Symposium on Burns

Nutritional Support of the Burned Patient P. William Curreri, M.D, * and Arnold Luterman, M.D.t

Major thennal injury is characterized by a hypennetabolic response, the level of which is proportional to the magnitude of burn. 2, 4, 16, 19 Resting metabolic expenditure may be increased 40 to 100 per cent above nonnal in patients with burns exceeding 30 per cent of the total body surface. These markedly elevated metabolic demands are a consequence of alterations in the neurohormonal control mechanisms which nonnally regulate energy utilization and substrate flow. 19, 20 Investigations during the past decade have shown that burn injury is associated with a resetting of the central nervous system temperature control centers. 20,21 As a result the critical temperature is slightly increased and the patient attempts to maintain an elevated core temperature. Increased sympathetic discharge is accompanied by elevated levels of plasma catecholamines that stimulate heat production and substrate mobilization. Thus the burned patient is internally warm and exhibits elevated core (38 C) and surface (33 C) temperatures. Simultaneously severe catabolism is observed during the immediate post burn period. Recent clinical observations suggest that the catabolic response, characterized by protein mobilization, increased rates of gluconeogenesis, decreased levels of insulin, and increased plasma concentration of glucagon, reflects an increased flow of glucose to the wound, where it is presumably required for wound healing.2, 17, 19 The clinical implication of the hypermetabolic and catabolic response is striking. Energy requirements of up to 5000 Kcal per day are often observed. Failure to supply enough exogenous calorie intake to meet these needs results in rapid consumption of endogenous fuel reserves and eventual morbid consequences associated with acute starvation. 0

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From the Department of Surgery, The New York Hospital-Cornell Medical Center, New York, New York *Johnson and Johnson Professor of Surgery; Director, Burn Center t Assistant Professor of Surgery; Attending, Burn Center

Surgical Clinics of North America-VoL 58, No.6, December 1978

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CONSEQUENCES OF INADEQUATE DIETARY SUPPLEMENTATION Acute nutritional deficiency may be difficult to recognize in the severely injured patient. The usual manifestations of vitamin and protein deficiency associated with chronic states of malnutrition are not apparent. More often, rapid but insidious muscle wasting may occur within a few weeks resulting in diminished capability for performing kinetic work. Loss of the respiratory musculature is frequently associated with inadequate ventilatory effort and secondary pulmonary sepsis. Weight loss following burn injury is inevitable unless extraordinary efforts are exerted to provide exogenous caloric support. Retrospective studies at recognized burn centers have shown that the mean body weight decreased 25 per cent within 6 to 7 weeks in patients with burns exceeding 40 per cent of the total body surface when unsupervised dietary programs were employed. 3. 14 The acute loss of more than 10 per cent of pre-burn weight is often associated with severe complications, including inhibited rates of wound healing and decreased immunologic responsiveness. L 10. 12 Death usually ensues when acute weight loss exceeds 30 per cent of pre-injury levels. Occasionally the superior mesenteric artery syndrome is observed in burned patients who have received inadequate caloric support. 1S The syndrome is manifested by a functional obstruction in the third portion of the duodenum, at the point where the duodenum passes between the aorta and superior mesenteric artery. Clinical signs include nausea and vomiting shortly after ingestion of food. The diagnosis is confirmed by cinefluoroscopic demonstration of a dilated proximal duodenum in which reversed peristaltic waves are prominent. Usually small contents of contrast material may be observed to pass the area of obstruction when the patient is placed in a prone or right posterolateral oblique position, allowing the superior mesenteric artery to fall in an anterior direction, and thus increasing the angle formed between the aorta and the origin of the superior mesenteric artery. It has now been demonstrated that cellular function is also diminished during acute starvation states in the hypermetabolic patient. s. 8 Active transport of sodium, which requires energy in the form of adenosine triphosphate CATP), is inhibited in both red blood cells and muscle when inadequate exogenous calories are provided. Failure of the cellular sodium pump results in elevation of intracellular sodium concentration and a "sick" cell. If caloric replenishment is provided prior to cell death, the cellular lesion is reversible.

