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Re: [IP] air bubbles

Reposted with a proper subject. (Sorry.)

Dave Hill recently wrote:
> ... If anyone has a fool proof cure for this minor but agonizing
> problem, please post it. Good luck Kathy! Dave

I've used a Minimed 507C and a 508 with 42" Sof-Set Ultimate QRs for
2= years. I have zero problems with bubbles. After emptying them from
the reservoir during the fill, I *NEVER* see them. Not EVER.

Bubbles aren't magic. If the insulin used to fill the reservoir is
already at room temperature, then the bubbles are present because
either they were _pushed_ into the tubing (from trapped air) or
_pulled_ into the tubing (from a loose fitting).

Perhaps you'll find the following procedure helpful. As in all things
diabetic, YMMV. However, I have never yet had feedback from someone
who said that they tried the procedure, but it didn't work.

1. Use insulin at room temperature to fill the reservoir. If the
   insulin is cold, it will liberate air as it warms up. The air
   liberated in a 300 unit reservoir of refrigerated insulin will form
   bubbles that occupy 3 units when the insulin reaches room
   temperature. Once I start using an insulin bottle, it stays out of
   the refrigerator until it's empty 4-5 weeks later.

2. Before filling the reservoir, pull (not all the way) and push on
   the plunger a couple of times to distribute the lubricant already
   inside. This will reduce the possibility of air leaks around the
   plunger while filling the reservoir in step 5.

3. Before filling the reservoir, twist on the filling needle with the
   plastic cover so it's *tight*. This will minimize air leaks through
   the needle in step 5.

4. Withdraw the plunger to fill the reservoir with air and then inject
   this air into the insulin bottle. If this step is omitted, the
   insulin bottle will be under a vacuum and air will be sucked into
   the reservoir from around the plunger in the next step.

5. Fill the reservoir from the insulin bottle with the needle
   pointed *up* so that air floats to the top of the reservoir. When
   the reservoir is half-full, withdraw the needle from the insulin
   bottle. Holding the needle *up*, tap very sharply several times on
   the reservoir so that the air around the plunger is knocked to the
   top. Then, hold the reservoir up to a bright light and push the air
   (and any insulin trapped between air pockets) out of the reservoir.
   Stop pushing on the plunger when insulin starts to flow out the
   needle and no bubbles are left in the reservoir. Then reinsert the
   needle in the insulin bottle and fill the reservoir the rest of the
   way. When the reservoir's full, tap it sharply several times again
   and make sure no bubbles are present.

   This step is NOT included in the "Instruction for Use" of the
   Minimed 3.0 ml Reservoir (REF MMT-103). Instead, Mimimed advises
   you to get rid of the air after you connect the infusion set (step
   6). However, it's much easier to manipulate the reservoir without
   the infusion set attached and I haven't yet filled a reservoir
   without seeing air at this point. IMHO, this is the single most
   important step listed for eliminating bubbles.

6. Holding the reservoir with the luer connection *up*, unscrew the
   (tight) needle with the plastic cover, and attach the new infusion
   set connector. Screw it on *tight*. My infusion sets are fastened
   so tightly that I cannot unscrew them by hand when I change them --
   I need to grasp them with a wadded tissue or handkerchief to
   increase the leverage. "Tight" means, well, *tight*.

7. Holding the reservoir with the luer connection *up*, push on the
   plunger until the insulin comes out the needle. Once insulin starts
   coming out, there should be no bubbles visible anywhere at this
   point. If you see bubbles, get rid of them before going any
   further. Try to figure out how they got there. THERE IS A REASON.

8. Insert the reservoir into the pump and (gently) push the driver
   arms against the plunger to minimize the priming quantity.

9. Prime the pump. 5 units should be sufficient. If insulin doesn't
   appear at the needle tip after 5 units, look for leaks and bubbles
   and try to figure out what went wrong. THERE IS A REASON.


regards, Andy
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