PEM POCUS Series: Pediatric Peripheral IV Access

PEM POCUS peripheral IV ultrasound badge

Read this tutorial on the use of point of care ultrasonography (POCUS) for pediatric peripheral IV placement. Then test your skills on the ALiEMU course page to receive your PEM POCUS badge worth 2 hours of ALiEMU course credit.

Take the ALiEMU PEM POCUS: Peripheral IV Quiz – test your skills

PATIENT CASE: Child with Sickle Cell Pain

Abigail is a 10-year-old girl with known sickle cell disease, who presents with severe atraumatic pain in her hips and back. She is afebrile, but tachycardic and tachypneic with 10/10 pain. Nurses have made several attempts but have been unsuccessful in establishing a peripheral IV(PIV) for giving IV fluids and medications. They now ask you to obtain access. You decide to perform an ultrasound-guided PIV placement.

Exam

Vital Sign	Finding
Temperature	37.6C
Heart rate	135 bpm
Blood pressure	135/90
Respiratory rate	23
Oxygen saturation (room air)	99%

General: Well-developed, appears in significant distress due to pain.
Cardiovascular: Tachycardic with regular rhythm, good distal pulses, and capillary refill
Pulmonary: Tachypneic without retractions; good aeration without wheezes, rales, crackles.
Abdomen: Soft, normal bowel sounds
Neurologic: Alert and oriented x3 with GCS 15; no focal deficits on cranial and sensorimotor exam

What are some potential challenges in peripheral IV placement?

Dehydration: Veins may collapse as a result of dehydration, making them harder to identify and cannulate.
Vein mobility: Veins are more mobile than arteries. Particularly mobile veins can “roll” or move during cannulation attempts.
Overlying soft tissue: Large body habitus can interfere with visualization of veins.
Vein size: Some patients, especially infants, have small veins.
Repeated venipuncture: Some patients with chronic conditions, such as sickle cell disease, often require frequent venipuncture. Repeated venipuncture can cause veins to change morphologically over time, making them difficult to identify and cannulate.

How can POCUS be helpful in obtaining IV access?

Direct visualization and guidance: Real-time visualization of IV catheter/needle in real-time as it approaches and cannulates the vessel.
Surrounding anatomy: Visualization of surrounding structures (e.g., nerves, arteries, other veins) which may not be apparent on visual examination.
Differentiating vein from artery: Distinguishing between different types of vessels.

Ultrasound-Guided Peripheral IV Access: Normal Findings

1. Differentiating Veins from Arteries

Veins and arteries can be difficult to distinguish. Below is a table to help differentiate using ultrasonography.

Characteristic	Veins	Arteries
Diameter	Typically larger than arteries (is dependent on fluid status)	Relatively fixed in size, round in shape
Wall Thickness	Thin	Thick
Compressibility	Easy	More difficult
Color Doppler Flow	Non-pulsatile	Pulsatile
Vessel Valves	Present (but not always visible)	Absent

Table 1. Anatomical and ultrasonography differences between veins and arteries

Compressibility: Typically, veins are easily compressed, while arteries with their thick walls are more difficult to compress.

Video 1: Ultrasound clip of a vein being compressed

Color Doppler Flow: Color Doppler can be used to differentiate pulsatile from non-pulsatile flow. Red and blue colors do NOT correlate with venous or arterial blood flow. Instead, the colors represent the direction of flow. A helpful acronym is BART – “Blue Away, Red Towards.”

Video 2: Ultrasound clip of a vein (red) with non-pulsatile flow and artery (blue) with pulsatile flow

2. Identifying Nerves

Nerves can be confused with blood vessels when looking on ultrasound. The following are ways to identify a nerve.

Honeycomb appearance: Classically nerves appear in cross-section with small hypoechoic (dark) areas separated by hyperechoic (bright) septae.

Video 3: Ultrasound clip of nerve (left) and artery (right). The nerve has a honeycomb appearance with several hypoechoic (dark) areas separated by hyperechoic (bright) septae whereas the artery is more uniformly hypoechoic. There is also a needle entering from the left of the screen. See below labeled still image of same anatomical structures below.

peripheral IV ultrasound nerve artery — **Figure 1:** Ultrasound still image with labeled nerve and artery. See Videos 3 and 4 for ultrasound videos of same structures with and without doppler flow.

No Color Doppler flow: While Color Doppler can be used to assess for pulsatile and non-pulsatile flow of arteries and nerves, respectively, nerves should not demonstrate any flow.

Video 4: Ultrasound clip of nerve (left) and artery (right) with color Doppler. This is a clip of the same location on the same patient in Video 3 and Figure 1. The nerve (center of yellow box) shows no flow under color Doppler. In contrast, the artery (partially captured at right of yellow box) demonstrates pulsatile flow.

