A 50 year old male suffers flame burns to 40% TBSA, including full thickness and deep partial thickness burns of his right arm. You enlist the help of a specialist and plan to transfer him to an intensive care unit at your regional burn center. However, during the hours preceding his transport, the nurse informs you that his right hand appears mottled and he can’t locate a radial pulse.
What emergency procedure is indicated?
In this post we’ll discuss escharotomy. Eschar refers to the leathery, coagulated dead skin layer that forms over a full thickness (or occasionally a deep partial thickness) burn. Once eschar formation occurs, the skin loses its elasticity and becomes restrictive. Progressive edema in the underlying tissues, especially after fluid resuscitation, can then lead to compartment syndrome, with risk of loss of limbs and digits.
An escharotomy releases the compression caused by the burned tissue and allows expansion. You may be thinking, what are the chances that I’ll ever really have to do this heroic procedure? True–although it rarely needs to be performed in the ED, studies have shown that a reluctance to perform escharotomies means nearly half of all burn patients who may have benefitted from the procedure have inadequately released burns prior to arrival at a tertiary burn center.
This is a simplified version of the algorithm (the complete version is in your syllabus) outlining the decision-making that goes in to performing an escharotomy. Anytime you have a circumferential (or near circumferential) burn of a limb, you need to watch it carefully to determining if perfusion is impaired or adequate. If you have any evidence of impaired perfusion at any time, you need to perform that escharotomy.
While escharotomy is rarely needed in the ED, when it is needed, it is REALLY needed. The principles of the procedure are outlined in the “LAID” mnemonic in the cartoon above. Escharotomy involves longitudinal incisions (with the exception of across the chest wall) along axial lines. You incise along the full length of the eschar extending in to viable unburned tissue. Beware that though an eschar is insensate, the normal tissue at either end should generally receive infiltration with local anesthetic if the patient is not intubated/sedated. The depth of the incision is about 1 centimeter, down to subcutaneous tissue. It can get bloody, as you will incise through the dermis in to where there are viable blood vessels, so use of electrocautery is advised. If not available, a scalpel can be used. You may see immediate tissue bulge with a successful escharotomy when compartment syndrome is imminent. If not, make sure to check a post-release pressure to determine if escharotomy was adequate.
Even after an escharotomy is done, the limb needs to be elevated and carefully monitored as compartment syndrome can still develop. This monitoring period is a great reminder to take a look at fluid administration and urine output. Compartment syndrome is a salient example of how over-rescuscitation with IV fluids can lead to tissue edema, which is a big risk factor for this condition. If still the tissues are doing poorly after escharotomy, you need to take a second look at the escharotomies to make sure they are adequately extended and of adequate depth. Beyond this, the next step would be fasciotomy, which is surgical territory.
And remember, it’s not just peripheral compartments such as extremities that are at risk from eschars. The most important compartment of all–the thorax–can be at risk when there is extensive burn eschar to the anterior chest. This can lead to ventilation failure.
Now let’s detail some anatomic considerations to keep in mind with escharotomy of the limbs:
- Lower limbs: The medial incision should pass behind the medial malleolus to avoid the long saphenous vein and saphenous nerve. Lateral incisions are made in the midlateral line, avoiding the common peroneal nerve at the neck of the fibula.
- Upper limbs: The medial incision should pass anterior to the medial epicondyle to avoid the ulnar nerve at the elbow. On the medial aspect of the hand the incision may progress as far as the base of the little finger. On the lateral aspect of the hand the incision can progress to the proximal phalanx of the thumb. Sometimes an incision along one side of a limb is sufficient to preserve circulation.
- Fingers: Can be released with a single longitudinal incision. When performing these escharotomies, make sure to incise along the non-working side of the finger.
- Neck: usually performed laterally and posteriorly to decrease risk of damage to the carotid arteries and jugular veins.
- Penis: a mid lateral incision will avoid injuring the dorsal vein.
- Chest wall: Escharotomy of the chest wall is the only exception to the use of longitudinal incisions. In this case, two transverse incisions, connecting the axial chest wall incisions, should be used.
- General: avoid incisions along flexural creases of joints.
The need for emergency escharotomy prior to transfer is identified. Incisions are carried along axial lines using an electrocautery device. The medial incision is performed anterior to the medial epicondyle to avoid ulnar nerve injury. The lateral incision, as pictured, extends in to the pink, viable tissue of the distal forearm. Perfusion is restored to the hand.