Lung Ultrasound (LUS) Part 1
July 29, 2021ID6846
To CiteDCA Citation Guide
- 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.