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1. University Section of Anaesthesia, Pain & Critical Care Medicine Clinical Skills in Venepuncture & IV Cannulation
Venepuncture and IV Cannulation
Medical Student
Practical Skill Session
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2. University Section of Anaesthesia, Pain & Critical Care Medicine Clinical Skills in Venepuncture & IV Cannulation
Contents
Anatomy And Physiology 3
Structure Of Veins 4
Superficial Veins 5
Antecubital Fossa 7
Veins 7
Arteries 7
Patient Assessment 11
Factors Influencing Vein Choice 11
Condition Of Vein 11
Improving Venous Access 11
Site Preparation 12
Infection Control 12
Venepuncture 13
Procedure Of Venepuncture 13
Equipment 13
Procedure 13
Intravenous Cannulation 14
Patient Assessment 14
Cannula Selection 14
Methods To Reduce Pain 14
Cannulation Procedure 15
Equipment 15
Cannulation 15
Securing The Cannula 16
Care Of The Cannula 16
Complications 16
Resiting Or Removal Of Cannula 16
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3. University Section of Anaesthesia, Pain & Critical Care Medicine Clinical Skills in Venepuncture & IV Cannulation
•
Anatomy and Physiology
• Structure of veins
• Superficial veins
• Antecubital Fossa
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4. University Section of Anaesthesia, Pain & Critical Care Medicine Clinical Skills in Venepuncture & IV Cannulation
Superficial Veins Of The Upper Limb
Cephalic vein
Median Cubital vein Basilic vein
Accessory Cephalic vein
Cephalic vein Superficial Median vein of the forearm
Palmar Venous Plexus
Palmar Digital veins
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5. University Section of Anaesthesia, Pain & Critical Care Medicine Clinical Skills in Venepuncture & IV Cannulation
The Forearm Veins
The Cephalic Vein
Forms from a confluence of veins at the base of the thumb and passes upward along the radial
(lateral) aspect of the forearm to enter the lateral part of the antecubital fossa.
PRO's.
• Readily receives a large cannula and is therefore a good site for blood administration.
• Splinted by the forearm bones.
• Cannula is easily secured.
CON's.
• Can be more difficult to cannulate than the metacarpel veins.
• May be confused with an aberrant radial artery.
The Basilic Vein
Forms from a confluence of veins on the postero-medial aspect of the wrist and passes upward
slightly posterior to the ulnar (medial) border of the forearm but winds round over the ulnar to enter
the medial aspect of the antecubital fossa.
PRO's
• A large vein that is frequently overlooked in the hunt for veins.
CON's.
• Requires awkward positioning of the limb to gain access to the vein.
• The vein tends to roll away when you attempt to cannulate it.
• Sites prone to phlebitis.
• Cannula port gets caught on sheets.
The Median Veins Of The Forearm
Many Veins with vary variable courses.
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6. University Section of Anaesthesia, Pain & Critical Care Medicine Clinical Skills in Venepuncture & IV Cannulation
•
Metacarpal Veins
PRO's
• Easy to see and palpate veins.
• Splinted by metacarpal bones.
• Allows use of more proximal veins in the same limb should the cannula need to be re-sited.
• Cannula is easily accessible in the theatre environment.
CON's
• Active patients may dislodge easily.
• Dressing may be compromised by handwashing.
• May be more difficult if the skin is thin and friable.
• Flow can be affected by wrist flexion or extension i.e. A POSITIONAL VENFLON.
Basilic vein
Cephalic vein
Dorsal Venous Plexus
Dorsal metacarpal veins
Dorsal Digital vein
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7. University Section of Anaesthesia, Pain & Critical Care Medicine Clinical Skills in Venepuncture & IV Cannulation
The Veins Of The Antecubital Fossa
At least 3 major veins;
Cephalic Vein
A continuation of the vein upward from the antero-lateral aspect of the forearm onto the antero-
lateral aspect of the arm over the biceps muscle. From here it passes up to the deltoid muscle where,
at a variable point, it passes through the superficial fascia to join the brachial vein to form the
axillary vein.
