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Ultrasound forBleeding Disorders
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ChrissyJ.Cherenfant
11
Principles ofUltrasound
Ultrasound imaging, also known as sonography, is the use of
high-frequency sound waves to visualize the body internally
[1, 2]. The frequency of ultrasound (US) is above 20,000
Hertz, which is beyond what can be heard by humans [1]. A
concept important to understanding ultrasound imaging is
resolution. Resolution is sonography’s ability to differentiate
between two points amidst a certain tissue depth. Lateral
resolution is the minimal distance differentiated between two
points located perpendicular to the ultrasound beam and is
determined by beam width. Axial or longitudinal resolution
is the minimal distance distinguished between two points
parallel to the direction of the ultrasound beam [3–5]. Axial
resolution is dependent on frequency. High-frequency
probes, also known as transducers, have shorter wavelengths
with less penetration and higher resolution. In contrast, lowfrequency probes have longer wavelengths, less resolution,
and better penetration, which is more suitable in viewing
deeper structures [1, 3, 4].
Tissue echogenicity is another concept that is essential to
the value of ultrasound. Echogenicity is a bodily tissue’s
ability to transmit and reect waves compared to surrounding tissues. Favorably, differences in echogenicity of structures allows for a visible contrast on image display.
Descriptions of echogenicity include hyperechoic, isoechoic,
hypoechoic, and anechoic. Hyperechoic describes brighter
echoes that appear white compared to surrounding structures, isoechoic are echoes equal in comparative appearance,
hypoechoic depicts darker echoes that appear gray, and
anechoic characterization is completely black on imaging.
For instance, ascitic uid and blood are anechoic, which
attribute to sonography’s usefulness in detecting uid among
solid hyperechoic or hypoechoic structures [1]. Echogenicity
C. J. Cherenfant (*)
NYU Langone Health, NYU Langone Orthopedic Hospital,
Department of Anesthesiology, Perioperative Medicine, and Pain
Medicine, New York, NY, USA
may also encompass imaging texture description, as heterogeneous being nonuniform and homogenous indicating uniform texture [3, 6].
Acquiring ultrasound imaging involves placing a probe
(transducer) onto skin or into a body opening such as vagina
or rectum. The purpose of the transducer is to convert electrical energy into the mechanical energy of sound waves that
are directed into the patient. The transducer also receives the
reected echoes of waves bouncing off of body tissues and
sends them to the computer for processing and image display
[5, 7]. To aid in image acquisition, a layer of gel is placed
onto the skin as a means of ultrasound wave transmission
from the probe into the body. The three most commonly used
probes are curved array, phased array, and linear. Curved
array, also known as curvilinear, is a low-frequency transducer with a wedge-shaped US beam. It has a large eld of
view due to its large footprint, which is the surface that ultrasound waves are emitted from. Its low-frequency leads to
greater tissue penetration, which contributes to the curved
array being known as the abdominal probe, as it is more suitable for abdominal imaging. Compared to a curvilinear
probe, the phased array probe also has a low-frequency, but
with a smaller footprint. Its small footprint is tting for visualizing cardiac and intrathoracic structures between ribs and
echocardiography. Lastly, the linear probe has high-resolution and frequency, and preserved lateral resolution, making
it better for procedural guidance and viewing supercial
structures like vessels, nerves, and lung apices [3–6, 8–10]
(Fig.11.1). Of note, although probe choice is reliant on the
particular objective, it is encouraged to choose the probe that
will achieve the best resolution for the required depth.
Nevertheless, probe selection and preference is ultimately
user dependent [6].
Mode selection signicantly impacts the quality and usefulness of ultrasound imaging. Amplitude or a-mode is the
simplest ultrasound type showing a one-dimensional image.
As a product of early ultrasonography, a-mode is used to
assess the depth of a structure by exhibiting echo amplitude
© Springer Nature Switzerland AG 2021
C. S. Scher et al. (eds.), Essentials of Blood Product Management in Anesthesia Practice,
https://doi.org/10.1007/978-3-030-59295-0_11
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Fig. 11.1 (a) Phased array (left),
curvilinear probe (right) (Reprinted
with permission from Bornemann etal.
