Nutrients and nitrogen balances in burned patients

Nutrients and nitrogen balances in burned patients

218 Haematological changes following burns Numerous studies in 45 patients with burns of varying extent show statistically significant changes betwee...

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Haematological changes following burns Numerous studies in 45 patients with burns of varying extent show statistically significant changes between the platelet counts, the concentration of fibrin degradation products and plasminogen levels. Measurements were also made of the C~ and 5-min kinin activity. The patients were divided into three groups with mortality probabilities--depending upon age and the severity of the b u r n - - o f more than 0.8, between 0"2 and 0.8 and less than 0'2. Within the first 48 h of burning there were marked decreases in C3, 5-rain kinin and plasminogen levels. Subsequently, the levels returned to normal or supranormal values. The platelet counts remained either normal or supranormal at all times. The concentration of fibrin degradation products increased enormously (10-20 times) during the first week after burning. Standard heparin therapy did not significantly inhibit Hageman Factor, plasmin, complement or kinin activation products, nor change the levels of fibrin degradation products. Caprini J. A., Lipp V., Zuckerman L. et al. (1977) Hematologic changes following burns. Y. Surg. Res. 22, 626.

Nutrients and nitrogen balances in burned patients Thirty-two patients with burned areas covering between 21 and 79 per cent of the body surface who at no time had a blood culture positive for any microorganism, and 15 patients with burned areas covering between 31 and 75 per cent of the body surface and had at least one blood culture which was positive, received either hypocaloric near iso-osmotic infusions of crystalline amino acids or equal caloric infusions of glucose without any amino acids. These two nutritional regimes had the same effect on nitrogen balance in the two groups of patients. Infusions of a 10 per cent soya bean oil emulsion (Intralipid) were indistinguishable in effect from low dosage glucose infusions when administered with amino acids. Near iso-osmotic hypocaloric diets containing glucose and amino acids significantly diminished the nitrogen loss in severely burned patients. The authors prefer a combination of both substrates in the solution infused. McDougal W. S., Wilmore D. W. and Pruitt B. A. (1977) Effect of intravenous near iso-osmotic nutrient infusions on nitrogen balance in critically ill injured patients. Surg. Gynecol. Obstet. 145, 408.

Intensive nutrition Intensive metabolic studies were made on 15 patients with burns covering between 20 and 70 per cent of the body surface. Oxygen consumption was measured frequently with a simple spirometer and the daily energy expenditure calculated. A hypermetabolic state was observed consistently which correlated best with the area of full-thickness skin loss (rather than with the total area of the burns). Nutritional management and energy intake were adjusted to balance the observed energy expenditure. When the energy balance

Burns Vol. 4/No. 3

was positive most patients maintained their body weight unchanged, while the remainder showed increases in body weight. Five hundred and fifty six other patients were maintained with a zero or positive energy balance by a mixture of an oral input supplemented with between 17 and 34 MJ (4000 and 8000 kcal/d) given via a nasogastric tube (a suspension containing 30-34 per cent fat, 45-50 per cent carbohydrate and 20 per cent protein adjusted to between 4 and 8 KJ/ml (1-2 kcal/ml). Parenteral nutrition was used only rarely. These patients showed an uncomplicated clinical course with only 23 deaths, mainly associated with smoke inhalation and respiratory failure. Bartlett R. H., Allyn P. A., Medley T. et al. (1977) Nutritional therapy based on positive caloric balance in burn patients. Arch. Surg. 112, 974.

A N I M A L STUDIES T and B cells in burned mice Studies were carried out on the number and function of T and B cells from the spleens of normal mice and those receiving burns covering 67 per cent of the body surface. The results showed a significant decrease ( P < 0.05) in the number of T and B ceils for 2-3 days after burning with a rapid return to normal and a subsequent rise above normal at 14 and 21 days post burn ( P < 0.05). In the tests for function, burned mice had a significant decrease in spontaneous mitotic activity of both T and B cells during the 21-day postburn period. When spleen lymphocytes were incubated with purified mitogens, both T and B cells showed a significantly diminished mitotic response in most of the burned animals. Markley K. and Smallman E. T. (1977) Effect of thermal trauma on numbers and function of T and B cells from mouse spleen. Int. Arch. Allergy Appl. Immunol. 54, 238.

The induction of immune responses The immunocompetence of leucocyte subpopulations from mice which had received a 10 per cent body surface area scald has been examined. Leucocytes from the burned animals showed an 80 per cent reduction in their ability to generate de novo antibodyforming cells in vitro. When leucocytes from the burned animals were supplied with the immunologically active factors produced by normal A and T leucocytes, their immunocompetence was restored. The experiments suggest that thermal injury directly reduces the immune activity of leucocytes, and that leucocyte injury induced by thermal injury is timedependent. The leucocyte subpopulation affected by heat is not that of the antibody-forming B cell. Miller C. L . and Trunkey D. D. (1977) Thermal injury: defects in immune response induction J. Surg. Res. 22, 621.

Studies of tissue oxygenation Subcutaneous tissue Po2 and Pcoz levels were measured in anaesthetized rabbits having had 10 per cent