Following a full thickness burn, pressure on the underlying tissue may increase due to the skin shrinking and an edema forming. In the acute setting, a surgical procedure can alleviate this pressure: an escharotomy (an incision to the depth of the subcutaneous fat) or a fasciotomy (an incision through the deeper underlying fascial layers).

Escharotomy

An escharotomy is a procedure in which an incision is made into the skin to the depth of the subcutaneous fat. The procedure may be required as a result of certain pathophysiological factors, and there are indications to be aware of before choosing this treatment.

Pathophysiology

After sustaining a full thickness burn, the skin shrinks by approximately 10% and becomes stiff and leathery. The result is called an eschar.

Subsequently, a local inflammatory response occurs and edema forms in the area of the burn. In the case of (semi-) circular burns, these two factors cause an increased pressure on the underlying tissue.

This increase in pressure has a number of potentially severe effects, dependent on the anatomical location of the burn.

Limbs: If the pressure on the tissue exceeds that of the venous and lymphatic pressure, this will cause an increase in edema. If the pressure on the tissue exceeds arterial pressure, there will be a loss of circulation.

The clinical signs of a constricting burn may include:

• Swelling
• Pain at rest or during passive movement
• Pallor
• Decreased capillary refill
• Loss of arterial pulsations and Doppler blood flow signals
• Coolness and numbness

Neck: Deep burns in the neck area can obstruct the airway. In the worst cases, cerebral edema may develop.

Trunk: An eschar on the chest can severely limit the movement required for breathing.

This decreased air entry would be noted during the A and B sections of the primary survey. In ventilated patients, these types of burns cause increased ventilation pressures. Abdominal compartment syndrome (ACS) may also occur.

Indications

Poor circulation and ischemia rarely occur immediately after burn injury. It is therefore important to reassess tissue perfusion frequently.

Ensure that there is no systemic cause of distal hypoperfusion, such as hypoxia, decreased cardiac output, hypovolemia or peripheral arterial constriction.

The timing of escharotomy is based on the clinical presentation. An escharotomy may be indicated in the following instances:

Limbs: When a circumferential or near-circumferential eschar of the extremities compromises the underlying tissues or the circulation distal to it.

Neck/Trunk: When a circumferential or near-circumferential eschar of the head, neck or trunk compromises aeration and breathing. Beware that near-circumferential burns in children, including those not extending to the posterior chest, may still reduce ventilation as breathing is principally diaphragmatic.

Abdomen: When a circumferential or near-circumferential eschar of the abdomen is associated with evidence of intra-abdominal hypertension (IAH), or signs of ACS. Breathing may also be compromised.

Abdominal compartment syndrome (ACS)

The signs and symptoms of abdominal compartment syndrome (ACS) may include an unexplained reduction in minute ventilation or oliguria.

The presence of an abdominal eschar is not always indicative of ACS. Conversely, the absence of an abdominal eschar does not exclude the possibility of ACS.

To diagnose ACS, measure intravesical pressure (IVP) through a catheter inserted into the urinary bladder.

• The normal range for IVP is <5mmHg.
• Values between 12 and 25mmHg indicate the need for close observation and re-evaluation, and any value >25mmHg requires intervention.

If measuring IVP through a urinary bladder catheter is not possible, a venous femoral catheter can be inserted. Both types of catheterization allow monitoring of the intra-abdominal pressure (IAP).

If measurements are not possible and any slowing or interruption of fluid flow in the catheter is observed in a patient with abdominal burns and adequate fluid resuscitation, there should be a high suspicion of an increased IAP.

Performing an escharotomy

Pre-operative preparation

Before starting, it is important to make an appropriate surgical plan.

1. Evaluate the location of the constricting burn
2. Plan and mark your incision lines, avoiding critical nerves, veins and vessels
3. Mark important structures close to the planned incision site that could be at risk

In general, two incisions are recommended in severe constricting burns to fully release the pressure. For specific incision sites refer to the following advice:

Arm: Make the two incisions along the longitudinal axis of the affected part of the arm on the medial and lateral side. Mark the ulnar nerve at the medial epicondyle of the humerus.

