Effects of Endotoxemia and Blood Pressure on Microcirculation and Noradrenaline Needs With or Without Dexmedetomidine in Beagle Dogs-A Blinded Cross-Over Study.

Endotoxemia often leads to microcirculatory derangement. In six sevoflurane anaesthetized Beagle dogs, we investigated the effects of 1 mg/kg of lipopolysaccharide endotoxin intravenous and blood pressure (mean arterial pressure of 65 mmHg versus 85 mmHg) on microcirculation assessed on buccal mucosa using side stream dark field microscopy. Dogs were afterwards resuscitated with fluids and noradrenaline. We investigated dose requirements of noradrenaline with or without dexmedetomidine. Microcirculatory parameters, and markers of sepsis (cardiac output, mixed venous oxygen saturation, carbon dioxide gap, and lactate) were analysed before endotoxemia, after endotoxemia, after a 30 mL/kg of Ringer's acetate fluid bolus, and during noradrenaline +/- dexmedetomidine infusion, after a second fluid bolus, and a second time after vasopressor treatment in a cross-over fashion. Endotoxemia and mean arterial pressure had no statistically significant effect on microcirculation; however, endotoxemia resulted in a decrease in cardiac output. Dexmedetomidine neither improved microcirculation nor reduced noradrenaline requirements.