Phenylephrine
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Is Push Dose Phenylephrine Safe in Septic Shock?
Sometimes, as we wait for a norepinephrine drip, we may use a push-dose pressor like phenylephrine to temporarily stabilize MAP. This seems to work in many cases. Phenylephrine is often used in patients with low vascular tone, such as those in a perioperative setting, but its use in septic shock may be very different. Is use of a pure alpha-1 agonist effective and safe in these patients?
Resources
Push Dose
It is pure alpha, so no intrinsic inotropy, and no increase in heart rate, but increases in coronary perfusion can improve cardiac output. Mixing Instructions: • Take a 3 ml syringe and draw up 1 ml of phenylephrine from the vial (vial contains phenylephrine 10 mg/ml) • Inject this into a 100 ml bag of NS • Now you have 100 mls of phenylephrine 100 mcg/ml • Draw up some into a syringe; each ml in the syringe is 100 mcg/ml Onset-1 minute Duration- 10-20 minutes Dose-0.5-2 ml every 2-5 minutes (50-200 mcg)
Vasopressors in the ED
Phenylephrine ONE LINER: USE FOR IATROGENIC HYPOTENSION OR FOR A FAST HEART - Mechanism: Pure ⍺ - Dose: Initial dose 50mcg/min (0.5mcg/kg/min) - Indication: Sedation induced hypotension, hypotension with arrhythmia (Afib with RVR) - Good/bad: (+) Not arrhythmogenic; (-) Bad in heart failure.
The safety and efficacy of push-dose phenylephrine in critically ill adults
Despite the paucity of available data, phenylephrine is a commonly used PDP to treat acute hypotension outside of the OR. This study further supports that utilizing phenylephrine as a PDP is a safe and efficacious practice.
Effect of phenylephrine push prior to continuous infusion norepinephrine in patients with septic shock
Caution is warranted when clinicians are considering the use of phenylephrine pushes in patients with septic shock.
Phenylephrine Pushes in Septic Shock
Moderators Viren Kaul, MD, and Vineesha Arelli, MD, and journal CHEST® authors Gretchen Sacha, PharmD, and Seth Bauer, PharmD, discuss the article, "Effect of phenylephrine push prior to continuous infusion norepinephrine in patients with septic shock," from the May 2021 issue.
Push Dose Phenylephrine
Draw 1 ml (10mg) from a phenylephrine 10 mg/ ml vial Inject into 100 cc bag of saline Shake thoroughly, then draw 10cc from the bag into an empty syringe. Label syringe. Now each 1 ml contains 100 mcg of phenylephrine.
Push-Dose Vasopressors: An Update for 2019
Phenylephrine is a pure alpha agonist that causes arterial vasoconstriction and an in increase systemic vascular resistance. Phenylephrine has no direct chronotropic effects, which makes it an attractive option for patients that are hypotensive and tachycardic. However, phenylephrine may induce baroreceptor-mediated, reflex bradycardia due to rapid increases in blood pressure. Push-dose phenylephrine also has a rapid onset (1 minute) and slightly longer duration of action compared to epinephrine (10 to 20 minutes vs. 5 to 10 minutes). Typical bolus doses of phenylephrine range from 50 to 200 mCg repeated every 2 to 5 minutes to achieve hemodynamic goals.
To Push or Not to Push? Vasopressors Outside the Operating Room
The most commonly used vasopressors for bolus dosing are epinephrine and phenylephrine. Phenylephrine is preferred over epinephrine in patients who present with tachycardia or tachyarrhythmias.
Is Push Dose Phenylephrine Safe in Septic Shock?
Push-dose phenylephrine improved early hemodynamic stability but was associated with increased ICU mortality in septic shock patients.
Life in the Fastlane
0.1-2mcg/kg/min (onset: minutes, duration: up to ~20 minutes)
ScienceDirect
Phenylephrine is a pure vasoconstrictor and is not recommended for empiric use, although niche uses for phenylephrine include (1) difficulty raising mean arterial pressure in the presence of high cardiac output as well as (2) serious tachyarrhythmias induced by norepinephrine (not usually an issue).
StatPearls
Phenylephrine is primarily an alpha-1 adrenergic receptor agonist with minimal to no beta-adrenergic activity; therefore, it is ideal for elevating mean arterial pressure. It does so by causing venous and arterial vasoconstriction and increasing cardiac preload without having any significant direct effect on cardiac myocytes.
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