How to administer inotropic drugs

Rationale and key points

This How to module aims to help nurses to administer inotropic drugs in a safe, effective and patient-centred manner. The mode of action of inotropic drugs makes them well suited to treat haemodynamic compromise experienced by critically ill patients. Effects such as increased force of myocardial contraction and vasoconstriction make them highly potent.

• Knowledge relating to cardiovascular physiology and the mode of action of inotropes enables the nurse to deliver inotropic drugs safely.
• Invasive blood pressure monitoring should be established before administering inotropic drugs, because of their rapid action.
• Inotropes should be administered via a central venous catheter.
• Drug administration procedures should be followed stringently.

Keywords

clinical procedures, clinical skills, drug administration, inotropic drugs, medication, medicines, medicines management, patient safety

Learning objectives

After reading this module, you should be able to:

• List the equipment used to administer inotropic drugs.
• Describe the procedure for administering inotropic drugs in a safe, effective and patient-centred manner.
• Identify medications used to increase myocardial contractility and heart rate.
• Discuss the complications and nursing care issues relevant to the administration of inotropic drugs. 

Preparation and equipment

The nurse should ensure the necessary equipment is available, including:

• An accurate and clear prescription of the inotropic drug.
• A central venous catheter (CVC) in situ.
• A Luer-lock 50mL syringe and an administration set.
• A ‘drugs added’ label.
• A high-risk syringe driver (this will be indicated on the syringe driver with the letter ‘H’ on a red sticker).
• A blunt filter needle for drawing up fluids.
• Non-sterile gloves.
• The inotropic drug and appropriate dilution fluid.
• Patient monitoring equipment in situ, including:
  • A three-lead electrocardiograph.
  • Invasive blood pressure monitoring.
  
  
  
  
  
  

  Box 1. Dosage calculation equation

  Dosage (mcg/kg/minute) = drug (mcg) ÷ dilutant (mL) ÷ minutes (60 minutes) ÷ patient’s weight (kg) x infusion rate (mL/minute). For example, an 87kg patient prescribed noradrenaline 4mg, diluted to 50mL at 4mL/hour would be:
  

  • (4mg x 1,000 = 4,000mcg) ÷ 50mL ÷ 60 minutes ÷ 87kg x 4mL/hour = 0.06mcg/kg/minute.
  

  Learning points

  1. Because of the potent effect of inotropic drugs on the patient’s cardiovascular system, a high-risk syringe driver is a necessary piece of equipment for administering these drugs.
  2. Inotropic drugs should never be administered via the central venous pressure port (distal port). The proximal port should be used.
  3. Once the infusion has been started, it is important to observe the patient for arrhythmias, excessive increases in arterial pressure or cardiac output. Any concerns should be reported immediately to a senior member of staff.
  4. Adrenaline, noradrenaline, dobutamine, dopamine, dopexamine and enoximone are inotropes that are used to treat haemodynamic compromise in critically ill patients. For accurate, safe administration of inotropic drugs, the dose must be calculated in mcg/kg/minute.
  5. The short shelf-life of inotropes means that any interruptions in administration may result in life-threatening cardiovascular instability.

  Procedure
  Ensure the prescription is legible and accurate. If you are in any doubt request clarification and, if appropriate, the prescription should be re-written.	Liaise with the medical staff caring for the patient with regard to the desired parameters, for example mean arterial pressure or cardiac output.
  Check the prescription and drug vial with a second nurse as recommended by the Nursing and Midwifery Council (NMC) (2010).	Complete the ‘drugs added’ label, providing all required details.
  Wash your hands and put on non-sterile gloves.	Attach the blunt filter needle to the Luer-lock 50mL syringe and draw up the appropriate volume of dilution fluid, ensuring enough volume is left in the syringe for the inotropic drug (for example, 46mL of 5% dextrose should be added to the syringe for a prescription of 4mg noradrenaline, allowing 4mL for the noradrenaline, resulting in a noradrenaline solution of 4mg in 50mL).
  Add the inotropic drug to the dilution fluid in the syringe and agitate to mix.	Remove the blunt filter needle and dispose of it safely in a sharps bin. Securely attach the administration set and prime the administration line, ensuring there is no air in the line.
  Stick on the ‘drugs added’ label prepared in step 4, ensuring the sticker does not cover the graduations on the syringe and can be examined once mounted onto the syringe driver.	Mount the syringe onto the syringe driver.
  Decontaminate a dedicated administration port, which will be the proximal port, on the CVC using 2% chlorhexidine in 70% isopropyl alcohol solution. Inotropic drugs should never be administered via the central venous pressure port (distal port) because of the risk of delivering boluses when flushing the port.	Attach the administration set to the port and start the infusion at a low dose or as the clinical situation requires.
  Table 1 Monitor the haemodynamic effects of the infusion on the patient using continuous monitoring and titrate the rate of administration to achieve the desired blood pressure and/or cardiac output. The dose should be calculated in mcg/kg/minute as per the equation in Box 1. Individual drug dose ranges are provided in Table 1.	Be vigilant for any arrhythmias or excessive increases in mean arterial pressure or cardiac output; report any concerns immediately to a senior member of staff.
  Ensure care is taken when renewing the infusion since the short half-life of inotropes means that any interruptions in the infusion may lead to cardiovascular instability.	Mount the renewal infusion onto a syringe driver well before the previous infusion is due to run out (when there is approximately 5-10mL of the infusion left).
  Start the replacement infusion before the administration set is attached to the CVC port, ensuring that the infusion fluid is dripping from the end of the administration set.	Attach the renewal infusion to a second port on the same CVC and stop the original infusion.
  Be vigilant for signs of haemodynamic instability, using continuous monitoring systems.	If you are unsure or inexperienced in changing the infusion, seek the support of a senior member of staff. The importance of this point cannot be overemphasised because the patient’s condition can become highly unstable during an infusion change.