58]:9); (b): curvilinear (left),
[
high-frequency linear (right)
(Reprinted with permission from dela
Cruz etal. [
59], p.175)
a b
over distance. A-mode is commonly used in ophthalmology
and therapeutic ultrasound as treatment for soft lesions, calculus, or tumor ablation [1, 11, 12]. Brightness mode which
is also known as b-mode or gray scale or 2D is two-dimensional black and white imaging that is usually the default on
ultrasound machines. B-mode/2D also displays echogenicity
in shades of gray images, and allows the chosen plane, sagittal, transverse, cornal or oblique, to be visualized. Motion
mode or m-mode is used to measure or display movement
over time with a line on the screen that is adjustable. M-mode
is mostly used in echocardiography and lung evaluation for
pathologies such as pleural effusion and pneumothorax [1, 3,
13]. Spectral doppler ultrasound modality displays ow
velocity over time in continuous and pulsed waves, which is
benecial for cardiac evaluation. Color doppler demonstrates
velocity and direction of ow by color, with the usual convention of red symbolizing ow toward the probe and blue
being away from the probe. There are additional modes such
as three dimensional and four dimensional that are often
used in obstetrics; however, the modes most commonly used
in medical imaging have been mentioned [3].
Additional features that may impact ultrasound imaging
include probe orientation, manipulation, angle of incidence,
sliding/alignment, and pressure application. These skills
and techniques are fundamentally dependent on the provider’s education, clinical exposure, and clinical experience.
Yet, it is important to note that they may impact the usefulness of ultrasound and consequently patient clinical management [3, 6].
and ultimately aiding in clinical decision making as an
adjunct to physical examination [1, 8, 14–17]. PoCUS has
the feature of being easily repeatable, which is advantageous
in monitoring patients as their condition change [1].
Additionally, it serves as a means of acute intervention and
therapeutic guidance, while also having the capacity to guide
invasive procedures [14, 18]. The fundamental difference
between PoCUS and regular ultrasonography is that regularly ultrasound can assess anatomy, bodily functions, and
procedural guidance, while PoCUS encompasses these features with the addition of being goal-oriented and providing
immediate clinical information at the bedside [19].
Indications
Within anesthesiology and its subspecialties, ultrasound is
used in many ways, including central venous catheter (CVC)
guidance, intravenous access, US-guided peripheral nerve
blockade, facet joint and transforaminal nerve root injections,
and echocardiography. PoCUS has the ability to execute these
existing features and further assist in diagnostic and procedural elements at the patient’s bedside in perioperative, intraoperative, and postoperative settings [1, 14, 20–23].
Furthermore, point-of-care ultrasound possesses value in
evaluating the whole body, from head to toe (Table11.1).
Ophthalmology/Neurology
Point-of-Care Ultrasound (PoCUS): What Is It?
Point-of-care ultrasound (PoCUS) is the real-time, goaloriented use of ultrasound performed and interpreted by a
healthcare provider at a patient’s bedside, with the intention
of improving patient outcomes. By its quality of rapid imaging that could be correlated with a patient’s symptoms,
PoCUS is the application of ultrasound for answering a specic diagnostic question, narrowing differentials, screening,
Optic nerve sheath diameter (ONSD) measured by PoCUS
has been found to be associated with intracranial pressure
[20] (Fig.11.2). In continuity with the brain subarachnoid
space, the optic nerve sheath can be reective of intracranial
pressure (ICP). Although diameter measuring 5–7mm can
be normal, ONSD greater than 5 mm has been associated
with evidence of increased ICP evident on CT [23–25]. In
obstetric populations, there have been ndings of thicker
optic nerve sheath among patients with preeclampsia [26]. In
pediatric population with neurological pathology, enlarged
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Table 11.1 Ultrasound application in anesthesiology: Critical care and perioperative medicine
Objective PoCUS Application
Airway Procedural: Endotracheal tube placement, double lumen placement, cricoid membrane puncture,
Abdominal Procedural: TAP /truncal blockade guidance, paracentesis
Cardiology Procedural: Pacing capture detection, pericardiocentesis
Ophthalmology/neurology Diagnostic: ICP estimation by optic nerve sheath diameter, foreign bodies, retinal detachment, lens dislocation,
Pulmonary Procedural: endobronchial/double lumen tube placement, thoracentesis
Regional anesthesia/pain
medicine
Shock Diagnostic: Fluid status monitoring, hemodynamic evaluation
Urinary Procedural: Foley catheterization conrmation
Vascular Procedural: Guidance for venous and arterial access (central and peripheral), central venous catheterization
Other Procedural: Abscess drainage
cricothyroidotomy, upper airway regional block, tracheostomy
Diagnostic: Cervical spine, anterior neck fat tissue, vocal cord mobility, diaphragmatic movement, predicting
extubation failure,
Diagnostic: Free uid (FAST), gastric volume and content
Diagnostic: Echocardiography, ventricular and valvular function, hemodynamics, uid status, pericardial effusion
vitreous hemorrhage,ocular hematoma
Diagnostic: Dyspnea, pleural effusion, pneumothorax, pulmonary edema, pneumonia, severe interstitial disease
Procedural: Peripheral nerve blockade, neuraxial blockade, trunk blockade,transforaminal/interlaminar nerve root
injections
Diagnostic: Renal obstruction
Diagnostic: arterial and venous patency, aortic dissection, aortic aneurysm, IVC collapsibility, Doppler ow across
peripheral arteries and LVOT, vascular compression for DVT
Diagnostic: Cellulitis and abscess assessment
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Fig. 11.2 Optic nerve sheath diameter (Reprinted with permission
from Jeong [60], p.151)
ONSD has also been correlated with increased ICP [27].
