Lung Ultrasound (LUS) Part 1

July 29, 2021

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00:03In this lecture we will review
00:05pediatric point of care lung ultrasound.
00:15In general, the approach to your
00:17patients will differ depending on
00:19the clinical picture and
00:21the presenting symptoms.
00:23Most common pathology you'll
00:24be looking for is the presence
00:27or absence of animal thorax.
00:28The presence or absence of
00:30a pleural effusion in the presence or
00:33absence of lung tissue consolidation
00:35or fluid filled alveolar spaces.
00:41So one common thread in pediatric
00:43patients is that they may not be
00:45too cooperative with your exam.
00:47They may be overly tired, fussy,
00:49irritable, arching their backs and
00:51bringing the scapula together so as to
00:54not expose the posterior lung field,
00:56or just simply trying to run a wing.
00:59Some potential tricks of the trade include
01:02engaging a caregiver so that the child
01:04feels more comfortable having an infant
01:07or toddler give their parents a hug.
01:09This will provide both a sense
01:11of comfort and expose their back
01:14for a good long examination.
01:16And finally,
01:16I would encourage distraction
01:18in whatever means possible.
01:19And yes, screen time is OK during
01:22a pediatric lung pocus.
01:29So to improve your patient cooperation and
01:32optimize your time performing lung focus,
01:34you may consider getting some warm gel.
01:36This can be done with some relatively
01:38inexpensive commercially available
01:39products if you're using typical gel tubes.
01:42If for some reason you happen to
01:44be using gel packets,
01:45a hack that
01:46I like to use is to put one or two
01:49in my pocket at the beginning of a
01:52shift and then have them at the ready.
01:55When the timing is right now
01:58in terms of the transducer,
01:59your probe selection is going
02:01to depend a lot on the question
02:03that you're trying to answer.
02:05In general, for younger patients in whom
02:08you're concerned mostly about pneumonia,
02:10a high frequency linear transducer is
02:12going to provide excellent resolution.
02:14The linear transducer would be my choice
02:16as well for pneumo thorax evaluation.
02:18That said, there are many instances
02:20where low frequency curvilinear
02:22transducer will be an adequate choice,
02:24and I certainly would use this probe.
02:27In my initial assessment for
02:28pleural effusion.
02:33So when clinical concern exists for
02:35either pneumothorax or pneumonia,
02:37your probe of choice will be the high
02:40frequency linear transducer and you
02:42will start by looking at the apex of
02:45the lung over the anterior lung fields.
02:48If clinical concerns exist for a
02:50pleural effusion, like would be
02:52the case in the context of trauma,
02:55then using a curvilinear probe to
02:57interrogate the lung basis would
02:59be my preferred initial approach.
03:04In pneumothorax occurs when air
03:06accumulates in the pleural space between
03:08the visceral and parietal pleura.
03:11The air buildup in this space,
03:13even when it is in small quantities,
03:15create visual changes on your
03:17ultrasound screen which will
03:19help you make this diagnosis.
03:24For the evaluation of pneumothorax,
03:25the following steps should be followed.
03:27First, it is important to position
03:29the patient in the supine position.
03:32This will increase your overall sensitivity
03:34for small pneumothorax detection,
03:35as air will rise to the top and
03:38therefore in a supine position
03:40that pneumothorax will be present
03:42between the probe and the chest wall.
03:44Evaluation of the apex with a
03:46linear probes over the midclavicular
03:48line with the indicator to the
03:50head is the ideal starting point.
03:53You look for signs of lung sliding.
03:55If lungs lighting happens to be absent,
03:57then you will want to slide the
03:58probe down the chest wall to get a
04:01general sense of how big of a pneumo
04:03thorax you will be dealing with.
04:07So let's start by looking at the appearance
04:10of normal lung tissue as seen by ultrasound.
04:13As discussed, you will place the
04:15linear probe we indicated to the head.
04:17If you look at the screenshot on the left,
04:20that indicator is represented by the P.
04:22The ribs can be seen in cross section
04:25with posterior acoustic enhancement
04:26and the goal here is for the pleura
04:29to be at the center of your screen.
04:31Note that the ultrasound machine
04:33is set on lung window setting
04:35and this makes the pleura.
04:36Bright or echogenic right above
04:39the pleura and between the ribs.
04:41You will find your intercostal muscle
04:44and again the first echogenic line
04:46represents the pleural interface.
04:49Now on the video on the right you can see
04:52that there is motion movement shimmering
04:55of the pleura which represents normal
04:58sliding of the visceral and parietal
05:01component during typical respirations.
05:03In addition you will see additional
05:06horizontal lines also echogenic.
05:07Which we refer to as a lines.
05:10This is a normal reverberation artifact
05:12that is seen in healthy lung tissue.
05:14We will come back to these a lines at
05:17another point in this presentation.
