Fluoroscopy of central venous catheters

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Author: Mikael Häggström [notes 1]

File:PAC met Gripper erin.JPG
Port with needle assembly inserted.

Fibrin sheaths of ports can be suspected when it is possible to infuse into it but not to aspirate.

Choice of investigation

Fibrin sheaths are usually detected by fluoroscopic catheter contrast angiography.[1]

A suspicion of a thrombotic occlusion of the vein passed by the catheter indicates a CT angiography.[2]

Preparation

  • Contrast should be non-ionic,[1] with an iodine concentration of at least 270 mg/ml.[2]
  • Syringe can be for example 10 ml or 20 ml, for injection by hand.[1] For pumps, the pressure should not exceed >40psi (275kPa or 2,75bar).[2]
  • The needle should be at least 20G (0.9mm), and needs to be designed for port use (to avoid fragmentation of the port membrane).[2] It should be connected by luer taper.[2]
  • The system needs to be closed to air at all times.[2]

The total amount of contrast is rather small (5-15ml) so a decreased renal function does not need to to be a contraindication.[2]

Image taking

Precontrast imaging

  • Including lateral projection of the port to confirm that the needle is in proper place before contrast infusion.[2]

Contrast imaging

  • A small field-of-view.[1]
  • Posteroanterior projection, or slightly oblique to avoid superimposing the spine.[2]
  • First image the contrast filling of the port chamber and the catheter to exclude malfunction.[2]
  • Imaging of the outflow from the catheter is imaged at 10-15 images per second.[2]

After the procedure, the system should be flushed with 20 - 30 ml normal saline.[2]

Evaluation

File:Central venous catheter with a fibrin sheath.jpg
The fibrin sheath is indirectly seen in these images before and after radiocontrast infusion, as the radiocontrast collects around the catheter.

In a normal case, the contrast flows straight out from the catheter.[2] Contrast flowing at a skewed angle compared to the catheter means a suspected fibrin sheath.[2]

A definite fibrin sheath is visualized as contrast flowing backwards around the catheter, looking like a thickening of the distal part, before exiting a bit proximal on the catheter.

Report

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Locations of the central veins.

The report should include:

  • Position of the catheter tip in relation to the central veins
  • Presence or absence of fibrin sheath

References

  1. ↑ 1.0 1.1 1.2 1.3 Knutstad, K.; Hager, B.; Hauser, M. (2016). "Radiologic diagnosis and management of complications related to central venous access ". Acta Radiologica 44 (5): 508–516. doi:10.1080/j.1600-0455.2003.00115.x. ISSN 0284-1851. 
  2. ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 . Porta-a-cath control. Röntgen Metodbok, Radiology Department of Helsingborg. Retrieved on 2018-07-25.


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