Abstracts 297

with sepsis was due to an increase in pulmonary capillary membrane permeability.

Peitzman A. B., Shires G. T., Corbett W. A. et al. (1981) Measurement of lung water in inhalation injury. Szct~er~~90,305.

Cardiac response to fluid therapy A modified pulmonary artery catheter and the thermo- dilution technique was used to measure right ventricular end diastolic volume and right Yentricular ejection fraction in comparison with other indicators of cardiac function in 16 patients with very extensive burns. Cardiac index was best correlated with right ventricular end diastolic volume and was only poorly correlated with mean pulmonary artery pressure. wedge pressure, right ventricular end diastolic pressure and urine volume. Unlike atrial pressures the right ventricular end diastolic volume and right ventricular ejection fraction were unaffected by malpositioning of transducers, airway pressures or compliance changes in the ventricle.

Martyn J. A. J.. Snider M. T., Farago. L. F. et al. (198 1) Thermodilution right ventricular volume: a novel and better predictor of volume replacement in acute thermal injury. J. 7%auma 21,6 I9

ANIMAL STUDIES High and low temperature injuries Full-thickness injury of rat skin by burning (100°C) results in wound healing with contraction whereas wounds of similar area and depth caused by freezing (-196°C) heal without contracting. High temperatures cause cell death and denaturation of the connective tissue matrix whereas freezing causes cell death, but the matrix is not immediately denatured and appears to maintain its integrity during the early phases of repair. Within 2 hours of burning there is reduced but obvious perfusion at the site of injury, whereas the site of freezing showed little perfusion. This pattern of responses had reversed by 4-5 hours after injury. By 24 hours after injury the burned site was nearly avascular and surrounded by an area of vasodilation. in contrast the frozen site had patent vasculature within the dermis and little vasodilation in the surrounding area. The persistent perfusion in the frozen dermis was presumably through vascular channels that were dead but not occluded.

Ehrlich H. P., Trelstad, R. L. and Fallon J. T. (I 98 I ) Dermal vascular patterns in response to burn or freeze injury in rats. Erp. ,Zfool. Pafho(. 34,28 1.

Chemical dhbriding agents I~I WYO and 111 viva studies in a variety of experi- mental animals and patients with burns have shown that N-acetylcysteine and penicillamine can induce ready separation of bum eschar from the underlying viable tissue. Dkbridement of full-thickness. skin-loss burns of rats is complete within 4-6 hours, and the take of immediately applied syngeneic skin grafts is complete and permanent. Unburned skin is not

damaged. There is no apparent systemic toxicity associated with the use of N-acetylcysteine for dibridement of IO-15 per cent deep burns of rats or IS-20 per cent deep burns of pigs. Sulfamylon and silver sulphadiazine can be used with ~-acetylcysteine without interfering with its debriding action. The effect of this mercaptan is probably due to its ability to depolymerize connect& ti~ue-proteogiycans and proteins, especially at the interface between living and dead tissue.

Levenson S. M., Gruber D. K., Gruber C. et al. (198 1) Chemical dkbridement of burns-mercaptans. J. Trauma 21,632.

Electrical injuries In anaesthetized pigs application of voltages between IO and I4 000 were associated with currents up to 70 A through tissues with a resistance of about 200 R. Below 1000 V, arcing and consequent skin necrosis caused a marked reduction in current flow, which was not observed at higher voltages. The energy required for tissue damage was dependent upon both the voltage and the duration ofcurrent flow. With stainless steel disc electrodes skin burning commenced at the periphery ofthe electrodes and moved inwards. Across the hindlimbs of the pig the current per tissue cross section was greatest in artery and nerve followed by muscle, fat, bone marrow and bone cortex.

Sances A., Myklebust J. B., Larson S. J. et al. (1981) Experimental electrical injury studies. J. Truztma 21, 589.

LABORATORY STUDIES Neutrophil migration and chemotaxis The random migration and chemotactic response (expressed as a chemokinetic ratio) of polymorpho- nuclear leucocytes has been studied in samples from 33 burned patients. An inverse and significant relationship was found between the chemokinetic ratio and the area of the burn. In the more severely burned patients the chemokinetic activity was heat labile (56°C for 30 minutes). The reduced chemo- kinetic activity in the major injuries was due to a deficiency of stimulatory activity during the first 1-2 weeks and to the presence of cell-directed inhibitors during the subsequent weeks. Of the two kinds ofcell- directed inhibitors which have been identified both were heat stable and showed no chemotactic activities. One agent interfered with the chemotactic responses of the leucocytes and had an apparent molecular weight of 20-30000 awu: the other inhibited both the chemotactic response and the random migration of normal cells, and had a molecular weight of between I50 and 300 000 awu. Four of 8 patients who died had developed migration inhibitory activity in their sera and 1 patient with the same inhibition survived possibly due to episodes ofplasmapheresis.

Venge P. and Arturson G. (1981) Locomotion of neutrophil granulocytes from patients with thermal injury. Identification of serum-derived inhibitors. Bzcms 8,6.