Swan Ganz/PA Catheter

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Which ports can you not use for IV medication administration? Why can you not use the port that lies in the pulmonary artery? Anatomically and physiologically speaking, the pulmonary artery carries deoxygenated/venous blood, not arterial blood. 

frozenmedic

frozenmedic

58 Posts

You can't use the PA port for medication administration because of the volume of distribution in the vessel to which that medication would go. 

The PA port is located in a small pulmonary artery branch vessel that will further branch into the pulmonary capillaries. So, any medication infused is potentially sent at high concentration through that vessel and into the pulmonary capillaries before returning to the heart and being diluted with the rest of the blood returning via the pulmonary veins.

RNSAC

RNSAC, MSN

Has 10 years experience. 20 Posts

We only used the PA port for SVO2 checks, any other blood work needs to be drawn in a different port/site

Blue and white port can be used to infuse any medication. The blue port goes to the RA and not sure about the white port. Not all PA catheters came with the white port.

offlabel

offlabel

1,403 Posts

On 8/31/2021 at 12:49 PM, frozenmedic said:

You can't use the PA port for medication administration because of the volume of distribution in the vessel to which that medication would go. 

The PA port is located in a small pulmonary artery branch vessel that will further branch into the pulmonary capillaries. So, any medication infused is potentially sent at high concentration through that vessel and into the pulmonary capillaries before returning to the heart and being diluted with the rest of the blood returning via the pulmonary veins.

The distal port of a PA catheter sits in the very large main pulmonary artery and sees 100% of the cardiac output. Putting medication through it is no different than putting it into the right atrium. The reason why it isn't ordinarily used is that its the port that the PA pressure is being monitored with so its connected to a pressure bag line. Beyond convenience, there's no reason why it couldn't be used for giving a medication. 

frozenmedic

frozenmedic

58 Posts

On 10/19/2021 at 10:44 AM, offlabel said:

The distal port of a PA catheter sits in the very large main pulmonary artery and sees 100% of the cardiac output. Putting medication through it is no different than putting it into the right atrium. The reason why it isn't ordinarily used is that its the port that the PA pressure is being monitored with so its connected to a pressure bag line. Beyond convenience, there's no reason why it couldn't be used for giving a medication. 

This is NOT true, the PA catheter itself transits through the main pulmonary artery.  However, the PA distal port sits in a branch vessel of the pulmonary artery. This is what allows the balloon to wedge with minimal volume.  See the attached photo, the distal port lies past the balloon in a branch vessel, even when the balloon is deflated.

This branch vessel does NOT see all the cardiac output and continues to branch into the pulmonary capillaries, allowing for the possibility of high medication concentrations before medication is further diluted on return to the L heart.

PAcath.JPG
offlabel

offlabel

1,403 Posts

On 8/31/2021 at 12:49 PM, frozenmedic said:

You can't use the PA port for medication administration because of the volume of distribution in the vessel to which that medication would go. 

The PA port is located in a small pulmonary artery branch vessel that will further branch into the pulmonary capillaries. So, any medication infused is potentially sent at high concentration through that vessel and into the pulmonary capillaries before returning to the heart and being diluted with the rest of the blood returning via the pulmonary veins.

The distal port of a PA catheter sits in the very large main pulmonary artery and sees 100% of the cardiac output. Putting medication through it is no different than putting it into the right atrium. The reason why it isn't ordinarily used is that its the port that the PA pressure is being monitored with so its connected to a pressure bag line. Beyond convenience, there's no reason why it couldn't be used for giving a medication. 

offlabel

offlabel

1,403 Posts

3 hours ago, frozenmedic said:

This is NOT true, the PA catheter itself transits through the main pulmonary artery.  However, the PA distal port sits in a branch vessel of the pulmonary artery. This is what allows the balloon to wedge with minimal volume.  See the attached photo, the distal port lies past the balloon in a branch vessel, even when the balloon is deflated.

This branch vessel does NOT see all the cardiac output and continues to branch into the pulmonary capillaries, allowing for the possibility of high medication concentrations before medication is further diluted on return to the L heart.

PAcath.JPG

Your picture shows a wedged pac which happens when the balloon is inflated, carrying the tip into a branch vessel. While it's true that in some patients when we place a PAC it ends up in the RPA (about 20%) of the time, vastly most of them sit in the MPA. This is pretty easily confirmed with echo cardiography. (Weird how your picture has it in the LPA. Where's that from?) Also, when we measure continuous PA pressure, we mean to measure the MPA, not some branch vessel pressure. Also when we measure cardiac output, 100% of that goes through the MPA so that's where the most accurate catheter placement for measurement is.  

And there is no magical "dilution/concentration" threshold for centrally given medications. The faster they get to the heart, the faster they work. If there is some kind of concern about that I guess you'd just give it slowly. And I don't think the way 'volume of distribution' as used in the above post is the traditionally understood pharmacokinetic definition of the term. 

MunoRN, RN

Specializes in Critical Care. Has 10 years experience. 8,058 Posts

22 hours ago, offlabel said:

Your picture shows a wedged pac which happens when the balloon is inflated, carrying the tip into a branch vessel. While it's true that in some patients when we place a PAC it ends up in the RPA (about 20%) of the time, vastly most of them sit in the MPA. This is pretty easily confirmed with echo cardiography. (Weird how your picture has it in the LPA. Where's that from?) Also, when we measure continuous PA pressure, we mean to measure the MPA, not some branch vessel pressure. Also when we measure cardiac output, 100% of that goes through the MPA so that's where the most accurate catheter placement for measurement is.  

And there is no magical "dilution/concentration" threshold for centrally given medications. The faster they get to the heart, the faster they work. If there is some kind of concern about that I guess you'd just give it slowly. And I don't think the way 'volume of distribution' as used in the above post is the traditionally understood pharmacokinetic definition of the term. 

To start, I would agree there is no real reason not to infuse medication through the PA lumen if you really need a 4th option.  The medication is sufficiently diluted even if in the left or right pulmonary arteries.

Since as a general rule we no longer wedge, there is an argument to be made for changing the definition of optimum tip position to be in the main PA, although probably distal MPA to leave some room for error, as a general rule the MPA is not considered appropriate tip position for a PA catheter.  

As for how it affects CO/CI calculation, it makes no difference if it is in the LPA, RPA, or MPA.  

As for depictions of PA caths that show it going into the Left pulmonary artery, I completely agree that is a complexing error.  I've noticed that nearly every single one shows it going into the left pulmonary artery, even though according to one study it's about 96% of insertions that have the tip in the right pulmonary artery.  But if you Google images if PA catheters nearly every single one will show it going into the left pulmonary artery.