Anatomy of the PA catheter

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:

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)