Basilic Vein
A continuation of the vein from the antero-medial aspect of the forearm. It may pierce the
superficial fascia in the antecubital fossa and join the deep veins to form the brachial vein or it may
traverse the antecubital fossa and pierce the fascia at a variable point on the medial aspect of the
arm.
Median Vein
There may be more than one ‘median’ vein in the antecubital fossa.
They are formed by the convergence and divergence of branches of the 3 forearm vems.
PRO's
• Large veins and so they will readily accept a large cannula.
• Do not "shut down" as quickly as the more peripheral veins.
• FIRST CHOICE IN THE EMERGENCY SITUATION.
CON's
• Can be very positional due to elbow flexion/extension.
• Can be very uncomfortable for the patient due to elbow flexion/extension.
• • Care must be taken not to cannulate the brachial artery.
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8. University Section of Anaesthesia, Pain & Critical Care Medicine Clinical Skills in Venepuncture & IV Cannulation
• The Antecubital Fossa.
Brachial Artery
Basilic Vein
Biceps Medial Cutaneous
Nerve of Forearm
Brachialis
Med. Cut. N of
Forearm and Loop
Lat. Cut. N of Forearm
Median N
Median Basilic Vein
Brachioradialis
Median Cephalic Vein
Bicepital Aponeurosis
Cephalic Vein Deep Communicating Vein
Pronator Teres
Superficial
Median Vein
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9. University Section of Anaesthesia, Pain & Critical Care Medicine Clinical Skills in Venepuncture & IV Cannulation
•
Veins
Definition
• A collecting system of vessels for blood RETURNING from the peripheries to the heart.
• All veins, except for the pulmonary veins, carry deoxygenated blood and carbon dioxide.
There are 3 venous systems;
Systemic:
Drains blood from all the organs, except for the lungs and G.I. tract back to the right atrium.
This system can be sub-divided into a SUPERFICIAL and DEEP system according to the
veins' relationship to the superficial fascia of the body.
Pulmonary:
Drains oxygenated blood from the lungs to the left atrium.
Portal:
Drains blood from the G.I. tract between the gastro-oesophageal junction and the recto-anal
junction and carries it to the LIVER. The blood then drains into the systemic system via the
hepatic veins.
All veins, except for the superficial systemic veins, have a similar pattern of distribution as arteries,
e.g
Femoral Vein and Artery
Carotid Artery and Internal Jugular Vein (external jugular is a superficial vein).
Structure
3 layers like arteries, but;
• There is much less muscle in the media which means the wall is much thinner and is
much more easily distended or collapsed by pressure.
• The intima is folded up to form venous valves.
Despite its thinner media the vein retains significant sympathetic innervation and so significant
VENOCONSTRICTION can occur leading to collapsed or ‘SHUT DOWN’ veins.
Arteries
Definition
• The vessels carrying blood AWAY from the heart.
• All arteries, except the PULMONARY arteries, carry oxygenated (bright red) blood.
Structure
3 layers
Intima: Consists of an ENDOTHELIUM surrounded by a thin layer of elastic tissue.
The endothelial cells are flat and line the vessel to promote the smooth laminar
flow of blood. They also release chemical substances involved in the initiation of
clotting. More recently it has been discovered that they synthesise and release
nitric oxide, a -simple molecule, involved in many physiological and pathological
processes.
Media: A thick layer of intermingled smooth muscle cells and elastic fibres.
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10. University Section of Anaesthesia, Pain & Critical Care Medicine Clinical Skills in Venepuncture & IV Cannulation
Its function is to distend as the heart ejects blood into the arterial tree and then to
contract back down when the heart goes into diastole. This maintains the normal
calibre of the vessel and also promotes forward flow of blood during diastole.
This effect can beseen on an arterial line or pulse oximeter trace as a "bump" on
the downstroke of the trace.
Adventitia: A tough fibrous layer.
