Methods of intravenous administration

6.1 Intravenous bolus


Introduction of a small volume of medicine solution into a vascular access device is referred to as a bolus injection. A bolus injection is usually administered over 3–5 minutes to minimise vein irritation and the risk of extravasation. Drugs typically given by bolus injection include penicillin antibiotics, such as amoxicillin, and antiemetics, such as cyclizine.


During cardiac resuscitation and other emergencies a bolus may be given over a few seconds as the risk of rapid administration is outweighed by the clinical need for immediate therapeutic effect. Adenosine, used for cardiac arrhythmias, is administered as quickly as possible as it is rapidly inactivated in the blood and would not reach the heart otherwise.


At UCLH a bolus is defined as any injection given in 5 minutes or less, and is less than 50 mL in volume. It is considered impractical to administer a bolus over longer than 5 minutes. The Guide recommends that medicines that need to be given over a time period of greater than 5 minutes or that are greater than 50 mL are prepared as an intermittent infusion.


Advantages



  • Achieves immediate and high medicine levels.
  • Easy and more convenient for the practitioner. There are much fewer steps required to prepare and give a bolus compared to an infusion. Bolus injections do not require dilution to large volumes of infusion fluid, priming of an administration set or programming of an infusion device.
  • After giving the dose the practitioner can be sure the patient has received the dose and does not need to monitor an infusion bag/device (c.f. intermittent and continuous infusions).

Disadvantages



  • Increased potential for adverse effects, particularly if the dose is given too rapidly, e.g. cyclizine.
  • Damage to the veins, e.g. phlebitis or extravasation, especially with potentially irritant medicines.

6.2 Intermittent intravenous infusion


Administration of an infusion over a set time period, either as a one-off dose or repeated at specific time intervals, is referred to as an intermittent infusion. An intermittent infusion of medicine is often a compromise between a bolus injection and continuous infusion. It achieves high plasma concentrations rapidly to ensure clinical efficacy yet reduces the risks of adverse reactions associated with rapid administration.


Many medicines are given as intermittent infusions, including gentamicin, metronidazole and Pabrinex.


At UCLH intermittent infusions are defined as any infusion given over longer than 5 minutes but less than 24 hours. Most infusions are given over an hour, although large-volume fluids, e.g. 1 L compound sodium lactate, are usually given over 8 hours.


6.3 Continuous intravenous infusion


Intravenous administration of a fluid or medicines over 24 hours is referred to as a continuous infusion. The infusion may be repeated over a period of days. Large volumes (i.e. 250–1000 mL) or small-volume infusions (e.g. 50 mL) may be delivered continuously.


Advantages



  • May be used to maintain a constant therapeutic concentration of a medicine. For example, some centres may use constant infusions of antibiotics to maintain high blood levels.
  • Allows the infusion rate of a medicine to be accurately titrated according to patient response. Morphine infusions for pain control may be adjusted according to the patient’s pain and also their level of sedation and respiratory rate. Insulin infusions are titrated according to blood glucose.
  • Allows administration of medicines with a short elimination half-life to be given, e.g. adrenaline infusions are used to improve the strength of cardiac contraction in critical care.
  • If the solutions are dilute they may be less irritating than bolus administration.

Disadvantages



  • May be complicated to prepare. May require complex calculations and multiple transfers of medicine/fluids to produce a solution with the correct concentration.
  • Requires the practitioner to be competent in the use of infusion equipment including syringe and volumetric pumps and administration sets.
  • During administration the practitioner will need to monitor the infusion to ensure it is running into the patient. This can be very time consuming if an infusion regularly stops.
  • Greater risk of microbial and particulate contamination (compared to bolus administration) because of the complexity of preparation.
  • Greater risk of infection (compared to bolus administration) as the solutions are used for up to 24 hours, in which time microbes may grow in infusion fluids (particularly those containing glucose or fats, e.g. intravenous nutrition).
  • The infusion occupies the VAD continuously. If the patient requires multiple medicines or fluids, more than one infusion may need to be given down the same lumen of a VAD leading to compatibility issues: before two infusions are given via the same lumen it must be confirmed they are compatible.
  • Large volumes of fluid may cause fluid overload in some patients.
  • Greater risk of pharmaceutical problems, such as drug degradation in solution and drug interaction with the infusion equipment.

6.4 Preparation and administration of intravenous medicines


The following checklist describes the process for preparation and administration of an intravenous medicine. The National Patient Safety Agency (www.npsa.nhs.uk) has produced an excellent and comprehensive standard operating procedure for the prescribing, preparing and administering of injectable medicines. Each item in the checklist below may be comprised of multiple processes itself. Practitioners should refer to the NPSA’s document for a breakdown of the full process. Note the Nursing and Midwifery Council now advises that the preparation and administration of all injectable medicines should be second checked by another practitioner in order to minimise error.



  • Check the prescription – check that the dose, time and route are correct.
  • Understand what the medicine is for and how it works.
  • Be aware of any local protocols for preparing and administering the medicine.
  • Plan drawing up doses.
  • Know how to administer each medicine, including:

    • Calculation of concentration and rate.
    • Reconstitution.
    • Addition of medicines to recommended diluents.

  • Use aseptic non-touch technique to prepare the medicine.
  • Thoroughly mix any additions, checking for precipitation or particles.
  • Complete yellow infusion additive label and attach to infusion.
  • Go to patient and check patient identification.
  • Explain what you are doing to the patient, when appropriate.
  • Check vascular access device.
  • Check that any equipment required is working.
  • Administer.
  • Monitor patient for response and adverse effects.
  • Monitor any infusion equipment to ensure it is functional throughout the administration. Monitor the drug solution for signs of precipitation.

6.5 Aseptic non-touch technique (ANTT)


ANTT is fundamental to the safe administration of injectables. Infection, as a result of poor aseptic technique when preparing injectables, or when handling a vascular access device, places a huge burden on healthcare systems. Infection from this route can be severe as microbes are introduced directly into the patient’s bloodstream, quickly leading to systemic infection, significant morbidity and high rates of mortality. All practitioners must use ANTT every time an injectable is administered to a patient.


ANTT is an evidence-based method for standardising the aseptic technique of healthcare workers. It is a simple, efficient and logical approach which is the same for peripheral and central line access and for all patients. In IV therapy the focus is on avoiding microbial contamination of the ‘key parts’ at all the preparation and administration stages.


Key parts are those parts of the equipment that come into direct or indirect contact with the liquid infusion.


Healthcare workers should identify all key parts and then protect them at all times using a non-touch technique. On top of this fundamental principle, the ANTT guideline, importantly, standardises all the equipment to be used and the order in which the procedure is performed. Standardisation is paramount. ANTT guidelines and resources can be found at www.antt.co.uk. Here is a simple written overview of the ANTT guideline for IV therapy:


Mar 14, 2017 | Posted by in PHARMACY | Comments Off on Methods of intravenous administration

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