Troubleshooting PAC insertion


  • PAC tip will not advance into pulmonary artery (stuck in SVC or RA, RV, or coronary sinus)
  • Wedged waveform after balloon deflation
  • dysrhythmias or complete heart block
  • malposition after advancing into pulmonary artery
  • PAC tip not in West Zone III


PAC won’t float into RV (good RA waveform)

  • this may be due to tricuspid regurgitation causing a jet of blood regurgitating from the right ventricle to push the catheter back out of the RV with each contraction
  • fill the balloon with 1.5ml of normal saline, and repositon the patient left side down when crossing the tricuspid valve
  • Gravity should guide the now heavier balloon into the right ventricle

PAC won’t float into PA (good RV waveform)

  • PAC is usually coiled in RV
  • may be due to pulmonary hypertension
  • Withdraw PAC tip and try to advance again using a slow continuous motion – no rapid thrusts
  • reposition the patient with the left side and head up when crossing the pulmonic valve

PAC entered coronary sinus

  • nice shot!
  • more likely if dilated coronary sinus (e.g. high CVP, tricuspid regurgitant jet, cardiac anomalies associated with persistent left SVC)
  • Because of extensive arteriovenous anastomoses in the coronary circulation, a catheter wedged in the coronary sinus would give an arterialized pressure tracing and reflect attenuated systemic pressures
  • Check SvO2 which is typically low in the coronary sinus (~20 mmHg) due to the high O2 extraction ratio (55-65%) of the coronary circulation
  • can be confirmed by fluroscopy or TOE
  • Withdraw PAC tip and try to advance again — reposition the patient with the right side up when crossing the tricuspid valve



  • PAC tip has migrated to a more distal artery that is so narrow that the catheter itself occludes the artery lumen without the need for balloon inflation.
  • if left in that position pulmonary infarction can occur


  • Withdraw the tip a few centimeters and gently attempt to wedge again.


  • due to myocardial irritation
  • dysrhythmias are generally transient and require no action
  • complete heart block may require withdrawing the PAC and pacing, which may or may not be transient (depending on the extent of AV nodal injury)


Correct position

  • insertion distance and waveform are appropriate
  • Chest x-ray should show the tip to be 3 -5 cm from the midline, no more than 2cm from the hilum (at the junction of the inner and middle third) and it should be below the left atrium.

If incorrectly positioned then withdraw and attempt repositioning


  • To maintain a column of blood between the pressure transducer and the left atrium, the balloon has to be below the atrium
  • This means the PAC tip must be in West Zone 3, which usually happens easily because this zone has higher pulmonary blood flow
  • In patients with raised intrathoracic pressure (e.g. positive pressure ventilation) other zones have increased blood flow
  • If the patient is turned on one side positioning in West zone II is more likely due to the increased blood flow to the dependent side

Confirmation of location in West Zone III

  • On lateral CXR, the tip of the catheter is at or below the left atrium
  • Respiratory variation of PAOP is < 50% of the static airway pressure (peak – plateau)
  • Change the PEEP: PAOP changes by 50% of the change in PEEP
  • The PAWP contour has recognizable a and v waves; in Zones 1 and 2 it is unnaturally smooth
  • Perform a gas: — Wedge PO2 minus Arterial PO2 = 19mmHg — Arterial PCO2 minus Wedge PCO2 = 11mmHg — Wedge pH minus Arterial pH = 0.008

Some experts do not consider PAOP useful, so positioning in West Zone III is not essential.

References and Links



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.