Burns: Clinical sciences

Burns are injuries caused by heat, cold, friction, radiation, electricity, or chemical exposure. When significant heat is applied to the skin, either in the form of a hot liquid, solid object, or flame, this thermal energy can result in irreversible tissue destruction. Extensive tissue destruction, especially in burns larger than 40% of the total body surface area, or TBSA; can cause fluid loss, and with it, hypovolemic shock! Burns are classified based on the depth of injury into first-, second-, third-, and fourth-degree burns, as well as burns accompanied by smoke inhalation.

When evaluating a patient with burns, your first step should be an ABCDE assessment to see if the patient is unstable or stable. If the patient is unstable, first stabilize their airway, breathing, and circulation. This means that you may need to intubate the patient, obtain IV access, and administer fluids before continuing with your assessment.

Now let’s move on to the stable patients. If your patient is stable, start with a focused history and physical examination. History reveals thermal injury and can identify the mechanism of injury, such as hot liquids, flames, or grease. The physical exam will vary depending on the depth of the burn.

Some burns might be accompanied by smoke inhalation, so let’s talk about that. History might reveal delayed extrication from a fire in an enclosed space. On physical examination, your patient may have facial burns, singed facial hair, wheezing, or stridor. They may also cough up carbonaceous material, or soot.

Once you suspect inhalation injury, you should obtain labs, including an ABG and carboxyhemoglobin level. Findings may include decreased paO2 and oxygen saturation. However, ABG might be completely normal initially. When it comes to carboxyhemoglobin, in non-smokers with inhalation injury it might increase over 3%; however, in smokers, those levels might be greater than 10%, since they are chronically exposed to carbon monoxide from tobacco smoke.

Next, order a chest x-ray. The initial chest x-ray can be normal; however, it is important to establish a baseline evaluation of the lungs. If your patient is intubated, you should also perform a bronchoscopy, which may show carbonaceous deposits, edema, and erythema throughout the airway. Other findings include bronchorrhea, or copious sputum, and bronchial obstruction. Mucosal sloughing typically appears later as bronchial inflammation worsens due to chemical byproducts in the inhaled smoke. Based on all these findings, you can diagnose inhalation injury.

The next step is to start inpatient management. This includes administering high-flow oxygen to maintain oxygen saturations above 90%. If the patient develops drooling, wheezing, or stridor, or is unable to maintain oxygen saturations higher than 90%, they should be intubated if they aren’t already. In an intubated patient, you can also perform serial bronchoscopies to monitor the progression of the injury and wash out any carbonaceous material within the lungs.

Burns are classified based on the depth of injury into first-, second-, third-, and fourth-degree burns. Let’s switch gears and talk about first-degree burns, also known as superficial because they involve only the epidermis. To remember first-degree burns, just imagine a sunburn. So, on physical exam, the skin is soft; it blanches when pressure is applied; and is typically painful. If you see this, then you are dealing with a first-degree burn. Once you diagnose a first-degree burn, you can treat them on an outpatient basis. Management includes wound care, like cleaning the burn with cool tap water and mild soap and applying topical analgesia such as aloe vera if needed. If they require additional pain management, acetaminophen is usually sufficient.

Now, let’s move on to second-degree burns, also called partial thickness burns since they extend into the dermis. On a physical exam, the involved skin is usually warm, soft, and erythematous, and there might be pain to palpation. The skin may blanch when pressure is applied; however, blistering is often present. Deep second-degree wounds are less painful since some nerve endings have been damaged. They also blanch less than superficial ones.

Alright, let’s switch gears and talk about third-degree burns. Third-degree burns, also called full-thickness burns, are deeper and extend to the subcutaneous fat. Patients usually report little or no pain, due to significant nerve damage. On physical exam, the skin may appear white, brown, or charred, feel firm or leathery, and doesn’t blanch with pressure. Lastly, let’s talk about the most severe burn category, fourth-degree burns. In fourth-degree burns, there is little or no pain due to extensive tissue necrosis. On exam, the skin appears charred, and the burn extends down to the muscle, tendon, or bone.