Effects of norepinephrine infusion on cerebral energy metabolism during experimental haemorrhagic shock

Abstract

Background The use of norepinephrine in the case of life-threatening haemorrhagic shock is well established but widely discussed. The present study was designed to compare the effects of early norepinephrine treatment vs. no treatment on cerebral energy metabolism during haemorrhagic shock. Methods Twelve pigs were subjected to haemorrhagic shock, 4 in the control group and 8 in the norepinephrine (NE) group. Following a 60 min baseline period haemorrhagic shock was achieved by bleeding all animals to a pre-defined mean arterial blood pressure (MAP) of approximately 40 mm Hg. When mean arterial pressure had decreased to 40 mmHg NE infusion started in the treatment group. After 90 min, NE infusion stopped, and all pigs were resuscitated with autologous blood and observed for 2.5 h. During the experiment cerebral tissue oxygenation (PbtO2) was monitored continuously and variables reflecting cerebral energy metabolism (glucose, lactate, pyruvate, glutamate, glycerol) were measured by utilizing intracerebral microdialysis. Results All 12 pigs completed the protocol. NE infusion resulted in significantly higher MAP (p < 0.001). During the shock period lactate/pyruvate (LP) ratio group increased from 20 (15–29) to 66 (38–82) (median (IQR)) in the control group but remained within normal limits in the NE group. The significant increase in LP ratio in the control group remained after resuscitation. After induction of shock PbtO2 decreased markedly in the control group and was significantly lower than in the NE group during the resuscitation phase. Conclusion NE infusion during haemorrhagic shock improved cerebral energy metabolism compared with no treatment.

Low-dose norepinephrine in combination with hypotensive resuscitation may prolong the golden window for uncontrolled hemorrhagic shock in rats

“…A similar result was observed in some other studies. Jakobsen et al (2022) found that early treatment with NE (0.03 mg/kg for 90 min) during severe and hemorrhagic shock restored MAP and chemical variables related to cerebral energy metabolism, and treatment with NE in hypovolemic shock did not cause cerebral vasoconstriction and hypoperfusion. In hemorrhagic shock pigs, Libert et al (2022) found that resuscitation with a combination of NE at two doses (moderate dose: mean rate of 0.64 µg/kg/min and high dose: mean rate of 1.57 µg/kg/min) and fluid restored renal microcirculation and oxygenation, as well as renal function, in a manner comparable to fluid resuscitation alone and without differences between the two NE doses.…”