What is the proper administration protocol for a phenylephrine (PE) drip?

From the Guidelines

Phenylephrine drips should be used with caution and only in specific circumstances, such as when norepinephrine is associated with serious arrhythmias, cardiac output is high and blood pressure is persistently low, or as salvage therapy when other vasopressors have failed 1. When using a phenylephrine drip, it is essential to start with a low dose, typically 0.5-1 mcg/kg/min, and titrate up to 5-6 mcg/kg/min as needed to maintain the target blood pressure. To prepare a standard concentration, add 10-20 mg of phenylephrine to 250 mL of normal saline or D5W, creating a 40-80 mcg/mL solution. Before administration, ensure proper patient monitoring, including:

• Continuous blood pressure
• Heart rate
• Oxygen saturation The drip should be delivered through a central line when possible, though peripheral administration is acceptable for short-term use. Regularly assess the patient for signs of excessive vasoconstriction, such as:
• Decreased urine output
• Cool extremities
• Worsening acidosis Phenylephrine works as a pure alpha-1 adrenergic agonist, causing arterial and venous vasoconstriction without direct cardiac effects, making it particularly useful in hypotensive patients who need to maintain or increase their blood pressure without increasing heart rate 1. Be cautious when using phenylephrine in patients with severe hypertension, cardiovascular disease, or those taking MAOIs, as dangerous blood pressure elevations may occur. It is also important to note that norepinephrine is the first-choice vasopressor, and phenylephrine should only be used in specific circumstances, as recommended by the Surviving Sepsis Campaign guidelines 1.

From the FDA Drug Label

2 DOSAGE & ADMINISTRATION

1. 1 General Administration Instructions Phenylephrine hydrochloride must be diluted before administration as bolus intravenous infusion or continuous intravenous infusion. Inspect the solution for particulate matter and discoloration prior to administration. The diluted solution should not be held for more than 4 hours at room temperature or for more than 24 hours under refrigerated conditions Discard any unused portion. During phenylephrine hydrochloride administration: Correct intravascular volume depletion. Correct acidosis. Acidosis may reduce the effectiveness of phenylephrine.
2. 3 Preparing a Solution for Continuous Intravenous Infusion For continuous intravenous infusion, withdraw 10 mg (1 mL of 10 mg/mL concentration) of phenylephrine hydrochloride injection and add to 500 mL of 5% Dextrose Injection, USP or 0.9% Sodium Chloride Injection, USP (providing a final concentration of 20 mcg/mL).
3. 4 Dosing for Perioperative Setting In adult patients undergoing surgical procedures with either neuraxial anesthesia or general anesthesia: 50 mcg to 250 mcg by intravenous bolus administration. The most frequently reported initial bolus dose is 50 mcg or 100 mcg. 0.5 mcg/kg/min to 1.4 mcg/kg/min by intravenous continuous infusion, titrated to blood pressure goal.
4. 5 Dosing for Septic or Other Vasodilatory Shock In adult patients with septic or other vasodilatory shock: No bolus. 0.5 mcg/kg/min to 6 mcg/kg/min by intravenous continuous infusion, titrated to blood pressure goal.

To use a phenylephrine drip, follow these steps:

• Dilute the phenylephrine hydrochloride injection before administration.
• Inspect the solution for particulate matter and discoloration prior to administration.
• Prepare a solution for continuous intravenous infusion by adding 10 mg of phenylephrine hydrochloride injection to 500 mL of 5% Dextrose Injection, USP or 0.9% Sodium Chloride Injection, USP, providing a final concentration of 20 mcg/mL.
• Administer the phenylephrine drip at a rate of:
  • 0.5 mcg/kg/min to 1.4 mcg/kg/min for perioperative setting, titrated to blood pressure goal.
  • 0.5 mcg/kg/min to 6 mcg/kg/min for septic or other vasodilatory shock, titrated to blood pressure goal.
• Correct intravascular volume depletion and acidosis before and during administration, as acidosis may reduce the effectiveness of phenylephrine 2.

From the Research

Preparation and Administration of Phenylephrine Drip

• The preparation and administration of phenylephrine drip can be done through a peripheral intravenous catheter, which is a safe alternative to central venous catheters 3.
• A study found that infusion of phenylephrine through a peripheral intravenous catheter is safe when used in moderate doses for a short time, with a mean maximum dose of 79 μg/min and a mean duration of 19 hours 3.
• However, another study found that push-dose phenylephrine had more major preparation and administration errors compared to continuous infusion, with 18.8% of preparations having at least one major error 4.

Dosage and Titration of Phenylephrine Drip

• The dosage of phenylephrine drip can be titrated to achieve a mean arterial pressure between 65 and 75 mmHg, with a mean dose of 1.04 μg/kg/min 5.
• A study found that phenylephrine increased mean arterial pressure without affecting systemic, regional, or microcirculatory flow, except for a 30% increase in jejunal muscularis flow 6.
• The dosage of phenylephrine drip should be adjusted based on the patient's response, with careful monitoring of blood pressure and other hemodynamic parameters.

Comparison with Other Vasopressors

• Phenylephrine has been compared to other vasopressors, such as norepinephrine and epinephrine, in terms of its effects on hemodynamics and microcirculatory blood flow 5, 6, 7.
• A study found that phenylephrine had no differences in terms of cardiopulmonary performance, global oxygen transport, and regional hemodynamics compared to norepinephrine 5.
• Another study found that phenylephrine had a more pronounced hepatosplanchnic vasoconstriction compared to norepinephrine, but this effect was not significant in terms of clinical outcomes 7.