WELCOME! Introduction to Bedside Ultrasound

WELCOME! Introduction to Bedside Ultrasound

TEACHERS University of California-Irvine School of Medicine Nathan Molina nathan.d.molina@gmail.com Trevor Plescia taplescia90@gmail.com Jack Silva jpsilva42@gmail.com

COURSE SUMMARY 7 topics Knobology/FAST Cardiac Abdominal Pulmonary Musculoskeletal Head and Neck Procedures For each topic Training with live models Training with SonoSim ultrasound simulator for randomly selected participants Final exam and survey at the end of the course

INTRODUCTION TO ULTRASOUND: KNOBOLOGY

WHAT IS ULTRASOUND? Ultrasound, or diagnostic sonography, is an imaging technique that uses high frequency sound waves to create images of internal body structures

ULTRASOUND PHYSICS Sound waves are made of high pressure and low pressure pulses traveling through a medium High pressure areas (compression) air particles are squeezed together Low pressure areas (rarefaction) air particles are spread apart Sonography is also called ultrasound because it uses sound frequencies that are higher than the normal hearing range

ULTRASOUND PHYSICS The ultrasound transducer: 1. Produces a sound wave, which 2. Bounces off structures creating an echo, which 3. Is received by the transducer and converted to an electrical signal, which 4. Is transformed into a digital image Higher frequency sound waves produce sharper images (high resolution), but are absorbed by tissue more easily (poor penetrance) Ideal for superficial structures Sound waves are reflected (produce an echo) wherever there is a change in density of the medium Soft tissue, bone, air, urine, blood, water, etc.

MODES AND SETTINGS Modes 2D or B-Mode Doppler, Color Doppler M-Mode Settings Depth Gain Presets Cardiac Abdominal more

2D or B-Mode B = Brightness This is for standard ultrasound use, where you will spend most of your time Press 2D to reset all your settings back to normal

M-Mode Motion mode Shows how the tissue in one slice moves over time

COLOR FLOW DOPPLER Shows fluid moving toward or away from the transducer BART: Blue Away, Red Towards

DEPTH The most important setting in ultrasound! You should try to maximize the space on the screen Put the structure you re looking at in the middle of the screen, and make it as big as you can!

TOO MUCH DEPTH Wasted Space

PERFECT DEPTH Less Wasted Space Much Better!

GAIN The strength of the sound waves coming back to the transducer The brightness of the screen Increasing gain brighter image Decreasing gain darker image Auto-gain is a good place to start

UNDER-GAINED Too Dark

OVER-GAINED Too Bright

PERFECT GAIN Just Right

LANGUAGE OF ECHOGENICITY Hyperechoic More echogenic than surrounding tissue Dense, hard structures

LANGUAGE OF ECHOGENICITY Hypoechoic Less echogenic than surrounding tissue

LANGUAGE OF ECHOGENICITY Anechoic Devoid of echoes

ATTENUATION The energy loss as sound travels through a medium Attenuating can describe The sound wave: High frequency sounds are high attenuating. They lose energy more quickly than low frequency sounds. The medium: Water is low attenuating. Very little energy is lost as sound travels through water. High attenuating: appears hyperechoic (white) Low attenuating: appears hypoechoic (black)

ATTENUATION Material Attenuation Coefficient Water 0.002 Black Blood 0.2 Marrow 0.5 Soft tissue (average) 0.5 Muscle 1.1 Air 1.6 Tendon 4.7 Bone, cortical 6.9 Bone, trabecular 9.9 Enamel 120 White

High Attenuating Structure Gallstone Echoes are diminished behind high attenuating structures, creating an acoustic shadow Shadow

Low Attenuating Structure Echoes are enhanced behind low attenuating structures May be used as a window to visualize anatomy Posterior Acoustic Enhancement

Increasing frequency = better resolution but lower penetration ICT C60 L38 P21

TRANSDUCER BASICS Convex Array C60

TRANSDUCER BASICS Phased Array P21

TRANSDUCER BASICS Linear L38

QUESTION How does increasing the frequency of the sound waves affect resolution and penetration?

HOW TO HOLD THE TRANSDUCER Like a pencil (usually) Anchor part of your hand or your forearm on the patient for stability Indicator

MOVING THE TRANSDUCER Scanning or Sliding or Sweeping Fanning or Tilting Rocking or Heel-toe Rotating Compressing

TRANSDUCER INDICATOR Position the indicator toward the patient s right or toward their head (there are some exceptions) The indicator on the transducer corresponds to the dot on screen

ARTIFACTS: MIRROR IMAGE Sound glances off diaphragm, returning to probe with a longer time of flight Machine misinterprets this as more liver tissue further afield Liver Mirror image of liver Diaphragm

ARTIFACTS: MIRROR IMAGE Liver Liver and its Mirror Image Mirror image of liver Diaphragm

ARTIFACTS: REVERB Recurrent bright arcs at equidistant intervals from the transducer

ARTIFACTS: GAS SCATTER Sound waves scatter when traveling through air. Causes a loss of signal and poor visualization of structures behind the air pocket

QUESTION Which artifact can be seen in a normal patient near the liver/diaphragm?

BENEFITS OF ULTRASOUND Non-Invasive Diagnostic tool Portable Dependent on proficiency of handler

Thank you!