Milrinone Infusion on Koala Ward

Introduction

Milrinone is a positive inotrope and vasodilator, with little chronotropic effect (heart rate). It works by selectively inhibiting phosphodiesterase in cardiac and vascular muscle leading to an increase in intracellular calcium and contractile force in cardiac muscle and relaxation in vascular muscle. This activity results in left ventricular afterload reduction, with an increase in cardiac output and a reduction in total peripheral resistance. On Koala Milrinone is indicated for severe congestive heart failure and low output states following cardiac surgery or weaning from cardiopulmonary bypass.

This guideline should be used in conjunction with the Medication Management procedure.

Aim

This guideline is to assist in caring appropriately for patients on Koala ward who require the commencement of a milrinone infusion or an increase of a current milrinone infusion.

Definition of Terms

Afterload: is the amount of pressure that the heart needs to exert to eject the blood during ventricular contraction.

Chronotrope: are drugs that may change HR.

Inotrope: Inotropes are a group of drugs that increase the force of contraction of the heart.

Peripheral resistance: Peripheral vascular resistance (systemic vascular resistance, SVR) is the resistance in the circulatory system that is used to create blood pressure, the flow of blood and is also a component of cardiac function. When blood vessels constrict (vasoconstriction) this leads to an increase in SVR. When blood vessels dilate (vasodilation), this leads to a decrease in SVR.

Congestive heart failure: Congestive heart failure is present when the heart cannot pump enough blood to satisfy the needs of the body.

Cardiopulmonary bypass: Cardiopulmonary bypass (CPB) provides a bloodless field for cardiac surgery. It incorporates an extracorporeal circuit to provide physiological support in which venous blood is drained to a reservoir, oxygenated and sent back to the body using a pump.

Extravasation: the unintentional leakage of vesicant fluids or medications from the vein into the surrounding tissue.

Arrhythmia: a general term that refers to any type of abnormal, irregular, or disorganized heartbeat.

ECG: Electrocardiograph records the electrical activity of the heart as a visual wave-formation.

BNP: Brain Natriuretic Peptide is a hormone released in response to high ventricular filling pressures. BNP is a sensitive, diagnostic marker for heart failure.

Echo: An echocardiogram is an ultrasound of the heart.

Assessment

Patients that require a milrinone infusion for cardiac support, should be assessed daily of the need for the infusion in conjunction with investigations.

Investigations as per medical team:

Bloods (including BNP and venous blood gas)
Echo
Any other investigations that the consultant/Medical team may deem appropriate/required.

PICU Outreach

A referral to PICU outreach should be made by the medical team/nursing staff for any patient who is commencing a milrinone infusion or increasing in dose. PICU outreach should plan to review a patient commencing or increasing a milrinone infusion within 4 hours.

Management

For dosing and preparation, please refer to the RCH Pharmacy Information: milrinone (link coming soon) under the pharmacy intranet.

Monitoring/observations:

A full head to toe assessment of the patient is to be completed and documented by the bedside nurse prior to commencement of infusion.

	*Commencement of Milrinone*	*Once Stabilised on infusion*	*Milrinone Rate Increase*
Nurse Ratio	Nurse as a Special (ratio 1:1) For minimum of 6 hours. To be reviewed by NUM/ANUM, to determine step down to HDU.	Nurse as a HDU (ratio 1:2)	Nurse as a Special (ratio 1:1) For minimum of 6 hours, To be reviewed by NUM/ANUM, to determine step down to HDU.
Monitoring	Continuous Cardiac Monitoring	Continuous Cardiac Monitoring To be reviewed by consultant at 72hrs for reduced frequency of monitoring.	Continuous Cardiac Monitoring
Observations	15 minutely BP for first hour 30 minutely BP for second, third and fourth hour Hourly thereafter. All other observations as per the nursing assessment guideline.	Hourly BP To be reviewed by consultant at 72hrs for reduced frequency of BP. All other observations as per the nursing assessment guideline.	15 minutely BP for first hour 30 minutely BP for second, third and fourth hour Hourly thereafter. All other observations as per the nursing assessment guideline.
Physical Assessments and Frequency	Assessment of insertion site of intravenous catheter or central venous assess device and line assessment – checked hourly. Central and Peripheral capillary refill time and pulses (age appropriate) – checked at least every 4 hours. More frequently if child is haemodynamically compromised.	Assessment of insertion site of intravenous catheter or central venous assess device and line assessment – checked hourly. Central and Peripheral capillary refill time and pulses (age appropriate) – checked at least every 4 hours. More frequently if child is haemodynamically compromised.	Assessment of insertion site of intravenous catheter or central venous assess device and line assessment – checked hourly. Central and Peripheral capillary refill time and pulses (age appropriate) – checked at least every 4 hours. More frequently if child is haemodynamically compromised.
Venous Blood Gas	1.Prior to commencement. 2.24 hours post commencement.	Every 24-48 hours To be reviewed by consultant at day 7 for reduced frequency of bloods.	1.Prior to Rate increase. 2.24 hours post increase.

Monitoring frequency, observations and bloods may be adjusted at the discretion of the consultant for patients on a long-term milrinone infusion.
Patient must remain on the ward for the duration of the infusion.
DO NOT administer any bolus doses unless an order is placed by a consultant, commence monitoring as per rate increase above.

Complications

Potential Complications

Hypotension – (Be cautious in commencing if other vasodilators are being administered).
Arrhythmia
Mild thrombocytopenia
Extravasation/phlebitis

Less Common Complications

Hypoperfusion
Tachycardia
Hypokalaemia
Headache
Myocardial ischemia

Management of complications

Strict monitoring of patient HR, BP and Sp02.
Monitor ECG trace for any evidence of arrhythmias or ischemia.
Monitor Electrolytes, correct if needed.
Observe limbs for adequate perfusion.
Observe line insertion site for any signs of extravasation/phlebitis, if extravasation occurs contact medical team, follow the extravasation injuries clinical practice guideline.
Report any complications to the medical team (including the cardiology fellow) and AUM.
Rapid Review or MET call if hypotension, signs of low cardiac output, worsening ventricular arrhythmia or concern.

Education

It is important to educate the patient and family about the importance of Milrinone, this should include why the patient has commenced Milrinone, signs of complications and the importance of notifying nursing staff of line disconnection, exposure of access device, not attending to IV pump beeping for a period of time which may be due to an occlusion and not leaving the ward whilst on this infusion unless cleared by a consultant.

Special Considerations

Milrinone infusion should ideally have a separate line from all other infusions, however if not possible check with pharmacy if drugs are compatible.
Milrinone syringe/bag should be changed every 24 hours.
Milrinone Half life is 2 hours.
Patients with mixed circulations will require filters on their inotrope lines, please see the clinical practice guideline for filters for venous access lines in select group of cardiac patients.

Evidence Table

The evidence table for this guideline can be found here.

Please remember to read the disclaimer.

The development of this nursing guideline was coordinated by Kate White, CNS, Koala Ward, and approved by the Nursing Clinical Effectiveness Committee. First published April 2023.

The Royal Children's Hospital Melbourne

Nursing guidelines