VOLUME 29 JUNE 1962 NUMBER 6
COMMENTARY
BURN THERAPY
E LSEWHERE ifl this issue appears a pa per by Meeker on management of
extensive third-degree burns in 35 chil
dren. The paper is an extension of a pre vious report which describes use of an
electric dermatome for preparing and ob
taining skin grafts.1 Although early skin
grafting (1 to 2 weeks after burn trauma)
has been used by many surgeons for a good many years, the débridement and grafting technique entails certain difficulties which may he alleviated by skillful use of the electric (Brown) dermatome as described by Meeker. Early débridement and graft ing within 1 to 3 weeks of the burn is a generally accepted surgical technique. Allen2 emphasized progressively earlier surgical débridement and grafting in an experience comprising 1,000 burned cliii dren. In 25% of these patients, the wound
was closed within 14 days of admission to the hospital. Later, Allen and Day3 indi cated that they preferred “¿free-hand―
grafting to dermatome techniques. Evalu ation of the benefits derived from the par ticular dermatome débridement and graft ing technique advocated by Meeker must await a controlled study in which the re sults of electric dermatome grafts are com pared with results obtained in a series of randomized, alternate patients, receiv ing similar surgical care, but in which early wound closure is achieved by other tech niques.
While grafting during the second post burn week may be expected to facilitate
ultimate recovery and shorten the total hospital stay to 1 to 2 days for each 1% of body surface burned, as Meeker also has emphasized, survival is often dependent upon efficacy of fluid therapy in the critical 48-hour period following trauma. Consid erable confusion still pervades this area of therapy, perhaps compounded by the numerous rather arbitrary “¿formulae― which have been developed by many sur geons to “¿simplify―the problem. The vast literature on parenteral fluid therapy in burns is generally premised upon the fol lowing assumptions: 1. Hypovolemia re sults from loss of a plasma-like fluid into the burned area and by seepage from the burned surface. 2. Volume of fluid to he administered is judged by hematocrit di lution and maintenance of a “¿normal―pre determined urine volume, collected and measured hourly. 3. Generalized edema is a consequence of the pathology of burns and the requirement to provide vigorous infusion of colloid, water, and electrolytes sufficient to satisfy the assumptions implicit in the preceding statements 1 and 2.
Most fluid therapy formulas for burns are modifications of the prescriptions orig inally offered by Evans et al.@ or the Brooke Army Group,5 which were based on careful study and on the premises pre viously noted. The description of parenteral fluid therapy for the shock period con tained in Meeker's paper is too general to be evaluated, but it would seem to be based on similar premises, and as far as
PEDIATRICS, June 1962
862 BURN THERAPY
can be estimated seems closely related to the Evans' prescription. Evans actually recommended that fluid therapy be calcu lated for the individual patient, but sug gested a simplified formula that might be readily applied either by those unable to calculate requirements or if time and facil ities did not permit detailed laboratory control, as in the case of mass casualties. Only this simplified formula appears to have survived and is applied to individual patients.
Recent data suggest that each of the assumptions on which “¿simplified―fluid therapy of burns is premised is largely in correct. While the hematocrit gives some indication of loss of fluid from blood, the peripheral hematocrit may not be repre sentative of the hematocrit in the “¿whole body.―6 Further, the direction of change in plasma volume indicated by the hemato crit occasionally may be opposite to that found by direct measurement of plasma volume.7 Fox and Lasker,8 in a recent important paper on experimental burns, demonstrated that the hematocrit value rose above control levels after scald or flash burns and remained elevated for at least 2 days. When dextran plus electro lyte solution was used as fluid therapy more prompt, but not particularly beneficial, in travascular dilution of hematocrit was ob served,8 a circumstance analogous to that observed by Birke et al.@among 73 patients in a series of 292 patients. Finally, it hardly seems necessary to mention that the plasma compartment remains in equilibrium with the extracellular fluid, modified by physi cal chemical limitations imposed by Gibbs Donnan, membrane, solubility, hemody namic, and distribution characteristics of the solutes. Since extracellular and intra cellular fluids also maintain equilibrium, administration of parenteral fluid requires consideration for its potential distribution in total body water. Depending on circum stances, the redistribution of fluids may or may not be reflected in the volume of the plasma.
It has been assumed that blister fluid
accumulating in burned areas character izes the losses occurring from the entire burned surface, and that the influx of fluid found in a localized burn occurs to similar degree throughout the entire burned area. Recent careful studies in adultsbO and chil
drenhl indicate that measured losses from
the burned surface during the 48 hours af ter trauma are smaller in volume and con tain much less nitrogen, sodium, chloride, and potassium than usually assumed. For example, in children, skin losses per 100 cm2 burned surface for the initial 12-hour pe riod averaged: H,O, 7.6 ml; Na, 0.72 mM; K, 0.11 mM; Cl, 0.53 mM; and N, 56 mg. Insensible H2O loss (skin and lungs) was approximately normal at 456 ± 54 ml/m2/ l2hr. Fox and Lasker demonstrated a marked difference between the distribu tion of fluid in tissues after flame or scald burns. After flash burns, the burned skin did not gain water or salt, but there was edema of the underlying muscle with an increase of H2O and sodium, but loss of potassium. In scald burns, on the other hand, the skin became edematous. The edema was increased by parenteral fluid therapy, although the animals so treated survived somewhat longer. The changes in water and salt content of the muscle were slight. The balance data on severely burned children indicate that usual fluid prescriptions provide a vast excess of so dium and chloride which are retained and contribute to “¿obligatory―edema. Excess quantities of nitrogen (as protein) are usu ally provided. An interesting feature of the more recent studies of electrolyte metabo lism in burns is the unusually large loss of potassium, in excess of nitrogen (hence not representing simple excretion of potassium derived from destroyed tissue) in the urine.10'1' The quantities of potassium pro vided by the usual repair fluids appear to be inadequate.
