Navigator

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tomjef Posted: Fri, Dec 19 2008 6:37 PM

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I've been using the FreeStyle Navigator since Aug 2008. I've been pleased with the results, but sometimes there will be at least 30 points difference between BG and interstitial fluid. You have to get used to the fact that the device is not monitoring BG.

Since I live in Arizona, and only get to Joslin once a year, I haven't been able to take very much advantage of the wonderful work being done by Dr. Howard Wolpert.

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RobertIA replied on Thu, Mar 26 2009 7:55 PM

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tomjef:

I've been using the FreeStyle Navigator since Aug 2008. I've been pleased with the results, but sometimes there will be at least 30 points difference between BG and interstitial fluid. You have to get used to the fact that the device is not monitoring BG.  

tomjef,  I am asking out of curiosity as well as interest in the Navigator for more information and how you are getting along with it.  How is it connected and how easy is it to read and compare to other methods.  Have you had to change batteries?

I have been researching about this and other similar devices plus possible plans to combine the navigator with the aviator for open loop use.  It is getting very interesting and I am going to continue to follow this development.  Any insights and information will be appreciated.

Bob

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tomjef replied on Thu, Mar 26 2009 10:12 PM

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Sometimes the continuous mode (CM) and the BG will only differ by a couple of points, and other times there will be 30 or 40 points difference, and either one can be the higher. It's more useful to watch how the CM is changing, whether it's going up, or down.

I have modified the hard plastic case that comes with the Navigator, so the case is attached to the handlebar of my bicycle, permitting me to see what the CM is doing while I ride. You can't make the CM display stay on continuously, but it just takes one button push to turn it on for about 12 seconds. Any button push within 12 seconds keeps the display turned on.

The sensor is inserted in the upper arm at 90 degrees, to a depth of about 5 millimeters (0.1 inch) by a relatively large sensor delivery unit (inserter) that is discarded. The sensor and the transmitter are held in place by a plastic sensor support mount about 60 mm x 32 mm (2.4 x 1.3 inches) and sticks up about 12 mm (0.5 inch). The sensor support mount is held in place by an adhesive sheet that is 100 x 120 mm (4 x 4.75 inches) with a hole in the middle.

There is no physical connection, only radio,  between the transmitter and the receiver, so the receiver can be anywhere within 10 feet of the transmitter. I keep the receiver in one of the side pockets of my trousers, or on the handlebar of my bicycle, or in the bookcase above my head when I am in bed. The receiver is 85 x 70 x 25 mm (3.5 x 2.75 x 1 inch). The screen of the receiver is 42 x 30 mm (1.625 x 1.125 inch). The numbers on the screen are 10 mm high. The software in the receiver limits the life of the sensor to five days, but it is possible to leave the sensor in place and use it for an additional five days. The software requires you to do four calibrations, by doing a BG test using the FreeStyle BG meter that's very conveniently built into the receiver. After sensor insertion, the receiver tells you to do a BG test at 10 hr, 12 hr, 24 hr, and 72 hr after insertion. You can do additional BG tests with this BG meter whenever you wish. Only the first BG test that's done after the receiver tells you to do a test for calibration, is used for calibration. No other BG tests are used for calibration.

The CM reading on the receiver is updated every minute, and is displayed along with an arrow that points 90 degrees up, 45 degrees up, horizontal, 45 degrees down, or 90 degrees down. The meaning of the arrows is obvious, and very useful.

The receiver uses two AAA alkaline batteries, which last for up to 60 days. The transmitter uses one Silver Oxide 357 HC watch battery, which lasts for up to 30 days. The status of these batteries is reported when you make the appropriate menu selections in the receiver. Sensors are packaged and shipped six at a time, and one 357 battery is included in this package.

If anyone has any questions I'll be glad to try and answer them.

Tom

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RobertIA replied on Thu, Mar 26 2009 10:24 PM

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Tom, 

Your answer is very much appreciated.  This is the type of information that I was looking for.  I had not found this in the reading to-date about the navigator, but I am just starting.

Thank you very much.

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JoyceL replied on Fri, Mar 27 2009 3:30 PM

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Hi

If you are planning to see dr. Wolpert,  perhaps, you can make an apt to attend our sensor logic class or met with his educator on the same day

JoyceL

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Melissata replied on Fri, Apr 3 2009 12:39 PM

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Hi there, My son and daughter are both using the Navigator and I would be happy to answer any questions that you may have about it. It has been life changing for them, and for us since our daughter is special needs. Right now Abbott is having manufactoring issues, so hopefully that will be worked out soon. We are using a broken transmitter right now and they have no idea of when they will be able to get us a new one. My son started using his in November and daughter started in January. I cannot imagine either of them not having it now. My son has hypo unawareness, so it has helped us feel much better about his living alone.

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GreenGiant replied on Mon, Apr 6 2009 12:44 PM

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You say the first required finger stick for calibration is at 10 hours?  do you have to wait that long to start getting readings?  I am using the minimed CGM with my paradigm 522 pump.  I don't have a receiver for the CGM, it is built right in to the pump.  After insertion the pump asks for the first BG reading for calibration at 2 hours, and I don't get any reading from the CGM until after that first calibration at 2 hours.  Overall, I am very pleased with the CGM.  It is a really great tool whose use I believe will become more and more common.