NUTRITIONAL MANAGEMENT Although the cornerstone of nutritional management is the provision of adequate calories from an exogenous source, much can be done to Ininimize energy demands. Since pain, anxiety, fear, and cold stress all stimulate the release of catecholamine stores, 19.20 every effort should be made to

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Figure 1. The Apollo Heat Shield suspended over the bed is used for patients with major thermal injuries. Radiant heat is directed onto each individual patient, providing maximum comfort to the patient while only minimally elevating the ambient temperature in the surrounding work space.

minimize these factors. Appropriate use of narcotics and tranquilizers to provide maximum patient comfort, as well as the provision of external heat are effective in this regard. Allowed to regulate their own environmental temperature, patients will select a room temperature of30 to 32° C to achieve maximum comfort.21 The overhead placement of radiant heat sources (Fig. 1), such as the Apollo Heat Shield, provides a local warm environment, while allowing nursing and medical personnel to work at a more comfortable room temperature. Another stimulus to higher metabolic expenditure is infection. 2,17 Although the prophylactic utilization of topical chemotherapeutic agents has decreased the incidence of burn wound infection in patients with less than 60 per cent total body surface burns, bacteriological monitoring of the wound via quantitative burn wound biopsy cultures is necessary to detect loss of bacteriologial control. l l The subeschar administration of specific antibiotics to which recovered organisms show in vitro sensitivity is indicated to discourage systemic dissemination when burn wound concentration exceeds 104 organisms per gram oftissue. 6 Metabolic expenditure may be reduced and burn wound infection can be avoided by early closure of the burn wound. Newer operating room techniques, which allow early excision of eschar with primary grafting, are being developed and should contribute significantly to the overall maintenance of a better postburn nutritional state. Daily caloric requirements of adult patients with burns of greater than 20 per cent of body surface area may be estimated by the formula: 25 Kcal per kg of body weight + 40 Kcal per per cent burn

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The maintenance requirements of children are higher and therefore estimates of expenditure should be revised upward by utilizing 40 to 60 Kcal per kg of body weight in the above formula. 7 After caloric requirements are calculated, dietary programs should be designed to provide enough nitrogen to ensure a calorie:nitrogen ratio of about 150:1 Whenever possible the enteral route should be utilized for dietary supplementation. Because pre-injury eating habits usually interfere with voluntary ingestion of higher calorie diets, the physician must regularly monitor calorie intake. Patients with burns of greater than 30 per cent total body surface will rarely achieve dietary goals necessary for maintenance of a good nutritional state if voluntary ingestion of oral diets is the only means of alimentation. Weight loss may not be appreciated during the first postburn week, since mobilization and excretion of excess fluid (administered during resuscitation) are not yet complete. Therefore, the use of small Silastic nasogastric feeding tubes, through which complete liquid diets may be delivered, is recommended as soon as gastrointestinal function has been restored following the initial injury. The diets are administered at a constant infusion rate utilizing a small pump (Fig. 2). As appetite improves and the burn wound is closed, the volume ofinfusion may be reduced. No abnormalities of digestion have been described in burned patients and therefore complete liquid diets should be administered rather than elemental dietary supplements. The latter solutions are extraordinarily hyperosmolar, limiting the concentration and volume which may be delivered without gastrointestinal symptoms such as vomiting and diarrhea. In patients with burns of greater than 40 per cent total body surface, complete diets of high caloric density are preferred in order to limit the volume of free water administration and to decrease the incidence of gastric overload with subsequent vomiting. One commercially prepared diet (Ensure-plus) contains 1. 5 Kcal per ml, allowing delivery of 4500 Kcal per day when given at a rate of 125 ml per hr. Adequate vitamins are provided in almost all commercially prepared liquid diets but most are deficient in sodium, which must be supplemented. When caloric requirements cannot be met entirely by enteral feeding, dietary supplementation may be accomplished by the peripheral administration of intravenous fat emulsions (Intralipid).13 After testing for anaphylaxis, 0.8 gm per kg per day may be administered, and this dose gradually increased to 2 gm per kg per day, which may provide slightly more than 1200 Kcal to a 70 kg adult. Septic complications often are associated with a paralytic ileus preventing enteral alimentation. In this case caloric requirements should be provided by conventional intravenous hyperalimentation techniques, in which hyperosmolar glucose solutions containing crystalline amino acids are delivered by a central vein. 9. 18 Septic contamination during catheter insertion must be scrupulously avoided and catheters should be changed every three days to decrease the incidence of subclavian septic thrombophlebitis. Nutritional programs should be initiated before the fourth postburn day, and daily caloric intake should approach levels that will satisfy nutritional requirements by the end of the first postburn week. If weight loss

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Figure 2. One of many manufactured constant infusion pumps which allow uniform delivery of either intravenous or enteral preparations is used to promote positive energy balance.

exceeds 10 per cent of the prebum weight, the patient must be considered a nutritional emergency and increased effort is required to decrease metabolic demand and improve dietary intake. When nutritional requirements are satisfied, weight loss may be prevented, wound healing enhanced, septic complications minimized, and organ function maintained. Well nourished granulation tissue, which provides an optimum recipient site for subsequent skin grafts, will develop and improved respiratory function is observed.

