IV Cannulas: Texts Reading A02
Reading A02
Text A
Overview
Intravenous (IV) cannulation is a technique in which a cannula is placed inside a vein to provide
venous access.
Indications
Indications for IV cannulation include the following:
• repeated blood sampling
• fluid administration
• medications administration
• chemotherapy administration
• nutritional support
• blood or blood products administration
• administration of radiologic contrast agents for computed tomography (CT), magnetic
resonance imaging (MRI), or nuclear imaging
Contraindications
No absolute contraindications to IV cannulation exist but avoid injured, infected, or burned
extremities if possible. Some vesicant and irritant infusions (pH < 5, pH >9, or osmolarity >600
mOsm/L) can cause tissue necrosis if they leak into the tissue, including sclerosing solutions, some
chemotherapeutic agents, and vasopressors. These fluids are more safely infused into a central
vein. They should only be given through a peripheral vein in emergency situations or when a
central line is not readily available.
Text B
Technique Rationale
After skin preparation, use a tourniquet to Increases surface tension so facilitates
increase the venous pressure and pull skin smoother incision of skin with less surface
taut in opposite direction of needle insertion. area contacting cutting edge of needle.
Avoid excessive pressure to cannulation site
to prevent flattening of vessel.
For an easily palpated vessel, use Less steep angles increase the risk of needle
approximately 25° angle with the bevel up. cutting along surface of vessel. Steeper
angles increase risk of perforating the back
wall of the vessel.
Once vessel has been penetrated Any manipulation may traumatise the intima
• Advance the needle slowly with the of the vessel. The use of a back-eye needle
cutting edge facing the top of the vessel will eliminate the need to rotate the needle
and do not rotate the axis due to poor flows.
• Tape the needle at the same angle or Pressing the needle shaft against the skin
one similar to the angle of insertion moves the needle tip from the desired
position within the vessel.
• Remove needle at angle similar to Avoid trauma to the intima by dragging the
angle of insertion and never apply cutting edge along it.
pressure before the needle is
completely out.
Reading A02
Text C
Size Flow rate Recommended use
14G 300ml/min For patients in shock, e.g. GI bleeds or trauma. Also for peripheral
16G 200ml/min administration of amiodarone, dopamine.
18G 90ml/min For blood transfusions or high volume infusions.
20G 61ml/min Multi-purpose IV; for medications, hydration and day-to-day therapies.
22G 36ml/min For patients with small veins; elderly or paediatric patients. Only for use
with saline, standard antibiotics and heparin.
Text D
Phlebitis is associated with IV therapy, and can occur in as many as 70% of patients. It is
defined as the acute inflammation of the internal lining of the vein. Phlebitis is characterised by
pain and tenderness along the course of the vein, redness and swelling, and warmth can be
felt at the insertion site.
Phlebitis Scale
Grade Clinical Criteria
0 No symptoms at access site
1 Erythema
2 As 1, plus pain
3 As 2, plus streak formation and a palpable venous cord
4 As 3 with a palpable venous cord > 1 inch in length and purulent drainage
Prevention measures include:
• Adhering to aseptic technique during insertion, dressing changes, mixing or drawing up
of solutions or medications, accessing ports or hubs on IV equipment.
• Cannula site rotation.
• Using the smallest gauge cannula in the largest vein.
• Adequate securement of the IV device.
• Close and regular monitoring of the IV site.
• Patient education of the signs and symptoms of phlebitis.
• Following guidelines on dilution of solutions to prevent particulate matter and to ensure
that the medication or solution doesn’t have too high or too low a pH.
Reading A02
IV Cannulas: Questions
Questions 1 – 7
For each question below, decide which text (A, B, C or D) the information comes from.
You may use any letter more than once.
In which text can you find information about
1 when it’s better not to insert an IV cannula? ______
2 a frequent complication associated with cannula use? ______
3 how to decide which is the most appropriate cannula? ______
4 ways of keeping a cannula site free of phlebitis? ______
5 the correct way to insert a cannula? ______
6 how cannulas aid in the process of diagnosis? ______
7 a ranking system to help judge the seriousness of a condition? ______
Questions 8 – 13
Answer each of the questions, 8-13, with a word or short phrase from one of the texts.
Each answer may include words, numbers or both.
8 What is the best size cannula to use for routine treatments?
____________________________________________
9 What can happen if you use excessive pressure when inserting the needle?
____________________________________________
10 What size cannula should you use to administer a large quantity of fluids?
____________________________________________
11 What kind of needle should you choose to ensure you don’t have to twist it after
insertion?
____________________________________________
12 What part of the blood vessel is at risk of damage while you are taking the needle
out?
____________________________________________
13 What part of the vein is affected in phlebitis?
____________________________________________
Reading A02
Questions 14 – 20
Complete each of the sentences, 14-20, with a word or short phrase from one of the
texts. Each answer may include words, numbers or both.
14 Inserting the needle too steeply can result in _________________________ the
underside of the vein.
15 If the patient’s only symptom is _________________________, then they have
grade 1 phlebitis.
16 Make sure that there is no _________________________ in IV solutions that
you make up.
17 When you are pushing the needle into the vein, keep the __________________
face up.
18 Make sure you stick to _________________________ working practices when
handling IV equipment.
19 When securing the IV device, make sure the __________________ of the
needle remains as it was when you inserted it.
20 The presence of a thickened vein together with ____________________tells you
the patient has grade 4 phlebitis.
