The "Just a Line Check" Portable Chest in ICU
Mrs. K is a 79-year-old woman, day 3 after CABG, intubated and ventilated with PEEP 10 cmH2O. One hour ago a right internal jugular central line was inserted because her oxygen requirement was climbing (FiO2 0.70, SpO2 91%). The intensivist orders a stat portable AP chest to check line-tip position. You arrive with a DR unit: the bed is against the wall, the head of bed is elevated 25 degrees, a right chest tube runs to suction, ECG leads and cables cross both lung fields, and an IV pump limits the tube angle so the greatest achievable SID is about 110 cm. The patient weighs 78 kg. The nurse handing over says only: "We just need a line check."
1. List the positioning and exposure decisions you would make before pressing the exposure button, and justify each one.
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The clinical question, not the requisition wording, drives the field. A line check that clips an apex or hides the retrocardiac space generates a repeat.
- SID of 110 cm instead of 180 cm. Geometry magnifies everything roughly 30–40% closer to the tube, including the catheter tip. I cannot fix this, so I manage it: detector as far from the patient as possible, tube as far back as the pump allows, and I document the SID so the intensivist knows the apparent tip position is magnified.
- kVp ~100–110 with a grid. For a 78 kg supine patient on PEEP, dropping kVp to "get contrast" would bury the catheter against the spine and mediastinum. Higher kVp plus a grid keeps the tip and the retrocardiac space visible - a repeat for penetration is the bigger dose.
- Move removable clutter. ECG leads and cables off both lung fields; they mimic pneumothorax and can overlay the tip. Loosen the gown, move the IV line out of the field.
- Timing and inspiration. Expose at end-inspiration using a ventilator breath-hold, not on a random phase of the cycle.
- Collimation and lead. Collimate to the lateral chest walls and both costophrenic angles, and place lead behind the detector cassette apron to reduce scatter to staff standing at the bedside.
2. The image shows the line tip projecting at the cavoatrial junction. The clavicular heads are offset by 2.5 cm, only 7 posterior ribs are visible above the diaphragm, and an ECG lead crosses the left lower zone. The radiologist asks whether you will repeat. How do you decide?
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I separate the adequacy criteria that affect the question asked from those that are merely unmet ideals.
- Rotation (2.5 cm) and poor inspiration (7 ribs) degrade the assessment of heart size, mediastinal width and pulmonary vascularity - none of which is the question. Rotation does slightly shift the apparent catheter course, but the tip is still clearly identifiable at the cavoatrial junction, and the lead confirms that.
- What would force a repeat: the tip not visualised, an apex clipped so a post-procedure pneumothorax cannot be excluded, or motion artefact obscuring the line. None applies here.
- The ECG lead over the left lower zone is a legitimate concern because it can simulate or hide a pneumothorax. If the radiologist cannot exclude a small apical or basilar pneumothorax, the repeat is justified on that basis alone, not on rotation.
My action: tell the radiologist exactly what I have and let the clinical question decide; recommend a repeat only if the left base or an apex is genuinely non-diagnostic. I document on the image the short SID, the rotation and the limited inspiration so the report reflects the limitations rather than implying a technically perfect film.
3. The nurse is impatient and says a repeat is unnecessary "because we only care about the line." How do you handle that conversation and the documentation?
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I keep it short, concrete and patient-safety framed rather than defensive.
- Acknowledge the request - the line tip is visible and I am not withholding the answer.
- State the residual risk in their language: "The tip is fine. What I cannot fully exclude on this film is a small pneumothorax at the left base, because a lead sits over it and your patient has only taken a shallow breath. If you are happy to accept that uncertainty, sign off; if not, I will repeat with the lead moved."
- Escalate to the radiologist, who owns the diagnostic decision, rather than arguing with the nurse.
- Document: short SID (~110 cm) due to bed/pump configuration, 25 degree semi-erect, 7 posterior ribs, 2.5 cm clavicular rotation, ECG lead over left lower zone, and the fact that the limitation and the offer to repeat were communicated to the bedside nurse at a stated time.
This protects the patient and also protects the department: if a pneumothorax is found later, the record shows what was known, what was offered and who declined.