Maverick Point of Care Modules Flashcards
Who studied bat’s echolocative capabilities?
Mod 1
Spallanzani
Who discovered the speed of sound through water?
Colladon
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Who invented the piezoelectric crystal?
Curie brothers
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Who invented the Hydrophone?
Langevin
mod 1
Who developed an ultrasonic apparatus in 1946?
Dusik
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Who developed the first 2D B-mode ultrasound?
Howry & Holmes at University of Colorado
mod 1
Sound velocity is a product of…
Frequency & wavelength
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Bone has a _____ propagation velocity. This results in a _______ image.
High : Hyperechoic
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Air has a _____ propagation velocity. This results in a ______ image.
Slow : Anechoic
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Soft tissue has an ________ propagation velocity. What image results from this?
- Average
- Isoechoic / Hypoechoic
mod 1
The acoustic impedance of a tissue is a product of what two characteristics of the material?
- Material density
- Material propagation velocity
mod 1
The evolution of US machines through history has followed what trend?
They have become smaller and more portable
practice 1
A cystic filled object or blood vessel will scan with a signal return more consistant with?
Anechoic
practice 1
Medical US is measured within what frequency range?
2MHz-20MHz
practice 1
Current ASA fasting guidelines are indicated for:
Guidelines may not be appropriate for pts with:
- Healthy individuals undergoing elective cases
- DM, hiatal hernia, reflux, ileus, bowel obstruction, trauma, enteral feeding or difficult airway
Routine administration of prokinetics, acid blockers, antacids or anticholinergice is not recommended
mod 2
What is the volume assessment accepted in fasted individuals? “volume threshold”
fluid volumes of 1.5ml/kg (approx 100mL total) are common and accepted in fasted individuals
POCUS exams offer good info
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How do you place your probe and what are you looking for to ensure you are midline for a gastric US eval?
- place the probe sub-xiphoid in plane with aorta
- look for the aorta to tell you that you are midline, the antrum of the stomach will look like a bullseye
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What does the antrum of the stomach look like when its empty?
bulls-eye
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what does the antrum of the stomach look like when theres clear liquid in it?
larger and anechoic
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What does the antrum of the stomach look like when someone has just ingested a carbonated drink or has just drank something?
starry night (bubbles)
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What does the antrum of the stomach look like when the stomach has just consumed solid food?
“frosted glass” - we see a hyperechoic line then a shadow below. We won’t be able to see the caudal part of the stomach because of the shadow
high risk for aspiration
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What does the antrum of the stomach look like in later stages of solid food consumption?
antrum has consolidated the food, and most of the liquid has moved to the duodemun
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What is the grading system for the volume in the stomach?
- Grade 0: antrum appears empty in both the supine and lateral decubitus positions
- Grade 1: antrum appears empty in the supine position, but contents are noted in the lateral decubitus
- Grade 2: contents appear in both positions
mod 2
What volume of fluid differentiates between Grade 1 and Grade 2?
Any solid is considered what?
liquid only
- Grade 1 is volume is less than or equal to 1.5 mL/kg
- Grade 2 is greater than 1.5 mL/kg
Solid is always considered high risk
mod 2
Which position is the best for determining the cross sectional area of the antrum?
right lateral decubitus - then apply the area to a predicted model table to determine the volume
green is low risk
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What is the “thumb sign”?
The antrum of the stomach is “squished” looking like a thumb instead of a bulls-eye
- if this happens, draw the boarder around the antrum to determine the cross sectional area
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What probe do you use for the gastric US exam?
Low frequency curved probe
mod 2
What the two most prominant and optimal upper arm veins for US IVs?
Cephalic vein: anterior and lateral
Basillic: medial
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What probe should you use for US IV insertion?
Linear high frequency probe
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How do you differentiate a vein from other structures on the US screen?
Compression - the vein will be collapsable with the probe and not have pulsations like an artery
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What angle should your needle be in the out of place approach to an US IV insertion? What do you want to always make sure of?
- 45-50 degrees
- Always make sure to visualize your needle tip
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What are the best steps to ensure your catheter tip is actually in the vessel?
- out of plane needle approach
- visualize the needle puncturing the vessel and sitting in the center
- Turn the probe longitudinally to get the view of the needle in plane
- this allows you to change the angle of the needle as we thread the catheter
the longituidinal view is very important to verify you are exactly where you want to be in the vessel
mod 3
Which vein has a surrounding artery and nerver making access difficult?
Brachial
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How can you keep the tip of the needle in view in an out of plane view?
Walking the beam away from the needle as you advance the needle
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How can an air embolism happen with an IJ insertion, and how do we prevent it?
An air embolism can happen when the hypovolemic patient takes a deep breath - this negtive intrathoracic pressure can draw air from the needle into the venous system
Maverick: “Prevent this by placing your thumb over the needle hub after the needle enters the vessel when you remove the syringe to place the guidewire”.
Mod 4
Where is a good place to put your needle when inserting an IJ?
