Confused -phlebostatic axis

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So the phlebostatic axis is supposed to be at the 4th ics and half the ap diameter of the chest. I'm early in my orientation as a nurse, and generally when I see this done the nurse just places the transducer on the bed at the level of the 4th ics. to also have it at half the ap diameter, does this require adjustment in the h.o.b or elevating the transducer itself so that it is not lying adjacent to the patient's back, which does not seem like half the AP diameter? even more specifically, how would you correctly place the transducer at the phleb axis if the patient is sitting in a chair..

thanks!

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Specializes in Critical Care, Education.

Check with the policy at your organization to determine the approved process - there are many ways to do this.

In most facilities that I have worked in, the transducer is NEVER placed on a bed - this would open up the possibility of cross-contamination as well as damage to the transducer or harm to the patient. Instead, it is maintained on the IV pole that holds the a-line set. There is also a level available so that a nurse can validate the transducer position prior to taking a reading, no matter what the patient's position. Rather than deal with a rigid level that gets lost or misplaced, it is pretty easy to create one by just attaching a mason's (string) level to the pole at the height of the transducer... it is a small 'bubble' level on a string reel that automatically retracts, so it never gets in the way or gets lost.

Good question.

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Specializes in ICU, telemetry, LTAC.

My a-line patients are generally too sick to get up in a chair.

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I work on a stepdown unit and actually had a patient with an a line who was sitting in a chair when we received him, so i guess it does happen from time to time ..

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If your facility does not use the IV sets to level the transducers then yes you place the transducer at the 4th ICS midaxillary position, so actually elevating the transducer itself against the patient. If your facility does use the IV sets then it's important to remember that the transducer needs to be releveled on the set with different HOB changes. If the patient was sitting in a chair, you would want them to get back in bed before you do any readings, if possible, because the more supine the patient can tolerate being for the procedure, the better.

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Specializes in Emergency/Trauma/Critical Care Nursing.

The ICUs in my facility also use those fancy transducer IV poles, but for some reason I've yet to figure out, they won't stock them in our ER, despite the fact that our ED has a 26 bed critical care area where we manage critical pts waiting for ICU beds for up to 24hrs (worst case scenario).

Now I can't honestly say that I've read our policy on this specific practice, but the way I was taught, & honestly, the only way I've ever seen others do, is to place the flat side of the transducer directly against the pt's skin (some prefer taping to the gown) at the phlebostatic axis and tape it to the pt directly above and below the rectangular part of the transducer so that the tape doesn't interfere w/the pigtail or caps, & so the tubing does not kink. I also would recommend using a durable tape such as the kind to secure ETTs (we call it boulevard tape).

One benefit of this method is that the transducer is always at the phlebostatic axis as it moves w/the patient.

Sent from my SPH-D700 using allnurses.com

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Specializes in Emergency/Trauma/Critical Care Nursing.

The ICUs in my facility also use those fancy transducer IV poles, but for some reason I've yet to figure out, they won't stock them in our ER, despite the fact that our ED has a 26 bed critical care area where we manage critical pts waiting for ICU beds for up to 24hrs (worst case scenario).

Now I can't honestly say that I've read our policy on this specific practice, but the way I was taught, & honestly, the only way I've ever seen others do, is to place the flat side of the transducer directly against the pt's skin (some prefer taping to the gown) at the phlebostatic axis and tape it to the pt directly above and below the rectangular part of the transducer so that the tape doesn't interfere w/the pigtail or caps, & so the tubing does not kink. I also would recommend using a durable tape such as the kind to secure ETTs (we call it boulevard tape).

One benefit of this method is that the transducer is always at the phlebostatic axis as it moves w/the patient.

Sent from my SPH-D700 using allnurses.com

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the phlebostatic axis is the level of the right atrium, by definition; you're looking for ra pressure, an indication of fluid status and pretty close to cvp. the right atrium is pretty much in the same place in the patient's chest no matter what the patient's position.

knowing that, you can measure ra/cvp accurately when the patient is on his side, too, if you eyeball the chest and identify where the right atrium is. you don't leave people on their backs all the time, but you still need to get hemodynamics for the patient as he is, and sometimes that's on his side. don't let anybody tell you that a side-lying pressure isn't accurate; that's nonsense, if you measure it at the ra, it's ra pressure. it might well be different, especially with people who are very hemodynamically unstable, but that doesn't mean it's wrong. you have to think in three dimensions here.

otherwise, if the patient is supine (on his back), whether flat, trendelenburg, sitting up in bed, or sitting up in a chair, you can use a marker or pen to mark the spot. it's at the intersection of the line from the fourth intercostal at the sternum and the mid-axillary line. even if that mark isn't exactly right, if everyone uses it as the spot for the transducer, it will give accurate trending data regrdless of position (except for sidelying, as noted above), which is what you want anyway. here's a picture. note change in position.

http://medical-dictionary.thefreedictionary.com/phlebostatic+axis

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Meticulous referencing to correct position is key. Locate the phlebostatic axis and use a leveler from the patient to the pole where your transucers are. Always level it and follow the patient's position, it can be challenging if your patient is moving a lot. A transducer that is leveled below the phlebostatic axis will have a false high pressure, and will give a false low pressure when above the phlebostatic axis. Everyone knows that the Phlebostatic Axis is on the level of the 4th ICS, midaxillary area. This is where the Right Atrium is. This is also where the Tricuspid Valve is. The tricuspid valve is the only place in the human body where central pressures are not influenced by hydrostatic pressure, this is according to a Wiley-Blackwell book. When a person is standing or upright, anything above the phlebostatic axis is negative pressure, anything below is positive pressure, and the phlebostatic axis is, well, zero. When a person is supine and flat, the hydrostatic pressure is equal on all parts of the body because everything is leveled with the right arium/tricuspid valve.

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