2013 Pediatric Subspecialty Boot Camp_US Fundamentals

Pediatrics

Kiyetta Alade, M.D., RDMS

Assistant Professor

Director, Pediatric Emergency Ultrasound

Section of Emergency Medicine

Department of Pediatrics

Baylor College of Medicine

Texas Children’s Hospital

Ultrasound Fundamentals

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Goals and Objectives

•Describe and operate the basic functions of the

ultrasound machine

•Discuss the common pitfalls with ultrasound-guided

vascular access

•Integrate the “landmark technique” and dynamic

ultrasound when performing central venous

cannulation

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Gain

•Gain: Adjusts the intensity of returned echoes

shown on display

‐ Increasing gain makes picture brighter

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Gain

Gain will amplify all returning echoes equally

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Gain

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•Depth: Can be adjusted to ensure entire structure

of interest is on the screen

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Depth

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Gain / Depth

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•Axial resolution: US machines ability to differentiate

objects in plane parallel to traveling wave

‐Increase frequency or decrease wavelength to

improve

•Lateral resolution: US machine’s ability to differentiate

objects in plane perpendicular to traveling wave

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Resolution

Axial Lateral

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Resolution

•Low resolution (2-4 MHz)

‐Lower frequency

‐Deeper penetration

•High resolution (8-14 MHz)

‐High frequency

‐Poor penetration (best to image superficial structures)

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Probe Selection

•High frequency

‐Linear Array

•Low frequency

‐Curvilinear

‐Phased array

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•Every probe has raised marker to correlate with the

side of the screen with some type of identifier (dot,

logo)

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Probe Marker

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User Orientation

•Remember the probe marker correlates with the

symbol on the screen

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User Orientation

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User Orientation

•Objects near the top of the screen correlate with

structures CLOSEST to the probe on the patient

•Objects near the bottom of the screen correlate

with structures furthest away from the probe on the

patient

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User Orientation

Probe

BED

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•D (doppler) mode: Senses the

movement of reflected US waves

toward and away from the probe by

color change or sound

‐Color represents flow toward or away from

probe… NOT arterial vs venous flow

‐(Blue Away Red Toward)

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Color Doppler

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Procedural

•Static ultrasound

locates structure of

interest but not used to

guide procedure

‐LP

‐Thoracentesis

‐Paracentesis

‐I&D

•Dynamic ultrasound is

used to locate structure

of interest AND allow

direct visualization of

procedure in real time

‐Vascular access

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The Agency for Health Care

Research and Quality (AHRQ)

•Supports the use of ultrasound guidance for the

placement of central venous catheters as a way to

improve success rates, reduce number of attempts

and reduce complications associated with their

placement

(AHRQ) AfHCRaQ. Making Health Care Safer. A Critical Analysis of Patient Safety Practices. July 20, 2001.

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Probe Selection

•4-10 MHz frequency

•Linear Array

•Small to medium

footprint

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Vessel Selection

Vein Artery

•Thin walled

•Compressible

•May have transmitted

pulsations from

nearby arteries

•Non compressible

•Pulsating

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Vessel Selection

•Must be able to differentiate arteries from

veins

‐Compression (veins more compressible)

‐Distal Augmentation

‐Color flow (look for pulsations)

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Screening Ultrasound

•Before preparing to cannulate a vessel you should

‐Screen the area of interest for a target

‐Evaluate the vessel size

‐Evaluate vessel compressibility

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Screening Ultrasound

•Before preparing to cannulate a vessel you should

‐Ensure you are targeting the correct vessel

‐Measure the depth

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Compression

IJ IJCA

CA

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Distal Augmentation

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Transverse Approach to Vessel

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Transverse Approach

•With a transverse approach to vessel puncture you

should orient the probe with the marker to YOUR

left and the US screen in FRONT of you

‐This allows for easy manipulation

‐ If on the screen the needle looks like it is to the right of the

vessel then you change direction more to the left

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Transverse Approach

•Locate target vessel in transverse plane

•Pucture skin adjacent to probe, locate needle

tip and follow it until it enters vessel

‐This requires you to move the probe as you advance the

needle (following the needle tip)

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Transverse Approach

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Transverse Approach

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Transverse Approach

•Able to visualize surrounding structures

•Have to locate needle tip through motion or comet

artifact

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Longitudinal Approach to Vessel

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Longitudinal Approach

•Locate target vessel in transverse approach

•Turn probe longitudinal over selected vessel (probe

marker to patients head)

•Puncture skin adjacent to probe

•Advance needle DO NOT move probe

•Keep vessel in screen

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Internal Jugular

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Internal Jugular

•Position the ultrasound screen in front of you

•Orient the ultrasound probe with marker to YOUR

left

‐This allows you to move the probe in the SAME direction as

visualized on the screen

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Internal Jugular Central Line

carotid

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Valsalva

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Internal Jugular Central Line

•US guided central line placement still with

complications (fewer than landmark technique)

‐Puncture of posterior wall of vein

‐Cannulation of carotid artery

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Femoral Vein

•Complete overlap of femoral artery over

vein 4 cm below inguinal ligament about

half of the time

•At least 50% overlap of femoral artery

over vein in same location

Hughes, et al. Brit J Anes. Ultrasonography of the femoral vessel in the groin: implicationsfor vascular access. 2000:84(5):668-669

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Femoral Vein

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Femoral Vein

•Position the ultrasound screen in front of you

•Orient the ultrasound probe with marker to YOUR

left

‐This allows you to move the probe in the SAME direction as

visualized on the screen

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Femoral Vein

•Single operator:

‐Hold probe with hand on outside of leg

•Left hand right leg

•Right hand left leg

‐Use free hand to access vein using Seldinger technique

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Femoral Vein

•Locate target vessel in transverse plane

•Measure depth of vessel

•Puncture skin at a ~ 30° angle (too sharp will inhibit

passing of guidewire)

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Sonosite M-Turbo Series

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Remember

•ALWAYS

‐ find potential puncture sight using landmark technique before

evaluating with US

•If time allows

‐Screen BOTH sides to determine the best site for needle

puncture

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Select your probe

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Thank You

Health & Medicine

2013 Pediatric Subspecialty Boot Camp_US Fundamentals