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Re: [IPk] Minimed 508 volume problem

> If you tie a knot in the tubing, or indeed block the cannula, there is a
> certain elasticity in the system. It will all expand slightly as the
> insulin is pumped with nowhere to go. So there's a slight delay before the
> alarm goes off. The delay is even longer if there is air in the system.
> But if you run out of insulin, where is the elasticity? There isn't any.
> The drive arm is pushing a solid plunger against the end of a solid
> syringe. The moment it tries to push another 0.1 units through, and can't,
> the pressure buildup will be immediate, setting off the no delivery alarm
> immediately.
> Or am I talking a load of twaddle?
> John

John - I take your point - but this is what I was told by Ray I believe (or at
least, someone "in authority". We had a discussion about it probably 2 years
ago now on this list. As far as I recall, the reason is that the alarm is
deliberately set not to be too sensitive, so it requires a certain amount of
pressure buildup before it will be activated. Otherwise you'd be getting no
delivery alarms a lot more frequently.
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