Anisotropy: This ultrasound artifact is exhibited by nerves (as well as tendons and ligaments), whereby the nerve changes brightness depending on the angle of ultrasound beam.

Video 5: Ultrasound clip of nerve exhibiting anisotropy. The brightness of the nerve (in center, labeled in Figure 2 below) changes with the angle of the probe.

PEM POCUS peripheral IV anisotropy ultrasound — **Figure 2:** Still image from Video 5 above with nerve highlighted in yellow.

Fun fact: Certain gemstones like tiger’s eye and figured woods like flamed maple exhibit chatoyance which is analogous to anisotropy, but occurs under visible light, rather than ultrasound beams like anisotropy.

gemstone anisotropy — **Figure 3:** Image of Tiger’s eye gemstone. These gemstones exhibit chatoyance, a characteristic of light reflection which is analogous to “anisotropy” under ultrasound. (Image: Benjamint444 [CC BY-SA])

3. Needle Artifact

Needles exhibit ultrasound artifacts which can help with identification.

Ring down artifact: This resonance artifact describes when ultrasound beams encounter trapped gas and create a spotlight effect. See additional information on Radiopaedia.org.
Reverberation artifact: This artifact describes when ultrasound beams reflect back and forth between two strong parallel reflectors and the machine interprets additional objects deeper than the actual object. See additional information on Radiopaedia.org.

Video 6: Ultrasound clip of needle in water bath with both ring down and reverberation artifacts. The tip of the needle appears to have a spotlight beam shining down, this is an example of ring down artifact from trapped air at the needle tip. This video also demonstrates reverberation artifact where there appears to be a deeper hyperechoic (bright) needle at the bottom left of the video seen best at the beginning of the clip.

TECHNIQUE

Vein Selection: Upper Extremity

Typically, pediatric patients receive a peripheral IV in the upper extremity in one of 2 locations:

Antecubital fossa (Figure 4):
- Access superficial veins, which includes the basilic, cephalic, and median cubital veins.
- Tip: Beware of tortuously curved paths of veins, branch points, and nearby nerves.

arm anatomy vein — **Figure 4:** Diagram of venous anatomy of the arm focused on antecubital fossa. The antecubital fossa area (the inside of the elbow) is shown in the blue box. Adapted from image By OpenStax College – Anatomy & Physiology, Connexions Web site. Jun 19, 2013. [CC BY 3.0]

Upper arm near medial bicipital groove (Figure 5):
- Access the deep brachial vein or more proximal aspect of the basilic vein.

upper arm vein anatomy — **Figure 5:** Diagram of venous anatomy of the upper extremity. By OpenStax College – Anatomy & Physiology, Connexions Web site. Jun 19, 2013. [CC BY 3.0]

Vein Selection: Lower Extremity

If unable obtain upper extremity access, the lower extremity can also be accessed. This is more typically performed in infants and young children.

Lower medial leg (Figures 6, 7): This site allows for access to thegreat saphenous vein.

leg vascular anatomy — **Figure 6:** Diagram of veins of the leg. Blausen.com staff (2014). “Medical gallery of Blausen Medical 2014“. WikiJournal of Medicine 1 (2). [CC BY 3.0]

**Figure 7:** Diagram of veins of the lower leg. Adapted from image by Blausen.com staff (2014). “Medical gallery of Blausen Medical 2014”. WikiJournal of Medicine 1 (2). [CC BY 3.0]

Set up for success

Prior to starting the procedure, set up the room for optimal visualization.
Place ultrasound system monitor in direct line of site with the angiocatheter.

ultrasound set up position peripheral IV — **Figure 8:** Ultrasound machine positioning such that the probe, patient, and screen are in one line of sight.

Apply tourniquet around the extremity.
Use the high-frequency linear transducer (Figure 9) to identify potential veins before the procedure to map out the course, depth, and size of veins. Initial scanning can be done without sterile precautions.
- The best vein: The ideal vein is large, superficial, not near other anatomic structures, and relatively straight.
- Depth: Set an appropriate depth on the ultrasound monitor such that the target vein is centered on the screen.

ultrasound linear probe — **Figure 9:** A high-frequency linear probe

Tip: Pre-scan multiple areas on both arms (or legs) to find the optimal site for ultrasound-guided peripheral IV placement.
Cleaning and probe covers
- Clean off any non-sterile gel from the patient’s skin.
- Prepare the skin with chlorhexidine or an alcohol swab.
- Use a single-use probe cover.
  - Consider a Tegaderm patch, sterile glove, condom, or sterile probe cover.
  - For further discussion of the relevant literature around probe covers, see this ALiEM post.
- Use sterile ultrasound gel between the skin and the covered probe.

linear ultrasound probe cover glove — **Figure 10:** Sterile glove as a makeshift probe cover. Here the entire probe fits into a single finger of a sterile glove. For another method of using a sterile glove as a probe cover see this Trick of the Trade.

