This came up in  Question 28.1 from the first paper of 2011. The anatomy of the pulmonary artery catheter  is discussed in greater detail elsewhere. This is a brief summary, of which the most important aspect is really this diagram:

anatomy of the PA catheter- actual catheter

When handling one of these things in a viva, one may be expected to mention some of the safety features.

Safety features of the PA catheter include the following:

  • The syringe plunger is limited to a maximum volume of 1.5ml
  • The syringe port can be locked in the closed position, preventing accidental wedging
  • The transparent sliding lock device allows the catheter depth to be manipulated without increased risk of infection
  • 10cm interval markings on the catheter allow depth of insertion to be reliably documented
  • The catheter is made of PVC, which softens at body temperature, reducing the risk of injury to intracardiac structures
  • Lumens have standard colours across manufacturers, to prevent confusion:
    • Red = balloon
    • Yellow = distal PA
    • White = RA (31cm)
    • Blue = RA (30cm)

References

This a full-text version of the seminal paper from 1970:

Swan HJ, Ganz W, Forrester J, Marcus H, Diamond G, Chonette D (August 1970). "Catheterization of the heart in man with use of a flow-directed balloon-tipped catheter"N. Engl. J. Med. 283 (9): 447–51.

A manufacturer (Edwards) offers some free information about the PA catheter on their product page.

The PA catheter section from The ICU Book by Paul L Marino (3rd edition, 2007) is a valuable read.

Armstrong, Ehrin J., James M. McCabe, and Melvin D. Cheitlin. "Pulmonary artery catheterization in the intensive care unit: just numbers floating by?."Archives of internal medicine 171.12 (2011): 1110-1111.

Additionally, UpToDate has an article on PA catheter complication