Definition• Eschar: A thick, coagulated crust, slough which develops following a burn injury or chemical or physical cauterization of skin.• In full thickness circumferential burns, coagulated collagen acts as a tourniquet in leading to vascular compromise of the affected body parts.• Escharotomy: incision of eschar for decompressing the constrictive effects caused by deep circumferential burns.
Pathophysiology• A circumferential deep or full thickness burn is inelastic and on an extremity will not stretch.• Fluid resuscitation --> burn wound oedema & swelling of tissue beneath the inelastic burnt tissue.• Increased tissue pressure may result in progressive obstruction of venous & lymphatic drainage, capillary perfusion, and ultimately, arterial flow.• Prolonged tissue ischaemia --> irreversible muscle & nerve damage• Systemic complications: myoglobinuria, hyperkalaemia, metabolic acidosis, renal failure.• Site-specific implications: extremities, chest, abdomen.
Indications• Clinical examination• Direct tissue pressure measurement
Indications - Clinical Examination• Circumferential deep dermal or full thickness burns• 5 Ps: pain, pallor, paraesthesia, paresis, pulselessness.• Could be difficult in severely burned patients• Important features: – Pain worse on passive stretch of affected muscle – Pain disproportionate with that expected from the injury – Extremity usually swollen, taut, and tender to palpation – Sensory deficit - earliest & the most sensitive finding – Motor deficit - late – Pulselesness - irreversible tissue damage
Indications - Tissue pressure• Direct tissue pressure monitoring - objective means for measuring compartment pressures• Invaluable adjunctive diagnostic technique for assessing the indications for and also the adequacy of escharotomy or fasciotomy.• Several methods available: open needle, wick catheter, and slit catheter techniques.
Indications - Tissue pressure• Normal intramuscular pressure: 0 - 10mmHg• Starling equilibrium: capillary perfusion diminishes or ceases at pressures that exceed 30mmHg• Therefore some recommended surgical decompression for compartment pressures > 30mmHg• However, compartment syndromes were not observed to occur until the pressure exceeds 45mmHg• Critical threshold pressure for surgical decompression: – Tissue pressure > 30-40mmHg; – Tissue pressure within 30mmHg of diastolic pressure.
Incisions• Medial and lateral aspects of the extremities to avoid damage to major neurovascular structures.• Incisions must traverse the depth of the eschar to viable tissue as well as the length of the eschar to unburned skin.• Must cross affected major joint areas where the attachment of skin to deep fascia is more secure than elsewhere
Complications• Bleeding• Damage to neurovascular structures• Infection• Inadequate or delayed decompression
Summary• Role of escharotomy in deep circumferential burns is crucial for relief of peripheral ischaemia or respiratory embarrassment.• Indications should be based on both careful clinical assessment and appropriate tissue pressure monitoring.• Proper escharotomy incisions should cover the full depth and length of the eschar over the circumferential burned area.• Timely escharotomy results in prompt improvement of distal ischaemia or respiratory compromise, with subsequent preservation of tissue and optimal functional results.• Further surgical decompression (eg. fasciotomy, laparotomy) may be required if escharotomy is not sufficient to relieve tissue ischaemia.
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