Induction of nitric oxide synthase by cytokines has been hypothesized as a mechanism of the hyporesponsiveness to catecholamines that occurs in clinical septic shock. We measured responses of resistance arterioles in rat cremaster muscle to topically suffused norepinephrine in vivo with the use of image-shearing videomicroscopy. Rats made septic by cecal ligation and puncture were compared with controls that underwent sham ligation. The norepinephrine concentration-response curve was shifted to the right in septic rats [50% effective concentration (EC50) 9.1 +/- 5.4 vs. 0.10 +/- 0.02 microM, P < 0.05]. Contractions at doses of 10(-9), 10(-8), and 10(-7) M norepinephrine were 26, 41, and 38%, respectively, of sham controls. Superfusion of the muscle with the nitric oxide synthase inhibitor NG-monomethyl-L-arginine at 100 microM restored the arteriolar responsiveness of the septic rats (EC50 0.14 +/- 0.07 vs. 6.8 +/- 3.1 microM, P < 0.05). This effect was reversed with superfusion of excess (1 mM) L-arginine. These experiments demonstrate impaired vasoconstriction in response to norepinephrine in resistance arterioles of septic rats in vivo. NG-monomethyl-L-arginine reversed this hyporesponsiveness, implying that nitric oxide synthase may mediate the decreased catecholamine responsiveness associated with sepsis.

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Sequential same arm measurements of the CVProfilor DO-2020 Cardiovascular Profiling System measures blood pressure by an oscillometric method (dynamic linear deflation) with reasonable agreement with a mercury sphygmomanometer.

Background: Most clinical trials of sepsis treatment modalities fail at their primary objective of establishing superiority over placebo when added to background standard of care. While there is no definitive explanation for the high failure rate, it might be stated that our attempts to insert a new therapeutic agent into standard of care encounters severe problems with definition of exactly what stage is ongoing, and what are the criteria for progression or resolution from that time point onwards. Clearly there is need for a means of defining steps in the septic process that would apply to individuals, and to better define the course of sepsis in each patient after they are enrolled in a trial. Methods: For core model development, 30 septic patients were studied for time-related progression in relation to biomarkers, employing a Load Model in a neural net algorithm in MatLab. Causative bacterial infections were linked to primary infection sites. In order to minimize overparameterization, the model was allowed to estimate outputs using the best three input parameters. Bacterial load was tracked from origin using clinical and microbiologic data to provide an estimate at the start of sepsis. The bacterial load as well as clinical and laboratory parameters were model inputs with the output parameter being organ failures and/ or mortality. Results: At onset of sepsis, human bacterial load estimates ranged from between 10 8 and 10 11 CFU, which is consistent with inocula in animal models of sepsis. Sepsis proceeds to organ failures and mortality in a series of steps that are initially linked to bacterial load and inflammatory response, followed by coagulopathy, ischemia, oxygen deprivation in organs and tissues, and culminating in organ failures. The later stages of sepsis are all driven by metabolic parameters, and there seems to be little benefit to blocking inflammation at later stages. Substrate and oxygen deficiencies must be addressed first. Conclusion: Neural net progression models based on biomarkers and physiological markers are able to describe the evolution of sepsis to septic shock, organ failures, and provide some evidence that mortality may be a consequence of the stages of sepsis. Overall, these models appear useful to the task of sorting out organ failure endpoints and mechanisms in individual patients with sepsis progression across sepsis to septic shock. P2 Extracellular matrix turnover, angiogenesis and endothelial function in acute lung injury: relationship to pulmonary dysfunction and outcome

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