CHEST Guidelines-Paradoxical-Reflex-Bradycardia-After-Epinephrine-I

Paradoxical-Reflex-Bradycardia-After-Epinephrine-I

Pdf Summary

The document describes a rare physiological phenomenon known as paradoxical reflex bradycardia in response to epinephrine infusion, observed in a patient with paroxysmal sympathetic hyperactivity and hypotension. The case involves a 20-year-old woman with a medical background of anxiety, depression, extensive marijuana use, and a presumptive diagnosis of multiple sclerosis. She experienced recurrent hospital admissions due to paroxysmal sympathetic hyperactivity symptoms.<br /><br />During her seventh hospitalization, the patient developed hypotension and was treated with norepinephrine and then epinephrine infusions, both of which resulted in bradycardia. This unexpected response necessitated atropine administration to manage her heart rate. The physiological mechanism behind this bradycardic response may involve the Bezold-Jarisch reflex, where cardiac sensory receptor stimulation leads to increased parasympathetic activity and decreased sympathetic activity, causing bradycardia, hypotension, and vasodilation. <br /><br />Eventually, she was treated with isoproterenol, a nonselective beta-adrenergic agonist lacking alpha-adrenergic activation, alongside low-dose epinephrine, which she tolerated well and maintained her mean arterial pressure. This case highlights a paradoxical response to epinephrine and norepinephrine, suggesting the potential for a catastrophic outcome due to a parasympathetic reflex in response to alpha-adrenergic activation. The document underscores the clinical challenges of managing such responses and the potential effectiveness of isoproterenol due to its lack of alpha-adrenergic activity, preventing the activation of the Bezold-Jarisch reflex.<br /><br />This case is notable as there is little documentation of such a response to epinephrine, with only one other case report available, underscoring the complexity and rarity of the patient's situation.

Keywords

paradoxical reflex bradycardia

epinephrine infusion

paroxysmal sympathetic hyperactivity

hypotension

Bezold-Jarisch reflex

isoproterenol

alpha-adrenergic activation

parasympathetic reflex

bradycardia

multiple sclerosis