In the IJ more caudal, when the IJ starts to run just slightly lateral to the common carotid
mod 4
The position of the heart is:
- The ventricles lie ____
- the atria lie ____
- the most anterior structure of the heart is
- the most anterior chamber is
- anterior
- posterior
- pulmonary artery
- right ventricle
Mod 5
What probe should we use for cardiac US?
- Phased array: will give you the best image (low frequency will help penetrate deep into the tissues and it has a small footprint)
- If you don’t have a phased array, you can use the curvilinear in the subcostal view
mod 5
Why is it important to use a cardiac setting on the US?
If you don’t you anatomy will look flipped (indicator will be on the R side of the screen)
mod 5
What are the 3 basic windows for cardiac assessment US
1 and 2 are the same view, the parasternal window (1 is long axis (PLAX view) and 2 is short axis (SAX view))
3. Apical window
4. Subcostal window
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Parasternal long axis view probe placement
Indicator knotch should be pointing towards the pts R shoulder, and the transducer should be placed around the 4th intercostal space
- pt should try to lie on their L side
this creates a long cut focusing on the L side with the RV being the most anterior
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Prasternal Short Axis view probe placement
From the parasternal long axis, turn the probe 90 degrees clockwise
- angle the transducer superior and inferior to look all along the heart with transverse cuts
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FYI slide for all the views you should be getting with the parasternal windows
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Placement of probe with an Apical view
- Find the point of maximal impulse (usually the 5th intercostal space at the mid-axillary line)
- Semi left lateral position will move the heart closer to the L chest wall
- face the knotch of the transducer down towards the bed
the heart will appear upsidedown
mod 5
In a normal heart, how big should each ventricle be?
the LV should be approx 1/3 larger than the RV
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In the subcostal view, where do you place your probe
At the xypoid process angle the probe up to scan from beneith the ribs
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How do you get the IVC view from the subcostal window?
From the subcotal 4 chamber, turn the counterclockwise so the knotch is pointing to the R shoulder
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How do we determine the EF?
EF is a percentage of how well the heart is functioning
mod 5
LVEF chart
We are considering any percentage above 70% hyperdynamic
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How do we know if the pt needs fluid or to be diuresed based on the EF?
- We see a lot of overfilled LV without wall movement in CHF - diuresis needed
- when the LV appears small, review fluid status (be mindful of hx though, there could be other pathologies making the chamber small)
an EF of >70% could mean they need fluid or that their walls are too thick
mod 5
Which window do you measure wall thickness? i.e. for hypertrophic cardiomyopathy or an obstructive cardiomyopathy
Parasternal Long axis
Always measure during diastole
Mod 5
Where are the best places to look for aortic stenosis?
- parasternal long and short axis views
might want a cardiac consult if you saw this and also heard a murmur on your preop assessment
mod 5
Where are the best places to look for mitral stenosis?
- Parasternal long and short axis views
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How do we evaluate the IVC?
Use the subcostal view and point the transducer towards the R shoulder
- evaluate the size and the collapsability of the IVC during the valsalva maneuver
- normal diameter should be <2.1cm
- with “nose-sniff”, the IVC should collapse about 50% to be normal
Mod 5
Should the IVC eval be performed on a spontaneously breathing or ventilated pt?
Spontaneously breathing pt.
Ventilated pts will have too much intrathoracic pressure and the IVC eval will be skewed
Mod 5
How can we eval the heart and have a strong suspition for Plumonary Hypertension?
In the 4 chamber view, if the RV is >2/3 the LV this is a good suspition for pulmonary issues
mod 5
How do we know if a clot in the heart is new?
It is Hyperechoic
Mod 5
What is a classic sign of Plumonary Hypertension using the Parasternal Short view?
At the level of the papillary muscles, the pressure overload state will cause the Interventricular septum to bulge toward midling during diasole
this is called a D-shaped septum
Mod 5
Which view should you assess for pericardial effusion?
Subcostal 4 chamber view
- The parasternal long axis view can help determine if it is a pericardial effusion or a pleural effusion
- if the fluid is anterior to the descending aorta = pericardial effusion
- if the fluid is posterior to the descending aorta = pleural effusion
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Cardiac Tamponade is a clinical diagnosis, but we can verify with US. What other Clinical presentations will the pt likely have?
- Becks triad
- Pulsus paradoxus (very good indicator with US)
- Pericardial friction rub
- Tachycardia
- Dyspnea
- Hepatomegaly
mod 5
What things might we see in Cardiac Tamponade?
- Swinging Heart
- Decreased LV diastolic and systolic dimensions
- RA diastolic collapse (late stage)
- RV diastolic collapse - bc of he equlization of pressures
mod 5
Indications for a pleural US
- chest pain
- dyspnea
- hypoxia
- hypotension
- pleurisy
- trauma
mod 6
Which probe do you use for the lung US?
Either the Curvilinear or the linear transducer
- the curviliniear will be good because the frequency is low, and the curved footprint allows you to look between more than 1 rib at a time
- the linear is useful to look for the normal lung sliding patter
no matter which one you use, use the lowest frequency available to get adequate depth penetration
mod 6
Zones of assessment and what they are assessing for
- Zone 1: 2nd to 3rd intercostal space. Assess normal lung sliding and A and B lines
- Zone 2: above nipple. Assess normal lung sliding and A and B lines
- Zone 3: Axillary pont directly above the diaphragm. Assess for Pleural Effusion or Lung consolidation
Knotch of the transducers should always be pointing up to the pts head
mod 6
What are A lines?
