You are talking about the syringe rebound problem that occurs
with traditionally designed syringes. When you flush all the fluid
into the catheter, the gasket at the end of the plunger is compressed.
Then you release the pressure on the syringe plunger,causing the
gasket to expand and pull fluid back into the syringe barrel. Blood is
also moving back into the catheter lumen at the same time. Traditional
syringes were not designed with the physics of flushing catheters in
mind. You are correct - we do not know if a positive displacement
connector will have enough fluid displacement to overcome syringe
induced reflux as well as the disconnection reflux.
There are 2 ways to handle this issue.
1. use a syringe designed to prevent this problem. There are 2 on
the market, one by BD and one by Tyco Kendall
2. do not completely flush all the fluid from the syringe to
avoid compressing the gasket on a traditional syringe.,
Lynn
At 8:13 AM -0600 10/11/06, Hallene E Utter wrote:
Has anyone else had problems with the prefills "backing up"? What I mean is after you remove the cap and push the fluid up to the tip, if you take your thumb off the plunger for an instant, the plunger and fluid slip back a bit. This is not so significant before you flush in terms of a significant amount of air,esp in adults, but if you are using a neutral displacement valve cap and you release your thumb from the plunger before you unscrew the last syringe (which would be normal in my opinion), it allows for blood to back up in the tip of the line. Even with a positive displacement cap, I am not sure the over flow with unscrewing is adequate to flush this backflow back out of the tip thoroughly. Particularly important if only using saline flushes. Anyone else seen this phenomena? Even clamping before you unscrew, unless you keep your thumb and hencefore pressure on the plunger, would not prevent this "plunger slippage". Any comments? I had the ICU nurses point this out to me and they were sure right. The fluid slips right back into the syringe after you push it up to get ready.
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Lynn Hadaway, M.Ed., RNC, CRNI
Lynn Hadaway Associates, Inc.
126 Main Street, PO Box 10
Milner, GA 30257
http://www.hadawayassociates.com
office 770-358-7861
Lynn Hadaway Associates, Inc.
126 Main Street, PO Box 10
Milner, GA 30257
http://www.hadawayassociates.com
office 770-358-7861
