Author: Robyn Buna 

Secondary Author(s): Mark Bromley, Melanie Willimann  

Reviewer(s): Nicholas Packer 

 

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Summary

Difficult IV access is a common issue faced in the pediatric patients and ultrasound guidance improves success and efficiency over the traditional land marking approaches. A dynamic approach is preferred, and the choice of out-of-plane vs in-plane technique is operator dependent. The ideal vessel for USG PIV placement is greater than 0.4cm in diameter, between 0.3 and 1.5cm in depth and at least 1cm in length. Long catheters are preferred to increase longevity.

 

Remember:

1. Prepare: Gather your equipment
2. Optimize: Position, tourniquet, warm compress, and local anesthetic
3. Identify: Select a target vessel. Confirm it is venous looking at wall thickness and compressibility
4. Poke: Introduce the needle and follow the tip through its course from the skin into the vessel
5. Confirm: Confirm catheter placement and secure it to the patient

 

Pitfalls:

Immediate: unsuccessful attempts are most commonly due to puncturing the posterior wall and failing to visualize the needle tip as it enters the vessel. If care is not taken accidental injury to surrounding structures or inadvertent arterial cannulation is possible.

Late: Dislodgement is the most common cause of USG PIV failure as is often due to the placement of a short catheter in a deeper vein. It is recommended that A MINIMUM of 1 cm of catheter is left within the vessel after placement to prevent dislodgement by movement of the skin and soft tissues and ideally at least half of the catheter length is intraluminal. Given deeper vessels are often targeted in the US-guided technique compared to the landmark technique it is often beneficial to choose a longer catheter for placement.

Performing USG PIV Access

1. Preparation
2. 1. Patient: position the patient in a comfortable position that allows the operator access to the area of interest. Don’t forget that commitment to comfort strategies can aid your IV placement whether using a landmark or US-guided approach. Remember to:
      1. Make a plan
      2. Apply numbing cream
      3. Use comfort positions
      4. Breastfeed or use sucrose
      5. Use distraction
      6. Use positive language
      7. Consider using procedural sedation as per local policy
   2. Ultrasound: Place the US machine in a place where both the US screen and patient’s vein can be seen simultaneously.
   3. Set the depth and gain for the anatomy being visualized. Use a vascular preset if available on your ultrasound machine. Ensure both the probe marker and dot on the screen are on the operator’s left.

 

2. Localize target vessel by ultrasound
3. 1. Prior to preparing the sterile field, apply a tourniquet and look for preferred sites: consider scanning both arms and saphenous until you find the best site.

TIP: To focus on ideal targets, set the machine depth to its minimum setting.

1. 2. Using anatomy to guide probe placement identify a site for USG cannulation: the preferred sites include the larger vessels of the forearm, saphenous and in cases of difficult access the distal upper arm.
   3. Remember ideal vessel characteristics include a 0.3-1.5 cm depth, 4 mm diameter (often difficult to ensure in smaller patients) and a straight segment of least 1cm in length.

 

3. Confirm identification of vein and surrounding structures
4. 1. Confirm the visualized structure is a vein using compression, lack of pulsatility and if doubt remains absence of pulsatile flow on color doppler to differentiate it from any surrounding structures. Remember if the tourniquet is up a vein may not show any flow, but an artery should have pulsatile flow.
   2. Identify any nearby structures to be avoided including arteries, nerves and tendons.
   3. Consider using a marker to mark the skin to approximate the path of the vessel and planned approach.

 

4. Preparing for the procedure
5. 1. Once the site is selected, wipe off any excess gel from the patient and transducer.
   2. Prepare the machine by cleaning the probe, cord and machine. Obtain sterile US gel and apply a thin strip to the US probe followed by a sterile sheath or adhesive dressing. Take care not to contaminate the sterile dressing during application.
   3. Ensure you have the proper catheter dependent on vessel size and depth, tourniquet, IV tubing, saline flushes, tape or dressing to secure the IV and additional people to aid with patient holding, traction on the vein and passing of supplies.

