In this Escherichia coli induced porcine model, severe sepsis was evident by conventional criteria at 4 hours while several - mostly hypoxemia induced - biomarkers were already altered by 2 hours.

The pathophysiology of hemorheological and microcirculatory disturbances in septic process -mostly during the early hours-still not clarified in all the details, yet. In anesthetized pigs living E. coli (ATCC 25922 strain) was administered intravenously with an increasing concentration and the animals were observed for 8 hours. Before the intervention and in every 2 hours arterial (cannulated femoral artery) and venous (cannulated external jugular vein) blood samples were collected for hemorheological laboratory tests: blood and plasma viscosity, ESR, leukocyte anti-sedimentation rate, erythrocyte deformability (together with osmoscan parameters) and erythrocyte aggregation (using light-transmission and laser back-scattering methods) Control animals were stable over the 8-hour anesthesia, while septic animals died by the 6th hours in a fulminant sepsis. Over the experimental period, the tendency of impairment in erythrocyte deformability (together with osmotic gradient ektacytometry parameters) and the controversial decreasing of erythrocyte aggregation values (declining all aggregation index values, elongating t 1/2 ) were well detected in this porcine model during the early hours (4-6) of fulminant sepsis. The in vitro effect of these bacteria on erythrocytes' micro-rheological parameter was similar: decreasing red blood cell deformability and lowering aggregation. Further studies are needed to clarify the early micro-rheological changes of bacteremia and the developing sepsis.

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Intellectual and scientific content of the study, conception and design of the study, critical revision, final approval of the manuscript. ABSTRACT PURPOSE:In the pathophysiology of sepsis tissue perfusion dysfunction is a crucial driving force. Thus the early recognition is highly important. Concerning the early hours of bacteremia, and the systemic inflammatory response reaction leading to sepsis we aimed to investigate the micro-and macrocirculatory changes. METHODS:In 20 juvenile Hungahib pigs were anesthetized and the femoral artery and external jugular vein were prepared unilaterally and cannulated. For assisted ventilation tracheostomy was performed. In Sepsis group (n=11) live E. coli was intravenously administered (increasing concentration, 9.5x10^6 in 3h). In Control group (n=9) bacteria-free saline was administered at the same volume. Modified shock index (MSI), core and skin temperature, and skin microcirculation (laser Doppler) were measured before inducing bacteremia then hourly for 4h. RESULTS:In Control group parameters were stable, while six animals in the Sepsis group died before the 4 th hour. Core and skin temperature did not show significant alterations. In Sepsis group microcirculation showed a large impairment already by the 1st hour, while in MSI only by the 3rd hour. CONCLUSION:During bacteremia and the early phase of sepsis microcirculatory impairment can be detected soon, even hours before the deterioration in hemodynamic parameters in this porcine model.Key words: Bacteremia. Sepsis. Microcirculation. Hemodynamics. Shock. Models, Animal. Swine. Skin microcirculatory changes reflect early the circulatory deterioration in a fulminant sepsis model in the pig

BackgroundThe aim of the present work was to assess cerebral hemodynamic changes in a porcine model of E.coli induced fulminant sepsis.MethodsNineteen healthy female Hungahib pigs, 10–12 weeks old, randomly assigned into two groups: Control (n = 9) or Septic Group (n = 10). In the Sepsis group Escherichia coli culture suspended in physiological saline was intravenously administrated in a continuously increasing manner according to the following protocol: 2 ml of bacterial culture suspended in physiological saline was injected in the first 30 min, then 4 ml of bacterial culture was administered within 30 min, followed by infusion of 32 ml bacterial culture for 2 h. Control animals received identical amount of saline infusion. Systemic hemodynamic parameters were assessed by PiCCo monitoring, and cerebral hemodynamics by transcranial Doppler sonography (transorbital approach) in both groups.Results In control animals, systemic hemodynamic variables and cerebral blood flow velocities and pulsatility indices were relatively stable during the entire procedure. In septic animals shock developed in 165 (IQR: 60–255) minutes after starting the injection of E.coli solution. Blood pressure values gradully decreased, whereas pulse rate increased. A decrease in cardiac index, an increased systemic vascular resistance, and an increased stroke volume variation were observed. Mean cerebral blood flow velocity in the middle cerebral artery did not change during the procedure, but pulsatility index significantly increased.ConclusionsThere is vasoconstriction at the level of the cerebral arterioles in the early phase of experimental sepsis that overwhelmes autoregulatory response. These results may serve as additional pathophysiological information on the cerebral hemodynamic changes occurring during the septic process and may contribute to a better understanding of the pathomechanism of septic encephalopathy.