382 Burns (1984) Vol. IO/No. 5

receiving diets containing calorie to nitrogen inputs of either 150 to 1 or 100 to 1. With the higher energy to nitrogen inputs the nitrogen balances were +2.33, + 0-13 and -3 -38 g per day when the wound sizes were respectively 1 10, 11-30 and 31 60 per cent of the body surface area. With the lower energy to nitrogen inputs the nitrogen balances were + 5.54, +3-49 and +3-38 g per day for the same wound areas. Thus the traditional 150 to 1 ratio may be adequate for patients with open wounds of less than 10 per cent of the body surface but is clearly inadequate when the burned area is more extensive. In the latter patients positive nitrogen balance can only be maintained with either a lower energy to nitrogen ratio or a higher nitrogen input.

Matsuda T., Kagan R. J., Hanumadass M. et al. �9 (1983) The importance of burn wound size in determin- ing the optimal calorie to nitrogen ratio. Surgery 94, 562.

A N I M A L STUDIES

Use of labelled leukocytes Polymorphonuclear leukocytes from normal and burned guinea pigs were labelled with 111indium to measure their body distribution and chemotactic abilities. While burning injury did not alter the degree of chemotactic ability the cells derived from burned animals left the circulation more rapidly and showed increased localiza- tion in the burned area and in the liver. There was no evidence of increased destruction of cells from burned animals occurring in the spleen or lungs.

Dominioni L., Alexander J. W., Ogle C. K. et al. (1983) Chemotaxis and body compartment distribution of Indium 111 labelled polymorphonuclear leukocytes in burned guinea pigs. J. Trauma 23, 911.

Modi f ica t ion of zone of stasis burns Guinea pigs with scalds were given either the anti- thromboxane, dipyridamol immediately after injury, or the burn wound was cooled or a combination of both these forms of treatment or no treatment (control animals). In addition half the animals had burn blisters removed immediately after burning. Removal of these blisters resulted in the conversion of partial thickness skin loss burns to either full thickness or very deep partial thickness skin loss. When the blisters were left intact complete reversal of ischaemia occurred without necrosis and, while dipyridamol and cooling each dimin- ished stasis soon after burning only cooled wounds showed any improved retention of hair follicles 3 weeks after injury. It has been concluded that blister removal eliminated any therapeutic effect of cooling or dipyri- damol, that when blisters were left intact the absorbed heat appeared at least as detrimental to healing as stasis and that some of the beneficial effects of cooling ap- peared to be unrelated to the prevention of stasis.

Saranto J. R., Rubayi S. and Zawacki B. E. (1983) Blisters, cooling, ant i thromboxanes and healing of experimental zone of stasis burns. J. Trauma 23, 927.

Hepatocyte dysfunction The t ransmembrane potential difference was measured in the tissues of baboons with burns covering about 50 per cent of the body surface area. After the muscle trans- membrane potential difference had fallen to - 70 mV the animals were resuscitated with large volumes of Ringers lactate solution. Prior to resuscitation the liver trans- membrane potential difference had halved and then returned towards normal with fluid therapy. In contrast the tissue ATP and glucose-6-phosphate contents did not change and the lactate content rose three fold prior to resuscitation. A severe cellular derangement was in- dicated by the marked hepatocyte depolarization which

�9 was not due to energy depletion. Shires G. T., Albert S. A., Illner H. et al. (1983)

Hepatocyte dysfunction in thermal injury. J. Trauma 23, 899.

Effects of a serotonin antagonist Ketanserin, a specific antagonist to serotonin, was tested in 15 pigs with full thickness burns covering a mean of 44 per cent of the body surface area to determine its haemodynamic effects. A control group of animals re- ceived no ketanserin, a second group received the drug both before and after burning while the third group received the ketanserin only after injury. Both groups of animals receiving ketanserin showed an improved car- diac index, decreased pulmonary artery pressures and smaller arterio-venous oxygen content differences com- pared with the control animals during the first few hours after injury.

Holliman C. J., Meuleman T. R., Larsen K. R. et al. (1983) The effect of ketanserin, a specific serotonin antagonist, on burn shock hemodynamic parameters in a pQrcine burn model. J. Trauma 23, 867.

Haemodynamic studies w i t h nitroprusside Haemodynamic studies were made on sheep with burns covering 40 per cent of the body surface area who received or did not receive sodium nitroprusside and the results were compared with those from unburned sheep (normal controls) and unburned sheep receiving nitro- prusside. Measured or derived values included cardiac index, pulmonary arterial and arterial pressures, pul- monary and systemic vascular resistance indices, shunt, arterial and mixed venous blood gases, pH and haema- tocrit. When burned animals with and without nitro- prusside were compared, significantly higher cardiac indices, expressed as per cent of base line, were noted for the sodium nitroprusside treated animals by 8 and 12 hours after burning. Thus nitroprusside treatment pro- duced a more rapid return to normal of cardiac index regardless of the origin of the decrement in cardiac index.

Stair J. M., Bowser B. H., Marvin T. H. et al. (1983) The effects of sodium nitroprusside on the haemo- dynamics of burn shock: Results of an experimental sheep model. J. Trauma 23, 939.