Insulin Firehose!

Today’s Diabetes Blog Week topic, diabetes bloopers, should make for some good reading. Here is my “man hit in groin by football” contribution. (BTW, this post contains videos that might not show up in your RSS reader. You might want to visit the page directly.)

I make a bunch of diabetes mistakes. (I know, I know. No stop; it’s true.) Mostly they’re miscalculations based on too little information or because I’m too busy/distracted/asleep to put the effort into getting things “just right.” Sometimes this causes me to have hypoglycemia and say ridiculous things, but mostly my life is pretty boring. (And that’s not always a bad thing.)

Occasionally, I make a big mistake or one of my devices malfunctions. Those are the real bloopers. Usually, they’re pretty tame and good for a “you’ll never guess what happened to me” story, but every so often one turns into a slow-motion, should’ve-seen-it-coming disaster.

This is one of those tales.

Those of us intimately familiar with the Medtronic Minimed Paradigm insulin pump know that it has an insulin-filled reservoir with a plunger at one end and tubing at the other. The tubing connects to our body, and the plunger is pushed by a very finely tuned stepper motor that pushes (usually) small amounts of insulin into our bodies.* Every few days, the pump has pushed all of the insulin into the body, and it’s time to change the “consumables.” That process goes something like this: disconnect the pump tubing from the body, rewind the motor, put in a freshly filled reservoir, start a “manual prime” to fill the tubing with insulin, insert a new infusion set into the body, attach the new tubing to the new infusion set, and give a very small “fixed prime” to finish the process.

As you can see, there are a few steps. If you do this enough times — about 100-150 times per year — you get pretty proficient. You can do it quickly in a variety of settings: at home, at the office, in the passenger seat of a car driving down the Kansas Turnpike, in a terminal of the Oakland airport, etc. In fact, it gets so routine you might be tempted to not think about it too much or to cut some corners. Which is usually fine.

A year or so after I got my first Minimed Paradigm pump, it started to have a problem. As noted above, there are two priming steps: “manual prime” and “fixed prime.” The manual one starts the motor moving rapidly toward the plunger and then continues more slowly after a sensor detects the initial contact. A typical manual prime moves about 20 units of insulin to fill the tubing. None of that prime goes into me initially. The fixed prime fills the space left by the starter needle and is only 0.3 units, which goes straight into the part that’s attached to me. It does this so that the next the motor steps, the insulin actually gets delivered and I can get it’s blood sugar-lowering goodness.

The problem with my pump is that the motor wasn’t detecting that it had made contact with the plunger. Can you see where I’m going?

On that day years ago, while changing my insulin and infusion set at the office, I started the manual prime like normal — that is to say, with the pump completely disconnected from my body. After seeing insulin drip (or rather spray) out of the end of the tubing I attached the tubing to my body and (by habit) pressed the button that should have delivered 0.3 units of fixed prime.

Instead, I heard a whirring of the motor as it delivered a whole bunch more insulin. I looked at my pump and saw that it still said “Manual Prime.” After disconnecting, I estimaged that I had given myself somewhere between 15-20 units of insulin, enough for about 150-200 grams of carbs, or about 1/3 to 1/2 of my daily dose at the time.

The good news is that I was ultimately unharmed by this adverse incident, and I had a new pump the next morning. But at the time, as I was drinking glass after glass of orange juice at my kitchen table with my meter next to me — having quickly driven home to be near new pump supplies, my refrigerator, and Lisa, not to mention a fire station full of first-responders just down the street — I made myself a promise that I’ve kept to this day: “I will never again attach the tubing to the infusion set before I see the flashing words ‘Fixed Prime 0.3u.’”

* — The pump bone connected to the reservoir bone. The reservoir bone connected to the tube bone. The tube bone connected to the infusion set bone. The infusion set bone connected to the skin bone. The skin bone connected to the fat bone. The fat bone connected to the blood sugar bone. . . .