Vasopressors should be seen as a temporary bandaid, a bridge to a patient-centered solution.
Introduction
Vasopressors should be seen as a temporary bandaid, a bridge to a patient-centered solution. These vasoactive agents support hemodynamics by introducing a surge of catecholamines, a lifeline for critically ill patients. However, the dosing of vasopressors is a complex endeavor. While there might not be a strict maximum dose, there's a point where even copious amounts of exogenous catecholamines cannot salvage a struggling heart. Let's discuss the delicate balance of vasopressor therapy and the importance of recognizing when interventions are needed to reduce vasoactive requirements.
The Complexity of Vasopressor Dosing
Technically, there is no maximum dose to vasopressors. You could crank the rate up as high as you want, but there comes a point where even copious amounts of exogenous catecholamines cannot overcome a flailing heart.
Recognizing Escalating Vasopressor Requirements
It is crucial to identify increasing vasopressor requirements and anticipate modalities that could reduce drip rates. High vasopressor requirements have been shown to be independently associated with mortality. But how do we define when vasopressor use becomes refractory?
Defining Refractory Shock
Refractory shock is a term that lacks a universally accepted definition but is generally agreed upon in clinical practice. The use of more than 0.5 mcg/kg/min of norepinephrine or epinephrine to maintain the target blood pressure is often used as a threshold in clinical trials. Beyond this point, the term "refractory shock" is often invoked, signifying a situation where traditional vasopressor therapy is no longer sufficient.
Adjunctive Agents to Vasopressor Therapy
While vasopressors are a cornerstone of shock management, adjunctive interventions can help reduce vasopressor requirements and improve patient outcomes. Corticosteroids have demonstrated their ability to reduce vasopressor requirements and promote the earlier resolution of septic shock. Additionally, vasopressin has emerged as a valuable tool in the management of refractory septic shock. Vasodilatory shock is characteristized by relative vasopressin deficiency, where vasopressin is often utilized in cases of refractory shock.
Summary
In conclusion, understanding the intricacies of vasopressor dosing is essential for emergency medicine pharmacists and healthcare professionals. While there is technically no maximum dose, recognizing when vasopressor requirements become excessive is critical for patient care. Refractory shock is a challenging scenario that requires addressing the underlying problem, and utilizing vasoactive agents as a bridging tool toward the solution..
Mark Nguyen, PharmD, BCEMP
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References
Bassi E, Park M, Pontes Azevedo L. Therapeutic Strategies for High-Dose Vasopressor-Dependent Shock. Crit Care Res Pract. 2013; 2013: 654708.
Sviri S, Hashoul J. Stav I. V van Heerden P. Does high-dose vasopressor therapy in medical intensive care patients indicate what we already suspect? J Crit Care . 2014 Feb;29(1):157-60.
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