 

 

5. Introduce the needle
   1. Out-of-plane technique:

1. 1. 1. Orient the probe so the vein is in the center of the screen, be sure the hand holding the probe is braced on the patient either with the palm or outstretched finger to minimize probe movement. Additionally, wrapping the US cord around the arm can eliminate any “pull” on the probe to decrease movement and slippage.
      2. Note the depth of the vessel and choose an appropriate angle of approach (45 degrees for deep structures, 30 degrees for more superficial structures)
      3. With the needle perpendicular to the center of the probe, advance the needle into the skin aiming for the vein visualized at the center of the probe.
      4. Once the needle and catheter have pierced the skin pause to find the hyperechoic needle tip on the ultrasound screen by fanning the US probe towards the needle. If having difficulty, try gently “jiggling” the needle to identify surrounding tissue movement. Once visualized move the probe slightly forward and continue to advance the needle tip towards the vein until it comes into view. Continue this process, following the tip of the needle by moving the US probe and then the needle until the needle tip enters the vessel lumen. This creeping technique ensures that the needle tip is visualized and helps prevent posterior wall puncture.
      5. As the needle enters the vein the vessel wall will indent or “tent”, at this point advance in small amounts until the vessel wall recoils and the hyperechoic tip of the needle is confirmed in the center of the vessel.
      6. Flatten the angle and advance the needle a little further in the vessel before advancing the catheter.
      7. Confirm the needle tip has not pierced the posterior wall of the vessel by moving the US past the end of the visualized needle prior to advancing the catheter over the needle and securing the IV.

 

Video 3: Out-of-plane technique (creep technique)

 

 

1. 2. In-plane technique:

1. 1. 1. Once the vessel is identified in the transverse orientation, rotate the probe 90 degrees while keeping the vessel centered on the screen until the entire length of the vessel is visualized on the screen. Brace the probe hand firmly on the patient so the probe does not move as even small movements can result in losing alignment. Additionally, wrapping the US cord around the arm can eliminate any “pull” on the probe to decrease movement and slippage.
      2. Note the depth of the vessel and choose an appropriate angle of approach.
      3. With the needle parallel to the probe enter the skin adjacent to the end of the probe and advance the needle along the plane of the US beam.
      4. Follow the entire length of the needle as it passes through tissues and advances into the target vessel. If the full length of the needle/needle tip is lost from view DO NOT MOVE THE PROBE as you will lose sight of the vessel, simply withdraw the needle towards the skin, adjust your angle and reattempt.
      5. Once the needle tip is visualized within the vessel lumen, flatten the angle and advance the needle a little further within the vessel lumen.
      6. Ensure you are visualizing the tip of the needle within the vessel lumen by imaging the length of the needle before advancing the catheter and securing the IV.

 

Video 4: In-plane technique

 

6. Confirm catheter placement
7. 1. Visualize the full length of the catheter in the vessel.
   2. Confirm with observation of saline turbulent flow within the vessel with flush.

 

7. After thoroughly cleaning the US gel from the skin secure the catheter. Finally remove sterile cover from the US probe and clean the machine and document the procedure in the chart as per local policy.

Technique

 

Techniques for USG PIV placement vary and can be adapted to best suit the user.

Techniques include:

1. Static vs dynamic
2. Single vs dual operator
3. In-plane vs out-of-plane

 

Static vs Dynamic

In the static approach US is used solely to identify vessels and the overlying is marked. In a dynamic approach the US is used to guide the placement of the catheter into the vessel from skin puncture to cannulation. The static approach has significant limitations in terms of success due to movement of skin and subcutaneous tissues in relation to the underlying vessels. The dynamic use of US to guide needle placement is the preferred method in PIV access but can be more technically challenging to learn.

 

Single vs Dual Operator

USG PIV access can be performed with either single or dual operators – one person performs the ultrasound while the other performs the procedure. This provides the advantage of freeing up the proceduralist’s hands for IV placement alone. This technique also does not require the dual hand eye coordination of directing the ultrasound transducer as well as performing the procedure.

The dual operator technique is particularly useful in the situation where the operators have different skills sets, such as a nurse with good cannulation skills but limited US experience or a doctor who is comfortable identifying veins on US but lacks confidence in advancing and securing catheters. In such cases a dual operator approach may be preferred. Yet, with two operators, coordinating the ultrasound image relative to the needle can be technically challenging, so there is no preferred approach.