Thus, in patients with symptoms of or pathologies susceptible
to increased intracranial pressure, PoCUS can be used diagnostically, especially in the acute setting.
Airway Evaluation
Ultrasound has the existing role of procedural guidance for
upper airway regional blocks [23]. Airway assessment and
management is an emerging application of PoCUS that poses
usefulness to intensivists and anesthesiologists, preoperatively and intraoperatively. PoCUS can conrm placement of
endotracheal and double lumen tubes and can differentiate
between endobronchial, tracheal, and esophageal intubations
[23, 28]. Linear probe use at the suprasternal notch has been
found to have high specicity and sensitivity in determining
endotracheal tube placement [21]. US can also be used at the
patient’s bedside preoperatively for airway examination.
Compared to regular airway screening tests such as, mouth
opening and neck mobility, US measured reduced mandibular condylar mobility is correlated with difcult laryngoscopy, with limited mobility dened as less than 10mm in
one study [29, 30]. PoCUS can also aid in identifying potential difcult laryngoscopies by measuring anterior neck soft
tissue thickness at the level of the hyoid bone and thyrohyoid
membrane [15]. Another study found US measured anterior
neck soft tissue thickness at the level of the vocal cords
greater than 0.23cm to be a possible predictor of challenging
intubation [31]. Other US airway measurements and imaging
that may predict difcult intubations prior to induction of
anesthesia include hyomental distance, tracheal diameter,
vocal cord pathologies or dysfunctions, and anatomic variations [23, 28]. PoCUS may also reduce risk of failure or
complications from emergency surgical airway, where US
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has been found to be more reliable than manually locating
the cricothyroid membrane in obese patients [32]. In the
setting of possible airway complications, point-of-care ultrasound can serve as a valuable tool that benets patient care
[14, 18, 26, 28, 32].
Pulmonary
In the elds of emergency medicine and critical care, ultrasound has the established role of diagnosing pneumothorax
by the absence of lung sliding [16, 33, 34]. Lung sliding is
visualized from US as an artifact of parietal pleura moving
against visceral pleura during respiration. The sliding is prohibited with a pneumothorax because air is between the visceral and parietal pleura [8, 35]. As a consequence of trauma
or an iatrogenic complication from central venous catheterization or peripheral nerve blockade, determining the occurrence of pneumothorax is very important. PoCUS is
benecial among patients concerning for pneumothorax due
to it providing rapid critical imaging that can be immediately interpreted and managed by the clinician at the bedside. Using B-mode or M-mode and a linear transducer with
higher frequency and better resolution (Fig.11.3), pneumothorax can be diagnosed via PoCUS.The imaging will demonstrate the absence of lung sliding on B-mode, while on
M-mode, pneumothorax displays as a uniform linear pattern
above and below the pleural line that is known as “barcode
or stratosphere sign.” In contrast, a normal lung ultrasound
on M-mode would show “seashore sign” pattern linear to
granular pattern change at the visceral pleural line [8, 26,
35] (Fig.11.4). In evaluating trauma patients, US has been
shown to be twice as more sensitive at detecting occult
pneumothorax than supine chest radiography [1, 36].
