Burns commonly present acutely to clinicians due to various modalities, such as thermal, chemical, electrical or radiation. Often, burns from domestic incidents result in superficial (first degree) and partial thickness (second degree) burns, and less commonly full thickness (third degree) burns. Burn depth usually is determined by the intensity of the source, duration of contact, and location on the body.
Circumferential, full-thickness burns, whether on limbs or trunk can produce a splinting or tourniquet effect which compromises circulation and reduces muscle movement, resulting in limited respiratory function. This is due to the inflexibility of the damaged tissue, which is the eschar that is formed. If untreated, this can result in distal ischemia, compartment syndrome, respiratory failure, tissue necrosis, or death. Escharotomy is an emergency surgical procedure involving incising through areas of burnt skin to release the eschar and its constrictive effects, restore distal circulation, and allow adequate ventilation. Unlike fasciotomies, where incisions are made specifically to decompress tissue compartments, escharotomy incisions do not breach the deep fascial layer.
The skin is made up of two layers, the epidermis and dermis, and their thickness varies depending on location, age, and gender. Deep in the skin is the subcutaneous fat and then a fascial membranous layer before the deeper structures, such as muscle. Heat (and other injury mechanisms) can denature proteins, leading to loss of plasma membrane integrity and cell necrosis. Superficial burns only affect the epidermis; they are clinically painful, erythematous, blanch on pressure, and are sensate. Partial thickness burns involve both the epidermis and dermis; clinically, they can appear pink or cherry red, blister, are sensate to touch, blanch on pressure, and are also painful. Full thickness burns affect the epidermis, dermis, and subcutaneous tissue forming an eschar. Clinically, these burns appear dry and leathery, but they are not painful, sensate, or blanching and can feel firm and waxy on palpation.
In limbs, circumferential full thickness burns would act as a tourniquet, and restrict circulation distally, resulting in tissue ischemia and necrosis. On the chest and abdominal wall, due to the inflexible nature of the eschar, normal respiratory chest and abdominal wall movements are restricted thus limiting normal respiratory function.
Escharotomies often are performed as part of a burn's resuscitation care, and the decision is made based on clinical assessment of the patient and their response to treatment thus far. Clinically, patients may complain of tingling or numbness in limbs; the affected areas may be cool to touch, have reduced oxygen saturation, a delayed or no capillary refill, and reduced distal Doppler signal. On the chest and abdomen, signs may include shallow respiratory effort, and restricted chest and abdominal wall movement. The escharotomy is usually performed within the first 48 hours of injury, due to initial injury from the primary source, and secondarily due to resuscitation and development of tissue edema.
Generally, escharotomy is performed when full circumferential thickness (and sometimes partial thickness) burns result in respiratory or circulatory compromise. For limb burns, it is performed if simple elevation does not improve circulation; for chest wall burns, this is performed if there is compromised respiratory function, which can occur even in non-circumferential burns; similarly, for abdominal wall burns, it is performed for compromised respiration due to the splinting effect on the diaphragm, especially in young infants under 12 months due to their predominant abdominal breathing pattern.
There are relatively few contraindications, due to the potential for limb- or life-threatening consequences if an escharotomy is not performed. It is not indicated in burns which will heal without surgical reconstruction (superficial burns) and when there is no compromise to respiration or circulation.
This procedure does not require many instruments and can be performed at the bedside. A general anesthetic is not usually required, although sedation can be used. A local anesthetic is required to infiltrate unburnt skin, into which the escharotomy will extend. A scalpel or cutting diathermy can be used to make the incision, and a diathermy cauterization device should be used to control bleeding.
Ideally, an escharotomy should be performed by a plastic or burn surgeon or an experienced emergency medicine physician. Before performing an escharotomy, appropriate advice and discussion should have taken place with the relevant burn specialist.
The patient should be in a supine position, with the upper limbs supinated and the lower limbs in the neutral position. Incision lines should be marked on the patient and the area prepared and covered to maintain sterility. Structures at risk should be marked, such as the ulnar nerve at the medial epicondyle of the humerus and common peroneal nerve at the neck of the fibula, so that extra care can be taken to avoid damage to deep structures.
The incisions should extend from unburnt skin to unburnt skin ideally, or at least into areas of more superficial burns, down to subcutaneous fat, and release any constrictions. In the limbs, incisions should be made in the mid-axial line, both medially and laterally, and on the chest and abdominal wall, the incisions are made in the mid-axillary lines, which can be joined by a transverse incision below the costal margin to allow adequate release. The wound edges should be adequately parted upon incision; any residual constrictions should be checked by running a finger along the length of the incision. Cautery should be used to control post-procedure bleeding. Once there is an adequate release of tissues, the incisions should be dressed with alginate dressings.
Following escharotomy, the wounds should be monitored regularly, especially in the first 72 hours, due to high risk of bleeding, and for signs of incomplete releases, such as distal ischemia in limbs and poor ventilation for chest and abdominal burns. Other complications include damage to deep structures, especially to ulnar and common peroneal nerves due to their relatively superficial course near the incisions. These wounds may require surgical reconstruction in the future, such as skin grafting, and may result in functional deficits as well as cosmetic problems.
Full-thickness burns affect the normal function of the skin: temperature regulation, perspiration, skin elasticity, sensory function, and infection barrier. Circumferential full-thickness burns with resultant loss of skin elasticity can produce a tourniquet effect on limbs and trunk, which can lead to compromised distal perfusion, airway obstruction, and poor respiratory effort. All of which could lead to limb- or life-threatening situations, which may be avoided through early and adequate burn resuscitation, including escharotomy, to release circumferential full-thickness burns.
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