There will be times when your child needs to use a syringe and needles (or another injection method) instead of the pump. For example, if the pump breaks down, if it's lost or stolen, or if he runs out of supplies for it. How do you figure out how much insulin he should take to replace the insulin in the pump?
Assuming your child's using rapid-acting insulin in the pump, the doses before meals remain the same with injections as they were in his boluses. The basal insulin is replaced by glargine or detemir insulin. Just calculate how much basal insulin he was taking, and replace it with a dose of glargine or detemir of the same amount. You'll probably find that you have to increase the dose over the next few days by about 20 percent because these insulins don't lower the glucose as efficiently as continuous insulin. Adjusting the insulin is always done by measuring the blood glucose.
A number of companies make insulin pumps, and each one promotes its product's own good points. In clinical practice, all the pumps on the market are useful and can help your child to control his diabetes. Figure 11-1 shows a typical pump.
In the following sections, I describe some of the most popular pumps on the market and give you some guidelines for selecting the right one for your child's needs (or your own).
Medtronic, the maker of the MiniMed pump, claims to manufacture the number-one prescribed pump for diabetes patients. I don't doubt it. The company has been around the longest and has the most experience in this field. Medtronic is very reliable and is set up to offer maximum help to the patient who uses its product.
As of this writing, Medtronic sells four different pumps: the MiniMed Paradigm 522 and 722, and the MiniMed Paradigm 515 and 715. The difference between the first set of pumps (the 522 and 722) is that the 522 reservoir holds 176 units of insulin and the 722 holds 176 or 300 units (and has to be slightly larger, therefore). That's also the difference between the 515 and 715 — the 515 holds 176 units and the 715 holds 176 or 300 units. The difference between the two sets is that the 522 and 722 work with the Guardian REAL-Time Continuous Glucose Monitoring System (see Chapter 7), whereas the 515 and 715 do not.
A typical insulin pump.
A typical insulin pump.
MiniMed Paradigm pumps
In the beginning, insulin pumps were just pumps. Now they're systems because insulin pump manufacturers are trying to combine glucose monitoring with insulin pumping. Ideally, this system would detect the level of the blood glucose and change the rate of insulin infusion based on that. This would be a closed system, just like the normal pancreas with no intervention by the patient. There are a few obstacles to this pump capability at the present time.
I The pump can't know the amount of carbohydrate that the person is about to eat and adjust for that.
I The pump can't know the exercise the person is about to do and adjust for that.
I The continuous glucose monitors that are currently available (see Chapter 7) aren't accurate enough to direct action on the basis of their readings. A finger-stick blood glucose check is necessary before changing insulin dosages. For example, when the blood glucose is falling rapidly, the continuous glucose monitor may lag behind the finger-stick blood glucose reading by as much as 30 to 45 minutes.
I The insulin infused by a pump has an effect on the blood glucose two hours later — too far behind the need for it. In contrast, insulin from the pancreas acts immediately.
Nevertheless, I have to give credit to the pump manufacturers for trying. One future solution is an implanted pump that would deliver insulin right into the bloodstream rather than under the skin, but that would only solve the insulin lag problem, not the measurement lag problem.
Some of the important features that all four MiniMed pumps share include:
I Changes can be as small as 0.05 units of insulin.
I The pumps store up to 90 days worth of information about insulin dosages, which can be downloaded to a computer.
I The accuracy of the delivery of insulin is plus or minus 5 percent.
I An occlusion alarm rings when the line of insulin is blocked.
I An over-delivery alarm prevents delivery of too much insulin.
I Remote controls are available to remotely give the bolus dose without exposing the pump.
I A Bolus Wizard Calculator combines blood glucose readings that you enter (515/715) or that are transmitted from the continuous glucose monitor (522/722) with food information that you enter to calculate the proper bolus.
I The bolus can be delivered immediately, either as a square wave (it's delivered slowly over 30 minutes to eight hours) or as a dual wave (part is delivered immediately and the rest by square wave).
I The smallest bolus is 0.1 unit.
1 The basal rate range is between 0.05 to 35 units per hour.
1 You can set up to 48 different basal rates (the day can be broken up into 48 different time periods) in three patterns.
1 Temporary basal rates can be programmed to manage special circumstances like sickness or prolonged exercise.
1 You can set up to eight blood glucose testing alarms per day as a reminder.
1 The keypad can be locked to prevent accidental changes or children changing the dosages.
1 An alert can be set to notify you when the reservoir of insulin is low or when a certain amount of time remains before it runs out.
1 They're water-resistant (but can't be worn in a shower or when swimming).
1 They require one AAA alkaline battery.
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