Doug, I'll take a stab at that question in relation to the Emfit sheets or mats that were mentioned in that Finnish research linked above. The Emfit sheets or mats were not really designed for the purpose of measuring transcutaneous CO2. During a PSG, clinicians can apparently do a number of sensor related magical feats with those nifty mats---monitor respiratory effort/rate, leg movements, positional changes, etc. They're just nifty pressure-sensitive mats that pick up on delicate and not-so-delicate pressures. It's up to the clinicians or researchers to frequency filter or otherwise signal process whatever they happen to be looking for by the way of signal-unique pressure changes---that are typically applied by the patient in a number of ways. So apparently the Finish researchers discovered that if they filtered or signal-processed just right, they could see the slight pressure elevations on the sensor mats due to "transcutaneous CO2 tension or pressure"----meaning CO2 tension or gas pressure given off at the skin.dsm wrote: What is the significance of a rise in TcCO2 (carbon dioxide tension) in anyone ?
Back to the concept that these mats were designed for a variety of other purposes. However, the medical industry can measure CO2 in a variety of ways. One way is to directly measure CO2 in the blood gas. Another way is to measure CO2 in the exhalation. However, a great way to monitor CO2 happens to be via a probe on the skin using what is referred to as transcutaneous CO2 monitoring. Utilizing the transcutaneous CO2 measurement method, the gas pressure or tension given off at the skin is what's actually measured. The various measurement methods all attempt to tell pretty much the same CO2 blood-gas story (each method having unique advantages). So when the Finnish researchers were noticing CO2 spikes, the fact that they were skin-based measurements wasn't so much the central issue as the incidental finding itself may have implied that something unknown is perhaps occurring in an unidentified SDB pathology/condition.
I think the only point being made by the Finnish researchers is that the transient characteristics of those CO2 spikes were simply different and of unknown implications for variable breathers who didn't qualify as PB breathers. And I don't think it's so important that they happened to be measured transcutaneously---perhaps more important that the Emfit sensors seem well suited to pick up on the spikes. A few posts above SAG speculates that maybe those CO2 spikes correspond to subcortical arousals. Since cortical arousals are easily measured during a PSG, but subcortical arousals are not... me thinks that's a darn good place to start wondering. I'm thinking that equipment is going to be a no-brainer choice for SAG's labs. Even if the Finnish research turns out to be non-reproducible or otherwise flawed, he's got some great PSG monitoring equipment to use in the various ways those mats were originally marketed for sleep lab use.dsm wrote:Is the point that it affects energy levels or fitness ?
Okay. I strung a bunch of best guesses together. But that's my best take. Caveat emptor none the less...
