Escharotomy

Anatomy and Physiology

The skin is made up of two layers, the epidermis, and dermis, and their thickness varies depending on location, age, and gender. Deep to 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.[2]

In limbs, circumferential full-thickness burns 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.[3][4]

Indications

Escharotomies often are performed as part of a burn victim's resuscitation care, and the decision is made based on clinical assessments of the patient and their response to treatment provided before that assessment. Generally, an escharotomy is performed when full circumferential thickness (and sometimes partial thickness) burns result in circulatory or respiratory compromise.  In the limbs, this can present with 6 “P”s: pain, pallor, paresthesia (either tingling or numbness), paresis, poikilothermia (usually the affected limb will feel colder than the unaffected one), and absent pulse (late sign). Moreover, decreased oxygen saturation (usually less than 95%), decreased or absent Doppler signals in the affected limb, and high compartment pressure (more than 30mmHg) can also be seen. [1][5][6] While the chest and abdominal full-thickness burn can interfere with full chest expansion leading to respiratory distress and circulatory compromise. 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.[1] 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 infants under 12 months due to their predominant abdominal breathing pattern. [7] 

Contraindications

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 that will heal without surgical reconstruction (superficial burns) and when there is no compromise to respiration or circulation.

Equipment

• Marking pen
• Local anesthetic +/- sedation
• Sterile preparation, such as chlorhexidine or non-alcoholic povidone-iodine
• Sterile drapes
• Scalpel +/- cutting diathermy
• Diathermy cauterization device
• Alginate dressing

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.[2][3][8][9]

Personnel

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.

Preparation

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.

Technique or Treatment

For the limb escharotomy, most of the literature suggests performing the incision along the longitudinal axis of the limb either in the mid-lateral or mid-medial line (e.g radial border and ulnar border for the upper limb). The incision can be done either by a scalpel or cutting cautery and hemostasis can be maintained by coagulation cautery. Ideally, the incision should extend between two unburnt skin areas and should be down to but not including the muscle fascia. Care should be taken not to injury any of the deep structures especially nerves and not to cross any of the flexural creases. Escharotomy should be done in a stepwise fashion by doing one incision either mid-lateral or mid-medial and then reassessing the limb condition. If there is no improvement, another opposing incision can be made. [1][10] Escharotomy should be done in proximal to distal order with frequent reassessment throughout the whole procedure and afterward. Once there is an adequate release of tissues, the incisions can be dressed with alginate dressings.[11] In upper limb escharotomy, the medial (ulnar) incision should be placed anterior to the medial epicondyle of the humerus to avoid injury of the ulnar nerve and this incision can be extended up to the base of the proximal phalanx of the little finger. While the lateral (radial incision) can progress to the base of the thumb. This can be followed by individual finger escharotomy if needed. When doing finger escharotomy, care should be taken to place the incision in the mid-axial line. While the thumb can be released in the radial border, other fingers should be released in the ulnar side as these are the least functional sites. Another two dorsal incisions may be done over the second and fourth metacarpal to release deep muscles of the hand if required. In lower limb escharotomy, the medial incision should be placed posterior to the medial malleolus to avoid injury of the great saphenous vein or saphenous nerve. While the mid-lateral incision should be curved around the fibular neck to avoid injury of the common peroneal nerve. In chest escharotomy, a breastplate incision is preferred whereby an incision is made along the anterior axillary line in both sides which is then connected by two transverse incisions in the upper chest and upper abdomen (below costal margin). Neck escharotomy is usually performed posteriorly and laterally to minimize the risk of damaging carotid arteries or jugular veins.[12][4][13]

Continuous evaluation and monitoring of the adequacy of escharotomy are crucial. Limb elevation, regular assessment of perfusion, and compartment pressure if possible are important as some patients may need a further extension of the escharotomy incisions or even fasciotomy. On the contrary, chest and abdominal escharotomy need adequate assessment of respiratory effort, circulatory status, and bladder pressure if needed. Some of these patients may develop intra-abdominal hypertension which may necessitate paracentesis or even decompressive laparotomy.[13]

Complications

As for any procedure, an escharotomy may cause complications related to the surgery or anesthesia. Following escharotomy, the wounds should be monitored regularly, especially in the first 72 hours to look for signs of incomplete releases, such as distal ischemia in limbs and poor ventilation for chest and abdominal burns. Other complications include bleeding which can be controlled by cauterization, infection, and damage to nearby structures, especially to the ulnar nerve, and the common peroneal nerve due to their relatively superficial course near the incisions. Furthermore, these wounds may require surgical reconstruction in the future, such as skin grafting, and may result in functional deficits as well as cosmetic problems (hypertrophic scar formation). [13]

Complications of inadequate or delayed escharotomy include muscle ischemia and necrosis, a neurovascular compromise that may lead to gangrene and amputation of the affected limb, respiratory compromise in case of chest full-thickness burn, and abdominal compartment syndrome in case of an abdominal burn. Moreover, systemic complications include myoglobinuria, renal compromise, metabolic acidosis, and hyperkalemia.[14][15]

Clinical Significance

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.

Enhancing Healthcare Team Outcomes

For best results, an escharotomy should be performed with the help of an interprofessional team consisting of an experienced nurse and a plastic or burn surgeon, or an experienced emergency medicine physician. [Level 5]