Burn Surgery
Kenneth K. Yim MD, FACS1
Melissa T. Berhow MD, PhD2
1SURGEON
2ANESTHESIOLOGIST
FREE SKIN GRAFT FOR BURN WOUND (WITH TANGENTIAL EXCISION, EXCISION TO FASCIA, OR DEBRIDEMENT)
SURGICAL CONSIDERATIONSDescription: Until the mid-1970s, management of burn wounds involved daily debridement, hydrotherapy, and spontaneous eschar separation, with subsequent skin grafts applied to the granulated tissue. Operative management has become much more aggressive with the description of tangential excision by Janzekovic. In burn patients without inhalation injury, early excision and grafting (days 1-5) can reduce mortality and length of hospital stay. There are two surgical approaches to burn wounds—tangential excision and fascial excision.
Tangential excision (TE) is the more frequently performed procedure. The concept of TE is extremely simple, but requires considerable experience and teamwork. Thin slices of burn eschar (burned, necrotic tissue) are shaved sequentially with manual or power dermatomes until a healthy wound bed is developed. Assessment of the wound bed is done with visualization of bleeding and/or the clinical appearance of the excised bed. Blood loss is generally diffuse and can be massive; therefore, communication between anesthesiologist and surgeon is essential. In large excision, PRBCs should be available in the OR before excision so that the anesthesiologist does not get behind in blood and fluid replacement.
Diffuse bleeding, especially dermal, is controlled by laparotomy pads soaked with warm 1:100,000 epinephrine solution. These pads are replaced every 3-5 min and, after ˜10 min, are removed one at a time, with persistent bleeding points controlled by electrocautery. Although very high plasma epinephrine levels have been reported after major burn excision, systemic manifestations are very rare in acute burn patients (probably 2° chronic high-level endogenous catecholamine secretion).
TE in the extremities usually is accomplished with a pneumatic tourniquet to minimize blood loss. In some centers, subcutaneous injection of a diluted (1:1,000,000) epinephrine solution under the burn wound also is used to minimize blood loss; however, the resulting vasoconstriction makes the end point of excision—i.e., bleeding—difficult to ascertain.
Fascial excision involves removing the burn eschar and all underlying fat en bloc to the level of muscle fascia or beyond. Fascial excision can be performed more rapidly and with less blood loss than TE. Its disadvantages, however, are the marked cosmetic deformities and functional limitations that occur because of the loss of all soft tissue overlying the musculature. Because of its disadvantages, fascial excision is reserved for 4th-degree burns or for patients with very extensive, life-threatening, full-thickness (3rd-degree) burns.
In patients with serious burns (> 40% total body surface area [TBSA]), excision usually commences on postop days 2-5, after completion of fluid resuscitation, and is performed every 2-3 d, as the patient’s condition permits. If eschar excision can be completed before secondary sepsis supervenes, management of the patient is easier and the complications and morbidity are lessened considerably.
The end points for surgical excision in large burns are (a) operative time of 2-3 h; (b) core temperature of 35°C; or (c) blood loss of 10 U of PRBC. The violation of any of these parameters invites coagulopathy and increasing problems with hemostasis and VS stability. Adverse effects occurring after 3-4 h of operative time are usually the result of massive transfusion or hypothermia.
Due to loss of skin integrity and large exposed surfaces, these patients lose heat rapidly. Fluids, gases, and the OR should be warm, although there is no demonstrable benefit to warming the OR past the point of isothermic neutrality (˜82°F [28°C]). Many surgeons, however, will maintain the room at ˜ 100°F (38°C). All areas not in the operative field should be covered, and a warming blanket (Bair Hugger) is used frequently.
Coverage: After excision of wounds and attainment of hemostasis, wounds are covered, using either an autograft or temporary coverage with an allograft, xenograft, or synthetic/biologic dressing. An autograft is used for coverage when the wound bed is deemed suitable, a donor site is available, and the patient is stable. A split-thickness skin graft (STSG) often is used for coverage of a burn wound. Because an STSG is harvested at the dermal level, bleeding also is controlled with topical epinephrine-soaked laparotomy pads before application of dressings. Depending on the location of donor sites, many surgeons use subcutaneous infiltration of diluted (1:1,000,000) epinephrine in saline solution to smooth out irregularities (e.g., underlying ribs) or to create a flat surface (e.g., scalp) to physically improve the ease of taking skin grafts. A substantial volume of saline may be infiltrated, and this should be added into the total fluids administered to the patient.
Intraop position change may be necessary between the burn excision and the STSG harvest. For example, donor skin may be harvested from the back for application to the chest or abdomen.
The STSG is held temporarily in place with staples or sutures. Uncontrolled patient movement may dislodge the graft. To protect against this eventuality, grafts are secured with circumferential dressings and splints. This procedure may be time consuming, and any uncontrolled patient movement should be avoided.
It has become apparent that early eschar excision is advantageous even if wounds are so extensive they cannot be covered with autografts. In this situation, temporary coverage of the excised wound is accomplished with the application of an allograft, porcine xenograft, or synthetic/biologic dressing. The wound is maintained in this way, with further debridement and biologic dressing changes as necessary, until autograft becomes available.
Usual preop diagnosis: Thermal, electrical, or chemical burn
▪ SUMMARY OF PROCEDURES
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