Since my small vessel stroke last September, I have become more aware of my activity level and blood pressure (BP). I bought a new Omron BP monitor, and I bought a fitbit type device too. It wasn’t an actual Fitbit or an Apple watch; it was a Chinese knock-off. I’m too stingy to spend big bucks on that kind of gear. So, I ordered a wrist band monitor in the $25 range. It didn’t take long to figure out that the BP readings were wildly inaccurate.
These devices rely on green LEDs and a sensor to monitor the distension and relaxation of small blood vessels in the wrist, and the device’s micro-controller does some fancy math to determine the first and second derivatives of the recorded waveforms in order to calculate proxies for things like heart rate (HR is pretty accurate), BP (your mileage may vary) and oxygen saturation (O2 sat is comparable to that of a finger monitor). Steps are sensed by internal accelerometers (probably as or more accurate than an inexpensive pendulum-based pedometer).
Charging this device was a pain in the butt because the USB connector was literally part of the wristband and connecting it to a USB port was difficult and unreliable because of its curved shape. After a couple of months, I decided to try something different. My next wrist monitor was a WoFit GT2 Smart Watch. It’s basically the same device that is sold under the Synoptix badge. It was about $50, and it did a reasonable job of monitoring HR, BP and O2sat. In addition, it monitored and reported sleep quality, steps, and could even do an EKG rhythm strip. One nice feature that it had was that it let you to enter your BP as recorded by a BP monitor. This allowed the watch to adjust its own reading by applying the correct bias. BP measured at the brachial artery isn’t really the same as BP measured in smaller arteries in the wrist. This device lasted about eight months before it died. The battery refused to recharge. Merde!
Last month I bought an AMAZTIM C20. It was $70. It doesn’t produce an EKG rhythm strip like the GT2, but to be honest, if I experience a brady- or tachy-arrhythmia, I’m going to go to take my pulse and then go to the ER rather than look at what my smartwatch says. The C20 looks and feels more rugged than the GT2; I hope that it lasts longer. I don’t like the way that its phone app reports sleep, but that’s a minor quibble. I sleep well enough these days. If I had to identify one thing that I do not like about it, it would be that in order to choose your step (activity) target, you have to choose from a menu in which the very lowest level of activity is 4000 steps. For young, healthy people, this level of activity is easily met. For me, not so much. I aim to achieve 2000 steps/day, and when the weather is nice, I may get 2800-3500 steps. When it has been raining or is very cold or 102+ outside, I am doing well to achieve 1800.
Needless to say, I am at risk of developing an inferiority complex from this app that demands more activity than I can achieve in my daily routine. Oh, that reminds me, the GT2 and the C20 each come with a downloadable iPhone and Android phone app.
Hmm, maybe I can hack the iPhone app and add a 2000 step target for woos-es.