Norepinephrine in low to moderate doses may not increase luminal concentrations of l‐lactate in the gut in patients with septic shock*

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Abstract
To investigate the effect of different doses of norepinephrine (noradrenaline) on luminal concentrations of L-lactate in the rectum and stomach in patients with fluid-resuscitated septic shock. This was a paired cross-over study in which the dose of norepinephrine was titrated to mean arterial blood pressures (MAPs) of 65 and 85 mmHg in random sequence. It was performed in a mixed intensive care unit at a university hospital. Eight patients with fluid-resuscitated septic shock requiring norepinephrine (>0.1 microg/kg/min) were included. Patients were treated with norepinephrine to a MAP of either 65 or 85 mmHg for 2 h. After a 'washout' period of 2 h, the dose of norepinephrine was titrated to the other endpoint of MAP for another 2 h. The concentrations of L-lactate in the rectal and gastric lumen were estimated by 1-h equilibrium dialysis during the second hour of the treatment periods. MAP and central venous oxygen saturation were increased by increasing the dose of norepinephrine [median (range) (microg/kg/min): 0.07 (0.00-0.60) and 0.18 (0.11-1.00) at MAPs of 65 and 85 mmHg, respectively], whereas the metabolic markers were unaffected [luminal concentrations (mmol/l) of L-lactate in the rectum of 1.9 (0.8-6.4) and 1.8 (0.9-5.7) (P =0.94) and in the stomach of 1.1 (0.1-10.0) and 1.3 (0.3-9.7) (P =0.88) at MAPs of 65 and 85 mmHg, respectively]. In this small study, luminal concentrations of L-lactate in the rectum and stomach were unaffected by norepinephrine at low to moderate doses. These data suggest that norepinephrine may not increase luminal concentrations of l-lactate in the gut in patients with fluid-resuscitated septic shock.