When the skin is burned and depending on the severity of the burn, tissue will die, this dead tissue is called an eschar which is inelastic and can't expand.
When the burn is a circumferential (burned all the way around) second and third degree burn, eschar will form and with the edema (fluid leak from injured vessels) formed; the pressure will increase in the burned area. If this happens in arms and legs, this will lead to compression of the underlying veins arteries and nerves acting like a tourniquet. If the circumferential burn happens in the neck or chest, the pressure will prevent chest expansion leading to breathing problems. In these situations escharatomy is often needed.
Escharotomy is a surgical procedure done by making an incision through the eschar to relieve the underlying pressure, measuring the pressure in the compartment (closed space of nerves, muscle tissue and blood vessels) distal (furthest) to the affected area is one of the parameters used to determine the timing of escharatomy. Another way to determine the timing of the escharotomy is clinically by assessing the perfusion (the flow of blood) distal to the area affected.
In the limb:
Signs in the limb that may indicate the need for an escharotomy:
1. Signs of compression of blood vessels leading to loss of circulation which may include:
- Pallor (pale color of skin due to reduced blood flow) of the affected area.
- Cyanosis (bluish discoloration of skin resulting from inadequate oxygenation) of the affected area.
- Reduced or absent capillary return (blood which fills empty capillaries) related to capillary return in non affected area (non burned area).
- The affected area becomes cold.
- As a late sign the pulses in the affected area will impalpable.
3. Decreased oxygen saturation detected by pulse oximetry (a non invasive device that measure the oxygen level in the blood).
In the chest:
Circumferential burns to the chest wall may lead to restriction of the chest wall movement leading to respiratory compression. Sometimes non circumferential burns may need escharotomy when they interfere with and restrict chest movement. Abdominal circumferential burns may lead to respiratory compression as they may lead to restriction in the movement of diaphragm which plays a role in respiration. The following may indicate chest escharotomy:
- Circumferential full thickness burns to the chest and abdomen.
- Examination showing reduced air entry on both sides.
- Examination showing restriction in the chest wall movement or abdominal movement.
- Increased respiratory rate.
- Shallow breathing because of restriction of chest wall movement.
- Hypoxaemia (Insufficient oxygenation of the blood).
- Infants under one year of age are abdominal breathers (their respiration is predominantly diaphragmatic); therefore burn to the abdomen in a pediatric patient may lead to respiratory compression.