PAWP readings - page 2

by dewp_63

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I'm looking for information about standards ralated to manual wedging of PA caths and frequency of such. We are having a "war in our facility about frequency of wedging in absence of direct MD order. Some of the nurses feel... Read More


  1. 0
    In the CT ICU where I used to work, we also only used the PAD as a wedge.

    I once saw a surgical resident reposition a swan while we were in report, and she wedged it. I don't know if she forgot to unwedge it, but not 2 minutes later, the pt asked our manager who was walking by for a tissue, which our manager handed her as she proceeded to cough up frank red blood, she went out moments later, coded and died. Made an impression on me, that's for sure! I am perfectly OK using the PAD as a wedge pressure!
  2. 0
    Hi, Cheryl!
    I have worked ICU/CCU for many years - lots of Hemodynamics (love them... teach them!). We have very specific standards for all policies and proceedures, according to recommended critical care safety guidelines. Routinely, PA lines are never wedged more frequently than q4hrs - often less, per individual Dr's order. Actual occlusion of pulmonary artery can cause rapid and severe distress in some patients. (have seen some patients develop immediate chest pain, ST elevation, dysrrhythmias, BP changes, respiratory problems, etc. with pulm artery occlusion - PCW). PADP should always be 0 to 4 less than PCW, if line properly positioned... can use initial PADP minus 0-4 per Dr ok, for PCWP/LVEDP/LAP estimation and calculations, most of time...

    If in proper position (optimal = lung zone 3), should wedge with between 1 to 1.5cc air - never more... If a catheter wedges with less than 1 cc - indicative of tip being too distal and line usually needs to be retracted. If no wedge obtained with full 1.5 cc air - usually tip too proximal and line needs to be advanced... After insertion and Xray confirmation, nursing should mount strip recording of PA and PCW waveform - helps future detection of trouble... and always note exact depth of insertion to tip of hub (and communicate to next shift). Most all catheters are 110 cm long with markings every 10 cm = thin black line and 50 cm markings = thick black line... Also, great to know normal insertion distances, depending on site ... from Int. Jug. - PA normally 40-55 cm, from SCV - PA 35-50, from Fem vein - PA insertion normally about at 60 cm, from right antecubital - PA shouild be at about 70 cm, and from left antecub - PA line should be inserted to about 80 cm. for proper pacement and accuracy..

    When wedging, we always have respiratory pattern visible and never leave catheter wedged for more than 2 full respiratory cycles - often less, if acceptable PCW waveform visible. We then edit all PCW waveforms for ventillatory effects and artifacts from pleural pressures. To avoid artifact, always read the waves at end expiration (when pleural pressures and atmospheric pressures are about equal) - choose the last clear wave that is not affected by breathing - before next inspiratory dip (when wave starts to be pulled down). And as explained by PatriceM, depending on pt. - spontaneous breathing = "peak" vs. mechanically controlled ="valley"...

    Then, we determine accurate PCWP by interpreting hemodynamic waveform...
    Each PCWP may contain 3 waves -
    1. "a" wave (pressure rise due to atrial contraction) - usually the largest wave; occurs near the end or after the QRS.
    2. "c" wave (mitral valve closure... rarely visible with PCW - more visible with right sided CVP waveform and tricuspid closure) -
    3. "v" wave (atrial filling - vent systole) - located after the T wave.( the T- P).

    The 2 Acceptable Methods to read PCWP are:
    1. "Mean of The "a" wave - most accurate method of reading the PCWP is to average the top and bottom values of the of "a" wave; unreliable with mitral stenosis, AV Blocks (at fib, flutter, paced rhythms = absent "a" wave, or junct rhythm, "cannon a waves", etc...

    ...Then must use alternative for correlating with EKG strip... (Remember, electrical activity always occurs before mechanical)...

    2. Z point Technique - useful when "c" wave is not visible and the "a" wave is abnormal. This method assumes that 0.08 seconds (or longer) after the end of the QRS complex correlates with LVEDP... So to read the PCWP via Z point- simply find .08 sec from the end of the QRS and draw a straight line down to the EKG - this the PCW value!

    ...Cheryl, Oops! ...I think I got carried away. But I do love hemodynamics and this is only a small piece of understanding
    them... I hope I helped with your question.... Cindy
    Last edit by CindyCCRN on Mar 30, '02
  3. 0
    Thanks Cindy,
    Our Doctors have written standing orders for us to follow. We pull back to CVP when our CABG patients are extubated. I have been caring for a long term patient with IABP (over 10 days). We diuresis and titrate based on the PCWP and CVP. The goal is to get the numbers down to wean off the IABP. The Doctors/Residents make frequent rounds to monitor.
    Thanks again for the info
    Cheryl
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    On the vented vs spontaneously breathing patient. If your vented patient is overbreathing the vent then it is considered a spontaneous breath and you would read the PAWP at the peak not at the valley. Whereas ventilator breaths are read in the valley. I just learned this last Fall from Dr. Tom Ahrens. So unless your patient is paralyzed then be sure to watch whta type of breath your patient is taking is it spontaneous (their own initiated breath) or ventilator forced breath....Hope this helps. As far as how often to wedge. I learned every 4 hours. Then learned whenever you thought the patient needed it(change in condition, BP, HR, etc.). I would suggest talking to the surgeons or cardiologists who most often use Swans how often they would like PAW readings.....Then take it to your manager to be looked at when and if your policies are reviewed..........Just my .02 worth
  5. 0
    A good site (free) to learn all about PA's and such is

    www.pacep.org

    Just a tidbit. I've looked into the site and it seems pretty decent.
  6. 0
    Wow, I am surprised to learn of the frequency of wedging at other places! Where I work we wedge q2h and even more often if needed. However, our patients generally do not have a Swan for more than two or three days. We do have a very high acuity of patients and alot of times the PA diastolic does not correlate with the wedge pressure. We generally treat off the wedge.


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