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IDEA Series: Ultrasound-capable, 3D-printed central line trainer

Problem: Central venous line (CVL) placement is a key skill for emergency medicine providers. Sites for central line placement include the internal jugular vein, subclavian vein, and femoral vein. Indications include, but are not limited to fluid resuscitation, medication administration, central venous pressure monitoring, pulmonary artery catheter introduction, and transvenous pacing wire placement. Procedural complications can include catheter-associated infection and arterial puncture. Success rates for CVL placement vary based on location and provider experience [1-3]. Point-of-Care Ultrasound (POCUS) increases both success rate and patient safety when used to guide CVL placement [4].

central line trainer 3d idea

Figure 1. Setup for ultrasound-capable, 3D-printed central line trainer

The Innovation

The ultrasound-capable, 3D-printed central line trainer was created to facilitate realistic training of POCUS-guided CVL placement, specifically utilizing the internal jugular vein. The trainer uses a ballistic gel insert that is ultrasound-capable and replaceable, as needed.

The Learners

The model can be utilized by anyone needing practice and training on central line placement. This includes medical and physician assistant students, residents, and fellows. It will be particularly useful with students familiar with POCUS basics.

Group Size

In our experience, 4-5 students were able to utilize the model before the wear from repeated use began to impact the imaging and structure of the model, necessitating replacement of the insert. The dilation step of the Seldinger technique can be skipped or simulated in order to prolong the life of the gel insert.

Equipment

Description of the Innovation

  • The initial head model was designed using 2 common 3D modeling software systems: Tinkercad and  Meshmixer
  • A generic head and neck model was imported into Meshmixer. Using the available tools in Meshmixer, the head was rotated to the side and the neck was manipulated to enhance the appearance of an extended neck with close attention to the sternocleidomastoid muscle and clavicle.
  • The model was then imported into Tinkercad and a section of the neck was removed, inverted, and manipulated inside of a box to create a negative (mold).

central line trainer tinkercad

Figure 2. Screenshot of head being edited in Tinkercad software

central line trainer tinkercad neck

Figure 3. Screenshot of neck mold being edited in Tinkercad software

  • The head was printed with Polylactic acid (PLA) filament in 2 sections that were then glued together with superglue. The seam was sealed and smoothed with latex caulk. The files for both the head and the mold can be found in this Google Drive folder.
  • A hole was drilled from the base of the neck through the top of the head. A second hole was drilled in the base of the model.
  • To make a suitable tray for the ballistic gel insert, a thin plate was printed and then cut to fit the shape of the neck. Finally, that piece was glued to the bottom of the model.
  • The model was painted using matte spray paint.

central line trainer spray paint

Figure 4. Use of matte spray paint to paint the model

  • The mold was printed next. Two holes were drilled on either side to allow for insertion of latex tubing.
  • The ballistic gel was heated according to the directions on the box. The gel can be colored using dye or acrylic paint. Caution should be practiced when using acrylic paint. The heated gel can foam up, increasing the possibility of injury from burn.
  • While the gel was heating, the mold was prepared. The bottom was coated with a thin layer of dish soap to assist with gel release. Two sections of latex tubing, approximately 2 feet each were inserted into the mold. Modeling clay was used to fill the gaps.
  • Once colored and thoroughly heated, the gel was poured into the mold.

central line trainer mold internal jugular vein

Figure 5. Preparation of the mold in which the heated gel will be poured

central line trainer mold pour

Figure 6. The heated, colored gel is poured into the mold

  • After curing, the latex tubes were removed. The gel neck model was then removed and placed into the accompanying space on the 3d printed trainer.
  • The latex tubing was fished back through the available holes, and filled with water. As an optional step, a 30 cc syringe was attached to one end of the thicker tube. Tube stoppers can also be printed and used in place of hemostats. Pumping the syringe plunger simulates the appearance of arterial flow on ultrasound.

Video Demonstration of Final Product

Lessons learned

We are currently investigating how best to research this model. The model is inexpensive compared to available commercial CVL trainers. We estimate the cost at approximately $80 per model in materials. This, of course, does not include the price of a 3d printer, 18v drill, or drill bit. Two comparable models available for purchase are both listed for over $1000 [5, 6]. The build time is approximately 1 week with time spent printing, glue-drying, and ballistic gel setting. The model can be used repeatedly and the insert remade many times over.

If another model were to be designed, the top of the head could be sacrificed in favor of an elongated neck section. The top of the head provides no value and consumes 3d printing filament. Furthermore, an elongated neck may be preferable for a new learner by allowing more room to practice probe and hand placement.

Theory behind the innovation

Simulation as a means of teaching has been a firmly established practice across the landscape of medical education. The model in question is high-fidelity and offers the user a realistic experience in a low-stress environment. The model is small enough to be portable and can be used with little preparation, making it an ideal tool for just-in-time training in the emergency department.

Tools that allow the learner to practice multiple steps of a skill during one exercise are invaluable for skill development, competency-based medical education and mastery learning.

Idea Series Logo debriefing

Led by series editor, Dr. Mary Haas, the IDEA series showcases examples of what programs worldwide have been doing to make residency conference more entertaining, engaging, and most of all, educational for residents. Read more publications from the series.

References

  1. McGee DC, Gould MK. Preventing complications of central venous catheterization. New England Journal of Medicine. 2003;348(12):1123-1133. doi:10.1056/nejmra011883
  2. Schummer W, Köditz JA, Schelenz C, Reinhart K, Sakka SG. Pre-procedure ultrasound increases the success and safety of central venous catheterization. British Journal of Anaesthesia. 2014;113(1):122-129. doi:10.1093/bja/aeu049
  3. E Portalatin M, Fakhoury E, Brancato R, et al. Factors contributing to unsuccessful central line placement in the neck and chest. Surgery: Current Trends and Innovations. 2019;3(2):1-5. doi:10.24966/scti-7284/100015
  4. Saugel B, Scheeren TWL, Teboul J-L. Ultrasound-guided central venous catheter placement: A Structured Review and recommendations for Clinical Practice – Critical Care. BioMed Central. Published August 28, 2017. Accessed September 21, 2022.
  5. Life/form Central Venous Cannulation Simulator. Universal Medical. . Accessed September 21, 2022.
  6. Blue Phantom internal jugular Central Line Ultrasound manikin. 3012495 – Blue Phantom – BPP-060 – Ultrasound Trainers. Accessed September 21, 2022.
By |2022-09-26T01:52:50-07:00Sep 30, 2022|IDEA series, Medical Education, Ultrasound|
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SAEM Clinical Images Series: Breast Swelling

A female in her 50s with a past medical history of coronary artery disease, pacemaker placement, hypertension, and ESRD presented to the emergency department with the chief complaint of missed dialysis, breast engorgement, and an increase in vascularity in her chest and abdomen. The patient reported an increase in breast swelling and increased vascularity in her belly over the past three months. Additionally, she woke up short of breath on the morning of presentation and reported dyspnea at rest. She denied chest pain, diaphoresis, breast pain, fever, rash, trauma to the breasts, or drainage.

 

Vitals: T 36.9°C; HR 105; BP 109/74; RR 20; O2 sat 97% on nasal canula @ 3L

Neck: JVD

Lungs: Bilateral crackles

Chest and abdomen: Increased vascularity

Breast: Bilateral breast swelling and redness

Lower extremity: Bilateral pitting edema and varicose veins

Basic metabolic panel (BMP): K 6.9; Cr 9.53

Brain natriuretic peptide (BNP): >35,000

Troponin I: 0.1

DDX: Inflammatory carcinoma, mastitis, superior vena cava syndrome, portal hypertension, pulmonary hypertension, pulmonary embolism.