 

Out-of-plane vs in-plane

Finally, ultrasound guided procedures can be performed with either an out-of-plane or in-plane technique. Each has it advantages and drawbacks. The out-of-plane approach (figure 9) is generally preferred by novice users and has similar success rates compared to the in-plane approach, but special care must be taken to visualize the needle tip and avoid posterior wall puncture [14]. In pediatric patients a dynamic out-of-plane approach has been found to be successful and may be easier for novices [8,15].

 

Figure 9: Out-of-plane technique

 

The in-plane technique (figure 10) allows for visualization of the needle along its entire path and can reduce the risk of puncture of the posterior vessel wall, but it is a technically more challenging approach as keeping the vessel and needle in plane is difficult and the technique can be limited by vessel characteristics, operator experience, and patient movement.

 

Figure 10: In-plane technique

 

Equipment

 

Ultrasound equipment:

• High frequency linear probe
• Sterile probe cover (sterile adhesive dressing or full cover)
• Sterile US gel

 

IV Equipment (figure 8)

• Topical anesthetic agent (may need to be applied after vessel selection)
• IV Catheter (long PIV or mid-length catheter preferred)
• Tourniquet (consider use of double tourniquet with proximal and distal placement)
• Disinfectant for skin preparation (i.e. alcohol swab)
• IV tubing/saline flush
• Material to secure PIV in place (tape, arm board, etc)

 

Figure 8: Equipment for US-guided PIV access

 

Indications

 

• Anticipated difficult access
• Difficult access (**defined at ACH as > 2 blind attempts in the inpatient setting)
• Preferred placement of a mid-lying catheter or long PIV

 

Contraindications

As per standard PIV placement:

• Infection or burn of overlying skin
• Lymphedema

 

Risk Factors for Difficult PIV Access

 

• History of prematurity
• Younger age
• Obesity
• Dehydration
• Critical illness
• Chronic disease
• Intravenous drug use
• Inability to visualize or feel veins with tourniquet applied

Ultrasound anatomy: What Am I Looking At?

Being familiar with the anatomy and trajectory of the veins will aid in their US localization. Vessels are most easily identified in the transverse axis, providing a cross sectional view. They appear as round or oval anechoic (black) structures (figure 5). Following the vessel along its length with the ultrasound ensures it is patent, straight and free of valves and allows for estimation of trajectory to guide needle approach.

 

Figure 5: Ultrasound appearance of veins

Veins can be differentiated from arteries, which are also round anechoic structures by assessing their relative wall thickness, compressibility, pulsatility and continuous blood flow. Veins are relatively thin walled compared to arteries and are easily compressed when pressure is applied with the transducer—in fact if you are having a difficult time seeing any veins it is often that the superficial veins are being compressed by the probe—a light touch with a braced hand is best. In addition, when pressure is applied with the probe pulsatility of blood flow being transmitted within the vessel can be seen in arteries but not veins (video 1). Some veins near arteries can appear pulsatile due to transmitted movement so the final step in differentiating the two involves using color mode to assess for continuous flow in veins vs pulsatile flow in the arteries (video 2).  Be aware that when a tourniquet is up veins often show no flow.

Video 1: Differentiating between veins and arteries on ultrasound: compression technique

 

Video 2: Differentiating between veins and arteries on ultrasound: color doppler technique

 

Many children requiring US-guided IV access will have already had multiple attempts, so it is also important to be able to identify a damaged vessel. Other than trying to avoid sites that are visibly bruised, damaged veins can also be identified on ultrasound. Damaged veins can have clot within the vessel which appears as echogenic material in the vessel lumen (figure 6). A clotted vessel is often not fully compressible as well. Other clues include a hematoma around the vessel which appears as a relatively hyperechoic collection next to or surrounding the vessel (figure 7). If you suspect a damaged vessel choose a section of vein proximal to the area or an alternate site.

 

Figures 6 & 7: US of damaged vessel with clot and surrounding hematoma

Veins best suited to US-guided catheter placement include those 0.3 to 1.5cm deep, 4mm in diameter with a straight course of at least 1cm in length [12]. Small or superficial veins can be more challenging to identify and cannulate via ultrasound but if successfully placed catheters in small veins have similar longevity to larger ones and those in superficial veins (less that 1.2 cm) have the best longevity and are less prone to dislodgement [12,13]. The relative location to surrounding structures such as arteries, nerves and tendons should also be considered, as they can be injured if in close proximity.  It is best to choose a site which is furthest from such key structures.