However, it is important to note that the absence of lung
sliding indicating pneumothorax must be in the presence of
no other concurrent lung disease and in the appropriate clinical context. The lack of lung sliding is not specic for
pneumothorax, as any lung disease process, such as pneumonia, atelectasis, or contralateral endobronchial intubation, can manifest as absent lung sliding. Also, small
pneumothorax may be missed by US and blebs or scarring
may cause false positives [1, 20, 21, 35].
Lung ultrasound having high accuracy in diagnosing
hypoxia strengthens PoCUS’s diagnostic role in pulmonary
presentations [38]. Pathological conditions that can be discovered by PoCUS include pulmonary edema, pulmonary
effusion, consolidations reective of pneumonia, dynamic
air bronchograms concerning for pneumonia, chronic
obstructive pulmonary disease, pulmonary embolism, pulmonary brosis, and alveolar interstitial disease [9, 14, 35,
37, 38]. One of the common ultrasound ndings are B lines,
which may represent uid overload, pleural effusion, lung
consolidation due to pneumonia, or interstitial disease [1, 21,
35]. After detecting pleural effusion, PoCUS can further
serve as a diagnostic and therapeutic aid in procedural guidance for thoracentesis [23]. There have also been some suggestions for use of PoCUS to detect atelectasis preoperatively
and to address desaturation on pulse oximetry intraoperatively [18]. Due to its sensitive, specic, and expeditious
Fig. 11.3 M-mode with sampling line in the intercostal space
(Reprinted with permission from dela Cruz etal. [59], p.180)
Fig. 11.4 Normal M-mode seashore
sign (left) and barcode/stratosphere
sign indicating pneumothorax (right)
(Reprinted with permission from dela
Cruz etal. [59], p.181)
b3
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Fig. 11.5 Parasternal left ventricular
long axis view (a) Diastole (b) Systole
IVS Interventricular septum, LV Left
ventricle, PMV Pulmonary valve,
LVPW Left ventricular posterior wall,
LA left atrium, AMV Anterior mitral
valve, AV Aortic valve, RV Right
ventricle, RVAW Right ventricle
anterior wall (Reprinted with
permission from He [
61], p.75)
Fig. 11.6 Parasternal four chamber
view (a) Diastole (b) Systole MB
Moderator band, RV Right ventricle,
RA Right atrium, RSPV Right
superior pulmonary vein, DAo
Descendign aorta, LA left atrium, LV
left ventricle, IVC Inferior vena cava
(Reprinted with permission from He
61], p.84)
[
a1
IVS
LV
PMV
LVPW
RVAW
AMV
b1
RVAW
IVS
LV
MV
a1 a2
MB
RV
RA
RSPV
DAo
a2
RV
AV
LA
RV
AV
LA
IVC
LV
LA
detection of a wide array of lung pathologies, especially during times of acute patient deterioration, lung ultrasound is
considered to be an essential PoCUS skill [9, 39].
Cardiology
Cardiac ultrasound is utilized by anesthesiologists diagnostically. Transesophageal echocardiography (TEE) is an
established practice in cardiac surgeries and is a PoCUS
skill that has standard guidelines [14, 21, 40]. At the bedside in the intensive care unit (ICU), focused cardiac ultrasound (FoCUS) with transthoracic echocardiography
(TTE) is used to determine ventricular failure and pericardial effusions [15, 27]. PoCUS can augment cardiac physi-
b1 b2
RV
LV
RA
LA
DAo
RSPV
cal examination performed by an anesthesiologist. For
instance, a murmur heard on examination can be rapidly
correlated with valvular pathology [40]. Cardiac pathologies detected by PoCUS include pericardial effusion, tamponade, pulmonary emboli, severe hypovolemia,
postpartum cardiomyopathy, myocardial thickness, and
dilated heart chambers [15, 26, 29]. PoCUS can also serve
as procedural guidance for pericardiocentesis and detect
pacing capture [23]. Of note, PoCUS differs from TTE
performed by cardiologists by being less comprehensive
and more goal-oriented with the aim of assisting physicians to quickly rule out or in diagnoses [21]. The phased
array probe, also known as the cardiac probe, in 2D or
M-mode is more suitable for cardiac evaluation [3, 9, 41,
42] (Figs.11.5, 11.6, 11.7, and 11.8).