Superior vena cava (SVC) syndrome results from any condition that leads to obstruction of blood flow through the SVC. Our case was caused by complete occlusion from a thrombus and the patient presented with bilateral breast swelling, skin changes (peau d’orange), and an increase in vascularity in the abdomen and chest (caput medusa). Breast tissue largely drains into the axillary veins, and more proximally into the subclavian veins. Due to occlusion of the SVC, a complete backup of venous flow occurs, resulting in all of the noted collateral hypervascularity.  Often SVC occlusion is caused by malignancy obstructing the superior vena cava or invading the vein.

The CTA demonstrates occlusion of the superior vena cava. There are multiple varices in the chest wall and the imaged upper abdominal wall. There is also diffuse subcutaneous edema with diffuse soft tissue swelling and skin thickening of the bilateral breasts.

Take-Home Points

  • Consider superior vena cava occlusion in patients undergoing hemodialysis who present with the above physical exam findings.
  • Consider occult malignancy as the source or cause of thrombosis.
  • Be sure to fully expose your patient when appropriate and keep your differential broad.

  • Corduff N, Rozen WM, Taylor GI. The superficial venous drainage of the breast: a clinical study and implications for breast reduction surgery. J Plast Reconstr Aesthet Surg. 2010 May;63(5):809-13. doi: 10.1016/j.bjps.2009.02.055. Epub 2009 Apr 3. PMID: 19345164.
  • Friedman T, Quencer KB, Kishore SA, Winokur RS, Madoff DC. Malignant Venous Obstruction: Superior Vena Cava Syndrome and Beyond. Semin Intervent Radiol. 2017 Dec;34(4):398-408. doi: 10.1055/s-0037-1608863. Epub 2017 Dec 14. PMID: 29249864; PMCID: PMC5730434.

Copyright

Images and cases from the Society of Academic Emergency Medicine (SAEM) Clinical Images Exhibit at the 2021 SAEM Annual Meeting | Copyrighted by SAEM 2021 – all rights reserved. View other cases from this Clinical Image Series on ALiEM.

By |2022-08-28T22:47:29-07:00Aug 29, 2022|Heme-Oncology, Radiology, SAEM Clinical Images|
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SAEM Clinical Images Series: Found Down

found down

A 67-year-old caucasian male experiencing homelessness was “found down” in a parking lot. EMS reported that he had a GCS of 6 with a systolic blood pressure in the 80’s, finger stick glucose of 100, and no response to intranasal naloxone. He was intubated in the field and arrived to the emergency department unresponsive with a BP of 95/60, HR 125, T 38°C, and O2 Sat 100%. Hemodynamic stabilization was achieved with central venous access, and laboratory and imaging studies for the evaluation of altered mental status ensued.

 

General: Disheveled male

HEENT: Normocephalic; PERRLA 3-2 mm; dried blood in nares

Skin: Warm; dry; no visible signs of trauma

Cardiovascular: Tachycardic with no murmurs, rubs, or gallops

Respiratory: Bilateral breath sounds on ventilator; diffuse rales

Gastrointestinal: Soft; non-distended; bowel sounds present

Musculoskeletal: No deformities

Neurologic: Unresponsive; GCS 3

COVID-19 rapid antigen: Detected

Complete Blood Count (CBC): WBC 17 k; Hemoglobin 15; Platelets 185

Comprehensive Metabolic Panel (CMP): Na 133; K 4.6; Cl 91; CO2 21; BUN 18; Cr 2.2; Ca 8.4; Alb 2.1; Tbili 0.4; Alk phos 112; AST 242; ALT 68

ABG on FiO2 100%: 6.99/>95/405/23/100%

Lactate: 16.4

Ammonia: 90

CK total: 716

Trop I HS: 809

PT: 14

INR: 1.05

PTT: 45

Urinalysis: Unremarkable

EtOH, Acetaminophen, Salicylate: Negative

UDS: Negative

Chest Radiograph: Diffuse ground-glass opacities

Air embolism to the right ventricle and pulmonary artery. As little as 20 mL or less of air rapidly infused may cause obstruction, ischemia, and hemodynamic collapse.

Risk factors include central venous catheterization, lung trauma, ventilator usage, hemodialysis, surgery (esp. coronary, neurosurgery), childbirth, and scuba diving barotrauma.

Take-Home Points

  • In the appropriate clinical scenario, especially those involving respiratory, cardiac, and neurologic findings where invasive procedures were utilized, the diagnosis of venous air embolism should be entertained.
  • Immediate management of an air embolism involves administration of 100% oxygen by nonrebreather mask (NRM) or ventilator and placement of the patient in the left lateral decubitus (Durant maneuver) and Trendelenburg positions. Hyperbaric oxygen therapy has also been used if there is no clinical improvement.
  • The purpose of the Durant maneuver and Trendelenburg position is to trap air along the lateral right ventricular wall, preventing right ventricular outflow obstruction and embolization into the pulmonary circulation.

  • Gordy S, Rowell S. Vascular air embolism. International Journal of Critical Illness and Injury Science. 2013;3(1):73. doi:10.4103/2229-5151.109428 Malik N, Claus PL, Illman JE, Kligerman SJ, Moynagh MR, Levin DL, Woodrum DA, Arani A, Arunachalam SP, Araoz PA. Air embolism: diagnosis and management. Future Cardiol. 2017 Jul;13(4):365-378. doi: 10.2217/fca-2017-0015. Epub 2017 Jun 23. PMID: 28644058.

Copyright

Images and cases from the Society of Academic Emergency Medicine (SAEM) Clinical Images Exhibit at the 2021 SAEM Annual Meeting | Copyrighted by SAEM 2021 – all rights reserved. View other cases from this Clinical Image Series on ALiEM.

By |2022-07-19T14:49:13-07:00Aug 8, 2022|Cardiovascular, Critical Care/ Resus, Pulmonary, Radiology, SAEM Clinical Images|
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Trick of the Trade: Getting the last bit of ultrasound gel from the bottle

It’s a busy shift and you need to perform a bedside ultrasound on a patient’s belly to rule out cholecystitis, when you realize that the ultrasound gel bottle is nearly empty. No matter how many times you vigorously shake the bottle, it’s impossible to get the viscous gel out. In a pinch, you could use hand sanitizer, sterile lubricant, or even water as a substitute for gel. Or you could run to the storage room on the other side of the busy department to grab a new bottle. Or…

Trick of the Trade

Use centrifugal force to move the gel to the top of the bottle!

trick ultrasound bottle gel out

  • Turn the bottle upside down so the cap is facing the ground.
  • Place the bottle into a (fresh) patient’s sock or transducer cover. Alternatively, you can use a plastic bag or ortho tubular stockinette.
  • Firmly holding the bag, and spin the bag for a few seconds in a circular motion, almost like you were throwing a grappling hook.
  • The centrifugal motion will generate an outward force pushing all of the viscous gel to the bottle cap!
  • Once you’ve used the gel, store the bottle cap-side down so you don’t have to do this again.

This trick is useful in a pinch, because it makes use of the entire gel bottle and promotes an eco-friendly use of ED resources.

Tip: Just don’t let go while you swing, lest you turn that patient with the belly pain into a trauma activation from a bottle to the face.

Interest in other tricks?

Read more articles in the Tricks of the Trade series.

