Troubleshooting PAC measurement


Pulmonary artery catheter measurement problems include:

  • dampened waveform
  • overdamping
  • underdamping
  • erratic waveform with highly variable pressures
  • spontaneous wedge
  • unable to obtain wedge
  • overwedging
  • absent waveform


ProblemPossible CausesTroubleshooting
Dampened Waveform
  • Incorrect scale selected on monitor
  • Incorrect referencing
  • Air in the system
  • Spontaneous wedging of catheter
  • Check the monitor to ensure the correct scale is in use
  • Check referencing
  • Check pressure in bag
  • Check for loose connections
  • Remove air bubbles
  • Flush system
  • see below-Spontaneous Wedge
Diminished systolic peak, loss of dicrotic notch, rounder wave forms
  • Compliant tubing
  • Large air bubbles
  • Clots/blood in system
  • Loose connections
  • Kinked catheter or catheter tip against vessel wall
  • Check tubing-right tubing, no air, no clots, no blood
  • Check for loose connections
  • Flush tubing
  • Perform square wave test
  • Collaborate with physician as
    needed to reposition/remove
    catheter as indicated
Falsely high systolic peak, falsely low diastolic value, artifact
  • Pressure tubing is too long
  • Too many components
    (i.e., stopcocks)
  • Small air bubbles
  • Defective transducer
  • Ensure that the correct tubing is in use - shorten if necessary
  • Ensure that there are no tubing extensions added
  • Remove extra components
  • Remove air bubbles
  • Change transducer
Erratic Waveform
with Highly Variable
  • Catheter whip/catheter fling is being caused by excessive movement of the catheter tip within the vessel
  • The catheter will probably have to be re-positioned to a less turbulent area of the vessel
Spontaneous Wedge
  • Catheter is advanced too far or is too flexible
  • Do not flush catheter
  • Assess for other causes of
  • dampened waveform-see above
  • Reposition or ask the patient to cough
  • Catheter will require repositioning -pull back slowly until PA waveform appears (if allowed by institution P&P)
  • Notify physician of need to reposition catheter
Unable to Obtain Wedge
  • Air returns to syringe - catheter is probably not advanced far enough into the PA
  • Air does not return to syringe - balloon is probably ruptured
  • Catheter will require repositioning as permitted by institution P&P
  • Notify physician of need to reposition catheter
  • Notify physician of need to remove catheter
  • Excessive air volume is injected into the balloon
    Catheter is advanced too far
  • Observe waveform on monitor while injecting air
  • - stop injecting as soon as the waveform dampens
  • Allow passive deflation of balloon
  • Catheter will require repositioning
  • - pull back slowly until PA wave-form appears (if allowed by institution P&P)
  • Notify physician of need to reposition catheter
Absent Waveform
  • Disconnect of monitoring system
  • Incorrect scale in use
  • Loose or cracked transducer dome
  • or air in dome
  • Defective transducer
  • Inadequate pressure in pressure bag
  • Check for kinks in the system
  • Catheter tip or lumen totally occluded
  • Check connections
  • Set correct scale on monitor
  • Change transducer
  • Adjust pressure to 300 mm Hg
  • Remove kinks
  • Slowly aspirate to check for blood return - if no blood return, notify physician of need to remove catheter

  • Bootsma, I.T., Boerma, E.C., de Lange, F. et al. The contemporary pulmonary artery catheter. Part 1: placement and waveform analysis. J Clin Monit Comput 36, 5–15 (2022). https://doi.org/10.1007/s10877-021-00662-8

CCC 700 6

Critical Care


Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also a Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of three amazing children.

On Twitter, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.