Probe Positioning

Proper orientation and terminology
- In this procedure, there are 3 objects to coordinate in space. All of these relationships should be in a perpendicular or parallel orientation (not oblique).
  - The vein
  - The probe
  - The needle
- The needle should always be parallel with (i.e., directly overlying) the vein. This leaves two other positional relationships: probe/vein and probe/needle.
  - Probe/vein: The probe is either transverse or longitudinal relative to the vein (Figure 11).
  - Probe/needle:The needle is either out of plane (i.e., perpendicular) or in plane (i.e., parallel) relative to the length of probe. When using the transverse orientation, the needle is typically also perpendicular, or out of plane, with the length of the probe. Conversely, when using longitudinal orientation, the needle will be parallel, or in plane, with the probe.

ultrasound short and long axis linear probe — **Figure 11:** Labeled axes of linear ultrasound probe

POCUS-Guided IV Cannulation Technique

There are 2 approaches in using POCUS for cannulating peripheral veins based on if the operator is using the transverse or longitudinal orientation.

Transverse orientation: This view is particularly helpful for keeping adjacent structures in view and requires less precision to keep the vein in view. It is important to keep in mind the distance the needle must travel to successfully enter the vein, which will depend on the angle of the needle and the depth of the vein. Videos 7 and 8 show the transverse orientation ultrasound views. Note that in this view, once the needle passes into the plane of the ultrasound beam, it can be difficult to distinguish the tip of the needle from the shaft.

Video 7: Ultrasound clip of a phantom model vein in transverse orientation with vein cannulation at end of clip. The needle can be identified based on the ring down artifact as it passes into the plane of the ultrasound beam.

Video 8: Ultrasound clip of a patient’s vein in transverse orientation with vein cannulation. The vessel is in the top center of the screen. The needle is the bright white (hyperechoic) dot entering it, seen out of plane.

Transverse technique (out of plane) with dynamic needle tip visualization: The shaft of the needle can appear indistinguishable from the tip of needle in the transverse or out-of-plane approach. The dynamic needle tip visualization technique allows the operator to continuously identify the location of the tip of the needle.
- As soon as the skin is entered, slide the probe closer towards the tip of the needle.
- Advance the probe just beyond the tip of the needle. As soon as the needle is no longer in view (i.e., just beyond the tip), it is clear where tip of the needle is.
- Hold the probe steady just beyond the needle tip, and advance the needle forward, returning it into the field of view.
- Advanced the probe just beyond the tip of the needle again.
- Repeat the previous steps until the needle is visualized entering the vein.
  - Tip: Make small movements and attempt to keep the vein in the center of the screen. For beginners with this technique, it is recommended to alternate moving either the probe or the needle, one at a time.

Video 9: Ultrasound clip of a phantom model in transverse orientation with vein cannulation using dynamic needle tip visualization. The operator alternates moving the probe just beyond the tip of the needle and advancing the needle toward the vessel until cannulation.

Video 10: Demonstration of the dynamic needle tip visualization technique, showing alternating movements of the probe and needle

Longitudinal orientation: Conceptually, this orientation is more straightforward (probe, vein and needle are all parallel), but the precision involved requires a steady hand and a stationary patient. The needle must stay parallel to the probe within the slice thickness of the ultrasound beam. This value will vary depending on the machine and the probe, but is on the order of millimeters. Video 12 demonstrates the importance of maintaining the vein and needle parallel to the ultrasound beam or else the vein and/or needle disappears from view.

Video 11: Ultrasound clip with needle in and out of view using the longitudinal orientation technique. Being slightly out-of-plane makes it difficult to visualize the needle and needle tip. Of note, this needle has a guidewire extended past the needle tip which is curved slightly upward from the length of the needle.

Longitudinal (in plane) technique
- Align the probe parallel to the vein. Ideally, the vein should be the same depth and thickness across the screen.
- Introduce the needle in-plane (parallel) to the probe marker at a shallow angle. Depending on the depth and size of the vein, this may be close to parallel with the skin.
- Maintain visualization of the needle tip as it enters the vessel.
- Tip: If it is unclear where the needle tip is, first stop moving the needle and assess if the probe has drifted or rotated. While keeping the needle still, make corrections with the probe until the needle and needle tip is once again visualized in plane.