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Fig. 11.7 Apical four
chamber view (a) Diastole (b)
Systole RV Right ventricle,
RA Right atrium, LV Left
ventricle, LA Left atrium,
RSPV Right superior
pulmonary vein, LSPV Left
superior pulmonary vein,
LIPV Left inferior pulmonary
vein, TV Tricuspid valve, MV
Mitral valve (Reprinted with
permission from He [61],
p.85)
Fig. 11.8 Apical ve chamber view
(a) Diastole (b) Systole RV Right
ventricle, Ao Aorta, RA Right atrium,
LA Left atrium, LV Left ventricle
(Reprinted with permission from He
[
61], p.93)
a1 a2
RV
RA
LIPV
RSPV
b1
RV
TV
RA
RSPV
LSPV
b2
LV
MV
LA
LIPV
LSPV
a1 a2
LV
RV
LV
LA
Cardiac PoCUS, which essentially is a focused TTE,
also has the ability to identify and monitor ventricular dysfunction and severe valvular pathology, not only during
cardiac procedures but also during non cardiac surgeries,
periods of hemodynamic instability, and preoperatively [1,
14, 23]. Focused TTE has been found to change patient
management and impact perioperative care. Studies have
shown that preoperative TTE in patients at risk for cardiac
Ao
LA
RA
b1 b2
LV
RV
Ao
LA
RA
disease or with periods of hemodynamic instability can
diagnose low ejection fraction, aortic and mitral valve disease, hypovolemia, tamponade, and ventricular failure.
These ndings often resulted in changed anesthetic management such as medication changes, cancellations, uid
boluses or restrictions, and implementation of invasive
monitoring [15, 29, 40, 43]. This effect supports the need
for cardiac PoCUS use preoperatively.
Probe placement
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PoCUS during pulse checks of cardiac arrests can also be
valuable in aiding decision making. This is due to PoCUS
providing further information such as detecting a potential
etiology like pericardial effusion or hypovolemia and displaying an absence of systolic contractions, which suggests
minimal likelihood for return of spontaneous circulation
after three rounds of cardiopulmonary resuscitation medication administration [16, 44]. In addition, focused assessment with sonography for trauma (FAST) examination
includes obtaining a pericardial view to diagnose cardiac
free uid such as blood, in trauma patients [16]. This also
exhibits PoCUS’s practicality in determining cardiac injury.
Fig. 11.9 FAST examination. (a) Probe
to subxiphoid with liver (L) showing
presence of absence of pericardial uid
(F). (b) Probe to RUQ, showing absence
or presence of free uid in Morrison’s
Pouch (MP) between liver and kidney
(K). (c) Probe to LUQ, showing absence
or presence of free uid (F) near spleen
(S) and kidney. (d) Long axis pelvic
view with normal bladder (B) on left
and free uid posterior to bladder on
left. B bladder, D diaphragm, F uid, K
kidney, L liver, MP Morrison’s pouch, S
Spleen (Reprinted with permission from
Bornemann etal. [58], p.15)
a
Probe placement
b
Abdominal
Abdominal point-of-care ultrasound aids in the immediate
visualization of abdominal tissues and organs [2]. This is
advantageous in the setting of abdominal trauma, symptoms,
or procedures. Curvilinear or curved array probe is better
suited for abdominal imaging due to its low-frequency and
greater penetrance [3, 8]. The FAST exam is well known in
emergency medicine as a focused abdominal assessment for
free uid. FAST encompasses evaluation of the hepatorenal
space, perisplenic space, subcostal/subxiphoid space, and
suprapubic area [8, 16, 21] (Fig.11.9).
Normal
Abnormal
Probe placement
c
Probe placement
d
Normal
Normal
Normal
Abnormal
Abnormal
Abnormal
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Abdominal PoCUS can acutely evaluate disease processes and diagnose etiologies of sepsis. Cholethiasis is
identied by rounded, hyperechoic structures and common
bile duct dilation, and cholecystitis displays as gallbladder
wall thickening and pericholecystic uid. US can detect
intestinal obstruction by loops of bowel >3cm, extra- luminal
uid, luminal air, and bowel wall thickening. PoCUS can
also evaluate etiologies of renal colic by displaying stones
and hydronephrosis and identify abdominal aortic aneurysms
[16]. Abdominal US is also used at the bedside in medicine
for diagnosis of ascites, and therapeutically by facilitating
procedural guidance for paracentesis [23].