By |2022-07-25T11:26:09-07:00Jul 27, 2022|Tricks of the Trade, Ultrasound|
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Trick of the Trade: Don’t fight the ultrasound cord for peripheral IV access

ultrasound POCUS peripheral iv trick

Ultrasound-guided IVs require hand-eye coordination and fine movements of probe in Goldilocks fashion. Apply too much pressure, and the vein in question is compressed. Slide a little to the right, and now it’s out of the window. Something that practitioners don’t think about is the tension from the cord. If left to its own devices, the cord will tug on the probe, making the probe harder to steer and handle, especially for those tiny veins.

Trick of the Trade: Reduce cord tension

Have the patient grasp the cord!

This makes them an active participant. Usually, if they are awake and good-humored, tell them “audience participation is required.” Doing so will give you enough slack to effectively visualize and troubleshoot the ultrasound-guided IV.

ultrasound cord trick POCUS

 

What if the patient is intubated, or altered, doesn’t quite grasp, or can’t handle the situation?

Tape the cord to the gurney side rail. Use a 2×2 gauze as a buffer between the tape and the rail so the tape doesn’t damage the cord itself.

ultrasound cord POCUS tape

 

Want to learn other tricks?

Read other articles in the Tricks of the Trade series.

By |2022-05-31T00:37:48-07:00Jun 3, 2022|Tricks of the Trade, Ultrasound|
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PEM POCUS Series: Pediatric Appendicitis

PEM POCUS pediatric appendicitis

Read this tutorial on the use of point of care ultrasonography (POCUS) for pediatric appendicitis. Then test your skills on the ALiEMU course page to receive your PEM POCUS badge worth 2 hours of ALiEMU course credit.

Module Goals

  1. Describe the indications for performing point-of-care ultrasound (POCUS) for appendicitis
  2. Describe the technique for performing POCUS for appendicitis
  3. Recognize anatomical landmarks for POCUS for appendicitis
  4. Interpret signs of appendicitis on POCUS
  5. List the limitations of POCUS for appendicitis

Case Introduction: Child with thigh pain

Mason is an 8-year-old boy who comes to the emergency department for abdominal pain. The pain has been present for 12 hours, started near his belly button, and now has migrated to the lower right side. He describes it as constant and worsening. His parents are concerned because he had a fever to 101F since 2 hours prior to arrival and had 2 episodes of emesis. They deny diarrhea or bloody stool. They gave acetaminophen for fever 2 hours prior to arrival. He has not wanted to eat anything today.

Vital SignFinding
Temperature37.5 C
Heart Rate120 bpm
Blood Pressure106/58
Respiratory Rate18
Oxygen Saturation (room air)100%

He is uncomfortable appearing, and abdominal examination is soft and tender to palpation periumbilically and in the right lower quadrant. The patient also endorses pain with jumping. Given his history and abdominal pain and tenderness on examination, you are concerned for appendicitis. You place a surgical consult and while waiting, decide to perform a point of care ultrasound (POCUS) examination of the appendix.

Why should I perform the appendix POCUS?

  • Lack of radiation exposure, lower cost, less patient preparation
  • Superior sensitivity and specificity for diagnosing pediatric appendicitis
  • POCUS can save ≥2 hours compared to radiology-performed ultrasound
  • Can help prioritize radiology studies or expedite surgical consult

Limitations of the appendix POCUS

  • Operator dependency and variability in sensitivity
  • Difficult visualization of appendix in retrocecal or aberrant locations
  • Limitation of visualization dependent on patient body habitus
  • Sometimes the appendix cannot be visualized (normal or otherwise)

What are the general principles behind the technique?

  • You are using POCUS to look for an abnormal appendix and/or secondary signs of appendicitis.
  • It is important to recognize anatomical landmarks.
  • The patient should be placed in a supine position.
  • Using the linear transducer is appropriate for most pediatric patients, but if the patient has a larger body habitus, the curvilinear transducer may be used (figure 1).

Figure 1. Linear (left) and curvilinear (right) transducer for ultrasonography

  • Place the probe over the point of maximal tenderness in the abdominal RLQ.
  • Slowly apply increasing gentle pressure (i.e., “graded compression”) to move bowel gas out of the way until able to identify the important landmarks:
    • Iliopsoas muscle
    • Rectus muscle
    • Iliac vessels
  • You can also lightly “jiggle” the probe as shown below to help mitigate bowel gas artifact.
Video 1: External view of the RLQ abdomen with the application of graded compression, such that bowel gas is moved out of the way to obtain a view of the desired anatomical structures
Video 2: POCUS clip of the RLQ abdomen demonstrating the application of graded compression and “jiggling” the probe

1. Start in the RLQ Abdomen

appendicitis pediatric abdomen

Figure 2: Starting in the RLQ abdomen and inferior to the iliac crest, visualize the iliacus muscle and pelvis with no bowel in view. The first bowel you visualize should be the cecum as you scan in a cephalad direction.

Video 3: POCUS clip of the RLQ abdomen showing the cecum coming into view

2. Move the probe more cephalad

Figure 3: Moving the probe in a progressively more cephalad direction, attempt to visualize the iliopsoas, abdominis rectus muscles, and iliac vessels. These anatomic landmarks to help identify the appendix (marked as *) with the CURVILINEAR probe. The appendix may appear in the triangle made by these structures as a blind-ended pouch that does not have peristalsis.[Image courtesy of Dr. Sally Graglia]

Figure 4: Anatomic landmarks to help identify the appendix with the LINEAR probe [image courtesy of Dr. Sally Graglia]

3. Identify the tubular appendix structure

Figure 5: Visualize the appendix in the longitudinal view. In this plane, visualize the end of the pouch to confirm it is a blind-ending tubular structure with no peristalsis that initiates at the cecum. [Image courtesy of Dr. Margaret Martore-Lin]

Figure 6: Visualize the appendix in the transverse view. In this plane, measure the diameter of the appendix from the outer wall to outer wall. An abnormal appendix is >6 mm and non-compressible. [Image courtesy of Dr. Margaret Martore-Lin]

A technique described in Sivitz et al. [1] involves placing the ultrasound probe in a transverse position and starting at the level of the umbilicus. Using compression, move the probe along POCUS-identified anatomical landmarks.

  1. Move laterally to identify the lateral border of the ascending colon.
  2. Move down the lateral border to the end of the cecum.
  3. Move medially across the psoas and iliac vessels.
  4. Move down the border of the cecum.
  5. Move up the border of the cecum.
  6. Rotate the probe into a sagittal position and identify the end of the cecum in the long axis and move medially across the psoas.

Figure 7: The Sivitz et al technique for identifying the appendix on POCUS

Sometimes there is a suboptimal view of the anatomy landmarks on POCUS. The following are troubleshooting tips that may be useful:

  1. Perform graded compression to displace bowel gas that may be obscuring your view.
  2. Apply posterior manual compression to the right lower back in an anteromedial direction of the ultrasound probe. This is usually done with the POCUS operator’s opposite hand (Figure 7).
pediatric appendicitis POCUS posterior compression

Figure 8: Posterior manual compression technique to assist with POCUS visualization of the appendix

  1. Position the patient in the left lateral decubitus position to help visualization of a retrocecal appendix.
  2. Administer analgesia before starting and distraction (videos, smartphone) during the exam to reduce patient movement.
  3. Position the patient with knees flexed, which can relax the abdominal wall musculature.
  4. Use a high-frequency linear probe to improve the resolution of regional structures and anatomy (although a curvilinear probe should be used if increased depth is required for a larger body habitus).

pediatric normal appendix POCUS

Figure 9: Normal appearing appendix on POCUS [Image courtesy of Dr. Will Shyy]

The appendix is a tubular, blind ending structure, which initiates from the cecum and has no peristalsis. A normal appendix is less than 6 mm, is compressible, and has little to no blood flow in the wall of the appendix.

