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RD5.1-4 | Core Image Interpretation Skills — PBL Case

CLINICAL SETTING

It is a busy night in the adult ICU. A 64-year-old woman with severe community-acquired pneumonia has just been intubated and a right internal jugular central venous catheter (CVC) inserted. The intensivist requests a portable AP supine chest radiograph to confirm the position of all tubes and lines before continuing care. As the resident covering radiology, you are asked to perform a disciplined 'tubes-and-lines-first' read and feed back any malpositions immediately. This case asks you to interpret device position on adult and paediatric ICU chest films, recognise malpositions and their harms, and perform the mandatory complication check — distinct from the emergency-film case you may have seen elsewhere.

Trigger 1: Reading the Post-Insertion Portable Film

The portable AP supine CXR is displayed. The heart and mediastinum look wide, and the clinical team is keen for you to comment quickly. You begin your tubes-and-lines-first read. You trace the endotracheal tube and find its tip lying ABOVE the carina; you trace the CVC from the right neck downward; you note the patient's neck position is neutral.

DISCUSSION POINTS

  • Why is the cardiomediastinal silhouette 'wide' on this film, and why does that mean you CANNOT comment on heart size or call cardiomegaly here?
  • Describe the disciplined method: how do you trace EACH device from its point of entry to its tip and judge it against its landmark before moving on?
  • What is the target position for the ET tube tip relative to the carina in a neutral neck, and how does neck flexion or extension change where the tip sits?
Click to reveal Trigger 2: An Unexpected CVC Course and the Mandatory Check (discuss previous trigger first!)

Trigger 2: An Unexpected CVC Course and the Mandatory Check

Following the CVC from the right neck, you see that instead of descending to the cavoatrial junction, the catheter turns and runs UPWARD into the neck on the same side; its tip is not where you expect. The team also reports the patient's oxygen saturation has dropped slightly since the line was placed.

DISCUSSION POINTS

  • Where SHOULD the CVC tip lie, and what does an aberrant upward (or contralateral) course imply about the line position?
  • What is the mandatory complication check that EVERY post-line film demands, and why is it especially important after a central line is sited?
  • Given the falling saturations, what specific complication must you actively exclude on this film, and what features would confirm it?
Click to reveal Trigger 3: The Paediatric ICU Film and Coupling Findings to Action (discuss previous trigger first!)

Trigger 3: The Paediatric ICU Film and Coupling Findings to Action

Later the same shift, a portable CXR arrives from the paediatric ICU on a ventilated 2-year-old with an ET tube, an NG tube and an umbilical/central line. You apply the same tubes-and-lines-first read but must adjust your landmarks for a child. Several devices need judgement, and the team waits for your verbal report.

DISCUSSION POINTS

  • How do device-position landmarks and tolerances differ in a small child compared with an adult (e.g. ET tube depth, the much smaller safe margins)?
  • How do you confirm correct NG tube position (path and tip) on the film, and what malposition must never be missed before feeding?
  • In critical care a finding that is detected but not acted upon is clinically useless — for each malposition you identify, what is the IMMEDIATE action you would communicate to the team?

Group Task Assignments

  • Group A: Build a one-page 'tubes-and-lines-first' checklist for the adult ICU CXR, listing each common device (ET tube, CVC, NG tube) with its target landmark and the single most dangerous malposition for each.
  • Group B: Prepare a short teaching aid contrasting adult vs paediatric device landmarks and safe margins, emphasising why the child's smaller margins make malposition more dangerous.
  • Group C: Draft the mandatory post-procedure complication checklist (including the pneumothorax check) and map each device malposition to its immediate clinical action.

Learning Issues

Research these questions and bring your findings to the discussion.

  1. [RD5.4] What are the correct target positions for the ET tube, CVC and NG tube on an adult ICU chest radiograph, and what are the named malpositions and harms for each?
  2. [RD5.4] Why is the ICU film almost always an AP supine portable projection, and how does that change what you can and cannot interpret (e.g. heart size, mediastinal width)?
  3. [RD5.4] How do device-position landmarks and safe margins differ between adult and paediatric ICU patients, and which complication check is mandatory on every post-insertion film?
  4. [RD5.1] Which normal CXR landmarks (trachea, carina, cavoatrial junction, diaphragm) anchor the device-position read, and how are they identified on a portable film?