What is the management of bradycardia (slow heart rate) with hypotension (low blood pressure) unresponsive to dopamine (Dopamine hydrochloride)?

From the Guidelines

In a patient with bradycardia and shock who is already on dopamine, the recommended approach is to immediately switch to epinephrine (starting at 2-10 mcg/min IV or 0.1-0.5 mcg/kg/min IV) or consider alternative treatments as outlined in the guidelines 1.

Key Considerations

• Dopamine is not ideal for this clinical scenario as it can worsen bradycardia at higher doses due to its beta-adrenergic effects.
• Atropine (0.5-1 mg IV, may be repeated every 3-5 min to a maximum dose of 3 mg) should be administered if the bradycardia is symptomatic, as recommended in the guidelines 1.
• If the patient remains unstable despite these measures, transcutaneous pacing should be initiated while preparing for transvenous pacing.
• Underlying causes such as medication effects, electrolyte abnormalities, hypothyroidism, or increased intracranial pressure must be identified and treated.
• Fluid resuscitation with crystalloids (30 ml/kg) should be considered if hypovolemia is contributing to shock.

Treatment Options

• Epinephrine: 2-10 mcg/min IV or 0.1-0.5 mcg/kg/min IV titrated to desired effect, as recommended in the guidelines 1.
• Atropine: 0.5-1 mg IV, may be repeated every 3-5 min to a maximum dose of 3 mg.
• Isoproterenol: 20-60 mcg IV bolus followed by doses of 10-20 mcg, or infusion of 1-20 mcg/min based on heart rate response.
• Other treatments may be considered based on the underlying cause of bradycardia and shock, such as glucagon, high-dose insulin therapy, or calcium channel blocker overdose treatment.

Important Notes

• The combination of bradycardia and shock represents a critical situation requiring immediate intervention, as inadequate cardiac output can rapidly lead to multi-organ failure and death if not promptly addressed.
• The guidelines recommend a step-wise approach to managing bradycardia and shock, with a focus on identifying and treating underlying causes, as well as providing supportive care to maintain cardiac output and perfusion of vital organs 1.

From the Research

Bradycardia with Shock on Dopamine

• The use of dopamine in shock has been compared to norepinephrine in several studies 2, 3.
• A randomized controlled trial found that dopamine was associated with higher tachyarrhythmic events and greater need for additional vasoactive inotropic agents compared to norepinephrine in patients with postcardiotomy circulatory shock 2.
• A meta-analysis of randomized controlled trials found that norepinephrine was associated with lower 28-day mortality, lower risk of arrhythmic events, and lower risk of gastrointestinal reaction compared to dopamine in patients with cardiogenic shock 3.
• Another study found that the requirement for additional vasoactive inotropic agents was more common in the dopamine group compared to the norepinephrine group 2.
• There is no direct evidence on bradycardia with shock on dopamine, but the available studies suggest that norepinephrine may be a better option than dopamine in certain types of shock 2, 3.

Comparison of Dopamine and Norepinephrine

• Norepinephrine has been shown to be superior to dopamine in terms of 28-day mortality, risk of arrhythmic events, and gastrointestinal reaction in patients with cardiogenic shock 3.
• A study found that dopamine was associated with higher tachyarrhythmic events and greater need for additional vasoactive inotropic agents compared to norepinephrine in patients with postcardiotomy circulatory shock 2.
• The choice of vasopressor may depend on the specific type of shock and the individual patient's condition 2, 3.

Limitations of Current Evidence

• The current evidence is limited by the small number of studies and the variability in study design and outcomes 2, 3.
• Further research is needed to determine the optimal vasopressor for use in shock, including the treatment of bradycardia with shock on dopamine 4.