What is the typical infusion rate of Isoprenaline (isoproterenol) in mL/minute via syringe pump?

Isoprenaline Infusion Rate via Syringe Pump

For shock and hypoperfusion states, dilute 1 mg of isoprenaline in 500 mL of 5% dextrose and infuse at 0.5 to 5 mcg/minute (0.25 to 2.5 mL/minute of diluted solution), which can be increased up to 30 mcg/minute in advanced shock. 1

Standard Preparation and Infusion Rates

Adult Dosing for Shock

• The FDA-approved preparation involves diluting 5 mL (1 mg) of isoprenaline in 500 mL of 5% Dextrose Injection, yielding a concentration of 2 mcg/mL 1
• Initial infusion rate: 0.25 to 2.5 mL/minute of the diluted solution (equivalent to 0.5 to 5 mcg/minute) 1
• In advanced stages of shock, rates exceeding 30 mcg/minute have been used, though this requires careful titration 1
• Concentrations up to 10 times greater (20 mcg/mL) can be prepared when volume limitation is essential 1

Pediatric Dosing

• The American Heart Association recommends an initial infusion rate of 0.1 mcg/kg/min in children, with the usual range being 0.1 to 1 mcg/kg/min 1
• No well-controlled studies exist to establish definitive pediatric dosing, so these recommendations are based on expert consensus 1

Titration and Monitoring

Adjustment Parameters

• Adjust the infusion rate based on heart rate, central venous pressure, systemic blood pressure, and urine flow 1
• If heart rate exceeds 110 beats per minute, consider decreasing or temporarily discontinuing the infusion 1
• Start at the lowest recommended dose and increase gradually based on patient response 1

Critical Monitoring Considerations

• Syringe pump performance at low infusion rates can cause significant start-up delays (89 to 1622 seconds to reach steady-state flow) and flow irregularities during vertical displacement 2
• Central venous pressure significantly impacts fluid delivery during pump start-up, with pressures of 10 and 20 mmHg causing retrograde flows and zero-drug delivery times of 3.22 and 4.51 minutes respectively 3
• Clinical alertness is required during syringe changes, as connection of a new pump can result in significant antegrade or retrograde fluid volumes depending on central venous pressure 3

Alternative Indications and Dosing

Bronchospasm During Anesthesia

• Dilute 1 mL (0.2 mg) to 10 mL with normal saline or 5% dextrose 1
• Administer 10 to 20 mcg (0.5 to 1 mL of diluted solution) as bolus intravenous injection 1
• The initial dose may be repeated when necessary 1

Repetitive Ventricular Arrhythmia in Brugada Syndrome

• Administer 1-2 mcg as bolus injection, followed by continuous infusion at 0.15 mcg/min 4
• This low-dose continuous infusion has been shown to suppress arrhythmic storm in Brugada syndrome patients for 1-3 days 4

Important Precautions

Contraindications and Warnings

• Contraindicated in patients with tachycardia, ventricular arrhythmias, or angina pectoris 1
• May induce cardiac arrhythmias and myocardial ischemia, especially in patients with coronary artery disease or cardiomyopathy 1
• Contains sodium metabisulfite, which may cause allergic reactions including anaphylaxis in sulfite-sensitive patients 1

Drug Interactions

• Should not be administered simultaneously with epinephrine, as both are direct cardiac stimulants and may induce serious arrhythmias 1
• Effects may be potentiated by tricyclic antidepressants, MAO inhibitors, levothyroxine, and certain antihistamines (chlorpheniramine, tripelennamine, diphenhydramine) 1
• Beta-adrenergic blocking drugs (e.g., propranolol) antagonize the cardiostimulating and bronchodilating effects 1

Administration Considerations

• Inspect visually for particulate matter and discoloration; do not use if pinkish, darker than slightly yellow, or contains precipitate 1
• Diluted solution should be used immediately and unused material discarded 1
• Physiological responses reach >90% of steady state after 8 minutes of infusion, though plasma concentrations may not reach definite steady state even after 40 minutes 5