Bums, 10, 147-l 49 Printed in Great Britain 147

Abstracts CLINICAL STUDIES Nitrogen intake and metabolism

Sixteen patients with burns covering over 50 per cent of the body surface received 3200 Kcal of energy as a mixture of fat and glucose over the period of 2 to 8 days after burning. In addition 8 of the 16 patients received 24 g amino acid nitrogen daily. Comparison of the patients receiving and not receiving the nitrogen input showed no significant changes in resting meta- bolic rate or noradrenaline excretion or a variety of other biochemical measurements. The only significant difference between the 2 groups of patients was urinary nitrogen excretion. The cumulative nitrogen balance was markedly less negative 8 days after injury in the patients receiving amino acids (-24gN+ 8gV.- 1OOgNf log). Thus a high nitrogen input together with an adequate energy supply improves the nitrogen balance significantly in the early postburn period.

Liljedhal S. O., Larsson J., Schildt B. et al. (1982) Metabolic studies in severe burns. Clinical features, routine biochemical analyses, nitrogen balance and metabolic rate. Acta. Chir. Stand. 148, 393.

Bacteria and air fluidized beds

Heavily infected burned patients contaminated the glass beads in air fluidized beds in spite of following the manufacturer’s rules for cleaning the bed and beads. Patients contributed Staph aureus, Staph epi- dermis, Strep faecalis, E. cob, and S. marcescens to the beads which could only be removed by machine wash- ing the filter sheet with detergent and disinfection of the sheet and beads with sodium hypochlorite and quaternary ammonium chloride. Solid matter within the bead mass should be removed by at least weekly sieving of the entire bead mass.

Scheidt A. and Drusin L. M. (1983) Bacteriologic contamination in an air fluidized bed. J. Trauma 23, 241.

Vasopreuin and serum sodium levels

Plasma arginine vasopressin levels were measured in samples from 20 patients with bums covering between 15 and 80 per cent of the body surface area on or after the fourth day after injury. In those plasma samples which contained I30 mmol/l or less of sodium the content ofarginine vasopressin was raised significantly (P<O.OOl). Most patients with normal serum Na+

concentrations had normal vasopressin levels. When a standard water load was given to 4 hyponatraemic burned patients, the hypotonicity and plasma content of vasopressin increased. The marked relationship be- tween hyponatraemia and arginine vasopressin secre- tion occurs without gross changes in blood volume or adrenal activity.

Shirani K. Z., Vaughan G. M., Robertson G. L. et al. (1983) Inappropriate vasopressin secretion (SIADH) in burned patients. J. Trauma. 23, 2 17.

Metocurine and neuromuscular blockade

Burned children anaesthetized with thiopentone, nitrous oxide and oxygen required a 3 fold greater dose of metocurine to achieve a given dose of neuromuscu- lar blockade compared with non-burned children. For the same degree of twitch depression the burned chil- dren required twice the plasma concentration of meto- curine. Despite this larger dose of metocurine the recovery time for twitch was not significantly different in the two groups of children. There may be changes at the neuromuscular junction following bums to account for this resistance to the effects on non- depolarizing blocking agents.

Martyn J. A. J., Goudsouzian N. G., Matte0 R. S. et al. (1983) Metocurine requirements and plasma concentrations in burned paediatric patients. Br. J. Anaesth. 55, 263.

Estimations of burn depth

Fibreoptic perfusion fluorometry and sodium fluores- cein have been used to assess the depth of burning in 63 patients. Fluorescein kinetics were monitored with- in the first 48 hours of iniurv and 3 to 6 davs later. Comparisons of the fluorescein uptakes in burned skin with that of normal skin, and biopsy and healingcharac- teristics of the burned skin indicated that fluorometric analyses consistently distinguished between partial and full thickness skin loss injuries. Partial thickness skin loss bums uniformly showed fluorescence within IO minutes whereas full thickness skin loss burns showed no fluorescence.

Gatti J. E., La Rossa D., Silverman D. G. et al. (1983) Evaluation of the burn wound with perfusion Buorometry. J. Trauma. 23,202.

Improved rate of survival

More patients with bums covering more than 50 per

148 Burns Vol. lo/No. 2

cent of the body surface area have survived recently as a result of:

1. Early endotracheal intubation with application of PEEP before evidence of pulmonary dysfunc- tion in patients flame burned in confined spaces.

2. Elimination of central venous lines for fluid resuscitation unless absolutely necessary.

3. Early use of hypertonic saline and protein in the fluid resuscitation.

4. Earlier introduction of intensive nutrition, and 5. Early excision and grafting. Demling R. H. (1983) Improved survival after

massive burns. J. Trauma. 23. 179.