Ultrasonography Signs of Acute Appendicitis

  1. Enlarged appendix >6 mm (Figure 10)
  2. Noncompressible (although can be compressible if perforated appendix)
pediatric appendicitis POCUS

Figure 10: Enlarged appendix measuring 1.36 cm (>6 mm is abnormal) with hyperechoic fat concerning for inflammation [Image courtesy of Dr. Will Shyy]

Secondary Ultrasonographic Signs of Appendicitis

  1. Peri-appendiceal free fluid
  2. Hyperechoic mesenteric fat
  3. Appendicolith
  4. Increased blood flow (“ring of fire”) surrounding the appendix on Doppler color mode
  5. Complex right lower quadrant mass, suggestive of ruptured appendix
Secondary Sign of AppendicitisUltrasound View
Peri-appendiceal free fluid secondary to inflammatory edema or perforation. You may also see an abscess that appears as a complex mass and is a sign of a ruptured appendicitis.
pediatric appendicitis POCUS

Figure 11. Appendix with peri-appendiceal fluid collection [image by Dr. Will Shyy]

Hyperechoic mesenteric fat as a sign of inflammation visible (also see figure 10)
pediatric appendicitis POCUS

Figure 12: Appendicolith (A) within the lumen of the appendix in addition to hyperechoic fat (arrows) concerning for inflammation [image courtesy of Dr. Will Shyy]

pediatric appendicitis POCUS

Figure 13. Appendicitis with hyperechoic fat suggestive of inflammation

Video 4: POCUS clip of a pediatric patient with appendicitis. Notice the hyperechoic fat surrounding the appendix, visible in transverse as a tubular structure at the bottom of the screen. [Video courtesy of Dr. Ashkon Shaahinfar]
Appendicolith: A hyperechoic structure within the appendiceal lumen has a dark, clean acoustic shadow, similar to the appearance of a gallstone.Figure 12 above
“Ring of Fire”, or increased blood flow surrounding the appendix: Using the color Doppler mode on the ultrasound, the appendix in transverse view will appear hyperemic, suggestive of appendiceal inflammation.
pediatric appendicitis POCUS ring of fire

Figure 14. “Ring of fire” appendiceal hyperemia using the color Doppler mode on ultrasound [image by Dr. Will Shyy]

pediatric appendicitis POCUS

Figure 15. Cross-sectional image of appendicitis with hyperemia

Complex RLQ mass: A ruptured appendicitis may appear as a complex right lower quadrant mass, where the appendix itself may be difficult to visualize. It can be difficult to distinguish this from other pathologies, such as intussusception or ruptured Meckel’s diverticulitis.

Video 5: POCUS clip of ruptured appendicitis, appearing as a complex right lower quadrant mass [Video courtesy of Dr. Ashkon Shaahinfar]​
pediatric appendicitis POCUS

Figure 16. Close-up POCUS view of the appendix from video 5 [image courtesy of Dr. Ashkon Shaahinfar]

Benefits of Appendix POCUS

An appendix POCUS benefits children with suspected appendicitis, as demonstrated in the literature:

  1. Decrease in CT scan utilization [2-4]
  2. Decrease in lengths of Emergency Department stay [3, 4]
    • Tsung et al, Critical Ultrasound J, 2014 [4]: There was a shorter ED length of stay (LOS) with mean LOS reported for the following modalities:
      • POCUS: 154 minutes
      • Radiology US: 288 minutes
      • CT scan: 487 minutes

Equivocal Findings on POCUS

  • Oftentimes an appendix cannot be visualized on both POCUS and radiology-performed ultrasound, especially in patients with higher BMI [5].
  • In situations with an experienced sonographer, where the appendix is not visualized and there are no secondary signs on radiology-performed ultrasound, patients are at low risk for appendicitis with a negative predictive value in the 80’s% [6, 7].
  • Serial ultrasound has been recommended in equivocal ultrasound cases as ultrasound’s sensitivity increases with length of pain [8].
  • For POCUS for appendicitis, non-visualized appendix studies continue to represent a diagnostic dilemma [1, 9]. For more on this topic, read a deeper-dive on this topic in a PEM Pearls post.

The studies below examine the sensitivity and specificity of appendix POCUS for identification of appendicitis in patients of any age with the exception of Sivitz et al., which specifically studied pediatric patients only. (Table 1).

StudyNPatient AgeSensitivitySpecificityComments
Sivitz et al., 2014 [1]264Pediatric
85%
(95% CI: 75-95%)
93%
(95% CI: 85-100%)
In this study, pediatric emergency medicine ultrasonographers were able to visualize the appendix in 71% of patients. Gold standard was either pathologic review, telephone follow-up to 6 months, or electronic medical records review up to 1 year, if unable to reach the patient.
Fields et al., 2017 [9]6,636Pediatric89%

(95% CI: 47–99%)

97%

(95% CI: 84–99%)

These test characteristics were derived from a pediatric-only sub-analysis of a larger systematic review and meta‐analysis study across all ages to identify the test characteristics of the appendix POCUS, performed by emergency physicians. The overall test characteristics across all ages was 91%
(95% CI: 83–96%) sensitivity and 97% (95% CI: 91–99%) specificity.
Chen et al., 2000 [10]317Any age85%98%After a 5-day intensive training course in abdominal ultrasound, emergency physician-performed POCUS was compared to surgeon’s clinical impression in diagnosing acute appendicitis, as confirmed by pathological reports. Ultrasonography performed better than surgeon clinical impression and resulted in a high sensitivity and specificity.
Fox et al., 2008 [11]132Any age65%

(95% CI: 52-76%)

90%

(95% CI: 81-95)

Emergency physicians performed a 5-minute appendix POCUS for patients with a clinical suspicion for acute appendicitis. The gold standard confirmation was either pathology specimens from appendectomy surgery or telephone follow-up.
Table 1. Published studies evaluating the sensitivity and specificity of appendix POCUS

Case Resolution

The patient has a leukocytosis with a WBC 13.3 x 109/L and an absolute neutrophils count (ANC) 10.3 x 109/L but otherwise unremarkable labs. His final Pediatric Appendicitis Score (PAS) is 8. You decide to incorporate appendix POCUS to your evaluation. You place a linear, high-frequency transducer on the patient and visualize his appendix. You observe the following:

Video 6. An appendix POCUS, demonstrating appendicitis.

Figure 17: Enlarged appendix measuring 1.36 cm in diameter (>6 mm is abnormal)

Normal anatomy for comparison:

Video 7: Appendix POCUS clip showing normal anatomy including the psoas muscle, vasculature, and a small, compressible appendix.

ED Course

The patient receives IV morphine and is made NPO. The general surgeon on call is consulted and agrees with the plan for an appendectomy.