Hand: Make the incision on the dorsum of the hand between the metacarpals. For the fingers, incise the ulnar aspect of the radial digits (thumb, index and middle finger), and the radial aspect of the ring and little finger, if required.

Leg: Make the incision along the longitudinal axes of the affected part of the leg, near the neurovascular bundles in the medial and lateral axial lines. Mark the peroneal nerve at the neck of the fibula.

Foot: Make the incision on the dorsum of the foot between the metatarsals.

Anterior chest and abdominal wall: Make the incision in the mid-axillary lines, which can be joined by a transverse incision below the costal margin to allow adequate release.

It is also important to evaluate the general condition of the patient and pay attention to their hemodynamic stability, fluid status and electrolyte management. Systemic perioperative antibiotics are not required for this procedure.

Prepare the patient and/or relatives for surgery by explaining the procedure and possible post-operative complications. These complications may include:

• Incomplete release
• Hemorrhage
• Increased fluid loss
• Subcutaneous infection
• Neuromuscular injury

Anesthesia

Ensure adequate analgesia and sedation or anesthesia.

Although an eschar consists of non-viable tissue in which all cutaneous nerves have been destroyed, the incision should be made until it reaches healthy viable skin, where nerves are intact.

General anesthesia is preferred, but not required, for an escharotomy. If general anesthesia is not available, provide adequate sedation.

Surgical procedure

Use a scalpel or electrosurgery machine set to “CUT” when incising the eschar. Make an incision over your marked lines, through the entire thickness of the circumferential eschar down to the subcutaneous fat. To ensure decompression, the incision should extend 1cm into healthy skin. If this is not possible, continue the incision at least just proximally and distally to the adjacent joints.

Evaluate the result of your escharotomy by assessing the perfusion of the distal extremities using capillary refill time, continuous saturation monitoring with pulse oximetry and Doppler blood flow signals.

In principle, an escharotomy is sufficient when only the burned skin layer is incised, leaving the subcutis intact. However, when an escharotomy is unsuccessful incisions should be reassessed.

If the incisions are indeed adequate but the tissue perfusion remains poor, the presence of an acute compartment syndrome is probable and therefore a fasciotomy may be indicated.

Hemostasis must also be ensured. Bleeding observed from the subdermal plexus and superficial veins may be stopped by electrosurgery, the application of thrombin-soaked gauze pads or light compression with plain gauzes.

A fasciotomy is rarely indicated. It should only be considered for high-voltage electrical injuries or severe full-thickness burns involving vital underlying structures.

Postoperative care

Cover the wound with alginate dressings. If these are not available, use a Vaseline gauze followed by an absorbent dressing and a light bandage.

Monitor the following parameters hourly, for at least 72 hours after the burn:

• Capillary refill time
• Doppler blood flow signals
• Pulse oximetry
• Sensation distal to the burned area
• Elevate the affected limbs

[Graphic from book]

Incision lines and at-risk areas

Fasciotomy

A fasciotomy is a releasing incision through the deeper underlying fascial layers.

Indications

Fasciotomies are rarely indicated, except for electrical burns or severe full-thickness burns with signs and symptoms of compartment syndrome. A fasciotomy is also indicated when the clinical signs and symptoms of compression persist following an adequate escharotomy. In these cases, post-ischemic edema in the muscles distal to the constricting eschar may lead to a compartment syndrome, for which a fasciotomy is required.

Surgical procedure

A fasciotomy must be performed at an early stage of treatment, once the patient’s ventilation and circulation have been stabilized. A fasciotomy must be performed in a well-equipped operating theatre, and it requires general anesthesia. In contrast, an escharotomy can be performed in the emergency room or intensive care department of a hospital.

In very deep thermal burns and high voltage injuries, muscular necrosis may occur. This is a very severe condition that may also lead to rhabdomyolysis and renal failure. In this case, instead of performing a fasciotomy alone, additionally all suspect muscle compartments need to be explored and all necrotic tissue removed.