Getting Ready for the Paradigm REAL Time 522 Insulin Pump
Posted Jun 05 2009 5:06pm
In anticipation of getting the Paradigm 522 Real Time System within the next couple of weeks, I've been boning up on the technical information for the pump/sensor/transmitter, as well as preparing my own diabetes management for the big change.
What does this mean? Well, I'm going to be doing some major testing during the next two weeks to establish the most consistent ratios possible. Granted, I'm enough of a control-freak that I test ratios monthly. Basal rates, CHO ratios, correction ratios (ISF), and bolus patterns are all a part of this monthly routine. Chances are that testing them again - I plan to do at least three of each, while I usually only do two - will not result in any huge change, but I want a baseline so that I can evaluate the efficacy of using the Real Time System. For this reason, I've also ordered a home A1c kit, though I don't expect to see much of a deviation from my last results of 6.2%.
I also want to truly see, in black and white, if my average of 12 manual BG tests per day is really missing The Big Picture.
But I won't bore you with those details...
I also want to know as much as I can beforehand about how the transmitter/sensor system works. So I sent an email to Medtronic of Canada asking for some sort of technical information. The brochures and informational packages on Minimed's website are disappointingly lacking in details about this new system - it's all "how great is this" and "get better control" and blah blah blah. Meat, people. We need some meat on this thing. Now, if you're a Canadian and you have a Minimed pump, then I'm sure you have, at some point, called or emailed the customer service line and spoken to Rachelle (whom I like to call my 'contact'). And I'm sure that it won't surprise you that she came through on my request, as she has for the past three years. She emailed PDF copies of the user guides for both the 522/722 and the sensor/transmitter. Oh, and she's sending me some free samples of the Sure-T Infusion set...but that is better kept for another post.
I'm not going to post the documentation that Rachelle provided me with, but I will do my best to summarize the salient points - in no particular order, of course! I'm not going to go into much technical detail of the actual pump, as it is the same pump as the 515/715, but will focus more on the transmitter and sensor applications and how they pertain to the operation of the pump.
Paradigm REAL Time Transmitter/Sensor Specifications & Features:
Blood Glucose Threshold: 2.2 mmol - 22.2 mmol (40 mg - 400 mg) *Like your glucometer, the Sensor is limited to values it can read accurately. For example, the results range of the Freestyle Mini (Flash) is 1.1 mmol - 27.8 mmol (20 mg - 500 mg) and any values below or above this will not display as a number, but as "HI" and "LO".
The sensor can be worn for 72 hours and MUST be calibrated twice a day (every 12 hours). More frequent calibration (4 x daily) means more accurate BG results. The status screen on the pump displays the remaining life of the sensor being worn, and an alarm will sound when the sensor is no longer any good.
The Sensor measures interstitial fluid. Glucometers measure whole blood or plasma, and scientific studies indicate that interstitial fluid and whole blood/plasma concentrations, while not identical, are very close with the exception of rapid blood glucose level changes. Plasma/whole blood reflects these changes more accurately, while interstitial fluid lags slightly and can cause a few minutes delay in accurate readings.
Once the sensor is inserted it takes 2 hours to initialize. That means that, for the first two hours, there are no BG levels being recorded. After the initialization, a manual BG must be taken with a glucometer, and then entered into the pump to be used as calibration for the sensor.
The sensors MUST be refrigerated prior to use, and then left - unopened - at room temperature for five minutes before insertion. Yep, I know, that's a big drawback on this one.
The sensor and 522/722 pump have alarms for everything, the following few being related to the sensor:
High Glucose - a user preset BG level. When the sensor detects a reading at or above this level, an alarm will sound and continue every five minutes until the sensor reading is below the set threshold. Alternately, there is a high glucose snooze function, much like on your alarm clocks at home.
Low Glucose - works just like the High Glucose alarm, except the threshold is a low number. Also has a low snooze function.
Meter BG Now Alarm - alarms every 5 minutes, when the sensor requires calibration. There is also a snooze option.
Cal Reminder - an optional alarm to remind to enter a manual BG for sensor calibration, above and beyond the BG Now Alarm.
The sensor can be inserted either manually or using the Sen-Serter. It is inserted subcutaneously, into the fatty layer under the skin, at a 45 degree angle.
The transmitter cannot be connected to a sensor site that is bleeding (bad, very bad). Minimed suggests waiting five minutes after sensor insertion before connecting the transmitter, to ensure that the site is not bleeding.
Alternate testing sites are not supposed to be used for sensor calibration. Fingertips should always be used when calibrating the system.
The status screen allows users to view graphs, current glucose levels, three hours of data and 24 hours. Arrow(s) next to the current glucose level show blood glucose trends; whether they are dropping or rising. One arrow up or down means BG has changed by 1.2-2.2 mmol in the last twenty minutes (relative to arrow direction). Two arrows up or down shows a change of more than 2.2 mmol over the last twenty minutes.
It is possible to bathe, swim and shower with the transmitter and sensor. However, Minimed gives direction that both parts of the system are to be covered by an occlusive dressing (IV3000) and submersion in hot water should be avoided.
Medtronic included a whole section in the user's guide that touches on the accuracy of the system and the results of clinical studies. I prefer to leave this kind of thing to individual research or a different post...so I won't be touching on it here, except to say that yes, the system obviously can be improved. And Medtronic themselves state that immediate therapy/treatment changes should not be made based on only the Guardian results; they should be confirmed with a manual BG test. Especially hypo/hyper episodes. But this is only the first in what is sure to be the next big deal for diabetes care.
As for the rest, well, I'm going to leave that to my own experiences. Good or bad.
In the meantime, have a look at this CGMS Comparison Chart. Looks like the Navigator is soon (and finally) to be another option - I've been watching and waiting forever on this one! (big Freestyle Fan here)