Learn More…

References

  1. Sivitz AB, Cohen SG, Tejani C. Evaluation of acute appendicitis by pediatric emergency physician sonography. Ann Emerg Med. 2014;64(4):358-364.e4. doi:10.1016/j.annemergmed.2014.03.028. PMID: 24882665
  2. Doniger SJ, Kornblith A. Point-of-Care Ultrasound Integrated Into a Staged Diagnostic Algorithm for Pediatric Appendicitis. Pediatr Emerg Care. 2018;34(2):109-115. doi:10.1097/PEC.0000000000000773. PMID: 27299296
  3. Elikashvili I, Tay ET, Tsung JW. The effect of point-of-care ultrasonography on emergency department length of stay and computed tomography utilization in children with suspected appendicitis. Acad Emerg Med. 2014;21(2):163-170. doi:10.1111/acem.12319. PMID: 24673672
  4. Tsung JW, Tay ET, Elikashvili I.  The effect of point-of-care ultrasonography on emergency department length of stay and CT utilization in children with suspected appendicitis. rit Ultrasound J 6, A32 (2014). https://doi.org/10.1186/2036-7902-6-S1-A32
  5. Abo A, Shannon M, Taylor G, Bachur R. The influence of body mass index on the accuracy of ultrasound and computed tomography in diagnosing appendicitis in children. Pediatr Emerg Care. 2011;27(8):731-736. doi:10.1097/PEC.0b013e318226c8b0. PMID: 21811194
  6. Cohen B, Bowling J, Midulla P, et al. The non-diagnostic ultrasound in appendicitis: is a non-visualized appendix the same as a negative study?. J Pediatr Surg. 2015;50(6):923-927. doi:10.1016/j.jpedsurg.2015.03.012. PMID: 25841283
  7. Ly DL, Khalili K, Gray S, Atri M, Hanbidge A, Thipphavong S. When the Appendix Is Not Seen on Ultrasound for Right Lower Quadrant Pain: Does the Interpretation of Emergency Department Physicians Correlate With Diagnostic Performance?. Ultrasound Q. 2016;32(3):290-295. doi:10.1097/RUQ.0000000000000214. PMID: 27082937
  8. Bachur RG, Dayan PS, Bajaj L, et al. The effect of abdominal pain duration on the accuracy of diagnostic imaging for pediatric appendicitis. Ann Emerg Med. 2012;60(5):582-590.e3. doi:10.1016/j.annemergmed.2012.05.034. PMID: 22841176
  9. Matthew Fields J, Davis J, Alsup C, et al. Accuracy of Point-of-care Ultrasonography for Diagnosing Acute Appendicitis: A Systematic Review and Meta-analysis. Acad Emerg Med. 2017;24(9):1124-1136. doi:10.1111/acem.13212. PMID: 2846445
  10. Chen SC, Wang HP, Hsu HY, Huang PM, Lin FY. Accuracy of ED sonography in the diagnosis of acute appendicitis. Am J Emerg Med. 2000;18(4):449-452. doi:10.1053/ajem.2000.7343. PMID: 10919537
  11. Fox JC, Solley M, Anderson CL, Zlidenny A, Lahham S, Maasumi K. Prospective evaluation of emergency physician performed bedside ultrasound to detect acute appendicitis. Eur J Emerg Med. 2008;15(2):80-85. doi:10.1097/MEJ.0b013e328270361a. PMID: 18446069

Additional Reading

  1. Benabbas R, Hanna M, Shah J, Sinert R. Diagnostic Accuracy of History, Physical Examination, Laboratory Tests, and Point-of-care Ultrasound for Pediatric Acute Appendicitis in the Emergency Department: A Systematic Review and Meta-analysis. Acad Emerg Med. 2017;24(5):523-551. doi:10.1111/acem.13181. PMID: 28214369
  2. Estey A, Poonai N, Lim R. Appendix not seen: the predictive value of secondary inflammatory sonographic signs. Pediatr Emerg Care. 2013;29(4):435-439. doi:10.1097/PEC.0b013e318289e8d5. PMID: 23528502Lin-Martore M, Kornblith AE. Diagnostic Applications of Point-of-Care Ultrasound in Pediatric Emergency Medicine. Emerg Med Clin North Am. 2021 Aug;39(3):509-527. doi: 10.1016/j.emc.2021.04.005. PMID: 34215400
  3. Vasavada P. Ultrasound evaluation of acute abdominal emergencies in infants and children. Radiol Clin North Am. 2004;42(2):445-456. doi:10.1016/j.rcl.2004.01.003. PMID: 15136027
By |2024-02-29T02:28:42-08:00May 31, 2022|Pediatrics, PEM POCUS, Ultrasound|
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PEM POCUS Series: Confirmation of Endotracheal Tube Placement

PEM POCUS endotracheal tube confirmation badge

Read this tutorial on the use of point of care ultrasonography (POCUS) for confirmation of endotracheal tube (ETT) placement in pediatric patients. Then test your skills on the ALiEMU course page to receive your PEM POCUS badge worth 2 hours of ALiEMU course credit.

Module Goals

  1. List indications for performing airway/lung POCUS to confirm ETT placement
  2. Describe the technique of performing airway and focused lung POCUS
  3. Distinguish between normal and abnormal airway and lung POCUS findings
  4. Distinguish between tracheal, endobronchial, and esophageal placement of ETT
  5. List the limitations of airway and lung POCUS

Case Introduction: The Postictal Toddler

Joey is a 2-year-old male with a history of epilepsy who presents to a community hospital emergency department with generalized tonic-clonic seizures of more than 45 minutes duration. After receiving 2 doses of IV midazolam, he stopped seizing. He has very shallow breathing and oxygen saturations as low as 90 percent on 2 liters of supplemental oxygen via nasal cannula. The pediatric transport team arrives to transport him to another hospital for admission and note that he is somnolent with poor respiratory effort. His current vital signs:

Vital SignFinding
Temperature37.0 C
Heart Rate115 bpm
Blood Pressure85/65
Respiratory Rate12
Oxygen Saturation (room air)92% on 2 L via nasal cannula

An end tidal carbon dioxide (ETCO2) monitor shows a ETCO2 level in the high 70s mmHg. The decision is made to intubate the patient given disordered breathing, hypercapnia, and hypoxia following medical management of seizures. The transport team would like to use POCUS to evaluate ETT placement at the outside hospital and during transport.

For simplicity, this module will focus on 3 modes of using POCUS for ETT confirmation. Collectively, these techniques can help improve evaluation.

There are many benefits of using POCUS to confirm ETT placement, such as in the following examples:

  • When compared to auscultation, POCUS ETT can be done in a loud environment where auscultation may be challenging (i.e., as may occur in transport or on scene).
  • When compared to radiography, POCUS ETT can be done rapidly at the bedside when chest radiography may be delayed or unavailable (i.e., in transport or during chest compressions).
  • When compared to capnography, POCUS ETT is helpful in scenarios of low pulmonary blood flow as in cardiac arrest or with poor tissue perfusion when capnography may be less reliable. Also POCUS can distinguish between tracheal and endobronchial ETT placement, whereas capnography cannot.
  • Unlike auscultation and capnography, POCUS ETT can confirm placement in real time, even before ventilating the patient, unlike auscultation and capnography to work.
  • POCUS ETT should typically be used as an adjunct to other methods of confirmation or in resource-limited settings, if other methods are not available.

Just as all methods of confirming ETT placement have their limitations, so does POCUS. This will be discussed in greater detail later in the module.

There are many factors to consider in the performance of ETT POCUS:

FactorOptions
Probe selectionLinear or curvilinear
Location on the anterior neckSuprasternal notch, cricoid, or thyroid cartilage
Probe orientationLongitudinal or transverse plane
TimingDynamic (while intubating) or static (for confirmation)
Evaluation techniqueDirect (visualize the ETT) or indirect (visualize lung movement0

Probe Selection

Two types of probes will be needed for POCUS ETT confirmation.

