From the Guidelines
Pressor Choice in Tachycardia
In patients presenting with tachycardia, phenylephrine is generally preferred over other pressors due to its pure alpha-adrenergic receptor agonist properties, which increase blood pressure without significantly increasing heart rate 1.
- A typical dose of phenylephrine is 50-100 mcg IV bolus, repeated as needed, with a maximum dose of 500 mcg.
- In contrast, medications like norepinephrine and epinephrine, which have beta-adrenergic receptor agonist properties, may exacerbate tachycardia and are typically reserved for patients with hypotension and bradycardia or those who are unresponsive to phenylephrine.
- Norepinephrine is advised in persistently hypotensive cardiogenic shock with tachycardia 1, indicating its use in specific shock states but with caution regarding its potential to worsen tachycardia.
- The choice of pressor should consider the underlying cause of hypotension and the patient's heart rate response, with phenylephrine being particularly useful when tachycardia is a concern 1.
From the FDA Drug Label
Because individual response to epinephrine may vary significantly, monitor blood pressure frequently and titrate to avoid excessive increases in blood pressure. Epinephrine may induce cardiac arrhythmias and myocardial ischemia in patients, especially patients with coronary artery disease, or cardiomyopathy
In a patient with tachycardia, epinephrine may not be the best choice as a pressor (vasopressor) because it can induce cardiac arrhythmias and myocardial ischemia, which may worsen the patient's condition. Norepinephrine may be a better option, but the FDA drug label does not directly compare the two drugs in this context. Therefore, the choice of pressor should be based on careful consideration of the patient's individual needs and medical history, and close monitoring of blood pressure and cardiac function is essential when using either of these medications 2, 3, 3.
From the Research
Pressor Options for Tachycardia
When considering a pressor (vasopressor) for a patient with tachycardia, several options are available, including phenylephrine and norepinephrine. The choice of pressor depends on various factors, including the patient's underlying condition and the desired hemodynamic effect.
Comparison of Phenylephrine and Norepinephrine
- Phenylephrine is a pure alpha-adrenergic agonist that can increase blood pressure but may cause reflex bradycardia 4, 5.
- Norepinephrine is a mixed alpha- and beta-adrenergic agonist that can increase blood pressure and heart rate, making it a potentially better option for patients with tachycardia 4, 6.
- A study comparing bolus doses of phenylephrine and norepinephrine found that norepinephrine resulted in a significant reduction in the incidence of bradycardia and fewer episodes of tachycardia compared to phenylephrine 4, 6.
Considerations for Patients with Tachycardia
- Patients with tachycardia may benefit from a pressor that can increase blood pressure without exacerbating the tachycardia.
- Norepinephrine may be a better option for patients with tachycardia due to its ability to increase blood pressure while maintaining or increasing heart rate 4, 6.
- Phenylephrine, on the other hand, may cause reflex bradycardia, which could be detrimental in patients with tachycardia 4, 5.
Other Pressor Options
- Ephedrine is another pressor option that can increase blood pressure and heart rate, but its use may be associated with more side effects compared to norepinephrine 6.
- The choice of pressor ultimately depends on the individual patient's needs and the clinical context, and should be guided by careful consideration of the potential benefits and risks of each option 4, 6.