What is the recommended starting dose for an isoprenaline (isoproterenol) syringe pump?

Isoprenaline Syringe Pump Dosing

For shock or hemodynamic support, start isoprenaline at 0.5 mcg/min via continuous IV infusion and titrate up to 5 mcg/min based on clinical response. 1

Standard Starting Dose

• The FDA-approved initial dose for shock is 0.5 to 5 mcg per minute as an intravenous infusion, with titration based on patient response 1
• The lowest recommended dose should be used initially, then increased gradually to achieve the desired hemodynamic effect 1
• For bronchospasm during anesthesia, the dose is 10-20 mcg as an IV bolus injection rather than continuous infusion 1

Preparation and Administration

• Isoprenaline must be administered via central venous access whenever possible to minimize the risk of tissue necrosis from extravasation, similar to other catecholamines 2
• The drug should be diluted in 5% dextrose solution; avoid using saline alone or mixing with alkaline solutions like sodium bicarbonate, as adrenergic agents are inactivated in alkaline environments 2, 3
• Continuous cardiac monitoring and blood pressure checks every 5-15 minutes are mandatory during titration 2

Dose Titration Based on Clinical Context

For Bradycardia/Heart Block

• Research suggests that very low doses (0.007 mcg/kg/min, approximately 0.5 mcg/min in a 70kg adult) may be sufficient for AV nodal effects, as the AV node is more sensitive to isoprenaline than the sinus node 4
• Higher doses up to 0.028 mcg/kg/min (approximately 2 mcg/min in a 70kg adult) can be used if needed 4

For Brugada Syndrome with Arrhythmic Storm

• A bolus of 1-2 mcg followed by continuous infusion at 0.15 mcg/min has been shown effective for suppressing repetitive ventricular arrhythmias 5
• This represents a much lower maintenance dose than typically used for shock 5

For Severe Bronchospasm (Refractory Asthma)

• Continuous infusion at 0.0375 to 0.225 mcg/kg/min (approximately 2.6 to 15.8 mcg/min in a 70kg adult) has been used successfully 6
• Maximal bronchodilator effect occurs within 2-5 minutes of starting or stopping the infusion 6

Critical Contraindications and Warnings

• Isoprenaline is absolutely contraindicated in patients with tachycardia, ventricular arrhythmias, or angina pectoris, as it may exacerbate these conditions 3, 1
• Use extreme caution in patients with coronary artery disease or cardiomyopathy, as it may induce cardiac arrhythmias and myocardial ischemia 3
• A defibrillator must be immediately available when administering isoprenaline 3
• The drug contains metabisulfite, which may cause allergic reactions in susceptible patients 1

Important Pitfalls to Avoid

• Do not administer isoprenaline simultaneously with epinephrine, as combined effects may induce serious arrhythmias 1
• When operating against a closed stopcock, syringe pumps may not alarm for 18-22 minutes, and opening the stopcock can deliver a 0.6-0.9 mL bolus 7
• Elevating the syringe pump by 120 cm can result in unintended delivery of up to 0.5 mL of infusate even when the pump is turned off 7
• Ensure proper tubing flush prior to use to avoid 2-3 minute delays in drug delivery at low infusion rates 7
• Beta-adrenergic blocking drugs will reduce the cardiostimulating and bronchodilating effects of isoprenaline 1
• Concomitant use with tricyclic antidepressants, MAO inhibitors, levothyroxine, or certain antihistamines may potentiate isoprenaline's effects 1

Alternative Agents to Consider

• For hemodynamic support requiring continuous infusion, norepinephrine (starting at 0.1-0.5 mcg/kg/min) or epinephrine (starting at 1-4 mcg/min) have more established safety profiles and should be considered as first-line alternatives 2, 8
• For bronchodilation, inhaled albuterol/salbutamol is preferred over systemic isoprenaline 8