Normal finding on Lung US
- An A line is an artifact created when the parietal pleura slides against the visceral pleura
- always runs horizontal
- reverberation artifact
mod 6
What is the comet tail on the lung US?
May be a normal finding (Also called B lines)
- these are hyperechoic lines that run vertically
- if more than 2-3 of these are seen between a 2 rib lung field, interstitial lung disease may be present
mod 6
What is M mode?
Allows the US to grab a linear image and overlay the area selected to determine if the lung sliding is normal
mod 6
What will a Pneumothorax look like with US, and where do you look for it?
- Lung sliding is not visible and no Comet tail artifact
zone 1 is the best area for pneumothorax assessment (air rises) - Negative Seashore sign (it looks like a barcode when its a pneumothorax, where the positive seashore sign looks like a sandy beach)
mod 6
What is the Lung point sign?
When you see the pneumothorax in zone 1, start going laterally into zone 2 and 3…once you see the lung sliding again and it reinflated - this is the lung point
- this is the juncture where the deflated and inflated lung tissue can be seen
- the lung point will tell you how large the pneumo is
mod 6
What will you see on the US with interstitial lung deasease or intersitial edema?
multitude of B lines
mod 6
What will you see on US with a pleural effusion and which zone?
Effusions will appear anechoic
Zone 3 (posterior chest)
Mod 6
What will you see on the US when you have lung consolidation?
Presence of fluid located in the pockets in the lung - fluid will take the place of the air (PNA, pulm edema, aspiration, cancer)
- the lung tissue starts to look similar to the liver US picture this is called hepatization of the lung
mod 6
Indications for EFAST
- penetrating trauma to torso
- blunt trauma to torso
- pregnant trauma pt
- unexplained hypotension
mod 7
What is often missed with an EFAST unless its very severe?
Retroperitoneal bleeding
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What is the order for the EFAST exam?
- RUQ
- Cardiac
- LUQ
- Pelvis
- Lungs
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RUQ assessment
- AKA the hepatorenal window
- ideally use a curvelinear probe to look through ribs
- place in coronal place about 8th or 9th rib
- point indicator to pts head
- assess liver interface with kidney (Morison’s pouch) and the diaphragm
- Morison’s pouch is the most dependent area of the peritoneal cavity in the supine pt (the peritoneal cavity can lose 500-600ccs before it will start accumulating here)
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What views do you want to do for the cardiac EFAST exam
Subxyphoid view and parasternal long axis
likely since your pt is supine, you wont get good views on both of these windows
mod 7
How do you get the image for the subxyphoid assessment?
- Place probe in the coronal plane and point the transducer towards the pts chin
- Start at the edge of the live in the RUQ and then follow the subcostal margin until the heart comes into view
- you must press down quite deep - sometimes skinnier pts are harder
mod 7
Why might you not be able to get the image for the parasternal long axis?
Left lateral decubitus is the position the pt needs to be in for the best image - still try, but you may not get it
mod 7
LUQ assessment
- Make sure the get both the kidney and the spleen in the same image to ensure you are viewing the correct window
- avoid the stomach (contents will make it look like free fluid)
- coronal plane, midaxillary line with the probe indicator towards the pts head (the examiner’s hand will typically be on the bed)
mod 7
Pelvic assessment
- First start with the suprapubic: sagittal place with the indicator towards the pts head just about the pubic symphesis
- scan side to side and look for free fluid
- In females, free fluid will usually collect in the rectouterine space (Douglas pouch)
- in Males, the fluid usually collects in the rectovesical pouch
mod 7
Transverse Pubic view
- From the Pubic view, turn the probe 90 degrees with the indicator to the pts right side
- transverse place
- look for free fluid all around the bladder
mod 7
Generally a ____ point lung exam is required to get a thourough lung exam
8 point lung exam for EFAST
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____ is 100% for no pneumothorax present, but if its not present, it doesn’t necessairly mean there is a pneumo. ____ is most specific for confirmation of a pneumo.
Lung sliding is 100% for no pneumothorax present, but if its not present, it doesn’t necessairly mean there is a pneumo. Lung point is most specific for confirmation of a pneumo.
mod 7
Symptoms of DVT
- Edema
- warmth
- erythema
- pain
- tenderness
but the CDC says 50% of pts wont have these s/s. If you are concerned, just do an US
mod 8
What’s the difference between a Deep vein, a Superficial vein and a perforating vein
- Deep: veins that are beneath the muscular fascia and drain the lower extremity muscles
- Superficial: above muscular fascia and drain the cutaneous microcirculation
- Perforating: pass through the muscular fascia and joing the superficial and deep veins together
mod 8
DVT assessment
- pt supine and frog leg the leg of interest out
- Consider reverse T-burg to pool some blood in the legs
- place the probe transversly at the inguinal canal
- Want the linear high frequency probe
- Look at the vessels in the short axis, not long axis
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