Pulse Oximeters are relatively new for most freedivers. Information about a particular pulse oximeter and its usability for freedive training is hard to find. Therefore a comparison of output and usability might be very handy, both for users and potential users.
There is already information posted on the forum about pulse oximeters, a lot of which comes from Eric fattah. From the posts I conclude that there is a huge difference among reported (low) O2 saturation values due to the generation (age) of the equipment, newer equipment being more accurate. Besides accuracy of low O2 saturation measurements there is also mention of the delay factor. The speed of the rise and fall of O2 is supposed to give quite different measurements depending on the model of pulse oximeter used, regardless of the recorded samplng rate. Furthermore there is also the difference in measurements caused by different types of sensors (for example: finger sensor, ear sensor, sensor on the forehead, reusable sensors versus disposable sensors, waterproof sensors?). All of these factors can produce different measurements, only caused by different equipent, which must be taken into account when comparing output or choosing equipment. Can there also be a difference caused by ambient temperature or the way the equipment is used (most will not be trained in the use of a pulse oximeter)?
Quote from erik fattah post in
http://forums.deeperblue.net/showthread.php?threadid=41519
Of the 1st generation, the Ohmeda is very inaccurate, and the Physio-control Lifestat 1600 is by far the most accurate. Of the 2nd generation, the most accurate are the Nellcor N-395, Nellcor N-595, Masimo Radical, and Ohmeda 3800 & 3900. The Masimo Radical with the earclip sensor is the most accurate of all oximeters, followed closely by the Nellcor N-595 with the forehead sensor.
A question that might be interesting is which difference there is between equipment for freediving use and how much effect this has on measurements caused by for example:
1 generation/ age of the equipment
2 inconsistency of readings (same equipment, same test, different readings)
3 delay factor in displaying changes in O2 saturation
4 sensor type
5 ambient influences like temperature, improper use of equipment, ...
I hope it is posible to say something about which equipment might be best suited and, when comparing output, how much gathered data can differ caused by different equipment.
Another question I would like to ask is if you think the differences between equipment are relevant when you always use the same machine for training? And for comparisons with others?