Thermoregulation and healed burns

The thermoregulatory responses to moderate exercise in a warm environment were studied in a group of young male subjects who had healed burned areas which originally covered about 50 per cent of the body surface (Group A); in another group with healed burns which originally covered about 35 per cent of the body surface (Group B) and in a group of normal subjects. After exercising for 3 hours in an environment main- tained at 40 “C and 50 per cent relative humidity the rectal temperature, mean skin temperature and heart rate of Group A subjects was markedly raised, whereas in Groups B and C they remained normal. The maxi- mal evaporative cooling capacity in the Group A patients was less than half that in the normal subjects because of the lack of sweat glands in the grafted skin. This disability is persistent and indicates that subjects with extensive healed burned areas should not be asked to work hard in hot environments.

Shapiro Y., Epstein Y., Ben-Simchon C. et al. (1982) Thermoregulatory responses of patients with extensive healed bums. J. Appl. Physiol. 53, 1019.

Resuscitation fluids and lung water volume

Lactated Ringers solution alone or admixed with 2.5 per cent albumin was given to 79 patients with exten- sive burns. Patients treated with crystalloid solution alone required significantly more fluid than did the colloid treated patients for adequate resuscitation. Cardiac index was lower in the 12 to 24 hour postburn interval in the patients receiving only crystalloid but this difference had disappeared by 48 hours after burn- ing. Subsequently the cardiac index increased pro- gressively and identically in both treatment groups over the 7 day study period. There was no evidence of myocardial depression.

ANIMAL STUDIES Endotoxin exacerbates lung injury

Lung water volume remained unchanged in the crystalloid treated patients but progressively increased and became significantly different (P<O.OOl) in the colloid treated patients over the study period of 7 days. This effect of colloid was disadvantageous from the ooint of view of lung function when oedema fluid was

Nine of 17 sheep with lung lymph tistulae received a bum covering 25 per cent of the body surface area. All I7 sheep were then given 1.5 ug per Kg E. coli endo- toxin. A biphasic lung injury was seen in all sheep after giving endotoxin with an early phase of pulmonary arterial hvnertension followed by an increased flow of protein-r& lymph. All 8 animals that only received endotoxin survived whereas 4 of the 9 burned animals died with pulmonary oedema, a more severe hypoxia, pulmonary hypertension and increased post burn lymph flow. Also in the burned animals there were significant increases in lymph thromboxane and glucuronidase activity. Thus burning injury increased the susceptibility of lung tissue to damage by agents liberated ‘from burned tissue.

Nerlich M., Flynn J. and Demling R. H. (1983) Effect of thermal injury on endotoxin induced lung injury. Surgery 93, 289. being absorbed from the burn wound.

Goodwin C. W., Dorethy J., Lam V. et al. (1983) Randomized trial of efficacy of crystalloid and colloid resuscitation on hemodynamic -response and lung water following thermal injury. Ann. Surg. 197, 520.

Prediction of morbidity and mortality

The records of 806 burned adults and children were retrospectively reviewed using probit analysis to indi- cate mortality probability and the LA,,s for burn injury. The LbOs were compared with those described by the USA National Bum Information Exchange. The authors present improved survival rates for children and patients up to 34 years of age and between 60 and 74 years of age. Discriminantanaly- sis was also used to predict survival and proved to be 95.8 per cent accurate. In addition the use of a bum severity scoring technique assisted in the identification of patients with a high risk of mortality.

Bowser B. H., Caldwell F. T., Baker J. A. et al. (1983) Statistical methods to predict morbidity and mortality: self assessment techniques for bum units. Burns 9, 3 18.

Increased evaporative water loss

Five patients with burns covering between 20 and 40 per cent of the body surface area nursed on an air- fluidized bed lost approximately 0.80 ml of water per cm* of burned area per day by evaporation from the lungs and burned tissue during the first 2 weeks after injury. For an 80 Kg body weight male with 50 per cent of the body surface area burned this amounts to about 8 litres of water per day. This rate of water loss is about twice that observed in patients treated by exposure on normal beds in warm dry conditions. In contrast the air-fluidized bed did not induce any in- crease in sodium loss which remained at about 0.02 mmol per cm2 of burned area per day.

Micheels J. and Sorensen B. (1983) Water and sodium balance: the effect of the air-fluidized bed on burned patients. Burns 9,305.

Vasopressin and blood loss

Piglets with deep bums covering one third of the body