A56-29 The Effect of Norepinephrine Dosing Strategies on Clinical Decision-Making in Obesity and Septic Shock: A Single-Center Retrospective Study

Rationale

Septic shock is a leading cause of admission to the medical intensive care unit (MICU), with norepinephrine serving as the cornerstone for hemodynamic management. However, the optimal dosing strategy remains controversial. Some studies demonstrate higher cumulative norepinephrine dose, prolonged vasopressors use, and increased mortality with weight-based dosing, while others demonstrate benefits like lower initial doses, shorter time to goal mean arterial pressure, and decreased need for additional vasopressors. No data exists regarding the impact of norepinephrine dosing strategy on clinical decision-making, such as the initiation of steroids or additional pressors, particularly in obese patients. We performed a single-center, retrospective study comparing weight-based versus flat-dosed norepinephrine in septic shock, analyzing clinical decision-making with regards to body mass index (BMI).

Methods

All patients aged 18-99 admitted to the MICU at the University of Kentucky with a diagnosis of sepsis/septic shock receiving norepinephrine from 2005-2020 were included. Patients who received both dosing strategies were excluded. After stratifying based on weight-based vs flat-dosing, we matched the groups on demographics, comorbidities and SOFA scores. Primary outcomes included time to hydrocortisone initiation and time to second pressor initiation. Secondary outcomes included mortality, time to enteral feeding, and length of stay (LOS). These outcomes were further compared between different BMI subgroups.

Results

After matching, 822 patients (411 patients in the flat-dose and 411 patients in the weight-based dosing groups) were evaluated. Time from norepinephrine start to hydrocortisone initiation was significantly lower in the flat-rate group compared to the weight-based group (29.8 hours vs 51.5 hours, p = 0.003). This effect was pronounced in the overweight (18.6 hours vs 40.1 hours) and the obese group (26.9 hours vs 57.5 hours), though the interaction was not significant. Enteral feed initiation was done earlier in the flat-dosing group (1.3 hours vs 2.1 hours, p < 0.001).

Conclusion

Our study demonstrates that norepinephrine dosing strategies may be associated with differences in clinical decision-making, such as timing of hydrocortisone. Several studies have shown mortality benefit and earlier resolution of septic shock with hydrocortisone. The 2021 Surviving Sepsis guidelines recommend using corticosteroids in patients requiring vasopressor support, but do not specify at what norepinephrine dose hydrocortisone should be initiated. With weight-based norepinephrine dosing, identical values may reflect a higher absolute dose for high BMI patients, delaying the initiation of steroids. Our study is limited by the non-randomized design, retrospective data collection, and the potential for changes in standard of care over the study period.

This abstract is funded by: None