05:21So when air collects between
05:24the visceral parietal pleura,
05:25the lack of lung sliding that results
05:28will cause physiologic changes
05:30easily detectable by ultrasound.
05:35Your first assessment is going to be a
05:38careful visual assessment of the pleura.
05:40These images represent lung
05:42ultrasound findings of a patient
05:43with a right sided pneumothorax.
05:45Note the normal clip on the left.
05:48You can see normal lung sliding
05:50with the appearance of shimmering or
05:52sometimes described as ants marching
05:53on a log which represents normal motion
05:56between the visceral parietal pleura.
05:58In contrast on the abnormal side you can
06:01see that that plural looks stuck together.
06:04There is no discrete motion
06:06that can be seen in this case.
06:08The probe was placed in the
06:10Midaxillary line around T4,
06:12precisely where a chest tube or pigtail
06:14catheter would typically be placed.
06:19So to quantify the size of new more thorax,
06:22you want to identify its transition zone,
06:25which many will refer to as
06:27long points during expiration.
06:29Air tracking into the
06:31pleural space will expand,
06:32while inspiration leads to air
06:34accumulation within the lungs themselves.
06:36Depending on the size of the pneumothorax,
06:39you will be able to determine at what
06:41point in the thorax a pneumothorax meets
06:44and opposes aerated lung with preserved
06:47visceral and parietal pleural sliding.
06:49Lung Point is the most specific
06:52ultrasound finding for pneumothorax
06:53and can be used to distinguish
06:55from other causes of abnormal
06:56lung sliding such as pleurodesis.
07:02In this video clip you can see
07:04lung points being demonstrated.
07:05Diplura again is the Echogenic line
07:07seen here between the ribs on the left
07:10side of the screen you can see motion
07:12which represents movement between
07:14the visceral and parietal pleura.
07:16While on the right side of the
07:18screen the plural line is still
07:20consistent with a pneumothorax.
07:26Now finally you can use M mode,
07:28which stands for motion mode to
07:30confirm your suspicion for the presence
07:33or absence of a normal thorax.
07:35So here you drop the motion line over
07:38the center of the pleura and this
07:40will split the screen and the bottom
07:43half will detect motion overtime.
07:45So the same concept applies when
07:46there is opposition and normal
07:48sliding between the visceral pleura
07:50you will see a distinct transition
07:52as your ultrasound devices.
07:54Picking up this movement,
07:55this is often referred to as a seashore sign,
07:58which is a good thing because most
08:00of us would rather be at the beach
08:02than listening to this lecture.
08:07In contrast, when a new
08:08more thorax is present,
08:10your ultrasound cannot detect
08:11motion between the pleura.
08:13Therefore, the appearance of
08:14a barcode will be present,
08:16which is only fitting because the next
08:19steps are likely to add additional
08:21expenses to the health care system.
08:26So here we have a case of a 14 year
08:29old with a spontaneous pneumothorax
08:31who was woken up suddenly with some
08:34shortness of breath and chest pain.
08:36Ultrasound images of the apex are significant
08:38for absent lung sliding on the video clip.
08:41In addition, when M mode was applied,
08:43there was a positive barcode sign with
08:46a straight horizontal lines above and
08:48below the plural as no transition zone
08:50or lung point was seen by ultrasound,
08:53this patient was triaged into
08:54the major treatment.
08:55Area where chest X ray is 30 minutes later,
08:59confirmed the presence of a large
09:02right sided pneumothorax. Let
09:04us now shift gears and look at
09:08ultrasound for the detection of
09:10pleural effusion. Be it simple, fluid,
09:13complex, fluid or hemothorax.
09:18So for assessment of pleural effusion,
09:20you will want a curvilinear probe which
09:22allows for greater tissue penetration,
09:24and you can do this in the
09:26supplying position again with the
09:28indicator to the patients head.
09:30Now here you want to evaluate at the level
09:32of the diaphragm with a starting point
09:35roughly around the mid axillary line,
09:37you'll have to obtain views in both
09:39the right upper quadrant and the left
09:42upper quadrant for a complete exam.
09:44As an example, let's take a look at.
09:47The image is created in the
09:50left upper Quadrant.
09:51The image produced should contain
09:53the following anatomy, ribs,
09:55spleen towards the top left of the screen,
09:59kidney towards the bottom
10:01right of the screen.
10:02The diaphragm,
10:03which is a thin curved echogenic
10:06structure which marks the transition
10:08zone between abdomen and lungs.
10:11In normal circumstances you will see mirror
10:14imaging or reflection of the spleen tissue.
10:17Slipped behind the diaphragm.
10:19However,
10:19when fluid collects at the costophrenic
10:22angle instead of spleen tissue
10:24reflected behind the diaphragm,
10:25you will now be able to
10:28detect a fluid collection,
10:29which will also make the thoracic
10:32spine more easy to identify.