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Melissata replied on Mon, Apr 6 2009 1:52 PM

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Hi Fred, Nice to "see" you again! You don't get readings for those first 10 hours, but many people believe that is why the Navigator is so darned accurate. I know many people that complain about the two other systems and have even stopped using them because they just don't feel that they are nearly accurate enough. They are doing trials of a Navigator with a 1 hour warm up time. One CDE explained that the longer length of time for warm up is because of the trauma to the skin and that it takes some people longer for the sensor to be able to read well. In fact Dexcom reps have been known to tell their customers that are having accuracy issues to give the Dex 8 ot 10 hours to start it. This system works well for us, because I don't have to look at Melissa's pump. The range is awesome on it and the alarms are loud. It has the built in Freestyle meter and uses the Copilot software, which is the same as the Cozmo, so both can be downloaded together. We are so sorry that we will lose the Cozmo in less than two years and are hoping that something new is out by then. The thing that I like best about this system is that you only need to calibrate it 4 times in the entire 5 days that you wear it. And the first 3 are within the first day, so you really can forget about doing calibrations for much of the time. How much of the time do you feel that your CGM is reading exactly the same as your meter? Is it catching you lows? I know that was your reason for getting one and Michael's as well. Mary

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GreenGiant replied on Mon, Apr 6 2009 3:08 PM

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I find the two readings to usually be within a few points of each other, so I am pleased with the accuracy.  Heck, you see that much difference between 2 finger sticks one right after the other.  The best thing is being able to see the graphs and looking at the trends.  I have been able to make meaningful changes to my basal rates because I can see what's happening.  When I first got it my basal rate in the middle of the night was way off, but I didn't know it until I could see graphs of the night time bg readings from the cgm.  To answer your question about lows, YES this thing is amazing in it's ability to alarm if you go above or below the programmed limits.  When I first got it, the trainer said the endo wanted the low alarm set to 80.  It was going off so often that I lowered it to 70.  That seems to work well.  It isn't going off all the time, and if it does, at 70 I can decide what I need to do before I get too low.  As a result, I haven' had a bad low since I got it.  I have two main complaints.  I use 90 degree infusion sets.  (mimimed quicksets)  I tried angled sets back when I started pumping, and didn't care for them as much.  With the minimed cgm I don't have a choice, the sensors are a 45 degree insertion.  I'd prefer 90 degree.  At least it did come with a spring loaded inserter, although even with that, I had ruined 2 sensors so far with bad insertions.  At $30 a pop, that's $60 down the drain.  Ok, I have good insurance and it didn't cost me the $60, but that's not the point.  By the way, for what it's worth, the list price on a box of ten sensors is $300.  I pay a $20 co-pay, so I only pay $2 each for the sensors, not too bad.  My other complaint about the minimed CGM is range.  I believe they claim either 3 feet or 6 feet, I don't remember which.  I'm not getting that kind of range.  I have to wear the pump on my belt on the same side body as the sensor is inserted.  If I move the pump to my other side, I start to get weak signal alarms.  This is not really a big problem during the day, but at night I have rolled over in my sleep putting the pump behind me, causing it to lose signal.  I've been clipping it to my underwear to prevent this from happening.  Also for those following this thread and comparing brands, the minimed transmitter is a very small, lightweight sealed unit with a rechargable battery inside.  The charger is a very small unit as well, which uses a AAA battery to charge the transmitter, so there is no power cord.  It is a very fast charger, and a full charge lasts 14 days.  the software in the minimed pump sends a "Sensor End" message at the end of 3 days, but you can tell it to start a new sensor, and you can get another 3 days out of the sensor.  I don;t know if it would work a 3rd time, but after 6 days I'd want to change the site anyway.  I don't normally go the whole six days, but if I get a sensor end and it's not convenient to change sensors, I will re-start it as a new sensor and leave it until the next morning when it's more convenient.  All in all, I am very please with the system.

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Melissata replied on Mon, Apr 6 2009 6:01 PM

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Just like anything, each has it's pros and cons. Some of the reasons why the Navigator is so great for kids is the range. It is supposed to be 10 feet, but most people find that it is at least 20 or 30. They can have the receiver in their room and the kids sleeping in another. One mom says hers works while her daughter is upstairs napping! One of the reasons that we got it was lows in the pool at school. Now someone holds onto the receiver and knows exactly what is going on. Nothing needs to be recharged on this unit and Abbott supplies the batteries that you need for the transmitter. The receiver just takes 2 AAAs. I have heard about the issues of losing the signal on both the Minimed and Dexcom but that isn't a problem with the Navigator. Right now we are waiting for a new transmitter though because a little alignment pin broke off of ours. They are saying that it is an inventory interuption, but a lot of people are speculating that they are fixing a couple of issues. For a while Michael couldn't get sensors, but that problem is finished now. This system is the most expensive one, but we are really lucky to have it covered 100%. Michael is paying a high price for COBRA coverage, but these supplies alone make it all worthwhile. The price per sensor is upwards of 65.00. We have also made some big changes to basal rates at night and found that she has likely been sleeping through a lot of lows all along. She has stopped being able to feel most of hers, and that may be the reason. I am really glad that it is working so well for you Fred. I have a friend that has a son on a Minimed one and it is doing him no good. He ignores the alarms, sleeps through them at night and gets lots of bad calibrations or does none, so gets no readings all night. I do like the 90 degree sensor and the hole that it makes is so tiny you can't even find it, even right after you take it out. Funny thing though, that just today I used an Inset 30 and it is awesome. She has always hated angled sets, but this one has it's own inserter and she said it didn't hurt at all. I'm hoping to use some areas that don't work well with the 90's.