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title: PA Catheter tags: #FFICM #cardiac notebook: 🌑-FFICM type: anki

PA Catheter

  • It will be ~30 cm to RV, ~50cm to wedged position
  • The catheters do have 10cm marking points on them

Flashcard type:basic
How far in should a PA catheter go to get into the RV? 30cm
How far in should a PA catheter go to get wedged in the PA? 50cm
How far in is too far in for a PA catheter? >60cm. You're going to get it kinked/coiled

Insertion

  • Clean and drape the patient
  • Clean the PA sheath a fair bit
  • check the balloon on the catheter
  • remove the cap on the PA sheath
  • the PA catheter has a twisting cap that will attach to the sheath
  • make sure the catheter is attached to a trace on monitoe
  • initially it will look like a cvp
  • at this point then what you need to do is inflate the balloon
  • you'll advance
  • and don't stop advancing til the end (if you stop and start you can get stuck)
  • if for some reason you need to pull back, NEVER pull back with the balloon inflated, you will damage something
  • look for the waveforms below
  • first cvp
  • then it's a ventricular waveform (with higher peaks, and diastolic coming down to close to zero)
  • then it's a pulm artery wave form (with same high peaks, but the closing of the pulmonary valve stops you getting the drop back down to zero with the diastolic)
  • then you go further still and wedge
  • it's here that you deflate the balloon

Flashcard type:basic
When inserting a PA catheter what is the first waveform you see? CVP
When inserting a PA catheter what waveform comes after CVP? Ventricular
When inserting a PA catheter what waveform comes after Ventricular? Pulm Artery

Waveforms

Physiology/Science 1

  • Uses direct measurement of LAP and PAP.
  • Uses pulmonary thermodilution for CO

Flashcard type:basic
How does a PA catheter measure Left Atrial and Pulm Artery pressures? Through direct measurement
How does a PA catheter measure Cardiac Output? Pulmonary Thermodilution
What is the point of a wedge pressure when you are using a PA catheter? It gives you a measure of the other side of the pulm vasculature (the left atrial pressure). The left atrial pressure is left heart preload
Which measurement from a PA catheter is reflective of left heart preload? Wedge pressure

  • When inflated balloon at end of catheter gets wedged in branch of PA, it is just measuring the pressure coming from the blood back the way from pulm system, rather than the blood out the heart.
  • So if the pulmonary vasculature is alright, then this is the same as the left atrial pressure (which itself reflects left heart preload)
  • There are some ifs there, so remember many things can mess up the results

Indications

  • Cardiac output monitoring in acute heart failure, when failure to improve without it
  • Assessing left vent preload, when we don't know if left atrial and right atrial pressures are the same or different
  • Low pressures would mean needs more fluid
  • Planning [[Inotropes and Vasopressors]]
  • Assessing right ventricular function

[[cardiac-function]]

[[Acute Heart Failure]]

These may not be as much use anymore as they were once thought to be. They are difficult to measure and interpret. In RCTs in critically ill patients they haven't shown any benefit. [@devices_critical_care]

But for patients with refractory shock, or RV dysfunction, or ARDS, or who need a mechanical support device, they may be useful. [@devices_critical_care]

Poor evidence for use of these. PAC-Man showed no improvement. [^@cardiac_output]

These are catheters floated down central vein into right atrium and ventricle into the pulmonary trunk. It's wedged in a pulmonary artery. [^@cardiac_output]

This measures pulmonary artery pressure, pulmonary capillary wedge pressure, cardiac output (through thermodilution of 10ml iced water) [^@cardiac_output]

This catheter can be difficult to insert. But it is the most reliable measure of cardiac output out of options above. [^@cardiac_output]

They measure:

  • Pulmonary Artery Pressure
  • Estimate pulmonary vascular resistance
  • Estimate right atrial pressure
  • Estimate ventricular work
  • Pulmonary Artery Occlusion Pressure
  • Mixed Venous Saturations
  • Oxygen delivery, consumption, extraction [@devices_critical_care]

Flashcard type:basic
What measurements can you get from a PA catheter? Pulm Art Pressure
Right Atrial/Ventricular Pressure
Pulm Vascular Resistance
Pulm Art Occlusion Pressure = Left Atrial Pressure (estimates)
Mixed Venous Sats
Systemic Venous Resistance
What was the name of the trial looking at the use of PA Catheters in critically ill patients? PAC-MAN
What did the PAC-MAN clinical trial show? In critically ill patients in ICU, you do not get any mortality benefit from the routine use of PA catheters
When was the PAC-MAN clinical trial 2005
How many patients were in the PAC-MAN clinical trial ~1000

Risks

  • Same as CVC plus extra
  • Risk of PA perforation (risk is 0.2% during maintenance)
  • Risk of air embolism
  • Dysrhythmia (12.5-70% on insertion, 1/3 on maintenenace)
  • Right BBB
  • Catheter knotting/kinking. Don't insert > 60cm
  • Valve damage (just under 1%) 2

Flashcard type:basic
How likely is it that PA catheter causes dysrhythmia? 33% during maintenence
Anywhere from 10-70% on insertion
How likely is it that PA catheter causes PA perforation 0.2% during maintenance (higher on insertion)
How likely is it that PA catheter causes valve damage ~1% during maintenance (higher on insertion)

Reference Ranges

[[cardiac-function-normal-figures]]

PA Occlusion Pressure

This is got with v v slow injection of air whilst watching pulm art waveform.

Overwedging (overinflating balloon) means you run risk of PA rupture, and it means you over estimate the occlusion pressure (as the pressure is how much you need to occlude).

Should be less than 1.5ml air.

This wedge pressure basically estimates left atrial pressure. You've created a static column of blood from left atrium back the way to this balloon. Left Atrial Pressure itself is basically left ventricular end-diastolic pressure. This is itself basically preload. So getting a measure of PAOP is basically preload.

Running the risk of PA rupture to get this measure seems a bit risky for maybe not great gain. Some people will use PA Diastolic pressure instead as it's normally v close.

Flashcard type:basic
Does a PA catheter directly or indirectly measure temperature? Directly
Does a PA catheter directly or indirectly measure CVP? Directly
Does a PA catheter directly or indirectly measure wedge pressure? Directly
Does a PA catheter directly or indirectly measure PA pressure? Directly
Does a PA catheter directly or indirectly measure cardiac output? Directly
Does a PA catheter directly or indirectly measure Mixed Venous Sats? Directly
Does a PA catheter directly or indirectly measure stroke volume? Indirectly
Does a PA catheter directly or indirectly measure systemic vascular resistance? Indirectly
Does a PA catheter directly or indirectly measure pulmonary vascular resistance? Indirectly
What equation uses blood temperature changes to calculate cardiac output? The Stewart-Hamilton equation
What is the Stewart-Hamilton equation used for in critical care? It helps you calculate cardiac output by changes in blood temperature

Source for questions above: [[mcqs-and-sbas-in-intensive-care-medicine-oxford-higher-special-training]]

Sources

[Inotropes and Vasopressors]: "Inotropes and Vasopressors"

[Acute Heart Failure]: "Acute Heart Failure"

  1. Oh's Intensive Care Medicine - Chapter 24 - Acute Heart Failure and Pulmonary Hypertension ↩

  2. Oh's Intensive Care Medicine - Haemodynamic Monitoring ↩