Venepuncture and cannulation

Chapter 33 Venepuncture and cannulation



Maureen Lilley



CHAPTER CONTENTS


Introduction 320
Learning outcomes 320

Rationale 321

Factors to note 321

Venepuncture 322
Equipment 322

Method 322

Intravenous cannulation 323
Equipment 323

Method 323

Observations and complications 324

Care of in situ intravenous cannula 325

Dos and don’ts 325


INTRODUCTION


Children may require blood sampling or the insertion of an intravenous cannula for many reasons, including the monitoring of the progress of a condition, the administration of medicine or the administration of fluids, blood or nutrition.


In the majority of circumstances, children’s nurses are now undertaking venepuncture and cannulation as part of the holistic approach to patient care. Nurses undertaking extended practice must be appropriately trained and fit for purpose (RCN 2005, NMC 2008). However, nurses may also assist medical staff in this procedure by providing support to the child during the procedure.



LEARNING OUTCOMES


By the end of this section you should be able to:


• Demonstrate an awareness of the differences between arteries and veins

• Identify the common sites for venepuncture and intravenous cannulation

• Support the child during the procedure

• Choose the appropriate size of intravenous butterfly/cannula for the individual child (use the smallest gauge required for treatment)

• Safely perform venepuncture/intravenous cannulation if extending the scope of practice under supervision and as per local policy

• Apply the necessary precautions to prevent dislodgement of the needle/cannula

• Safely dispose of equipment used during the procedure.


RATIONALE


Obtaining access to the blood vessel of a child is a relatively common occurrence within paediatric practice. However, it should be borne in mind that obtaining a blood sample or insertion of an intravenous cannula is a traumatic and distressing event for the child and parents. The children’s nurse plays an important role in performing this procedure with the necessary support and comfort to the child and/or parents but also provides expert assistance to any healthcare professional obtaining the blood sample or inserting the intravenous cannula. Firm support of the child will help to reduce the distress that they may be experiencing, bearing in mind the need to avoid excessive restraint (RCN 2003). More commonly, children’s nurses, in a variety of settings, are extending their scope of professional practice to include such areas as venepuncture and intravenous cannulation.


Guidance from the Nursing and Midwifery Council (NMC) emphasises knowledge and skills as prerequisites for taking the responsibility for practice (NMC 2008).



FACTORS TO NOTE



• Intravenous access may be more difficult to obtain in young children owing to the size of their veins and the possibility of the veins being covered with subcutaneous fat, as well as because of their level of cooperation (Ingram & Lavery 2007).

• Both arteries and veins are composed of three layers or tunics and have a hollow core called the lumen (Tortora & Derrickson 2006).

• Arteries contain blood at higher pressure than within veins, with the blood moving within the artery in a pulsatile manner caused by the longitudinal arrangement of smooth muscle. Arterial blood is brighter in colour than venous blood.

• When an artery is punctured, the blood will leave in a pulsatile fashion. Greater quantities of blood can be lost from an artery; however, constriction of the walls of the artery helps to delay the escape of blood (Tortora & Derrickson 2006).

• Veins have less elastic tissue and smooth muscle than arteries; however, they contain more white fibrous tissue.

• Veins are distensible and adapt to changes in volume and pressure. Gentle squeezing of the area above a vein will cause the blood to pool within the vein and the vein to become palpable.

• Veins tend to be more superficial than arteries.

• The pressure of the blood within the vein is low and when the vein is punctured the blood will tend to flow out of the vein evenly.

• The venous anatomy differs in each individual child; hence a thorough assessment of all possible sites will help relieve distress by identifying the best site. Possible sites for intravenous cannulation and venepuncture are displayed in Figure 33.1. Care must be taken to avoid adjacent structures, e.g. arteries, nerves. The scalp vein should only be used as a last resort

• Accidental puncture of an artery may cause painful spasm and will result in prolonged bleeding.

• If the nerve is touched, severe pain may result.

• Venepuncture and intravenous cannulation are painful procedures. The use of local topical anaesthetic cream has been proven to reduce the pain of these procedures. EMLA (eutectic mixture of local anaesthetic) cream is one such cream that is universally used in children (Scales 2005, Tak & Bon 2006). In children < 6 months of age, the use of EMLA cream is contraindicated as the risk of methaemoglobinaemia is thought to be increased (RPS & BMA 2008) and therefore EMLA cream is only licensed in the UK for children aged ≥ 1 year. Tetracaine gel (Ametop) is another local anaesthetic and can be used in children/infants > 1 month old (Tak & Bon 2006, RPS & BMA 2008). Local topical anaesthetics should be applied as prescribed by medical practitioners or independent nurse prescribers.

• Methaemoglobinaemia is a condition wherein the haemoglobin of the blood has been altered to a form that cannot transport oxygen (Hockenberry & Wilson 2006).

• EMLA cream should be applied 1 h prior to the needle puncture; Ametop can be applied 30 min prior to procedure. A thick layer of cream/gel should be applied over the site and should be covered with an occlusive or semi-permeable dressing, e.g. Tegaderm (Scales 2005, Tak & Bon 2006).

• It is important to have a thorough examination of all sites to ensure that the best site is chosen. Distal sites should be used to preserve the proximal sites in case the initial attempts are unsuccessful (Hockenberry & Wilson 2006).

• Some hospitals/trusts employ phlebotomy technicians to perform venepuncture and cannulation. Healthcare assistants may also be trained to perform these tasks.

• Registered nurses should be fully conversant with the NMC Code of Standards of Conduct, Performance and Ethics (NMC 2008) if considering extending their scope of practice within this area.

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Figure 33.1 Common sites for venepuncture.

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Mar 7, 2017 | Posted by in NURSING | Comments Off on Venepuncture and cannulation

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