Emergency War Surgery: Part I: Types of Wounds and Injuries: Chapter III: Burn Injury

Emergency War Surgery NATO Handbook: Part I: Types of Wounds and Injuries: Chapter III: Burn Injury

Initial Treatment Of Extensive Burns

At the definitive treatment facility, control of hemorrhage and airway adequacy again must be insured. Initial consideration of the burn patient includes a complete physical examination following removal of the patient's clothing Once a secure intravenous pathway has been established, one then must estimate the resuscitation fluids to be given to the burned patient.

First 24 hours postburn:

     Adult: 2 ml lactated Ringer's solution/kg body weight/% burn

     Child: 3 mL lactated Ringer's solution/kg body weight/% burn

Second 24 hours postburn:

     Adult and child:

          Colloid: Estimated deficit and replace with a plasma

                   equivalent, e.g., albumin diluted to physiologic

                   concentration in normal saline or fresh frozen

                   plasma

               (a) 30-50% burn: 0.3 ml/kg body weight/% burn

               (b) 50-70% burn: 0.4 ml/kg body weight/% burn

               (c) >70% burn: 0.5 ml/kg body weight/% burn

 

          5% Dextrose in water: Volume necessary to maintain urinary

                                output.

Several formulas exist for calculation of the fluid requirement of the burn patient. They are based upon body weight and extent of the burn. Clinical success has been reported for each such formula and, in a civilian setting with unlimited amounts of the full spectrum of intravenous fluids available, the attending physician's preference can certainly dictate the resuscitation regimen employed. In a combat situation, logistical considerations speak strongly for simplicity of resuscitation using readily available fluids in a volume sufficient to prevent renal or other organ failure, yet avoid later complications of fluid overload.

Extensive clinical and laboratory studies have demonstrated that: (1) in the first 24 hours postburn, colloid has no specific restorative effect on cardiac output beyond that of electrolyte-containing fluids and is retained within the vascular compartment to no greater extent than an equal volume of electrolyte containing fluid, and (2) in the second 24 hours postburn, capillary integrity is largely restored so that fluid and salt loading can be minimized by using colloid-containing fluid to correct any persistent plasma volume deficit. These studies have led to a revision of the Brooke formula, simplifying the logistics of initial resuscitation (only electrolyte-containing fluid is administered in the first 24 hours postburn) and reducing fluid and salt loading (no electrolyte-free water is administered in the first 24 hours postburn and no electrolyte-containing fluid is administered in the second 24 hour period postburn).

The formula, which is detailed in Table 2, should be modified according to the individual patient's response in terms of urinary output, vital signs, and general condition. The fact that children have a greater cutaneous surface area per unit body mass and therefore form a relatively greater amount of edema per unit body surface burn necessitates that their initial electrolyte fluid resuscitation needs be estimated on the basis of 3 ml/Kg of body weight multiplied by the percentage of body surface burned. One should plan to administer one-half of the total fluid volume estimated for the first 24 hours postburn within the first 8 hours following injury, the time of most rapid edema formation. The actual rate of administration is adjusted according to the patient's response as noted below.

If the casualty is not received immediately following burn injury, the first half of the resuscitation fluid should be administered in the time remaining prior to 8 hours postburn. The remaining half of the estimated fluid should be administered, ideally at a uniform rate, in the succeeding 16 hours of the first 24 hours postburn. Patients with massive burns (greater than 70% of the body surface) and those in whom initiation of resuscitation has been delayed may require considerably more than the estimated volume of resuscitation fluid. Such patients require frequent observation and examination, and one must not hesitate to increase the volume or infusion rate of resuscitation fluids, or to otherwise alter therapy to obtain the physiologic response desired. Even in these patients, the proposed formula should be used to plan fluid therapy, keeping in mind that it is safer to add fluid as necessary than to deal with the complications of excessive fluid administration. Only in this manner can treatment be properly supervised and individualized.

The electrolyte-containing solution should be lactated Ringer's, which contains a more physiologic concentration of the chloride ion, but isotonic saline may be employed if the former is not available. Even though red blood cell destruction occurs after thermal injury, whole blood is not administered as a portion of the resuscitation fluids, since loss of the plasma, due to increased capillary permeability and intravascular retention of the red cells, would further elevate the patient's hematocrit and adversely affect the rheological properties of the blood. The colloid solution administered during the second 24 hours postburn can be fresh frozen plasma or albumin, with each 25 gram bottle of that material diluted with normal saline for administration as a 5% solution.

Potassium supplements are not needed and may be deleterious during the first 48 hours, since the serum potassium is commonly elevated as a result of the destruction of red blood cells and other tissue. Potassium, lost from injured cells, appears in the blood at a time when renal function may be depressed. From the third postburn day onward, potassium supplements should be added to the intravenous fluids if renal function is unimpaired. Average daily potassium requirements range from 60-200 meq per day.

From the third postburn day onward, an adequately resuscitated burn patient commonly has a normal and, in some instances, a supranormal plasma volume, so that further administration of salt- or colloid-containing fluids is usually unnecessary and should be carried out with great caution. In patients treated by the exposure technique, the burn wound acts essentially as a free-water surface with considerable evaporative losses (that is, 6-8 liters per day in patients with very extensive burns), following the third postburn day and until it is healed or grafted. Evaporative water losses can be estimated according to the formula: evaporative water loss in ml/hr = (25 + percent of body surface burned) x total body surface in square meters. This formula estimates evaporative water loss at the low end of the observed range, and replacement of the evaporative water loss should be guided by assessing the adequacy of hydration, which can be determined by careful monitoring of patient weight, serum osmolality, and serum sodium concentration. In patients treated with occlusive dressings, evaporative water loss is considerably less. Following resuscitation, salt-containing fluid need be given only for the treatment of symptomatic hyponatremia. Following elimination of the resuscitation-related salt and water load, salt-containing fluid should be administered in the amount needed to maintain a "normal" serum sodium concentration. Later in the postburn course, whole blood should be administered to maintain the hematocrit between 30-35%.