In pain management of abdominal surgeries, ultrasound is
used for procedural guidance of nerve blockades like rectus
main sheath and transversus abdominis plane (TAP) blocks.
Ultrasound use has decreased complications and improved
anesthesia placement [26, 39, 45, 46]. Abdominal PoCUS has
further applications that can be benecial to care provided by
anesthesiologists. Preoperatively, PoCUS can aid in decreasing the risk of aspiration, by examining gastric content and
volume [17, 21, 23, 27, 41]. Ultrasound measurement of gastric antrum cross-sectional area and stomach content volume
are indicators of aspiration risk at induction, where a patient
in right lateral decubitus position having a cross-sectional
area<4cm is 95% specic for an empty stomach [20–22].
Gastric PoCUS can therefore lead to anesthetic management
changes in patients who do not follow fasting instructions
[22]. Postoperatively, abdominal PoCUS examination can
detect intra-abdominal uid extravasation (IAFE) that has
correlated to increased pain scores in the postanesthesia care
unit [29, 47]. Another indication of abdominal PoCUS is conrming gastric tube placement in the ICU, which reduces
x-ray exposure [20]. Overall, with its many applications,
abdominal PoCUS can enhance perioperative care.
Regional Anesthesia
Ultrasound guidance in regional anesthesia is conventionally
used for peripheral nerve and truncal blockade and in interventional pain medicine with a comparable effectiveness to
uoroscopy [20, 23, 48].Ultrasound has made regional anes-
thesia safer, more efcient and effective, and easier to teach
[
20, 21, 26, 29, 41, 45, 46, 49–52]. Although not replacing
the gold standard of radiographs, musculoskeletal PoCUS
can diagnose dislocated shoulder and reduction [8].
US-guided neuraxial anesthesia can be benecial in the setting of obesity, edema, previous spinal surgery, scoliosis, lordosis, and difcult landmark identication by locating
vertebral spaces, interspinous spaces, angulation, and epidural depth, better than palpitation [18, 26, 48, 53]. The
American Society of Regional Anesthesia and Pain Medicine
(ASRA) has supported the recommendation that neuraxial
ultrasound increases lumbar neuraxial anesthesia efciency
and is more accurate in predicting depth to target than palpation [52]. Despite these advantages, US-guided neuraxial
anesthesia is not widely utilized due to the success of palpitating lumbar spinous processes [41].
Vascular/Shock
Ultrasound is often used by healthcare providers as guidance
for venous and arterial access, with examples of intravenous
line placement and central venous catheterization [1, 18, 21,
23, 26, 39, 41]. PoCUS can be used by intensivists in the
ICU and anesthesiologists in the perioperative period to rapidly characterize shock. Ultrasound can differentiate between
hypovolemic, cardiogenic, and distributive etiologies of
shock by evaluating the heart, lungs, inferior vena cava
(IVC), and abdomen [9, 44]. PoCUS has been found to aid
clinicians in narrowing their differential diagnosis in patients
with undifferentiated hypotension in the emergency department [16]. Thus, PoCUS can lead to faster diagnosis and
consequently sooner treatment, while also providing a platform for monitoring treatment results [44]. PoCUS has also
been shown to assess for uid administration response preoperatively and in the PACU.This is done by IVC measurement during spontaneous ventilation, which is correlated to
intravascular volume [27] (Figs. 11.10 and 11.11).
Additionally, ultrasound is the screening modality for
abdominal aortic aneurysm in men with smoking history of
ages 65–75 and can be used to evaluate for aneurysm in
patients with symptoms of aortic rupture [20] (Fig.11.12).
Fig. 11.10 Short axis view of IVC
MHV middle hepatic vein, LL liver,
IVC inferior vena cava (Reprinted
with permission from He [61], p.94)
a1 a2
LL
MHV
IVC
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Fig. 11.11 Long axis view of IVC IVC
inferior vena cava, LL Liver, RHV right
hepatic vein, Ao Aorta (Reprinted with
permission from He [
61], p.95)
a
b
Fig. 11.12 Abdominal aortic aneurysm (a) short axis (b) long axis
(Reprinted with permission from Bornemann etal. [58], p.29)
Ultrasound Views
Depending on its objective, PoCUS is optimally utilized in
certain views. Generally, structures can be viewed in short
axis, long axis, and oblique views. Vessels, nerves, and other
anatomical structures are commonly viewed in short axis,
while a long-axis approach is preferred for needle vascular
access, so the needle can be visualized during the procedure.
