A COPD patient on chronic O2 therapy at 3 L/min comes to your office and asks if he can use a portable pulse oximeter. He wants to take the device with him when he goes outside. Are there any available?
Yes, there are ultra-portable pulse oximeters. One patient showed up at the office recently with a pulse oximeter the size of a match box. The oximeter is fully portable and is powered by a AAA battery which needs replacement every 4-5 months. Similar devices are used to alert climbers at high altitude to the potential onset of acute mountain sickness. Not all of them are certified for medical use though.
Nonin Medical, Inc. makes a portable pulse oximeter called Onyx. The price is about $ 300. See a flash movie.
Disclaimer: I am not connected to Nonin Medical, Inc. in any way and I do not recommend the device. It is just an example of a portable pulse oximeter.
Image source: Nonin.com