Norepinephrine Dosing in Obese and Nonobese Patients With Septic Shock.

BACKGROUND Whether or not norepinephrine infusions for support of hemodynamic status in patients with septic shock should be weight based is unknown. This situation is particularly pertinent in patients who are extremely overweight or obese. OBJECTIVE To compare dosing requirements and effect of norepinephrine on blood pressure in obese and nonobese patients with septic shock. METHODS In a retrospective cohort study, data on adult patients with septic shock who received norepinephrine infusion for support of hemodynamic status in a tertiary care, academic medical center were analyzed. Patients were categorized as obese (body mass index ≥ 30) or nonobese (body mass index < 30). The primary outcome was dosing requirements of norepinephrine at 60 minutes after the start of the infusion. The secondary outcome was the log-transformed ratio of mean arterial pressure to norepinephrine. RESULTS The final cohort consisted of 100 obese and 100 nonobese patients. Mean norepinephrine infusion rate at 60 minutes was 0.09 (SD, 0.08) μg/kg per minute in the obese group and 0.13 (SD, 0.14) μg/kg per minute in the nonobese group (P = .006). The non-weight-based dose at 60 minutes was 9 μg/min in obese patients and 8 μg/min in nonobese patients (P = .72). The log transformed mean arterial pressure to norepinephrine ratio at 60 minutes was 2.5 (SD, 0.9) in obese patients and 2.5 (SD, 0.8) in nonobese patients (P = .54) CONCLUSIONS: Compared with nonobese patients, obese patients with septic shock require lower weight-based doses of norepinephrine and similar total norepinephrine doses.