Critical Care in the ED: Mechanical Ventilation, Sepsis, Neurological Hypertensive Emergencies, and Pressors in Shock

Dobutamine

Dobutamine is another adrenergic agonist that is similar to dopamine but with a greater effect on inotropic cardiac contractility due to a preferential action at b₁ receptors.⁶⁰ It can potentially induce peripheral vasodilatation due to its effect on arterial b₁ receptors.  Given this balance, dobutamine is an agent that should be utilized for cardiogenic shock when increased contractility is needed. These effects are particularly useful in patients with “wet and cold” heart failure who have a low cardiac output and volume-overloaded status.^{61, 62} However, it may be necessary to add another agent to provide additional peripheral vasoconstriction should the use of dobutamine affect lead to excessive vasodilatation.  

Epinephrine

One of the most powerful vasoactive agents, epinephrine has a high affinity for all b₁, b₂ and a₁ receptors.⁶³ These combined effects lead to increased cardiac output and improved BP by increasing cardiac contractility and peripheral vasoconstriction. The effect of epinephrine in limiting mast cell release of histamine makes it the preferred choice for the treatment of anaphylaxis.⁶⁴ However, side effects of epinephrine include hypertension, tachydysrhythmias, tissue ischemia from vigorous vasoconstriction, and induced lactic acidosis.⁶³

Phenylephrine

Phenylephrine is an a-adrenergic agonist that activates a₁ receptors on arteriole smooth muscle, resulting in vasoconstriction.⁶⁵ It is currently recommended only for hypotension related to procedural sedation.⁴⁷ Phenylephrine is not recommended for treating patients with septic shock, except when there are concerns about tachydysrhythmias; persistent hypotension with a high cardiac output after treatment with other vasoconstrictor and inotropic drugs; or when a “pure” vasoconstrictor may be preferred.^24,56,65

Summary

Although there are many other vasoactive agents that can be used, the selected agents discussed above represent those most commonly used in the ED. All demonstrate significant crossover effects and receptor activation, as well as impact on cardiac contractility and vasoconstriction. The suggested specific indications for each agent are based on current evidenced-based medicine, clinical guidelines, and theoretical benefits on clinical scenarios. But, as always, clinical decisions should be individualized for critically ill patients.

Conclusion

The resuscitation and initiation of care for critically ill patients must typically be immediately upon their arrival in the ED. While general guidelines or recommendations exist for commonly encountered pathologies, treatment should always be patient-centered, based on the needs and nuances unique to each patient in this vulnerable population. The initiation of mechanical ventilation, treatment of sepsis, management of hypertensive neurosurgical emergencies, and use of pressors in shock states are among the most critically important tasks an EP is called upon to perform. This review of current evidence-based guidelines and recommendations will help EPs provide the appropriate and unique care each patient requires.

Dr Brubaker is a resident in the department of emergency medicine at the University of Pittsburgh, Pennsylvania. Dr Yu is a fellow of adult critical care medicine – emergency medicine in the department of critical care medicine, University of Pittsburgh Medical Center, Pennsylvania. Dr Goodmanson is a resident in the department of emergency medicine at the University of Pittsburgh, Pennsylvania. Dr Schott is an assistant professor, department of emergency medicine and critical care medicine; assistant director of ultrasonography; director, critical care elective student rotation; and director, point of care ultrasound elective student rotation, at the University of Pittsburgh, Pennsylvania