How do you determine bloodflow direction in a PTFE graft? Does your unit have a P+P to follow? How is the information documented on the chart? Does anyone use the Blue Thumb (regular flow) Red Thumb (reversed flow) Did you know that 20% of grafts will be a Red Thumb due to the natural placement of the pt's artery? Do you use any devices to help varify flow direction such as a Transonic? This is a basic vascular access issue that is not well understood by the implanting surgeons and often not checked in the dialysis unit. Any comments?
Could you please explain, in layman's terms, the Red Thumb and Blue Thumb procedure that you mentioned. I don't understand a lot of the abbreviations that you use, so please write everything out. I've just started learning all this.
Sure. A PTFE Graft has an arterial inflow side where the graft is attached to the artery. The mid point of a loop graft (in the curved section that is not used for needle placement) is the change point of the graft and the remining side of the graft is called the venous. The venous end of the graft is attached to the vein for the blood return back into the body. Correct needle placement is needed to get the best dialysis treatment with out reciculation of the just cleansed blood. The arterial side of the graft has the arterial needle placed into the graft segment with the needle pointing up or down (either way is fine). The arterial needle (red side of the dialysis blood tubing) pulls the "dirty" blood out and into the hemodialyzer. The blood is then returned back into the graft via the venous needle (blue side of the blood tubing) The venous needle MUST always face the direction of the blood flow back into the vein (up). So the arterial side of the graft is the red side and the venous side of the graft is the blue side. Most grafts are in the lower arm in a loop. So the thumb can be used to tell the matching side of the graft. A Regular graft has the arterial side of the graft closest to the body on the little finger side of the arm. This graft and patient will have a Blue Thumb the match the venous side of the graft on the thumb side of the arm. A reversed or backward graft will have the artery and the arterial side of the graft on the outside or thumb side of the arm. This is a Red Thumb. The thumb color can be used to help patients and dialysis staff know which side is the arterial/venous. Patients can then check to be sure the red and blue marking on the blood tubing (clamps or ends are usually color coded red/blue) are connected up correctly for each dialysis treatment.
How about just occluding the middle of the graft with your thumb and feel each side for a pulse. Pulse side is arterial.
Well you can do that- but you can get a false result. If a new graft is deep and edemous it is often hard to occlude the graft enough to tell- or if the graft has a venous outflow stenosis it but also effect the results. The best way is to have a picture done at the time of graft placement detailing the graft and vessel used for the artery/vein- I know dream on! Most surgeons don't know why the dialysis unit needs to know which side is arterial and venous. MD education can help with that issue. TecDude- When you occulde the mid graft do you also watch the blood flashback for changes? Do you use the dialysis machine to help verify the results?
Please bear with me while I struggle through this.
If you have a patient show up in the unit with a PTFE graft with no documentation or knowledge about the graft, what do you do to determine the flow direction? Assume we don't have any special equipment.
Well a several step assessment of the graft can be used. These steps should be written into a dialysis unit policy/procedure. 1. Physical accessment of the graft- look at the graft configuration. Feel for the thrill in the entire graft. Listen with a stethoscope for the bruit in the entire graft. The stronger side of the loop might be the arteial. Then compress the mid graft and feel the thrill/listen for the bruit- if the graft is a Blue thumb- the bruit/thrill will be stronger on the little finger side of the graft. when the mid graft is compressed the arterial flow through the graft will decrease causing the venous side to have a drecreed flow/thrill/bruit. 2. cannulate the graft with both needles up (that way the venous needle will be pointing the correct direction no matter the flow). Observe the bloodflash back in the needles. The arterial side should have a stronger flashback- then compress lightly the mid graft section and watch the blood flashback. In a regular graft or Blue thumb the little finger side of the graft will maintain a strong flashback and the venous (thumb) side will have a decreased flashback. Then LIGHTLY compress the graft 1 inch or more above the needle- the bloodflash back should decrease as the arterial inflow blood is impeded. Repeat the step above the venous needle and the flashback should increase as you imped the venous return. If you have guessed wrong the reverse will be seen. 3. Initiate dialysis. When any saline in the bloodlines has cleared- set the flow rate low at 200 ml/min. Apply LIGHT compression 1 or more inches above the needle. If you use a pre pump arterial pressure monitor- when the graft is compressed above the arterial needle (placed correclty in the arterial side) the AP will become more negative (AP is a neg # and shows how hard the bloodpump is working to get blood from the patients access) Light compression is only needed for a quick moment to see the AP pressure become a more neg #. Then LIGHTLY compress 1 or more inchs above the venous needle and the VP will increase- care must be taken to use LIGHT pressure to prevent any infiltration of the neeldes. If you have then needles correctly identified the above thinks will be noted- if an error has occured- swith the bloodlines around and repeat the steps. Try this and see if the grafts in your unit are correctly identified. A reverse graft or Red Thumb might be found that was not identifed correctly. Let me know what you find.
The method of identifying the arterial and venous side of a graft that you have just explained - does this technique have a specific name?
That's a good question- I guess the "Brouwer Technique" since I developed it several years back. The technique was described in 2 published forms- D&T "Cannulation Camp" and a book chapter in the Vascular Access for Hemodialysis-IV (book from the Ohio State VA q 2 year meeting- W.L.Gore has reprints). I never thought to give it a name.
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