by degrees, with first being the mildest (sunburn) and fourth the most severe (charcoal). Medical professionals now grade burns in terms of ‘thickness’, which is more straightforward. The three classes of burn under this system are superficial, partial thickness, and full thickness injuries to the skin.

Your skin is a complex organ with a number of tasks to perform, but for this discussion we’ll limit ourselves to three layers of skin and three critical functions. Our model skin is composed of epidermis, dermis, and subcutaneous layers, and its tasks are to prevent infection, maintain body temperature, and keep the body from drying out. As a burn works its way through the three layers of skin, these functions degrade or cease entirely. Failing to hold fluids inside the body or maintain a consistent temperature will kill you in the short term, while opening the body to infection kills in the medium to long term.

Superficial burns (first degree) only affect the epidermis, the outermost layer of skin. The epidermis is typically around 1mm thick, thinnest on the eyelids and thickest on the soles of the feet. These burns are red, dry, and painful. Unless they’re seriously extensive, or you have a complicating medical issue, superficial burns are rarely dangerous and typically heal without medical intervention. Sunburns and mild scalding injuries are the most common examples you’ll come across.

Partial thickness burns (second degree) reach down to the dermis, which is the second layer of skin. It’s roughly forty times thicker than the epidermis and houses most of your touch- and heat-sensitive nerves.   Superficial partial thickness burns are wet and blistery, with reddened skin; deep partial thickness burns may feature either bloody blisters, or none, and appear moist, waxy, and red. As your sweat glands, the majority of your blood vessels, and the connective tissue keeping your skin together run through this layer, extensive damage here qualifies as a Serious Problem.

Full thickness burns (third degree) have destroyed the epidermis and dermis, damaging the subcutaneous layer and, likely, underlying organs or musculature. The center of the burn, at the surface, is dry and appears charred and leathery (“eschar”). The full thickness burn isn’t itself painful, as the dermal nerves are destroyed, but the injury will likely be surrounded by painful areas of partial and superficial thickness burns. Full thickness burns with injury to underlying muscles or organs are life-threatening, emergency situations. The deepest areas of the burn are dead, the cells which normally replace damaged skin tissue are dead, and the area surrounding the burn (the ‘zone of stasis’) could go either way.


Minor, Moderate, or Major Burns

Each of class of burn can be either minor, moderate, or major. Location and extent are the two determining factors, though being very young or very old immediately upgrades the injury.

Two loose rules to keep in mind as you determine the extent of surface coverage: a human’s palm is around 1% of their total surface area and each side of the torso is roughly 9%.

Minor burns typically heal on their own and can be either superficial burns, partial thickness burns of less than 15% of the body surface area, or full thickness  burns (without underlying injury) of less than 2% of surface area. Moderate burns require medical attention and consist of either partial thickness burns of15-25% or full thickness burns of between 2-10% of total surface area.

Major burns are more complicated and need attention at a specialized burn unit. Partial thickness burns over more than 25% of your body, or full thickness burns over greater than 10%, qualify as major burns, but there are a number of other factors to consider. Major burns are a life-threatening emergency.

Some factors upgrade a burn to major, regardless of extent. Any burn involving an inhalation injury is automatically a major burn (inflammation will block the airway almost immediately), as are burns involving the hands, major joints, face, genitals, perineum, or which cross another traumatic injury, such as a fracture. Electrical burns are typically treated as major burns, as the damage is mostly likely internal (along the path of least resistance at time of injury) and even relatively low voltages can be wreck havoc on vital organ systems. Circumferential full thickness burns, forming a ring around an extremity or the torso, have specific complications requiring immediate surgery in a specialized burn unit.


How Bad Can It Get?

As with many injuries, it’s rarely the immediate damage that kills you, but the body’s hysterical overreaction to trauma. Briefly: fluid shifts to the site of the burn, which will cause either moderate swelling or the complete breakdown of your metabolism at the cellular level.

First, the skin will be unable to perform its three critical functions, exposing muscles and organs to infection, allowing fluid to leak out of the body from extracellular space, and degrading your ability to regulate body temperature. The first failure will kill you later, the latter two can kill you within minutes to hours after injury.

When heat is applied to human flesh, it cooks. Its proteins warp and denature, triggering a domino effect which ends in the release of secondary cytokines, which in turn increase the permeability of blood vessels. This causes an inflammation response, as the tissue around the burn swell with fluid escaping the vascular system. (Red blood cells are too large to leak out in this way, but become sluggish as fluid drains from the capillaries.)

Inflammation responses to smaller injuries are adaptive, as they speed access of immune cells and repair mechanisms to the affected area. With deep partial thickness burns of more than ten percent total surface volume, however, the shift of fluid volume gets out of hand. Your burned skin can’t keep the fluids inside your body, where they belong, and you begin to drain out through the injured site.

With circumferential burns, the leathery, burned eschar will function like a tourniquet, cutting off circulation as the surrounding tissues swell with fluid. Increased pressure and lack of oxygen, in turn, lead to compartment syndrome, with permanent damage to any tissue ‘downstream’ of the burn. Circumferential burns to the torso can similarly stop breathing by preventing expansion of the chest. A surgeon can cut expansion joints through the damaged tissue (escharotomy) to avoid these complications.

With inhalation injuries, where the airway itself is burned, the inflammation response may block your airway while your lungs fill with fluid.

