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Point of Care Ultrasound. For Rural Emergency Prepared by Shane Barclay MD. Goals and Objectives. Learn basic terminology and settings on the ultrasound machine. Learn the techniques for: substernal cardiac for detecting pericardial effusion aortic scanning for AAA
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Point of Care Ultrasound For Rural Emergency Prepared by Shane Barclay MD
Goals and Objectives Learn basic terminology and settings on the ultrasound machine. Learn the techniques for: substernal cardiac for detecting pericardial effusion aortic scanning for AAA detecting free fluid in the abdomen detecting fluid or air in the chest cavity
Why these scans? They form most of the basis of the eFAST exam. These are technically some of the harder scans to perform. Therefore ‘everything’ after this is easy!
What the student needs to learn • Sight recognition • Muscle memory
EDE eFAST RUSH POCUS
EDE: “Emergency Department Echo” Developed by Dr. Ray Wiss EDE 1, IP certification, EDE 2, EDE 3
eFAST: Extended Focused Assessment for Shock Trauma Extended Focused Assessment with Sonography for Trauma
RUSH: Rapid Ultrasound for Shock and Hypotension
Types of ultrasound teaching POCUS – Point of Care Ultrasound Is the general descriptor for Physicians using ‘bed side ultrasound’.
Before you start scanning patients • Demographics on the patient. Know how to enter. • If at all possible save your images. • Tell the patient what you are going to do and what you are NOT going to do. You are not doing a ‘formal ultrasound’.
Terminology Ultrasound produces sound waves that either pass through tissues, or if the tissue is ‘solid’, reflect back to the probe, which in turn ‘makes an image’. As the waves pass through tissue, they lose energy, called attenuation. The energy lost is converted into heat.
Terminology Depth Gain Echogenic Echolucent Hyperechoic Hypoechoic Frequency /penetration/resolution Modes of Transmission Artifact types
Terminology Depth This is the depth, in centimeters, the probe will generate an image, from the skin into the body cavity or organ.
Terminology Gain This allows you to change the ‘strength’ of the signal being returned to the probe. Increasing gain makes the image ‘brighter’. Decreasing gain makes the image ‘darker’.
Terminology Depth and Gain These are the 2 things you will manipulate to get a clear image. Third ‘factor’ is gel. So if you can’t see the image:Add more gel, change your gain, change your depth.
Terminology Echogenic Tissues that ‘reflect’ back waves (ie bone) will produce an ‘echo’ which on the screen will appear ‘white’. Echogenic structures are white.
Terminology Echogenic
Terminology Echolucent Structures that don’t reflect back waves, or allow the waves to pass through them, such as fluid, are called ‘Echolucent’. We like echolucent structures to use as an ‘acoustic window’.
Terminology Echolucent
Terminology Echolucent Acoustic ‘windows’ can be: gel between the probe and skin, fluid (urine filled bladder) or solid (structures like the liver)
Terminology Hyperechoic Refers to structures that ‘produce more waves’ (ie are more solid) and will therefore appear more ‘white’. Often used interchangeably with ‘Echogenic’.
Terminology Hypoechoic Refers to structures that ‘produce less echo waves’ therefore are ‘darker’. Often used interchangeably with ‘echolucent’.
Terminology Frequency /penetration/resolution Ultrasound probes have different frequencies – range 2.0 – 5.0 MHz. Frequency is what determines the degree and depth of penetration as well as resolution of ultrasound waves.
Terminology Frequency /penetration/resolution Frequency and penetration are inversely related: Higher frequency – lower (shallow) penetration Lower frequency – higher (deeper) penetration Higher frequency – higher resolution Lower frequency – lower resolution
Terminology Probes (Transducers) Most eFAST can be done using a ‘curved array’ probe. These are low frequency which allows for deeper penetration, but at the expense of resolution.
Curved – low frequency, good penetration but lower resolution. Used for abdomen and eFAST Phased – high freq, shallow penetration, good resolution. Mainly for cardiac. Linear – high freq. shallow but good resolution. For superficial structures.
By any other name! Endocavity Transvaginal
By any other name! Do not start using this on a 15 year old male with suspected peritonsillar abscess and call it a ‘transvaginal ultrasound probe’! Call it an ‘endo-cavity probe’.
Terminology ‘Mode’ (Mode of Transmission) B – Brightness. Most common use. M – Motion. D – Doppler. Can be color Doppler or pulsed wave.
Terminology Artifact - any structure in an ultrasound image that does not have a corresponding anatomic tissue structure • Refraction or Edge artifact • Shadowing artifact • Reverberation or ring down artifact • Comet tail artifact • Mirror (image) artifact • Anisotropy • Slide Lobe artifact
Terminology 1. Refraction or Edge artifact – shadow like image when u/s waves are passing by a small walled or large curved structure (ie bladder)
Terminology 2. Shadowing artifact – appearance of ‘blackness’ behind solid structures – ie shadow behind bone or stone.
Terminology 3. Reverberation or Ring down artifact – highly reflective interfaces which cause waves to reflect multiple times back to the probe superimposing images on the monitor (i.e. pleura)
Ring down artifact These lines are often called “A” lines.
Terminology 4. Comet Tail artifact – hyperechoic reverberation artifacts arising from the pleural line and spreading down toward the lower edge of the screen and are most frequently normal findings. In the lung when several comet tail artifacts (or B lines) are present they are often called ‘lung rockets’.
Terminology 5. Mirror image artifact – another form of reverberation artifact, occurring when reflective surfaces return multiple echoes back to the probe.
Mirror image artifact Kidney Actual liver ‘Mirror’ image of the liver Here the liver appears to be on the chest cavity side of the diaphragm (bright white line).
Terminology 6. Anisotropy – when u/s waves hit tendons, nerves or ligaments NOT at 90 degrees, they can appear very dark or Echolucent (look like fluid)
Terminology 7. Side Lobe artifact – u/s beams from the edge of the probe are weak and when they hit a highly reflective object an echo returns to the probe which can be misinterpreted as an object from the center of the probe.