  • Use a linear probe to visualize the superficial airway and lung structures. The linear probe uses high frequency sound waves to create high resolution images of superficial structures such as the trachea and pleura.
  • Use a curvilinear probe to visualize deeper structures, such as the diaphragm. The curvilinear probe uses lower frequency sound waves to create higher resolution images of deeper structures.
POCUS ultrasound probes

Figure 1: Linear probe (left) and curvilinear probe (right)

Timing of Image Acquisition

If time permits, pre-scan the patient’s neck to locate the trachea. Adjust the gain and depth accordingly to visualize the trachea clearly in the middle of the screen.

pocus neck trachea endotracheal tube ett

Figure 2: Positioning and ultrasound images of the anterior neck anatomy for ETT placement confirmation. Left: Transverse orientation of the linear probe just above the suprasternal notch. Center: Corresponding pictorial display of the trachea and surrounding structures. Note that below the trachea is a dirty shadow artifact, resulting from the air-mucosa interface. Right: Corresponding ultrasound image of the thyroid lobes flanking the empty trachea, with the ovoid esophagus seen posterolaterally (ultrasound image by Jade Sequin).

1. Static Assessment

  • We recommend using the static assessment (i.e., after the patient is intubated), rather than dynamic (i.e., watching the ETT enter the trachea in real time) which is technically more challenging.
  • Positioning: Stand at the patient’s waist, facing the patient’s head, with the probe marker pointing towards the patient’s right (transverse plane) to confirm ETT placement in the neck. Place the linear transducer midline on the anterior neck, slightly above the suprasternal notch (figure 2, left). The orientation of the image on the screen corresponds to the probe direction. This orientation is helpful for procedural POCUS and conceptually allows for easier redirection.
  • Identify the trachea: The trachea is visible in the midline as a semicircular structure with a hyperechoic bright line (upside down U) and shadows distally (figure 2, center). Shadows are reverberation artifact from the air in the trachea (often called “dirty shadows,” or referred to as the air-mucosa interface). The thyroid overlies the trachea as a homogenous structure with the lobes extending bilaterally.
  • Identify the esophagus: The esophagus is generally posterolateral and to the left of the trachea. The esophagus is seen as a collapsed round or oval shaped structure with concentric layers, without air in it (figure 2, right).
    • Anatomy variability: A pediatric study noted that the esophagus can be seen in variable locations in relation to the cricoid ring and trachea. It was partially to the patient’s left (62%), completely to the left (20%), behind the cricoid ring (16%), and partially to the right (2%) [1].

When the ETT is placed correctly in the trachea, you should still see only a SINGLE air-mucosa interface, similar to an empty trachea. An ETT properly positioned in the trachea will have a similar ultrasonographic appearance with one air-mucosal interface as the air-filled tube will be in the trachea and the esophagus will be decompressed without air (figure 2, right).

2. Dynamic Assessment

Dynamic assessment involves watching the ETT pass into the trachea in real-time. In this technique, you will see a brief disturbance within the trachea termed the “snowstorm” which is a subtle finding (Video 1). A dynamic assessment is made more challenging with the multiple tasks and personnel at the bedside during intubation.

Video 1: Dynamic assessment of ETT placement confirmation using a linear probe in the transverse orientation on the anterior neck . With the probe marker to the patient’s right, the trachea is often on the left of the screen in relationship to the esophagus, as in this video. As the ETT enters the trachea, there is a slight disruption termed a “snowstorm” noted in this dynamic view. Video credit: Jade Sequin

Erroneous Esophageal Intubation

If the ETT is placed incorrectly in the esophagus, there will be TWO air-mucosa interfaces with reverberation artifact and posterior shadowing. This has been called the “double trachea sign” or “double tract sign” (figure 3, left). Contrast this to normal anatomy with an empty esophagus (figure 3, right).

Figure 3. Left: Double tract or double trachea sign on ultrasound, visualized when the ETT is placed incorrectly in the esophagus. Note the esophagus appears curved with dirty shadow artifact like the trachea. Right: Normal collapsed esophagus. Images credit: Jade Sequin.

Video 2: Esophageal intubation seen on ultrasound. Note the ETT entering the esophagus, generating the “double tract” or “double trachea” sign. Video used with permission by authors of [2].
Video 3: “Double tract” or “double trachea” sign and esophageal de-intubation. The video starts with the ETT in the esophagus, but then is removed. Video used with permission by authors of [2].

This indirect visualization method uses ultrasound to identify bilateral lung sliding as a means to confirm ETT placement, because this implies that both lungs are ventilated. This method is often used in conjunction with and after direct confirmation using POCUS, seeing the ETT in the trachea.

  • If the ETT is in the right main stem bronchus, ONLY the right lung will have sliding.

Ultrasound Probe Placement

Place the linear transducer on the superior, most-anterior chest wall in the mid clavicular line over the 3rd-5th intercostal space. Ensure that the probe marker is towards the head. Scan both lungs (Figures 4).

pediatric lung sliding positioning

Figure 4. Positioning of the linear probe on the patient’s anterior chest wall to check for lung sliding

Normal Lung Findings on POCUS

ultrasound lung sliding landmarks

Figure 5. Ultrasound of a normal lung: Just deep to the chest wall and ribs, the pleural line of the lung slides horizontally to and fro with each breath.This line is the first hyperechoic line deep to the rib and is the place to look for lung sliding.

Alveoli filled with air have the ARTIFACTS that are the hallmark of airway POCUS.

  • A lines (figure 6): Hyperechoic lines that are parallel to the pleural line (typically horizontal) that are caused by reverberations between the pleura and transducer. They are equidistant from the chest wall. A lines are seen with normal aerated lungs along with lung sliding
  • Z lines or comet tails: Perpendicular lines to the pleura (often appear vertical as the pleura is typically visualized as horizontal) that arise from the pleura. These lines typically do not go to the bottom of the screen.
  • Lung sliding (figure 8): Shimmering artifact of the parietal and visceral pleura sliding against each other. Lung sliding indicates that the lung visualized under the probe is filled with air and ventilated (video 4).

Figure 6. Normal lung with A lines – The most superficial hyperechoic line below the chest wall is the pleural line. The subsequent hyperechoic lines parallel and deep to the pleural line are A lines. A lines are always normal findings.

Video 4: Normal lung ultrasound: Most superficial are the chest wall tissue and 2 ribs (the circular anechoic structures). The hyperechoic line just deep to the ribs is the pleural line. Lung sliding is the subtle movement at the pleural line, referred to as “ants marching.” The hyperechoic lines horizontal and parallel to the pleural line are A lines, and the thin vertical lines are Z lines, or comet tails.

B Lines

In contrast to A lines, B lines may be visualized in patients with abnormal lungs. B lines are hyperechoic lines (typically vertical) that arise at the pleural line and go all the way to the bottom of the screen (at least 4-8 cm depth with some experts recommending to 16 cm). This is in contrast to Z lines which do not go to the bottom of the screen. The presence of multiple B lines indicates increased fluid in the interstitium of the lungs, which can be seen in conditions such as bronchiolitis and pulmonary edema (figure 7, videos 5 and 6). Note that the presence of B lines also indicate aerated lungs.

Figure 7. Lung POCUS showing A and B lines. A lines are the hyperechoic lines parallel to the pleural line. B lines are the hyperechoic projections perpendicular to the pleural line that extends to the bottom of the screen. A lines are normal, while multiple B lines may be pathogenic.

Video 5: Lung ultrasound showing multiple hyperechoic, perpendicular B lines.
Video 6: Lung ultrasound showing lung sliding and multiple B lines. Note that this image uses a curvilinear probe.

M-Mode Setting

For additional confirmation of lung sliding, press the M mode button (motion mode) without lifting the probe to visualize motion of the sliding pleura. The M-mode view represents a small narrow slice of the ultrasound image (where the bold white vertical line appears) and runs only that portion over time.