Yet, it may be easier for the vessel and needle to both be in
view in short axis [1, 6]. For cardiac PoCUS, parasternal
long- and short-axis views are recommended. To further
evaluate valvular pathology, apical or subcostal chamber
views and color Doppler are useful [40]. FAST examination
is composed of pericardial view, also described as subcostal
a1
LL
RHV
a2
IVC
Ao
or subxiphoid, right upper quadrant or perihepatic view, left
upper quadrant or perisplenic view, and suprapubic or pelvic
view. The extended FAST also includes bilateral anterior
chest wall views to assess for lung sliding usually at the midclavicular line in M-mode [1, 8, 16, 21]. Fundamentally,
multiple views and modes can be easily selected and are ultimately user dependent.
Benets andDrawbacks
The major advantage of point-of-care testing is improved
speed of diagnostic testing with accuracy. The time between
onset of symptoms and therapy initiation is decreased, resulting in better patient outcomes [16]. The benets of point-ofcare ultrasound are that it is reliable and time saving since
immediate clinician interpretation eliminates the waiting on
radiologists and cardiologists readings, which is favorable
for acute issues [1, 18]. PoCUS is also easily repeatable
which is ideal for monitoring [1]. With no ionizing radiation,
diagnostic ultrasound is safe, especially in obstetric and
pediatric populations [1, 20]. PoCUS used for procedural
guidance decreases number of attempts and complication
rates and improves safety and quality of care [20, 21]. PoCUS
equipment is also becoming less expensive and portable,
making it more accessible and suitable for low resource settings [1, 20, 21].
The major drawback of PoCUS is that the provided information is user dependent, relying on the user’s skills with
the transducer and ability to accurately identify ndings
while avoiding artifacts. In the hands of an unskilled user,
PoCUS may not be benecial to patient care since an inaccurate diagnosis can lead to complications or inappropriate
therapies [1, 5, 54]. Ultrasound imaging may also be negatively impacted by patient immobility [37]. In certain scenarios, although PoCUS provides rapid imaging, it does not
replace diagnostic imaging interpreted by radiologists [20].
There is also a concern that PoCUS use on multiple patients
may increase disease transmission if not disinfected. PoCUS
may also be overused, leading to unnecessary interventions
due to false-positive ndings or inadequate further assessment due to false negatives that can be harmful and expensive [1, 21]. Furthermore, many anesthesiology PoCUS
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applications have no guidelines for education, training, or
appropriate use. This contributes to the concern of PoCUS
utility without substantial knowledge or prociency demonstration [54].
The Future
The main barrier to widespread point-of-care ultrasound use
in anesthesiology is the decit of PoCUS education and
training in the eld, especially when compared to emergency
medicine. In the USA, most anesthesiologists have not had
any training in PoCUS, and there is no standard PoCUS curriculum in most anesthesiology residencies [14, 55].
However, there has been many calls for action to create a
curriculum and develop guidelines for perioperative PoCUS
use [14, 23, 54, 55].
In 2015, a perioperative PoCUS special interest group
was created within ASRA.In 2016, they held their rst meeting and continue to have a growing membership today [14,
56]. One paper discusses the perioperative anesthesiology
ultrasonographic evaluation (PAUSE) approach during perioperative management. It is a tool for anesthesiologists to
“pause” various times and use PoCUS to assess patients and
extend upon information from physical examination and
vitals monitoring [40]. With increasing interest in PoCUS,
there have been many discussions and investigations on the
possible methods of institutionalizing perioperative PoCUS
and evaluating its existing and additional applications. There
is a need for a multipurpose curriculum to be reective of the
many settings anesthesiology is practiced [15]. There have
been suggestions of implementing PoCUS via many modalities such as e-learning, didactic teaching, practical sessions,
and human model or stimulation practicing. Among anesthesiology residents, online didactics, hands-on training, and
simulation-based curriculum have resulted in increased
knowledge, improved image acquisition and manual dexterity, high participant satisfaction, and clinical transferability
of skills. It has been suggested that teaching and training
should be longitudinal, across years and rotations, to decrease
the likelihood of diminished skills that occurs without reinforcement and continued use [34, 39, 54, 57]. PoCUS curriculum must also continue to have the goal of improving
patient care [34, 56]. Fundamentally, there continues to be a
need for research on point-of-care ultrasound effect on
patient care and outcomes, applications, and how to implement effective PoCUS training.