SUMMARY Patients with major thermal injury exhibit hypermetabolism as a result of neurohormonal alterations. Thus caloric requirements are exaggerated. Failure to provide supranormal caloric intake by both enteral and parenteral routes is associated with pronounced weight loss, delayed wound healing, decreased host resistance, and cellular dysfunction. Special dietary programs delivered early in the course of treatment must be utilized to prevent these complications of acute postburn malnutrition.

REFERENCES 1. Alexander, J. W.: Emerging concepts in the control of surgical infections. Surgery, 75 :934, 1974. 2. Bradham, G. B.: Direct measurement of total metabolism ofa burned patient. Arch. Surg., 105:410, 1972.

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3. Curreri, P. W.: Long-term supranormal caloric dietary programs in extensively burned patients. In Scheetz, W. L., and Cowan, G. S. M., Jr. (eds.): Intravenous Hyperalimentation. Philadelphia, Lea and Febiger, 1972, pp. 136-144. 4. Curreri, P. W.: Metabolic and nutritional aspects of thermal injury. Burns, 2:16, 1975. 5. Curreri, P. W., Hicks, J. E., Aronoff, R. J., et aI.: Inhibition of active sodium transport in erythrocytes from burn patients. Surg. GynecoI. Obstet., 139:538,1974. 6. Curreri, P. W., and Marvin, J. A.: Advances in the clinical care of burn patients. WesternJ. Med., 123 :275, 1975. 7. Curreri, P. W., Richmond, D., Marvin, J. A., et aI.: Dietary requirements of patients with major burns. J. Am. Diet. Assoc., 65:415, 1974. 8. Curreri, P. W., Wilmore, D. W., Mason, A. D., Jr., et al.: Intracellular cation alterations following major trauma: Effect of supranormal caloric intake. J. Trauma, 11 :390, 1971. 9. Dudrick, S. J., and Ruberg, R. L.: Principles and practice of parenteral nutrition. Gastroenterology, 61 :901, 1971. 10. Law, D. K., Dudrick, S. J., and Abdau, N. 1.: The effects of protein caloric malnutrition on immune competence of the surgical patient. Surg. GynecoI. Obstet., 139:257, 1974. 11. Loebl, E. C., Marvin, J. A., Heck, E. L., et al.: The use of quantitative biopsy cultures in bacteriological monitoring of burn patients. J. Surg. Res., 16: 1, 1974. 12. Meakins, J. L., Pietsch, J. B., Bubernick, 0., et al.: Delayed hypersensitivity: Indicator of acquired failure of host defenses in sepsis and trauma. Ann. Surg., 186:241, 1977. 13. Meng, H. C.: Fat emulsions. In Total Parenteral Nutrition. Acton, Massachusetts, Publishing Science Group, Inc., 1974, pp. 178-179. 14. Newsome, T. W., Mason, A. D., Jr., and Pruitt, B. A., Jr.: Weight loss following thermal injury. Ann. Surg., 178:215,1973. 15. ReekIer, J. M., Bruck, H. M., Munster, A. M., et aI.: Superior mesenteric artery syndrome as a consequence of bum injury. J. Trauma, 12:979,1972. 16. Reiss, E., Pearson, E., and Artz, C. P.: The metabolic response to burns. J. Clin. Invest, 35: 62,1956. 17. Roe, C. F.: Temperature regulation and energy metabolism in surgical patients. Prog. R. Surg., 12:93, 1973. 18. Schaffner, W. F.: Problems in preparation and handling of solutions. In Total Parenteral Nutrition. Acton, Massachusetts, Publishing Sciences Group, Inc., pp. 313-317, 1974. 19. Wihnore, D. W.: Nutrition and metabolism following thermal injury. Clin. Plast. Surg., 1: 603, 1974. 20. Wilmore, D. W., Long, J. M., Mason, A. D., Jr., et al.: Catecholamines: Mediator of the hyper metabolic response to thermal injury. Ann. Surg., 180:653,1974. 21. Wilmore, D. W., Orcutt, T. W., Mason, A. D., Jr., et aI.: Alterations in hypothalamic function following thermal injury. J. Trauma, 15:697, 1975. 525 East 68th Street Room F-758 New York, New York 10021

Nutritional support of the burned patient.

Symposium on Burns Nutritional Support of the Burned Patient P. William Curreri, M.D, * and Arnold Luterman, M.D.t Major thennal injury is character...
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