Anatomy Review: Where Am I Looking? 

The veins of the forearm and the saphenous are the primary targets for ultrasound guided peripheral venous access. An ideal site involves choosing a vein that in less than 1.5 cm deep, 4mm in diameter and at least 1 cm in length [12]. The vessels of the distal upper arm are also considerations in those with difficult access, although can be more challenging to cannulate due to surrounding structures and deeper location [12]. If canulating the vessels of the upper arm the cephalic vein is preferred for its superficial location and distance from other structures. The basilic vein of the upper arm is the preferred site for PICC placement and should be avoided. The brachial veins lie very deep and in proximity to arteries and nerves which make access challenging. When using the vessels of the upper arm, consider placing a mid-length catheter as dislodgement of short catheters is more common at these sites.

The cephalic vein begins at the anatomic snuff box and courses laterally along the forearm and upper arm, draining into the axillary vein (figures 1&2).  The basilic vein drains the ulnar dorsal veins of the hand and courses medially up the forearm and upper arm, halfway up the forearm the basilic vein penetrates the brachial fascia and continues to run medial to the brachial artery (figures 1&2). Another site in the forearm includes the median antebrachial vein which courses the ventral aspect of the forearm between the cephalic and basilic veins before joining the basilic vein near the elbow (figures 1&2).

 

Figures 1&2: Upper extremity venous anatomy

The saphenous originates anterior to the medial malleolus and ascends the medial aspect of the leg (figures 3&4).

 

Figures 3&4: Lower extremity venous anatomy

 

Introduction

Point of care ultrasound (PoCUS) is the use of portable ultrasonography to answer focused clinical questions or to guide procedures.

Peripheral intravenous (PIV) access is one of the most frequent and essential emergency and inpatient medical procedures. It allows for the timely administration of medications, intravenous fluids and the collection of blood samples. Despite being a high frequency procedure, PIV access is often challenging in children, resulting in multiple attempts and significant distress.  Risk factors for difficult PIV placement include young age, history of prematurity, obesity, dehydration, critical illness, chronic illness, IV drug use, difficulty visualizing or palpating veins with a tourniquet and patient anxiety [1,2,3]. The difficult IV access score (DIVA) is externally validated to predict children likely to fail PIV access attempts and includes age, prematurity, and vein characteristics [4]. Difficulty in obtaining PIV access results in diagnostic and treatment delays, as well as increased patient discomfort, anxiety and stress. In this patient population, PoCUS allows for direct visualization of the vasculature and can facilitate access.

 

Why Ultrasound?

Traditionally, peripheral intravenous (PIV) access is performed blindly using a basic knowledge of human anatomy, surface landmarking, and palpation. Ultrasound allows for the visualization of veins that are not clinically apparent and guides placement through visualization of the catheter and the vein [5].

Studies show the use of ultrasound to guide PIV placement results in increased overall success rates [6]. Importantly, ultrasound use decreases the numbers of attempts and number of needle redirections required; this results in less pain and anxiety for the patient and results in a faster time to successfully obtain IV access [7]. In addition, ultrasound allows access to the larger vessels of the upper arm in the case of difficult access or preference for mid-length catheter placement. Ultrasound guided (USG) PIV access is an easily acquired skill. Following a one-hour course, emergency technicians showed significant improvements in speed, patient satisfaction, number of punctures and complications [8]. A study looking at the competency of emergency nurses trained on ultrasound guided PIV procedure for difficult access patients found an 88% success rate was achieved after 15-26 attempts [9].

These benefits are particularly salient in the pediatric setting where PIV access is inherently challenging and creates significant distress for patients and their caregivers. In one hospital setting where a USG PIV program was established, there was a 20% reduction in referral for PICC placements [10] and a recent randomized controlled trial found for every 3 UG PIVs one missed attempt was prevented [11]. Finally, the use of ultrasound guided PIV access has been endorsed by the Agency for Health Care Research and Quality in the United States.