Summary
Point-of-care ultrasound is a tool and skill that can optimize
clinical evaluation, beyond physical examinations. PoCUS is
advantageous due to its abundance, diverse applications in
cardiac, pulmonary, abdominal, neurological, airway, hemodynamic, and vascular systems. Its role of safely and immediately answering specic diagnostic questions, directing
therapy, and guiding procedures further validates its signicance. As point-of-care ultrasound positively impacts patient
care, there continues to be a need for development of curriculum and guidelines for PoCUS education and training, as
well as research to provide further evidence of its benets
and uses. Just as ultrasound is commonly known to be
employed in regional anesthesia and for central venous catheterization, it is conceivable that in the future point-of-care
ultrasound may also be used ubiquitously.
References
1. Moore CL, Copel JA.Point-of-care ultrasonography. N Engl J Med.
2011;364(8):749–57.
2. Center for Devices and Radiological Health. Ultrasound imaging. U.S. Food and Drug Administration. https://www.fda.gov/
radiation-emitting-products/medical-imaging/ultrasound-imaging.
Published 8 Aug 2019. Accessed 5 Sept 2019.
3. Baston CM, Moore C, Krebs EA, Dean AJ, Panebianco N, editors.
Physics and knobology. In: Pocket guide to POCUS: point-ofcare tips for point-of-care ultrasound. NewYork: McGraw-Hill.
http://accessmedicine.mhmedical.com.ezproxy.med.nyu.edu/content.aspx?bookid=2544§ionid=210344236. Accessed 5 Sept
2019.
4. Ng A, Swanevelder J. Resolution in ultrasound imaging. Contin
Educ Anaesth Crit Care Pain. 2011;11(5):186–92. https://doi.
org/10.1093/bjaceaccp/mkr030.
5. Rumack CM, Leṿin D, editors. Diagnostic ultrasound. 5th ed.
Philadelphia: Elsevier; 2018.
6. Ihnatsenka B, Boezaart AP. Ultrasound: basic understanding and
learning the language. Int J Shoulder Surg. 2010;4(3):55–62.
https://doi.org/10.4103/0973-6042.76960.
7. NCI Dictionary of Cancer Terms. National Cancer Institute. https://
www.cancer.gov/publications/dictionaries/cancer-terms/def/ultrasound-transducer
8. Gleeson T, Blehar D. Point-of-care ultrasound in trauma. Semin
Ultrasound CT MR. 2018;39(4):374–83.
9. Díaz-gómez JL, Via G, Ramakrishna H.Focused cardiac and lung
ultrasonography: implications and applicability in the perioperative
period. Rom J Anaesth Intensive Care. 2016;23(1):41–54.
10. Coté CJ, Lerman J, Anderson BJ, Karmakar MK, Kwok
WH. Ultrasound-guided regional anesthesia. In: A practice of
anesthesia for infants and children. 6th ed. Philadelphia: Elsevier;
2019. p.988–1022. https://www.sciencedirect.com/science/article/
pii/B9780323429740000434
11. Silverman RH. Focused ultrasound in ophthalmology. Clin
Ophthalmol. 2016;10:1865–75. Published 2016 Sep 27. https://doi.
org/10.2147/OPTH.S99535.
12. Miller DL, Smith NB, Bailey MR, etal. Overview of therapeutic
ultrasound applications and safety considerations. J Ultrasound
Med. 2012;31(4):623–34.
13. Carovac A, Smajlovic F, Junuzovic D.Application of ultrasound
in medicine. Acta Inform Med. 2011;19(3):168–71. https://doi.
org/10.5455/aim.2011.19.168-171.
14. De marchi L, Meineri M. POCUS in perioperative medicine: a
North American perspective. Crit Ultrasound J. 2017;9(1):19.
15. Jasudavisius A, Arellano R, Martin J, Mcconnell B, Bainbridge
D.A systematic review of transthoracic and transesophageal echocardiography in non-cardiac surgery: implications for point-of-
. Accessed 5 Sept 2019.
. Accessed 5 Sept 2019.
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