With more severe burns, the inflammation response isn’t localized. Your whole body will begin venting fluid into extracellular space, then out through your damaged skin. Dehydration is even more rapid, with circulatory shock to follow.

As the volume of fluid in the blood vessels decreases, your red blood cells flow sluggishly. Decreased blood flow means less oxygen, so the heart drives itself into tachycardia to compensate (consuming more scarce oxygen and generating more acidic waste). Your breathing becomes rapid and shallow, again to compensate, but the buildup of carbon dioxide will only trigger acidosis and further organ damage.

Sensing a crisis, your body will constrict blood flow to all but the heart, lungs, and brain. The rest of your body tries to get along anaerobically, but the decreased fluid volume from inflammation, the acidosis from rapid breathing and decreased blood flow, and pure starvation begins to cause massive organ damage, then failure. Body temperature can crash at this point, do to a combination of shock and the failure of the skin to regulate temperature.

The lack of oxygen in your mitochondria will eventually lead to ATP breaking down into free adenosine, which escapes along a now-familiar route into extracellular space and out through the skin. Known as the refractory stage of shock, recovery at this point is impossible. Even if provided sufficient oxygen and nutrition to support metabolism, your body could make no use of it. It simply takes too long to rebuild ATP (about 2% of baseline demand per hour) and the requisite structures will starve and die before regaining the ability to feed themselves.


How to Survive a Burn

Before we discuss first aid for burn victims, please take a moment and reread the disclaimer which opens this article. Then read this one, too:  EngineerJobs is not providing medical advice or training, is not qualified to provide medical advice or training, and will not be held responsible if you treat this article as sufficient substitute for medical advice or training.

That said:  suppose you, or a colleague, are on fire and wish to survive.

First, deal with any immediate hazards. If you or the victim are on fire, put it out. The mantra is stop, drop, and roll. Stop running (it just fans the flames), drop to the ground (where the cleanest air is), and roll around to smother the fire. If the victim can’t move, don’t roll them; smother the fire with a blanket or jacket if no water is available. Remove yourselves from the area if possible, staying low to minimize carbon monoxide and smoke inhalation (see inhalation injuries, previous section. These are emergencies.)

Now, quickly check over the victim. Are they conscious? How’s their breathing? You want to see what kind of burn they’ve received and how bad it is. Minor burns rarely require medical attention, moderate burns should get checked out as soon as possible, and major burns are a critical emergency.

Pay attention to the airway; is the skin of their face singed, especially around the noise and mouth? This may indicate an inhalation injury and a serious problem. Even if there are only minor burns to the exterior of the victim, damage to the lungs and airway is an emergency.

Call 911 (or your regional equivalent). We cannot underscore this enough:  calling for help is more important that anything you can do in terms of first aid. As soon as you’ve an idea what’s going on, either call 911 or have a bystander do it while you administer first aid.

Minor burns rarely require hospitalization or emergency medical personnel. Cool the area with water to  pull out the heat and discourage inflammation. Do not use ice water, or submerge the injury in ice water, as freezing temperatures will do more harm than good. Never use oils or creams and never, never pop a blister in the epidermis; that just opens a pathway for infection.

Minor burns should be covered with a loose, sterile dressing to keep them clean. Avoid putting pressure on the wound, which is a common mistake (direct pressure is for bleeding, not burns). Drink plenty of water and have your doctor check it out in a day or two if it doesn’t seem to be healing or if there are signs of infection.

As an untrained person, it’s safest to treat moderate burns as though they were major. Major burns are major problems and you really, really don’t want to be wrong. Your task, as a first responder, is not so much to treat the injury as support the victim until the professionals arrive.  There’s not much for you to do, but the stakes are much higher.

Check the victim for breathing and circulation. If they aren’t breathing, you can’t find a pulse, or both, begin CPR. This takes precedence over treating the burn.

Loosen any restrictive clothing, especially watches or rings. When swelling occurs, a ring or a watch may become a tourniquet, or a tight shirt a corset. Do not pull clothing or accessories out of a burn,  as this will cause serious damage and needless agony.  Exceptions are made for objects retaining a dangerous amount of heat, which will continue to damage the victim if left in place. The principle of least harm applies.

Flush the area with water, if available, but do not use moist dressings or immerse the burned area in water. As the skin is damaged, temperature regulation is degraded. Anything that steadily drops the body temperature courts the fatal irony of hypothermia. Cover the burn with a loose, sterile cloth of a material which won’t leave lint or threads in the wound. Infection risk is high and cleaning a major burn is agonizing.

If possible, elevate the burned area above the heart, to slow the inflammation response.

Finally, it’s best to treat for shock before it sets it. Get the victim comfortable and warm, with their legs elevated above the heart, and turn them on their side if possible. If moving the legs or rolling the victim risks further injury, don’t do it.) If the victim can swallow, encourage them to drink water. Remember that circulatory shock and runaway inflammation are the likely killers, so elevating the legs and getting fluids into the victim can make a real difference.

As you wait for emergency personnel, keep your eye on the victim’s breathing and circulation. Be ready to begin CPR, if needed.


EngineerJobs wants you to receive proper medical care. Do not tweet us @EngineerJobs if you are currently on fire or require urgent medical care.


Image Credit: Nestor Galina