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Impact of Norepinephrine Weight-Based Dosing Compared with Non-Weight-Based Dosing in Achieving Time to Goal Mean Arterial Pressure in Obese Patients with Septic Shock
Vadiei N, Daley MJ, Murthy MS, et al. Pharmacotherapy. 2017; 51: 194-202.
Study Question: Which norepinephrine dosing strategy will obese patients with septic shock achieve a goal MAP more quickly, weight-based dosing (WBD) or non-weight-based dosing (NWBD)?
Study Description: A multicenter, retrospective cohort analysis was performed in obese patients (BMI ≥ 30 kg/m2) treated with norepinephrine in a NWBD fashion (3 mcg/min, titrated by 3 mcg/min every 5 minutes with a maximum of 30 mcg/min) or WBD fashion (0.03 mcg/kg/min, titrated by 0.03 mcg/kg/min every 5 minutes with a maximum of 0.4 mcg/kg/min) for septic shock. Notable exclusion criteria were not receiving norepinephrine as the first vasopressor or a goal MAP that was not ≥ 65 mm Hg. Time to goal MAP was defined by the time to maintain a MAP ≥ 65 mmHg for at least one hour from the start of norepinephrine infusion.
Results: Of the 287 enrolled patients, 143 received NWBD norepinephrine and 144 received WBD norepinephrine. No differences in median time to goal MAP between the two groups were found (58 minutes WBD vs. 60 minutes NWBD, p = 0.28), even after adjusting for baseline severity of illness (HR 1.14, 95% CI 0.90-1.44). Compared to the NWBD strategy, patients receiving the WBD strategy were exposed to 20% higher median cumulative doses of norepinephrine (12.6 mg versus 10.5 mg, p = 0.04) and had a longer median time to discontinuation (33 hours versus 27 hours, p = 0.03). No differences in mortality, need for RRT, atrial fibrillation or length of stay were found.
Conclusion(s): Obese patients with septic shock treated with WBD norepinephrine compared to NWBD norepinephrine did not have a difference in the time required to achieve a goal MAP.
Perspective: Although norepinephrine is the first-line vasopressor in septic shock, dosing strategies in obese patients are not well established. While these results do not favor a particular dosing strategy in obese patients, additional studies should focus on evaluating any negative sequelae that may arise from the use of either strategy to guide practices.