Anesthesia for burn-injured patients

Published on 07/02/2015 by admin

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Last modified 07/02/2015

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Anesthesia for burn-injured patients

Christopher V. Maani, MD, Peter A. DeSocio, DO and Kenneth C. Harris, MD

Patients with thermal injuries may have problems in the perioperative period that are distinct from those of other surgical populations. These issues require consideration and planning by the anesthesia provider and surgical team to obtain optimal outcomes.

Acute injury

The first 24 to 48 h after a major burn occurs is considered the resuscitation phase. Depending on the extent of injury, the patient will often require massive amounts of intravascular fluids to maintain intravascular volume, cardiac output, and urine output. Several different formulas can be used to guide therapy, but the primary goal is to administer sufficient fluid to maintain urine output between 0.5 and 1.0 mL·kg−1·h−1, not to restore intravascular euvolemia. During this phase, the patient may require escharotomy or fasciotomy to preserve blood flow to extremities or to allow for chest expansion. Less commonly, a laparotomy may be required to treat abdominal hypertension (abdominal compartment syndrome). Blood transfusion is typically not required during these initial procedures.

For patients with burns that cover less than 40% of total body surface area (TBSA), tracheal intubation is rarely required; however, almost all patients with burns that cover more than 60% of TBSA require intubation. Patients with inhalation injury may require intubation to protect their airways regardless of the size of their burn. The decision to intubate a given patient often requires considerable judgment, but, once the decision has been made, the procedure does not require any unusual considerations beyond those for any other patient with a traumatic injury. If the decision to intubate is delayed until the patient is in respiratory distress, the time remaining before complete arrest occurs may indeed be short. In this situation, because of the increased risk that these patients may develop glottis edema, an “awake” intubation may be indicated. Larger-than-normal tracheal tubes are preferred due to the likely need for bronchoscopy and suctioning of clots or mucous plugs.

General burn care

Full-thickness burns, unless very small, must be treated with excision and grafting. Partial-thickness burns may require excision and grafting depending on their depth, size, and location. Antibiotic creams and solutions—silver sulfadiazine or mafenide acetate, a carbonic anhydrase inhibitor—are the drugs most commonly used on some partial-thickness and full-thickness burns. Silver sulfadiazine is considered less painful to apply but does not penetrate intact burn eschar. Silver sulfadiazine may also cause significant leukopenia, typically in the first few days of use. Mafenide acetate cream penetrates burn eschar but can be painful to apply. In patients with large burns or renal failure, a hyperchloremic metabolic acidosis is occasionally seen that may be attributable to the application of mafenide acetate cream and may not resolve until the drug use is discontinued.

Excision and grafting

Excision of burned skin and placement of skin grafts are the primary reason that patients with burns make frequent trips to the operating room (OR). Some controversy exists over the exact timing of surgery but this approach has changed from delayed intervention to the current practice in which many burn surgeons will operate within 24 to 48 h of the patient’s admission; other surgeons will wait 48 h to ensure that the patient has been adequately resuscitated.

Excision may be either tangential, in which the burn is shaved off until unburned tissue is reached, or fascial, in which all skin and underlying fat is removed down to fascia, usually by using an electrocautery device. Tangential excisions generally produce a better functional and cosmetic result. Fascial excisions may be faster to perform and usually result in less blood loss, as compared with tangential excisions. Whichever method is chosen, these procedures can be quite bloody, with blood loss varying from 123 to 387 mL for each 1% of TBSA of burned tissue excised. Several factors affect the volume of blood loss (Table 233-1).

Table 233-1

Factors Related to Blood Loss in Patients with Burns

Blood Loss
Factor Decreases Increases
Excision technique Fascial Tangential
Age of burns Fresh Older
Location of burns Torso Hands, feet, or shoulders

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The use of tourniquets and fibrin glue may substantially reduce blood loss. Harvesting of the skin graft may produce considerable blood loss itself, especially if scalp is harvested, but bleeding can be decreased with the infiltration of epinephrine solution into the area to be harvested. Pitkin solution, lactated Ringer’s solutions with 1 to 2 mg/L of epinephrine, or other combinations of vasoconstrictors in crystalloid solutions are often used to try to decrease blood loss.

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