Venepuncture and IV Cannulation

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					University Section of Anaesthesia, Pain & Critical Care Medicine   Clinical Skills in Venepuncture & IV Cannulation




           Venepuncture and IV Cannulation
                                     Medical Student
                            Practical Skill Session




                                                    Page 1 of 16
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




                                                    Page 2 of 16
University Section of Anaesthesia, Pain & Critical Care Medicine   Clinical Skills in Venepuncture & IV Cannulation
•

Anatomy and Physiology
    • Structure of veins

    • Superficial veins

    • Antecubital Fossa




                                                    Page 3 of 16
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




                                                    Page 4 of 16
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.




                                                    Page 5 of 16
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




                                                    Page 6 of 16
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.




                                                    Page 7 of 16
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




                                                    Page 8 of 16
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.
                                                    Page 9 of 16
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




                                                   Page 10 of 16
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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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.




                                                   Page 12 of 16
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.

                                                   Page 13 of 16
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




                                                   Page 14 of 16
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.




                                                   Page 15 of 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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