  • Lung is aerated: Looking below the pleural line level ,you will see a grainy display, known as the “sandy beach” or “seashore” signs (figure 8). You’ll find yourself feeling very relaxed when you see this, because this indicates a successfully aerated lung.
  • Lung is NOT aerated: Looking below the pleural line level, you will see multiple horizontal bar-like, striated lines instead of the grainy, sandy beach (figure 9). This is called the “barcode” or “stratosphere” sign, and may be seen in a pneumothorax or a main-stem bronchus intubation.

Figure 8: Lung ultrasound with M-mode view in a normal, aerated lung (left), showing the grainy, “sandy beach” appearance of the lines deep to the pleural line. Contrast this to an abnormal, non-aerated lung (right), showing the horizontal “barcode” appearance of the lines deep to the pleural line.

Figure 9: Another example of a normal (left) and non-aerated (right lung) in M-mode view

Ultrasound Technique

Visualize lung sliding in both 2D (also known as B mode and is the typical ultrasound mode) and M mode on the both the left and right chest.

  • Note: If the ETT is in the right mainstem bronchus, you may still see subtle movements of the pleural line on the left due to cardiac activity. The lung sliding in this case will be asymmetric with less movement of the pleural line on the left compared to right.

Alternative Causes for Abnormal Lung Sliding After Intubation

Abnormal lung sliding on ultrasound may be worrisome for an esophageal intubation, because the lungs are not aerated with PPV breaths. However, there are other causes to consider before removing the ETT for a re-intubation attempt.

1. Pneumothorax

In order to see lung sliding, visceral and parietal pleural need to be touching. With a pneumothorax, there is air in the pleural space. The parietal pleura will still be visible, but the visceral pleura and moving interface are not seen. In the M-mode view, a “barcode sign” will be present (figure 10), highlighting the importance of evaluating both 2D (B mode) and M mode if there is any doubt about lung sliding.

Figure 10: Lung POCUS demonstrating no lung sliding (“barcode sign”) in M-mode view

Video 10: Lung POCUS of a patient with a pneumothorax, showing no lung sliding for one lung in 2D view (B mode)

2. Main stem bronchus intubation

If there is no lung sliding in just one lung (especially if it occurs on the left), this may be caused by the ETT being too deep into a mainstem bronchus. This results in non-ventilation of the contralateral lung. Be aware that since the visceral and parietal pleural are still touching (unless there is also a pneumothorax), you could see some sliding movement, as the heart still causes some movement of the lungs.

3. ETT obstruction or apnea

This results in the loss of lung sliding bilaterally.

Take Away

When you see symmetric lung sliding on both sides of the chest, the ETT is in good position in the trachea.

Ultrasound Probe Placement

Use a curvilinear probe, because it gives you deeper tissue penetration than the linear probe. This allows you to better visualize the diaphragm, which is a deeper structure.

Figure 11. Left: Using a curvilinear probe with the probe marker towards the head, position it along the mid-axillary line to identify the diaphragm. Continue sliding the probe to the lower edge of the ribcage until you see the diaphragm meeting the spine along the bottom of the ultrasound image. Right: Ideal ultrasound view of the hyperechoic diaphragm. Also seen is the liver with mixed echotexture, a hypoechoic kidney, and the hyperechoic spine.

Normal Findings on POCUS (figure 11)

  • The diaphragm is a hyperechoic line, seen curving vertically on the screen, with a solid organ (liver or spleen) caudal to that.
  • The spine appears as interrupted hyperechoic structures (vertebral bodies), extending caudally from the diaphragm at the bottom of the image. The vertebral bodies shadow as all calcified structures on ultrasound do. Normally the spine is only visualized caudal to the diaphragm, because aerated lung obscures visualizing the spine in the thorax (cephalad to the diaphragm).

Ultrasound Technique

  1. Watch the movement of the diaphragm. In a patient who is paralyzed for intubation, the diaphragm will only move with delivery of positive pressure ventilation (PPV).
    • Normal: If the ETT is in good position, with a PPV breath, the diaphragm moves caudal toward the abdomen as the lungs inflate, and upwards when the lungs deflate (video 7). In M mode, normal diaphragm movement creates a smooth wave with inspiration and expiration (video 8).
    • Esophageal intubation: The diaphragm moves in the reverse direction than is expected. With a PPV breath, the diaphragm moves cephalad, because the abdominal cavity is getting inflated.
    • Mainstem bronchus intubation: The diaphragm on the side of the main stem intubation (typically right) will show exaggerated motion toward the abdomen during PPV. The diaphragm on the contralateral side, where the lung is not properly ventilated will either not move or move paradoxically cephalad during PPV. In M-mode, there is no sinusoidal, wave pattern for the diaphragm in the non-ventilated lung (video 9)
Video 7: Ultrasound view showing diaphragmatic movement with regular breaths. The diaphragm pushes the spleen and kidneys caudal into the abdomen (to the right of the screen) with each breath.
Video 8: Ultrasound M-mode view of the diaphragm with regular breaths. Normal diaphragmatic movement is demonstrated by the hyperechoic sinusoidal line (at 12 cm depth) at the bottom of the screen.
Video 9: Ultrasound of the diaphragm in M-mode setting. The hyperechoic diaphragm does not move either in 2D (top) or M mode (bottom). This could be seen if the ETT is in the esophagus or in a mainstem bronchus, for example.

Abnormal Findings While Assessing Diaphragmatic Movement

1. Hemothorax or pleural effusion

Best seen at the costophrenic angle because fluid is dependent, a hemothorax or effusion will appear anechoic or hypoechoic. Additionally the spine can now be seen cephalad to the diaphragm, known as the “spine sign,” because air now no longer obscures the view of the spine (figure 12). A hemothorax and pleural effusion can look the same on POCUS. The clinical scenario aids in determining the potential cause of the fluid.

Figure 12. Left: Normal lung showing the spine only caudal to the hyperechoic diaphragm. Right: Hemothorax on lung POCUS. Right: Lung POCUS showing a pleural effusion, suggested by the hypoechoic fluid collection and “spine sign”.

Take Away

In a patient paralyzed for intubation and thus with no spontaneous respirations, the ETT is in good position when you see movement of the diaphragm towards the abdomen on both sides of the chest with PPV.

Lin et al. published a systematic review of bedside ultrasound for tracheal tube verification in pediatric patients. The authors proposed the following algorithm (figure 13) for confirming ETT placement.

Figure 13: Algorithm for using and interpreting POCUS to confirm ETT placement in pediatric patients. Image permission granted by author of [3].

  • Operator dependent: As with all POCUS studies, image acquisition and interpretation is operator dependent. The more you practice the concepts and techniques in this module, the more comfortable you will be in obtaining and accurately interpreting these images.
  • Challenging anatomy: It is difficult to perform airway POCUS on a small neck, with a cervical collar in place, or if there is subcutaneous emphysema (air obscures structures below).
  • Depth: Airway POCUS is not able to determine the exact depth of ETT within the trachea, but can be a good surrogate of position:
    • Visualization of the ETT cuff at the suprasternal notch using a linear probe in the transverse orientation correlated with the ETT depth on chest x-ray in 57/60 children (Cl, 86-98%) in a single center, prospective observational study [11]
    • If you are concerned about a mainstem bronchus intubation, slowly pull back on the ETT to see if the lung opposite the main stem intubation starts sliding. If the depth of the tube at the gums/teeth/lips seems appropriate and one side still does not have sliding, there may be a pneumothorax on that side.
  • False negative for ETT placement: In the rare patient with thyroid gland calcifications, there may falsely appear to be 2 shadowing structures (double tract sign), even when the ETT is correctly in the trachea. Calcifications shadow. This can be anticipated with pre-scanning the neck before intubation.
  • False positive for ETT placement: If the esophagus is structurally immediately posterior to the trachea, you wouldn’t see a “double tract” sign if the ETT is in the esophagus. But you should have other signs soon if the ETT is in the wrong place such as lack of ETCO2 and lack of breath sounds.
  • Lack of lung sliding may not always be due to pneumothorax or right mainstem ETT intubation. Other explanations include:
    • ETT obstruction
    • Apnea in a spontaneously breathing patient or no breath being delivered to a patient who is intubated.
    • Lack of sliding or “barcode” (on M-mode) should be interpreted with caution in patients who have parenchymal lung disease or pleurodesis (a procedure where the pleura is surgically or mechanically adhered to the chest wall) making the lung appear not to slide. These patients may not have pneumothorax nor a main stem intubation on the other side.