This protects the artery and merges in with the surrounding connective tissu
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11. University Section of Anaesthesia, Pain & Critical Care Medicine Clinical Skills in Venepuncture & IV Cannulation
Patient Assessment
Factors Influencing Vein Choice
Age of patient
Previous uses and condition of the veins
Clinical status of patient e.g. Dehydrated, shock, amputee, mastectomy, oedema, thrombocytopenia,
CVA
Other clinical procedures required during admission
Type and length of treatment
Medications: warfarin, heparin, steroids
Patient preference
Patient co-operation, previous experiences
Try to use non dominant arm
Sites: median antecubital veins, forearm veins, dorsum of hands and in difficult patients’ dorsum of
foot.
Condition Of Vein
A good vein is:
• Bouncy
• Soft
• Refills when depressed
• Visible
• Has a large lumen
• Well supported
• Straight
A void veins which are:
• Thrombosed / sclerosed / fibrosed
• Inflamed / bruised
• Hard
• Thin / Fragile
• Mobile / tortuous
• Near bony prominences, painful
• Areas or sites of infection, oedema or phlebitis
• In the lower extremities (unless none else available)
• Have undergone multiple previous punctures
Improving Venous Access
• Application of a tourniquet promotes venous distension. The tourniquet should be tight
enough to impede venous return but not affect arterial flow.
• Lower the extremity below the level of the heart
• Use muscle action to force blood into the veins - e.g. open and closing of the fist
• Light tapping of the vein
• Apply warm compresses or immerse limb in bowl of hot water to increase vasodilatation
• Consider GTN Patch
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12. University Section of Anaesthesia, Pain & Critical Care Medicine Clinical Skills in Venepuncture & IV Cannulation
Site Preparation
Position the patient appropriately to facilitate the procedure, you may need help.
Choose an appropriate site
Infection Control
Asepsis is vital as the skin is breached and a foreign object is introduced into a sterile circulating
system. The main sources of microbial contamination are:
• Cross infection from practitioner to patient
• Skin flora
Hands should be clean, having been washed prior to the procedure, and an alcohol solution/gel
applied to the hands before donning a pair of gloves. Gloves will protect your hands against
contamination from the patients blood, and will provide some additional protection in the case of a
needle-stick injury by wiping some of the contaminating blood from the needle prior the skin
puncture.
The site of the proposed venepuncture should be wiped with an isopropyl alcohol 70% swab (e.g.
mediswab) and this should be allowed to dry (for a minimum of 30 seconds) prior to proceeding
with venepuncture. This will clean any gross contamination of the patients skin and will reduce the
patients skin flora at the site of puncture.
The skin must not be touched or the vein re-palpated once the skin has been cleaned,
Sharps should be immediately disposed of in a sharps container, and no needles should be re-
sheathed.
This is to avoid needle-stick injuries to you or others involved in the patient's care, lowering the
incidence of blood borne viral illnesses (In particular Hepatitis B/C and HIV)
Use a no-touch technique for any part of the needle or cannula which is to puncture the patient's
skin.
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13. University Section of Anaesthesia, Pain & Critical Care Medicine Clinical Skills in Venepuncture & IV Cannulation
Venepuncture
Procedure Of Venepuncture
Equipment
• Tray
• Mediswab
• Tourniquet
• Small adhesive dressing.
• Sharps Container
• Gloves
• Isopropyl alcohol 70% solution hand rub solution
• ‘Vacutainer’ system
needle, holder, appropriate evacuated tubes
Or
Sterile syringe, Sterile needle, Appropriate evacuated tube
Procedure
1. Assemble equipment
2. Inform patient of procedure
3. Select a suitable vein - e.g. the vein in the antecubital fossa or forearm
4. Palpate the vessel to exclude the possibility that it is an artery
5. Apply a tourniquet medial to selected site
6. Put on gloves
7. Cleanse skin with alcohol wipe
8. Fix the vein by applying pressure to skin over the vein, approximately two inches below
venepuncture site
9. Leaving the coloured shield on the needle, screw it onto the holder
10. Remove shield and approach the skin, with needle bevel uppermost at an angle of 35~45
degrees
11. When the needle has penetrated the skin, realign it with the vein and reduce the angle to about
15 degrees
12. Introduce the tube into the holder, with middle and forefmger supporting flange of the holder,
push the tube with the thumb to the end of the holder, puncturing the diaphragm of the
stopper.
