Peripheral intravenous cannulation under ultrasound guidance is the placement of a cannula into a peripherally-located vein under the direct vision of ultrasound. This process allows the cannulation of veins that are unable to be visualised or palpated without ultrasound. In trained individuals this method of cannulation results in higher first-pass and overall success rates with fewer complications ^1,2. 

Indications

For cannulation in general: 

• repeated blood sampling

• IV administration of fluids, contrast, medications, chemotherapy, nutritional support, blood or blood products

For ultrasound-guided cannulation specifically:

• unable to visualise or palpate veins due to

  • body habitus

  • oedematous skin

• multiple unsuccessful blind insertion attempts

• severe dehydration

• multiple previous cannulations (e.g. intravenous drug use, chemotherapy)

Contraindications

No absolute contraindications but avoid intravenous cannulation if:

• previous lymphoedema/lymph node dissection of that limb

• local burns

• local injury

• local infection

Procedure

Preprocedural evaluation

• review indications for peripheral cannulation ⁴

  • assists with the decision of what gauge cannula to use

• review relevant past medical history

Positioning/room set up

Patient

• comfortably lying or sitting

• arm well supported; arm board (if available) with the limb abducted and externally rotated 

• adequate exposure for clean field

Operator

• ergonomically positioned: sitting or standing

• align ultrasound monitor, patient and patient's peripheral access point within the operator's line of sight

• equipment close, reachable and in order to be used

Equipment

• ultrasound machine

  • linear transducer (7.5-10 MHz): superficial structures

  • curvilinear transducer (2-5 MHz): deeper structures

• probe cover

• sterile gel ⁴

• tourniquet

• gloves

• cannula bung

• syringe of normal saline (flush)

• skin preparation - alcohol/antiseptic wipes

• cannula

  • check required flow rate to determine gauge required

  • standard vs longer cannula dependant on the depth of vein being accessed

• adhesive transparent dressing (e.g. Tegaderm)

• +/- blood vials for pathology (as required)

Technique

Initial scout 

Using the ultrasound survey potential vessels for cannulation ⁴.

• start in the antecubital fossa with a transverse probe

  • upper limb venous targets: basilic, brachial, and/or cephalic veins

    • the basilic vein, while variably present, lacks flanking arteries and nerves, and is usually the more superficial target

    • in contrast the deep brachial vein is near ubiquitously present, but has nerves and arteries in close proximity, and is found at a greater depth

• confirm identified vessel is venous ⁴

  • patent peripheral veins easily and completely collapse with gentle probe compression

  • non-pulsatile

  • colour Doppler can be used if available

  • pulsed wave Doppler also can be used to demonstrate the pulsatile flow pattern in adjacent arteries and the non-pulsatile, phasic flow in veins

• appropriate vein

  • large diameter, achievable depth, straight path ⁴

    • using a standard 48 mm angiocatheter, success rate drops to 0% when vessel depth is above 1.6 cm ³

    • no significant difference between more superficial veins at different depths

    • linear increase in success with increasing venous diameter

      • 56% when less than or equal to 0.3 cm

      • 92% when greater than or equal to 0.6 cm

    • desirable targets are, therefore, found between 0.3 cm and 1.5 cm from the surface, with an internal diameter of at least 0.4 cm ⁴

  • note and avoid venous valves

Preparation

• clean probe after initial scout

• place a cover directly on the clean probe

• apply a tourniquet to the upper aspect of the patients arm

• prepare the skin over the previously identified venous target with alcohol/antiseptic wipe

Needle Insertion

• gloves donned

• US probe held in non-dominant hand with stable grip

  • apply sterile gel

  • check probe orientation

    • touch one end of probe and watch for reaction on monitor

    • align for use on patient so that medial is medial and lateral is lateral. 

• relocate venous target

  • probe approach

    • transverse

      • advantages: improved ability to centre needle to midline of vessel ⁴

      • disadvantages: loss of direct needle tip visualisation each time the probe or needle are moved

    • longitudinal

      • advantages: entire needle visualised throughout procedure with better perception of depth within the vessel ⁴

      • disadvantages: inability to identify if needle is off the midline of the vessel

  • optional confirmation of position prior to insertion of needle by placing needle between transducer and skin to illicit shadow artifact

  • note depth of vessel to approximate final insertion depth

• insert needle through skin at a 45 degree approach angle

  • concentrate on monitor after initial insertion

  • find needle tip through fanning or small movements of ultrasound prior to further movement. Identifying the needle tip on ultrasound is important for cannulation success ⁵.

• progressive targeted movement of needle towards vessel

  • 1 mm movements at a time directed towards vessel

  • process of moving ultrasound probe forward off the needle tip, stabilising and then moving the needle further forward into the ultrasound's view

Confirmation of cannulation

• visualisation of cannula and needle within the lumen of the vessel

  • on transverse orientation: bull's eye sign

  • on longitudinal orientation: needle seen entering and lying within lumen 

• a positive "saline flush test"

  • identify cannula in long axis and push 5-10 mL of saline

  • positive test is direct visualisation of bubbles within lumen

  • may be aided by colour Doppler ⁴

• flashback of blood through cannula

The ultrasound probe can be put down at this point so that both hands can be used to advance the catheter, remove the needle, attach the bung, flush the cannula, clean the surrounding skin and secure in place with a transparent dressing. 

Complications

In comparison to blinded techniques, complications associated with peripheral IV insertion under ultrasound guidance are typically minor but include:

• nerve injury: median or median cutaneous nerve

• arterial cannulation: highlights the importance of confirming venous characteristics on ultrasound prior to cannulation