Burn injury represents a significant problem worldwide. Advances in therapy strategies, based on better understanding of the pathophysiologic responses after burn injury have improved the clinical outcome of patients with burn injuries over the past years. This article describes the present understanding of the pathophysiology of a burn injury including both the local and systemic responses, focusing on the many facets of organ and systemic effects directly resulting from hypovolemia and circulating mediators following burn trauma.

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Endotoxin [lipopolysaccharide (LPS)] has been reported to reduce hypoxic pulmonary vasoconstriction and thus increases venous admixture. The time course of this failure of pulmonary blood flow regulation was investigated in six chronically instrumented unanesthetized sheep after infusion of Escherichia coli LPS (1 microgram/kg). The change in left pulmonary arterial blood flow (LPBF, ultrasonic transit time) in response to unilateral lung hypoxia (10 min of N2 alternately to the left and right lungs) was compared before and at various time intervals after the administration of LPS. During baseline conditions, LPBF was 33% of total cardiac output and decreased to 15% when the left lung was ventilated with a hypoxic gas mixture. One hour after endotoxin infusion, LPBF remained at 33% of total cardiac output yet only decreased to 28% during the hypoxic challenge. The response to one-lung hypoxia was still significantly depressed 10 h post-LPS administration. It is concluded that hypoxic pulmonary vasoconstriction is almost completely abolished for a prolonged time period after a small dose of LPS.

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— Sterilization levels found in inoculated test packs are commonly in disagreement with predicted values. This study was made to determine if predicted sterilization values would be closer to actual test values if the population distribution of the slope indices from a sample of heat rise curves were used instead of the traditional slowest or mean single value of slope index in the sterilization calculations. A computer was programmed to calculate from the basic equations of thermal death times and heat penetration, the amount of sterilization achieved at designated time intervals in a population of food packages. Means and standard deviations of slope indices from both real and postulated heat penetration tests were fed into the computer together with specified processing conditions. Predicted spoilage levels were very close to those obtained from actual inoculated test packs. From input of postulated heat penetration values, it was demonstrated that the larger the standard deviation, the greater the error will be if only a single value of the slope index is used. Manual procedures are given for an accurate determination of the minimum process time required for sterilization. Methods are also given for data expansion to show a curve illustrating the complete relationship between process time and food sterility.