Objective: Norepinephrine is the first-line vasopressor recommended for patients in septic shock. Weight-based dosing may increase drug exposure and the risk of adverse effects in obese patients. The objective was to evaluate the safety and efficacy of weight-based norepinephrine dosing using actual body weight in the morbidly obese compared with normal weight patients.
Methods: This was a single centre, retrospective study of adult patients admitted with septic shock requiring norepinephrine for at least 12hours. The primary endpoint was the incidence of tachycardia within 48hours after norepinephrine initiation. Secondary endpoints included timing and dosing of norepinephrine when adjunctive agents were added.
Results: The incidence of tachycardia was similar between groups. Total norepinephrine exposure was significantly greater in obese patients on day 1 (p=0.02). Obese patients were more likely to be started on vasopressin (p<0.001) and steroids at a lower weight-based norepinephrine dose (p=0.016).
Conclusions: Weight-based norepinephrine dosing using actual body weight did not result in more tachycardia in the morbidly obese compared to normal weight patients, despite greater total exposure. These results were limited by the low doses used and a small cohort. However, use of actual body weight in morbidly obese patients appears to be safe.
Keywords: Critical illness; Norepinephrine; Obesity; Septic shock.
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