Friday, January 01, 2010

a post on cannula

This is in response to my dad's previous entry on his colonoscopy experience in which he mentioned 'the thing' and he was baffled at how the needle was removed. I initially wanted to write a comment but realised that it would be better if I posted an entry on it (with pictures!) as I have an unopened cannula sitting on my desk. So why not, since it's Christmas hols (and I nothing to do atm), take pictures of it and 'dissect' it to show the readers who have never seen the cannula in its original form and packaging?

This is called a venous cannula or venflon.

we hold it like this

When the needle is inserted, the doctor would fiddle with the bottom end of the plastic (which is connected to the needle) by withdrawing it a little to look for any blood (flashback) which will appear in the tube.

If there is blood, hurray to both the doc and the patient coz the doc has hit the vein!

If there is no blood, the patient has to suffer while the doc probe or wriggle the needle in the person's arm.

Did you notice the thin plastic tube surrounding the needle? So when the needle is withdrawn a bit, blood will enter the plastic tube so the doc knows whether he has found the vein or not.

When the doc noticed flashback in the plastic tube, he gently but swiftly withdraws the plastic end which has the needle.

It is by no means magic or the needle dissolves in the body which makes the needle disappear! lolz.

This is how the cannula looks like, dissected:

So the plastic bit will sit in the vein of the patient with the screw back on again while the needle bit will be thrown away in a special bin called the sharps bin.

Happy New Year everyone!


wenn said...

Happy New Year!

Sarawakiana@2 said...

thanks for the info.
Happy New Year.

William said... the plastic is outside! I always thought that the plastic is inside! LOL. Make sense! No wonder when the needle was inserted, I felt my skin was stretched.
I noticed white liquid in the cylinder (at the screw). Are they there to prevent air to get through? I think the design looks simple but a lot of technology is in there, even the way the cap is designed. Otherwise air will be pushed through when the cap is closed.

William said...

Janice, I suppose the guinea pig is an old photo?