10:38In this video clip,
10:39we can see normal appearance of
10:41anatomy and the left upper quadrant.
10:43The spleen is a relatively homogeneous
10:46structure which appears in the
10:47middle of the screen to the right
10:49of the screen and below the spleen
10:51you will see the left kidney.
10:53The lungs will be above and to the
10:56left of the spleen and not visible.
10:58On these images,
10:59the most important structure
11:00to note is the diaphragm,
11:02which will demarcate the area
11:04of the cost for Fennec.
11:05Angle where fluid would build
11:07up should it be present,
11:09but in this case we see we are
11:11imaging and reflection of the
11:13spleen behind the diaphragm,
11:14which you would expect
11:16in normal circumstances.
11:20In this video clip,
11:21you can see a moderate size Pearl
11:24diffusion by ultrasound with
11:26its corresponding chest X ray.
11:28The fluid is accumulating above
11:29the liver and above the diaphragm,
11:32and in this instance you can
11:34also see disease lung tissue
11:36within the pleural effusion,
11:38and additional important finding
11:39is the thoracic spine sign,
11:41which can only be visualized when
11:43there's enough fluid presence
11:45between the ultrasound probe
11:46and the thoracic vertebral body
11:48that allows for sufficient.
11:50Ultrasound transmission to reach and
11:52be reflected by the thoracic spine.
11:54This is a key finding to look for
11:57when diagnosing pleural effusions or
11:59hemothorax in the setting of trauma.
12:06In this video clip,
12:07we can see a large postoperative
12:09pleural effusion and a 3 year old who
12:12is status post liver transplantation.
12:14You can clearly make out a thoracic
12:17spine sign and see lung tissue movement
12:19within this large fluid collection.
12:25In this case, we can see a massive
12:28left sided parapneumonic effusion
12:30in an 8 year old who was eventually
12:33diagnosed with pneumonia caused
12:36by Group A strep which grew out
12:39of her thoracic thesis fluid.
12:44In contrast, smaller pleural effusions
12:46may be more subtle to pick up,
12:48especially when a coexisting
12:50pneumonia is present.
12:51In this example, we have an
12:5311 year old with a right lower
12:55lobe pneumonia as seen by X-ray.
12:58In this particular ultrasound,
12:59there's only a small area that
13:01appears hypoechoic with a
13:03visible spine sign just
13:04deep to this collection.
13:06Lung Hepatization is present,
13:07so this ultrasound would be diagnostic for
13:10a pneumonia with a small non drainable.
13:13Fusion in this next example,
13:14we have a 12 year old with
13:17right lower lobe pneumonia.
13:18The cost of frenic angle does have
13:21a blunted appearance on chest X ray,
13:23making a diagnosis of effusion difficult.
13:25However, ultrasound evaluation
13:27of this area reveals Hepatization
13:28and Bronchograms which are
13:30consistent with infiltrate alone,
13:31and there's no secondary
13:33pleural effusion to be seen.
13:34Let's take a moment to look at
13:37these two ultrasound clips side
13:39by side so you can appreciate the
13:41difference between no effusion.
13:43And a small effusion.
13:47Second, here you can see a rather
13:51complex pleural effusion with internal
13:54septations and honeycomb, like appearance.
13:57Note at the bottom of the screen that the
14:01thoracic spine can be clearly visualized.
14:08Now, if you happen to be using a
14:11linear probe to assess for new motor
14:13acts or a pediatric pneumonia,
14:15you should be able to detect pleural
14:17effusion should it be present and
14:19the appearance of fluid within
14:21the visceral and parietal pleura
14:23will give you a much different
14:25image than if that potential space
14:27was occupied by air.
14:30So let's take a look at this
14:32clip with a pleural effusion,
14:34as seen by a linear probe.
14:36First will make note of the ribs,
14:38which are superficial Bony structures
14:40that should be bright or echogenic,
14:42but also cast a shadow.
14:44The pleural effusion will displace
14:45the pleura posteriorly and in
14:47this case we lose our normal
14:49sonographic lung architecture
14:50as there is no reverberation,
14:51a line artifacts to be seen,
14:53so the pleural effusion here can
14:55be detected as an anechoic fluid
14:57collection that is below the ribs, but.
15:00In front of the lungs.
15:04And in this example we can see a
15:06pleural effusion filling in the left
15:09costophrenic angle with the linear probe.
15:11You can actually see tremendous
15:13resolution of the diaphragm,
15:15and note that it has a double line
15:18appearance as the muscle is found
15:20between the parietal pleura and
15:22the lining of the peritoneum.
15:24Due to the poor penetration
15:25available with a linear probe,
15:27we cannot reliably assess for
15:29mirror imaging artifact nor for the
15:32presence of a thoracic spine sign.