Adult Literature

In a metanalysis of 30 adult studies assessing the use of POCUS for ETT placement confirmation, the overall sensitivity was 0.98 (95% CI 0.97–0.99) and specificity was 0.96 (95% CI 0.90–0.98) [4].

Other studies have evaluated using various techniques for POCUS evaluation of ETT placement, with no clear winner (Table 1).

VariableSourceFindingsRecommendation
Probe type: Linear vs CurvilinearSahu 2020 [4]No differenceLinear probe
Technique: Static vs DynamicSahu 2020 [4] No differenceStatic technique
Probe placement:

  • Transverse at suprasternal notch
  • Longitudinal at cricoid or thyroid cartilage
Lonchena 2017 [5]Successful ETT visualization

  • Suprasternal notch: 100%
  • Cricoid: 70%
  • Thyroid: 40%
Place probe transverse in suprasternal notch in the anterior neck
Table 1: Published studies in the adult population, comparing different techniques for confirming ETT placement with POCUS.

Pediatric Literature

The pediatric literature for the application of POCUS to evaluate ETT placement is not as robust compared to adult studies; however, it is still compelling. A systematic review by Lin et al. in 2016 [3] included studies that evaluated intubations using direct visualization of tube tip in trachea, diaphragmatic movement and/or lung sliding. All modalities had high sensitivities though the esophageal intubation rates included in the studies were relatively low (Table 2).

StudyEndotracheal IntubEsophageal IntubPOCUS Technique UsedSensitivitySpecificity
Galicinao 2007 [6]501Direct visualization of tube tip in trachea1.00 (0.93-1.00)1.00 (0.03-1.00)
Alonso Quintela 2014 [7]315Direct visualization of tube tip in trachea0.92 (0.75-0.99)1.00 (0.48-1.00)
Hsieh 2004 [8]612Diaphragmatic or lung pleural movement1.00 (0.94-1.00)1.00 (0.16-1.00)
Kerrey 2009 [9]1270Diaphragmatic or lung pleural movement1.00 (0.97-1.00)Not reported
Table 2: Summary of pediatric studies that evaluated using POCUS for ETT confirmation by direct visualization of the tube in the trachea over the anterior neck or indirectly by assessing for diaphragmatic or pleural movement.

Another systematic review of using POCUS to confirm ETT position in the pediatric population by Jaeel et al [10], found that POCUS was comparable to confirming ETT placement by x-ray and capnography for patients outside the neonatal intensive care unit. They concluded that POCUS agreed with x-ray or capnography confirmation in 83-100% of cases. Compared to x-rays, POCUS had a sensitivity of 91-100%.

Case Resolution

After administration of fentanyl, midazolam, and rocuronium, the patient was intubated with a 4.0 cuffed ETT by direct laryngoscopy with a Macintosh blade.

POCUS was used to confirm ETT placement by the transport team in the community hospital ED. Specifically, the provider directly visualized the in the anterior neck (with a single air-mucosa interface), the presence of bilateral lung sliding, and movement of the diaphragm towards the abdomen with PPV. End tidal CO2 further confirmed accurate placement. Once loaded into the ambulance, the ETT was again confirmed to be in the trachea.

Video 11: POCUS showing bilateral lung sliding
Video 12. POCUS showing diaphragmatic movement down to the abdomen with breathing.

Learn More…

References

  1. Tsung JW, Fenster D, Kessler DO, Novik J. Dynamic anatomic relationship of the esophagus and trachea on sonography: implications for endotracheal tube confirmation in children. Journal of Ultrasound in Medicine. 2012 Sep;31(9):1365-70. PMID 22922616
  2. Tessaro MO, Salant EP, Arroyo AC, Haines LE, Dickman E. Tracheal rapid ultrasound saline test (TRUST) for confirming correct endotracheal tube depth in children. Resuscitation. 2015 Apr 1;89:8-12. PMID 25238740
  3. Lin MJ, Gurley K, Hoffmann B. Bedside Ultrasound for Tracheal Tube Verification in Pediatric Emergency Department and ICU Patients: A Systematic Review. Pediatr Crit Care Med. 2016;17(10):e469-e476. PMID 27487913
  4. Sahu AK, Bhoi S, Aggarwal P, et al. Endotracheal tube placement confirmation by ultrasonography: A systematic review and meta-analysis of more than 2500 patients. J Emerg Med. 2020 Aug 1;59(2):254-64. PMID 32553512
  5. Lonchena T, So S, Ibinson J, Roolf P, Orebaugh SL. Optimization of ultrasound transducer positioning for endotracheal tube placement confirmation in cadaveric model. J Ultrasound Med. 2017 Feb;36(2):279-84. PMID 28072483
  6. Galicinao J, Bush AJ, Godambe SA. Use of bedside ultrasonography for endotracheal tube placement in pediatric patients: A feasibility study. Pediatrics 2007; 120:1297–1303. PMID 18055679
  7. Alonso Quintela P, Oulego Erroz I, Mora Matilla M, et al: [Usefulness of bedside ultrasound compared to capnography and radiograph for tracheal intubation]. An Pediatr (Barc) 2014; 81:283–288. PMID 24560730 
  8. Hsieh KS, Lee CL, Lin CC, Huang TC, Weng KP, Lu WH. Secondary confirmation of endotracheal tube position by ultrasound image. Crit Care Med. 2004 Sep;32(9 Suppl):S374-7. PMID 15508663
  9. Kerrey BT, Ceis GL, Quinn AM. A prospective comparison of diaphragmatic ultrasound and chest radiography to determine endotracheal. Pediatrics. 2009;123:1039-43. PMID 19414520
  10. Jaeel P, Sheth M, Nguyen J. Ultrasonography for endotracheal tube position in infants and children. Eur J Pediatr. 2017 Mar;176(3):293-300. PMID 28091777
  11. Uya A, Gautam NK, Rafique MB, et al. Point-of-Care Ultrasound in Sternal Notch Confirms Depth of Endotracheal Tube in Children. Pediatr Crit Care Med. 2020;21(7):e393-e398. PMID 32168296

Additional Reading

  1. Adhikari S, Blaivas M. The Ultimate Guide to Point-of-Care Ultrasound-Guided Procedures. 1st Ed. Springer Nature; 2020.
  2. Blaivas M, Tsung JW. Point-of-care sonographic detection of left endobronchial main stem intubation and obstruction versus endotracheal intubation. J Ultrasound Med. 2008;27(5):785-789. doi:10.7863/jum.2008.27.5.785. PMID 18424655
  3. Chou EH, Dickman E, Tsou PY, et al. Ultrasonography for confirmation of endotracheal tube placement: a systematic review and meta-analysis. Resuscitation. 2015;90:97-103. doi:10.1016/j.resuscitation.2015.02.013. PMID 25711517
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By |2022-04-30T19:47:20-07:00May 2, 2022|ALiEMU, Pediatrics, PEM POCUS, Radiology, Ultrasound|
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