When film ruled the world

♪♫♪♪♫ So Mama, don’t take my Kodachrome away…♪♫♪♪♫

--Paul Simon, 1973

Readers half-way through their statistical lifespans, or further, likely owned a film camera at one time or another. For you younger readers, back in our day, things were different. Our objects didn’t multitask. Rather than having an iGadget that did everything, we used typewriters to send mail, phones plugged into walls to make calls, pocket calculators for math that was beyond our mental abilities, watches on our wrists to tell the time, and our contact lists sat on top of our desks in circular filing cabinets called Rolodexes. Yes it was all very primitive, but we got by just fine. And to take pictures we used a camera that was only a camera. Its sole job was to make images on this stuff called “film,” that you had to take to a camera shop, who then sent it to a big lab somewhere to be processed. It took us a week or more to get our pictures back after a big event.

The King of these cameras, used by pros and avid shutterbugs alike, was the SLR. That stood for Single Lens Reflex. These were heavy metal beauties that took a range of interchangeable lens. You would have a wide-angle lens, a normal lens, a portrait lens, and a variety of telephoto lenses. Oh, and if it was dark—defined as not outside in bright sunlight—you needed a flash, too. Back in the day, photography required lugging some serious gear.

The great innovation of the SLR, over the cameras that came before it, was that you could hold it up to your face and actually see through the lens that was taking the picture. Prior to that, we had cameras you held at waist-level and looked down into, or ones that used a view finder that never quite let you see the same thing the camera was seeing. The technological marvel of the SLR was accomplished by using a mirror and a large glass prism to bounce and flip the incoming light around. (Camera lenses see the world upside down from they way your brain does, but that’s a subject for someone else’s blog.) It was this pyramid-shaped prism, sitting proudly dead-center atop generations of SLR cameras that gave them their distinctive look—a look that became so iconic that it can only be described as cameresque. For decades before the digital era, if you said the word “camera” to almost anyone in the world, they would picture in their mind’s eye the iconic pyramid profile of the SLR. I bet you could even have gone into the heart of Africa with a deck of flash cards, and if you showed a clip-art drawing of a SLR to the bush people there, they would have known exactly what it was.

And just what the fuck does this have to do with the Snap insulin pump? Why, everything, of course. Because buried inside the Snap is a prism that reminded me of the cameras of my younger days.

OK, granted. It’s a lot smaller. And plastic. But still…

So what is it doing there? Surely there’s no film in the Snap. Well, I don’t actually know that there’s no film inside a Snap, as I’ve yet to dismember one (don’t worry, it’s on my “to-do” list). And, come to think about it, that description is less than accurate. Technically, the Snap prism isn’t part of the pump. It’s part of the infusion set, built into the tubing connector. Here, look for yourself:

 Remember when I told you that Snap infusion tubing was unique? That you couldn’t use the left over Luer lock sets from your Animases, Cozmos, Spirits and pre-Paradigm Med-T pumps? Right. The part of the Snap tubing that connects to the pump is unique, proprietary, and not compatible with the closet-full of horded infusion set supplies you’ve been jealously guarding just-for-in-case you lose your health insurance.

Sucks to be us.

Now, when Med-T did this a while back, I cried foul. I saw, and still see, no technological need for the Paradigm ® Tubing Connector. (Seriously, is there anything these people haven’t tried to patent, trademark, or copyright?) To me it seemed like they replaced the Luer lock to make sure no one else’s infusion sets would work with their pumps. It was a monopolistic marketing move that provided no technological improvement. Bastards. Hell, even the highly innovative t:slim pump uses the standard Luer lock infusion pump connections, making it fully backwards-compatible with your supply closet. Although, in the case of t:slim this is a mixed blessing, because it created the bizarre “pig tail” connection that people either love or hate.

Now, just to be clear: the body-set end of the Snap infusion set is compatible with old gear, but the tubing and connector are not. I suppose you could use up some old supplies by just reusing the Snap tubing and connector with surplus body sets until the needle that pierces the penfill of insulin gets so dull that you can’t force it through the top membrane anymore…

But I digress.

The prism is actually part of the Snap’s occlusion detection system. For you pump virgins, (that sounded a lot worse than I had intended it to) an occlusion is any blockage in the insulin delivery system. Often occlusions are caused by kinked tubing. Just as twisting a garden hose can cut off the water flow, a twisted infusion tube can cut off the life-sustaining flow of insulin. At other times occlusions are caused by bent or twisted cannulas inside the body. And sometimes occlusions are caused by biological fouling—basically, the cannula gets plugged up by fat, dead white blood cells, or whatever.

Pumps are designed to detect occlusions and alert the pumper to the risk, hopefully before the lack of insulin puts the pumper through the roof blood sugar-wise, or into the ICU in a coma. Pumps do this by monitoring the pressure of the system. Too much pressure indicates that the insulin isn’t getting through, and an alarm is triggered. Realistically, if the problem is a blockage during basal delivery, most pumps won’t warn you in time. There’s just not enough insulin being delivered to build up a high enough pressure. Accordingly most occlusion alarms happen inconveniently during an attempt at meal delivery, and your food gets cold while you try to trouble-shoot the problem and then worry about what percentage of the failed bolus really got into your body.

Sucks to be us.

Now, truth be told, I’m not really sure how other pumps detect occlusions, but I know how the Snap does. It uses Kodachrome.

Well, not quite. But it uses a cousin of the good ol’ SLR technology to ferret out occlusions. The prism on the hub is installed above an ultrathin sheet of material that lies against the tubing. The hub, when attached to a Snap body, and when the body is snapped onto a controller, fits snugly down inside of the pump:

 The prism is mated to a window on the controller :

 This window sends out a light beam that travels through the prism and back into the window again. So long as the light is sent and received, all is well. However, if the pressure builds up too much in the tubing, the light is blocked off as the expanding tubing pushes the ultrathin material upwards. If the pump can’t see either one lamp or two, it knows the British have already gotten to Boston and captured the church. It doesn’t really matter if they came by land or by sea, the shit has hit the fan. When the pump can’t see the light, an occlusion alarm goes off. All thanks to the little prism built into the infusion tubing connector. Very clever, Black and Decker. (’Cause very clever, Asante don’t rhyme.)

The Snap may not take snapshots, but it has camera technology under the hood.

Next time: The light of your life