Abstract
BackgroundThe 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.MethodsTwelve 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.ResultsAll 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.ConclusionNE infusion during haemorrhagic shock improved cerebral energy metabolism compared with no treatment.
Highlights
The use of norepinephrine in the case of life-threatening haemorrhagic shock is well established but widely discussed
NE infusion during haemorrhagic shock improved cerebral energy metabolism compared with no treatment
A decrease in mean arterial pressure (MAP) below the lower autoregulatory limit will result in a decrease in the cerebral perfusion pressure, which could compromise cerebral energy metabolism [10]
Summary
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. The prevailing regimen in treating patients in haemorrhagic shock is damage control resuscitation and damage control surgery [1,2,3,4,5]. During permissive hypotension the clinician allows a lower target-mean arterial pressure (MAP), to avoid adverse effects, such as dilutional coagulopathy or acceleration of haemorrhage [7,8,9]. A decrease in mean arterial pressure (MAP) below the lower autoregulatory limit will result in a decrease in the cerebral perfusion pressure, which could compromise cerebral energy metabolism [10]. Some guidelines promote the use of vasoactive drugs in the face of lifethreatening haemorrhage, whereas others warn against them [12,13,14]
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