13. As soon as blood starts to flow into the tube, remove the tourniquet.
14. When blood flow ceases, gently disengage tube from holder - if more samples are required,
repeat from stage 12
15. Tubes with additives should be gently inverted to mix contents - shaking may cause
haemolysis.
16. Always draw samples without additives first.
17. Place a clean swab or piece of cotton wool over the needle as it is gently withdrawn, pressure
should be applied to the site until haemostasis occurs, at which time an adhesive dressing is
applied. It is not recommended that the patient bend their arm as this increases the
intravascular pressure.
18. Ensure all samples are clearly labelled
19. Never re-sheath needles as this is the commonest source of needles tick injury.
20. Ensure all sharps are disposed of safely and examine holder for any contamination, in which
case it should be discarded - in normal practice the holder does not come into contact with
blood products and is intended for multiple use.
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14. University Section of Anaesthesia, Pain & Critical Care Medicine Clinical Skills in Venepuncture & IV Cannulation
Intravenous Cannulation
Patient Assessment Site Selection
Site selection
Inspect both arms (and legs if required)
Try to use non dominant arm
Palpate the vein
Does it bounce? Make sure it does not pulsate. Is it thrombosed?, will it take the size of cannula
needed? Will you be able to secure the cannula easily? Does the venous drainage look normal (is
there evidence of fracture, extravasation from previous proximal cannula, lymphoedema or
paralysis? Have you avoided a joint area which may need to be splinted?
Cannula Selection
When considering the choice of cannula consideration should be given to the following: minimising
discomfort to the patient, ensuring good flow rates, and easy insertion with no tissue reaction to the
cannula. It should be of the smallest practical size to provide the required fluid regimen and take
into account the size of vessel cannulated, the time scale of the proposed administration of infusion
and the viscosity of the fluid to be infused.
Flow through the cannula is proportional to:
The fourth power of the radius i.e. 2xr=16xflow
The pressure difference across the cannula (i.e. pressurised infusions flow faster)
Flow through the cannula is inversely proportional to:
The length of the cannula
The viscosity of the fluid being administered
Colour Size mm Max flow/min (length) Common uses
Orange/brown 14g 2.0 265mllmin (l=42mm) Rapid transfusions, blood
Grey 16g 1.7 170mllmin (l=42mm) As above
Green 18g 1.2 90mllmin (l=40mm) IV maintenance fluids
Pink 20g 1.0 55mllmin (l=32mm) IV drugs/infusions
Blue 22g 0.8 25mllmin (l=25mm) Paediatrics/difficult veins.
Methods To Reduce Pain
Good technique, skill and vein selection
Local anaesthetic infiltration
Topical anaesthesia e.g. EMLA and Amethocaine gel
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15. University Section of Anaesthesia, Pain & Critical Care Medicine Clinical Skills in Venepuncture & IV Cannulation
Cannula Procedure
Equipment
• IV cannula
• Alcohol wipe
• 2ml syringe
• 25g needle
• 5ml amp of 1 % lignocaine solution
• Adhesive dressing for fixation of cannula
• Tourniquet
• Sharps Container
• Gloves
• Isopropyl alcohol 70% solution hand rub solution
Cannulation
1. Assemble equipment
2. Inform patient of procedure
3. Select a suitable vein - e.g. the vein in the forearm or dorsum of the hand
4. Palpate the vessel
5. Apply a tourniquet medial to selected site
6. Put on gloves
7. Cleanse skin with alcohol wipe
8. Infiltrate skin over proposed puncture site with 1 % lignocaine solution
9. Hold patient's hand with your non-dominant hand, using your thumb to keep skin taut, and
anchor vein to prevent it rolling
10. Inspect needle tip to ensure cutting edge is smooth and intact. Place cannula needle in line
with direction of the vein, and a few mm below proposed entry site, with bevel pointing
upwards to reduce tissue trauma
11. At a low angle, gripping the cannula as in demonstration, insert the needle through the skin
and into the vein, as identified by the flashback of blood into the chamber at the hub of the
cannula
12. Once inside the vein advance the needle 2-3mm in a parallel motion to ensure the cannula is
also in the vein
13. Withdraw the needle stylet (holding the cannula steady) about 5mm to avoid piercing the
posterior vein wall, there should be a further flashback of blood along the shaft of the cannula
and now advance the cannula into the vein.
