Escharotomies is required in which type of burns:

When deep second- and third-degree burn wounds encompass the circumference of an extremity, peripheral circulation to the limb can be compromised. Development of generalized edema beneath a nonyielding eschar impedes venous outflow and eventually affects aerial inflow to the distal beds. This can be recognized by numbness and tingling in the limb and increased pain in the digits. Aerial flow can be assessed by determination of Doppler signals in the digital aeries and the palmar and plantar arches in affected extremities. Capillary refill can also be assessed. Extremities at risk are identified either on clinical examination or on measurement of tissue pressures greater than 40 mm Hg. These extremities require escharotomies, which are releases of the burn eschar performed at the bedside by incising the lateral and medial aspects of the extremity with a scalpel or electrocautery unit. The entire constricting eschar must be incised longitudinally to completely relieve the impediment to blood flow. The incisions are carried down onto the thenar and hypothenar eminences and along the dorsolateral sides of the digits to completely open the hand, if it is involved. If it is clear that the wound will require excision and grafting because of its depth, escharotomies are safest to restore perfusion to the underlying non burned tissues until formal excision. Ref: Sabiston, 17/e, page 527