Video 12: Ultrasound clip of needle cannulating vessel in longitudinal view using in-plane technique

After Cannulation

After the needle tip is visualized entering the vein and a flash of blood appears in the hub of the needle, advance the needle forward an additional 1-2 mm before threading the catheter. Why? The catheter does not extend fully to the tip of the needle. Thus the needle must be advanced past the initial flash of blood to ensure that the catheter has also penetrated the vein. If there is resistance when threading the angiocatheter into the vein, reassess the needle tip position using the ultrasound and confirm the needle is still positioned intravascularly.

Peripheral IV catheter with needle — **Figure 12:** Typical angiocatheter for peripheral IV access. The first few millimeters of the needle tip extend beyond the catheter.

After successful threading, retract the needle, attach pre-primed IV tubing, and flush and lock the tubing. Secure the catheter in place.

LITERATURE REVIEW

There have been many studies evaluating ultrasound-guided peripheral IVs in patients, and below are several key articles involving pediatric patients. Overall, ultrasound-guidance appears to be helpful in pediatric patients with difficult access, but the exact technique involved and the experience of the operator likely have an effect.

Year	Authors	Title	Major Findings
2009	Doniger et al. [1]	Randomized controlled trial of ultrasound-guided peripheral intravenous catheter placement versus traditional techniques in difficult-access pediatric patients	Ultrasound-guided peripheral IV placement in difficult-access patients took less time, was more often successful, and required fewer needle re-directions.
2010	Oakley and Wong [2]	Ultrasound-assisted peripheral vascular access in a paediatric ED	Ultrasound-guidance was associated with slightly increased success rates in peripheral IV placement. This effect was more pronounced in cases with difficult-access patient.
2018	Otani et al. [3]	Ultrasound-guided peripheral intravenous access placement for children in the emergency department	In contrast to many other publications on ultrasound-guided peripheral IV procedures, the authors report a LOWER success rate for patients that had one failed IV attempt, as compared to the conventional method. An important potential confounder was that this study used a “dual-operator” method, in which one clinician operates the ultrasound, and the other places the IV.
2018	Desai et al. [4]	Longevity and complication rates of ultrasound guided versus traditional peripheral intravenous catheters in a pediatric emergency department	Ultrasound-guided peripheral IVs had a longer catheter survival time compared with traditionally-placed peripheral IVs. Complications from the peripheral IVs were similar between the two groups.

Table: Key literature on pediatric cases studying ultrasound-guided peripheral IV access

References [click to expand] +

Doniger SJ, Ishimine P, Fox JC, Kanegaye JT. Randomized Controlled Trial of Ultrasound-Guided Peripheral Intravenous Catheter Placement Versus Traditional Techniques in Difficult-Access Pediatric Patients. Pediatr Emerg Care. 2009;25(3):154-9. doi:10.1097/pec.0b013e31819a8946.
Oakley E, Wong A-M. Ultrasound-assisted peripheral vascular access in a paediatric ED. Emerg Med Australas. 2010;22(2):166-70. doi:10.1111/j.1742-6723.2010.01281.x.
Otani T, Morikawa Y, Hayakawa I, et al. Ultrasound-guided peripheral intravenous access placement for children in the emergency department. Eur JPediatr. 2018;177(10):1443-49. doi:10.1007/s00431-018-3201-3.
Desai K, Vinograd AM, Abbadessa MKF, Chen AE. Longevity and Complication Rates of Ultrasound Guided Versus Traditional Peripheral Intravenous Catheters in a Pediatric Emergency Department. J Assoc Vascular Access. 2018;23(3):149-54. doi:10.1016/j.java.2018.06.002.

CASE RESOLUTION

Using POCUS, you begin by visualizing Abigail’s veins at the antecubital fossa and are able to identify the basilic and cephalic veins. Tracing the basilic vein proximally, you note that it is relatively large and straight; however, you see a honeycomb-like structure nearby it, which displays anisotropy and appears to be a nerve. You opt instead to follow the cephalic vein. There do not appear to be any nerves or other vessels nearby. You clean her skin appropriately and apply a sterile glove over the probe, and apply sterile gel. After these preparations, you re-identify the vessel in the transverse plane, use dynamic needle tip visualization with an out-of-plane approach, and successfully guide the tip of the needle into the vein.

Video 13: Ultrasound clip of a vein in transverse orientation being successfully cannulated.

After visualizing the tip of the needle in the vein, you slightly advance the needle another 2 mm and then thread the catheter. You are able to obtain bloodwork. After flushing the catheter and cleaning the surrounding skin, you secure the catheter. Abigail is now able to get pain medications and fluids.

She soon feels much improved after 3 hours. Her laboratory results are similar to her baseline values. She is able to return home with ongoing management as an outpatient basis with close follow-up.