14. Never re-insert the stylet as this can shear off the end of the cannula and cause an embolus.
15. Release the tourniquet
16. Place a finger over the vein above the tip of the cannula to prevent bleeding as you now
remove the needle stylet.
17. To separate the needle and the lure lock cap, hold the cap between thumb and third finger and
use your index finger of the same hand to push on the guard, away from you.
18. Place the cap on the cannula and safely dispose of the needle
19. Flush the cannula with heparinised saline to ensure cannula patency
20. Cover the insertion site and immobilise the cannula by applying a sterile non-occlusive
dressing.
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16. University Section of Anaesthesia, Pain & Critical Care Medicine Clinical Skills in Venepuncture & IV Cannulation
Securing The Cannula
It is important to secure the cannula to prevent mechanical phlebitis.
This can be done with clean tape or a special adhesive dressing. Care should be taken to avoid the
insertion site.
If the device is located over a joint, the joint should be immobilised and splinted to prevent
movement and dislodgement of the cannula.
Care Of The Cannula
Once sited the cannula should be flushed with either normal saline or heparinised saline. The site
should be regularly inspected for signs of phlebitis.
Peripheral cannulae should be re-sited every 48-72 hours to reduce the risk of phlebitis, but this
may be difficult in patients with difficult veins.
Complications
If Cannulation is unsuccessful do not reinsert stylet into cannula as it may shear off the cannula and
lead to catheter embolism.
Chemical irritation from the infusion may cause phlebitis and pain. An acidic pH and high
osmolality are particularly likely to cause problems. Dilute solutions appropriately for peripheral
administration. Where osmolarity of the solution exceeds 600molmolal avoid peripheral venous
administration and give into a central vein. Buffering of solutions prior to administration with small
quantities of phosphate or bicarbonate buffers up to a pH of 7 will reduce the incidence of phlebitis
from chemical irritation but introduces the risk of making the environment more suitable for
bacterial contamination.
The cannula may block from thrombus formation if it is not kept flushed.
Extravasation occurs when cannula pulls out of the vein, or becomes partly occluded by venous
constriction causing back flow of the infusate through the puncture site into surrounding tissues.
The patient may complain of tightness, burning and discomfort around the iv site and there may be
swelling and blanching of the tissues. Treatment is to stop infusion immediately and re-site cannula.
Haematoma is formed when blood leaks into the tissues surrounding the insertion site after failure
to penetrate vein properly during insertion, puncture of posterior wall of vessel or removal of the
cannula. Treatment is to apply pressure to puncture site for 3-4 minutes.
Infection: This can cause phlebitis and thrombus formation. It is prevented by good aseptic
technique, keeping the dressings clean and not leaving the cannula in for any longer than necessary.
Phlebitis: This is acute inflammation of the intima of the vein. It is caused by mechanical and
chemical irritation, or by microscopic particles that may contaminate infusion fluids. Clinically
there is erythema over the cannulated vein and surrounding skin and it is warm to touch. Treatment
is to remove the cannula. Thrombophlebitis. This is acute inflammation of the intima of the vein
with the formation of a thrombus.
It is commonly associated with infection at the site of the cannula and may present with raised
white cell count, lymphadenopathy and positive blood cultures. There may be pus visible around
skin entry site. Treatment is to remove cannula and commence parenteral antibiotics.
Resiting Or Removal Of Cannula
Cannulae should not remain in situ for any longer than necessary to reduce the risks of infection.
Consideration should be given to resiting them after 48-72 hours.
When removing the cannulae, pressure should be applied to the site for at least a minute and the site
should be occluded with a sterile dressing.
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