Arterial lines, TLCs, and vents

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I just read in my notes that an A line is required for a vent. Is this always true? I had a pt last week on vent on CPAP with only a TLC (unless I missed it, yikes!!). Did the pt not need the A line because the mode was CPAP? Right now I'm studying last week's notes, trying to make sense of the A line vs a Swan-Ganz cath. At first I thought the S-G was a type of A line, yet couldn't understand how if it's going into the RA, PA, etc. So now I get that they are different, they just sort of ran together during the lecture. But I need to figure out if a) my pt didn't need an A line or b) if I missed it!!

And also, the MD came in on my shift and changed the TLC. I was able to watch, and I'm still confused. He removed the old cath (and cut to send off to culture), and inserted a new one with a guidewire. How is this different than putting in a new one? And just to be totally clear, a TLC is just a central line, right? It just didn't seem that long to me. This one was put in on the left and I have only seen them on the right, but she had a pacemaker so is that why? Do they usually go on the right?

Thanks!! Just started back a few days ago and intro to critical care is not an easy way to ease into the semester! I sure hope it gets better...

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Specializes in Cardiac.

Wow! Lots of questions.

An A line is not required for a vent. It's nice to have though. The benefit of it on vented pts is easy access to ABGs without having to poke the pt each time. Your pt being on CPAP means they may come off the vent soon, so no need for the Aline.

An Aline goes into an artery, and a TLC goes into a vein. Also, a Swan is totally different than either of these. A central line terminates in the SVC, but a Swan terminates in the pulm artery . Here's a cool pic of a swan insertion with the associated waveforms.

http://www.edwards.com/products/pacatheters/thermodilutioncatheter.htm

We change out Central lines in the way you've described. The benefit of the guidewire is that it remains in the correct position, so the new central line can be slipped right into place. It saves a lot of steps for the MD, although a CXR is still required to check for placement.

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Thanks. So the guidewire stays in the vein? Why do they need a new guidewire?

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Specializes in Cardiac.

The guidewire stays in until the TLC slides over, then it is removed.

When a central line is inserted, the MD finds the spot with a needle, then inserts a guidewire, then makes the whole bigger until he can fit the catheter over the guidewire, then takes the wire out.

In a replacement, the guidewire is slid into place, the old catheter is removed, the new one replaced, and the wire removed as well.

The guidewire is temporary...

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That makes a LOT more sense now!! I just couldn't get it at clinical and asked the nurse and my instructor, and still didn't get it. When we learned about central lines, they didn't say anything about guidewire. Now I see!! Thanks so much for your explanation!!

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Specializes in med/surg, telemetry, IV therapy, mgmt.
i just read in my notes that an a line is required for a vent. is this always true?
no. your notes are wrong.

did the pt not need the a line because the mode was cpap?
neither has anything to do with the other. arterial lines are inserted in order to directly monitor the patient's systolic, diastolic and mean arterial blood pressure. it is called intra-arterial pressure monitoring and has nothing to do with the patient's respiratory status. it is done when highly accurate or frequent blood pressure measurements are needed in patients with low cardiac output and high systemic vascular resistance or when an intra-aortic balloon pump is used. another use for it is to obtain arterial samples for abgs.

a swan-ganz line is a catheter whose distal tip is nested in the pulmonary artery and has a balloon at its tip. there is a transducer (pressure/energy converter - converts the energy it detects in the heart to a graphic wave form you see on a monitor) attached to the tubing system. recall that the pulmonary artery is the vessel that carries deoxygenated blood from the right ventricle to the lungs to be oxygenated and dump its carbon dioxide. pressure in the left side of the heart can also be monitored with these catheters, but it is the pressure in the right side of the heart that is primarily being sensed. to understand something about this type of monitoring you should review the pathophysiology of how shock occurs. pap (pulmonary artery pressure) is done for

  • hemodynamic instability
  • fluid management
  • continuous cardiopulmonary assessment
  • patients who are in shock
  • patients who have had severe trauma
  • pulmonary or cardiac disease
  • multiorgan disease
  • when multiple cardioactive drugs are being given

some of the swan-ganz catheters have multiple lumens that are for a number of different things: temporary pacemaker wires, oxygen saturation measurement, wedge pressures, and cardiac output,

[the doctor] removed the old [triple lumen] cath[eter] (and cut to send off to culture), and inserted a new one with a guidewire. how is this different than putting in a new one? and just to be totally clear, a tlc is just a central line, right? it just didn't seem that long to me. this one was put in on the left and i have only seen them on the right, but she had a pacemaker so is that why? do they usually go on the right?

a triple lumen catheter (tlc) is a central line that lies in the subclavian vein which runs parallel with the collarbone. we only have two of them so it is either inserted in the left or right subclavian vein. the right subclavian approach is better anatomically because it has a straight shot right into the superior vena cava. sometimes the doctors will advance the distal tips of these central catheters into the superior vena cava. why? more turbulence so the iv fluids get mixed into the blood quicker and there is better hemodilution. if they go into the left subclavian vein, reaching the superior vena cava is a little more difficult anatomically--a lot of tricky twisty turns to maneuver the catheter through. however, in the case of your patient, they may not have had any other choice.

yes, a tlc is shorter than a swan-ganz catheter. the swan has all kinds of junk that gets attached to it for all kinds of different things. what i'm saying is that the swan-ganz serves many different functions. your patient alone has a temporary pacemaker attached to hers. the central line has one basic purpose--it is an iv access for iv fluids--short and sweet--that's all it is. it doesn't need to be any fancier than it is.

tlcs are recommended to be changed about every 10 days for aseptic reasons. when i worked on an iv team we were constantly on the doctors butts about this. they are changed over a new sterile guide wire or j-wire. the wire is basically a place holder and is inserted in order to maintain the placement of where the catheter is seated. the catheter is then pulled off over the wire and a new, sterile catheter inserted over the wire. the advantage of doing this is that the patient doesn't have to go through the trauma of being stuck again and putting up with the doctor having to dig around, find the subclavian vein and successfully puncture it.

i have weblinks about central iv lines posted on post #6 of https://allnurses.com/forums/f205/any-good-iv-therapy-nursing-procedure-web-sites-127657.html - any good iv therapy or nursing procedure web sites. here are two websites on the pulmonary arterial catheter:

and these websites have all kinds of information/discussion about the various tubes and what nots used in icu:

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Specializes in Cardiac.

A triple lumen catheter (TLC) is a central line that lies in the subclavian vein which runs parallel with the collarbone. We only have two of them so it is either inserted in the left or right subclavian vein.

They are also placed in the IJ as well. But they terminate at the SVC.

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