COMMENTARY 863
McCollum (personal communication) rec ommends sufficient fluid to “¿establisha consistent, though lower than normal, hourly urine output.― Consistent hourly urine outputs are not only difficult to achieve but require catheterization and may be contraindicated by the inability of the kidney to respond effectively to relatively excessive fluid infusions in the 48-hour post-bum period. Lack of correlation be tween parenteral fluid intake and urinary output frequently has been observed. Care ful studies of renal functions in burned pa tients demonstrated that GFR fell consid erably during the first few hours after trauma despite vigorous plasma transfu sions, particularly in children.12 The fall was thought to result from reduction in RPF, and the volume and electrolyte composi tion of the urine were considered conse quences of the hemodynamic change. Very similar data were obtained in another study,― which unfortunately was com pleted without knowledge of Graber and Sevitt's work. Despite vigorous infusions of fluid in four severely burned children, urine volume averaged 110 ml/m2, or about 7% of the infusate, in the initial 12 hours after the burn. The urine volume gradually increased to 264, 387, and 462 ml/m2_equivalent to 17, 38 and 49% of the infusate volume, respectively—in sub sequent 12-hour periods. The reduced urine volume was associated with a 80 to 60% reduction in RPF and 40 to 50% decrease in GFR in the two patients studied, as in ferred by Graber and Sevitt. Tubular free water reabsorption (T°H2o) also was in creased. Similar relative urine volumes were noted by Eagle'3 and Batchelor,14 although interpreted somewhat differently.
From the currently available data, it seems clear that the generally accepted, arbitrary, easy-to-remember, simplified pre scriptions of fluid therapy in severely burned patients commonly employed to correct shock and maintain consistent hourly urine volumes tend to produce over hydration and excessive salt and nitrogen retention. Consideration for the nature and
extent of the surface area burned; meas ured losses of sodium, water, and electro lytes from the burned surface; and marked limitations in renal function which cannot be changed by vigorous fluid infusions dur ing the early periods after injury, leads to a rationale for fluid therapy which is less simple but more appropriate for the indi vidual patient.
At present, the most important cause of death after severe bums is the develop ment of infections in the second post-burn week. These often may be due to gram negative organisms such as pseudomonas15 and/or Escherichia coli or to endotoxin production by such organisms. Since these organisms may not be evident on the burned and treated surface, but may be hematogenously spread, the possibility of infection originating from and being re lated to the indwelling urethral catheter must be considered. Numerous recent re
ports emphasize the dangers inherent in
repeated or protracted urethral catheriza tions, particularly in sick, hospitalized pa tients. If the fetish of the maintained pre determined hourly urine volume can be abandoned, the need for the indwelling urethral catheter also will disappear. Then both the report by Meeker in this issue and this Commentary will have been useful.
Chicago 16, Illinois
JACK METCOFF, M.D.
Michael Reese Hospital and Medical Center
REFERENCES
1.Meeker, I. A., and Snyder, W. H.: Dermatome debridement and early grafting of extensive third degree burns in children. Surg. Gynec. Obst., 103:527, 1956.
2. Allen, H. S.: Treatment of the burned wound
based on the experience of 1000 hospital patients. Ann. Surg., 134:566, 1951. 3. Allen, H. S., and Day, S. W.: Bums in chil
dren. Arch. Surg., 72:788, 1956.
4. Evans, E. I., et al: Fluid and electrolyte re quirements in severe bums. Ann. Surg., 135:
804, 1952.
S64
bolic response to burns. J. Clin. Invest., @5: 62, 1956.
11. Metcoff, J., et al.: Losses and physiologic re
quirements for water and electrolytes after extensive burns in children. New Engl. J. Med., 265:101, 1961.
12. Graber, I. C., and Sevitt, S.: Renal function in
burned patients and its relationship to
morphological changes. J. Clin. Path., 12:25, 1959.
13. Eagle, J. F., Jr., Schenck, W. G., Jr., and Shim, W.: Parenteral fluid therapy of burns: use of single solution during first forty-eight hours. J.A.M.A., 174:1589, 1960.
14. Batchelor, A. D. R., Kirk, J., and Sutherland,
A. B. Treatment of shock in the burned child. Lancet, 1:123, 1961.
15. Markley, K., et al.: Clinical evaluation of saline solution therapy in burn shock: II. Compari son of plasma therapy with saline solution
therapy. J.A.M.A., 170:1633, 1959. 6. Gibson, J. G., II., et al.: Circulating red cell
volume measured simultaneously by radio active iron and dye methods. J. Clin. Invest., 25:838, 1946.
7. Fox, C. L., Jr., and Baer, H.: Redistribution of potassium, sodium, and water in bums and trauma, and its relation to the phenomena of shock. Amer. J. Physiol., 151:155, 1947. 8. Fox, C. L., and Lasker, S. E.: Response to fluid therapy and tissue electrolyte changes in
scalded and flash burned monkeys. Surg. Gynec. and Obst., 112:274, 1961.
9. Birke, G., Liljedahl, S-O., Troell, L. Studies on
Burns. I. The primary treatment with special reference to the mortality and hospitalization
time. II. Dextran concentration, electrolytes, blood volume and total hemoglobin. III. The serum protein pattern and nitrogen metab
olism. Acta Chir. Scand., 228 (Suppi.), 1937. 10. Reiss, E., Pearson, E., and Artz, C. P. Meta
1962;29;861
Pediatrics
Jack Metcoff
BURN THERAPY
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