Since you're in CA, I'm refering to California Code of Regulation Title 22 Division 9 Chapter 2 Article 1
§ 100063. Scope of Practice of Emergnecy Medical Technician
(a) During training, while at the scene of an emergency, during transport of the sick or injured, or during interfacility transfer, a certified EMT or supervised EMT student is authorized to do any of the following:
...
(3) Obtain diagnostic signs to include, but not be limited to, the assessment of temperature, blood pressure, pulse and respiration rates, level of consciousness, and pupil status.
Taken off CA EMSA website
http://www.emsa.ca.gov/laws/default.asp >>
www.emsa.ca.gov/laws/files/ch2emtIupdate.pdf
Personally, I'd consider pulse oximetry a diagnostic sign that you could record and report, however, in most counties in CA, you cannot base your treatment off of it. In fact, usually it's something like "BLS treatment If the patient is showing signs and symptoms of shock, administer O2 by NRB 15 L/m", or something like that. Some counties have something like "Treatment algorithms should be used as a guideline and are not intended as a substitute for sound medical judgement. Unusual patient presentations make it impossble to develop a protocol for every possible patient situation" (taken from Alameda County Protocols) so be sure that pulse oximetry isn't the only factor for why oxygen should/shouldn't be administered (remember a lot of EMTs/Paramedics, the ones they'll compare you to, would administer O2 "just because" so you should include why you didn't administer other than "it's not indicated", list signs and symptoms of the patient being saturated well without supplemental oxygen). Some counties have under their protocols for pulse oximetry "Oxygen administration is not to be excluded based on a saturation value obtained by pulse oximetry. Patients with conditions including, but not limited to, ischemic chest pain, trauma, respiratory conditions, congestive heart failure, carbon monoxide poisoning, and complications of thrid trimester pregnancies, etc. should receive appropriate concentrations of oxygen regardless of saturations. Like other physiologic parameters, pulse oximetry is used only as a guide in providing overall care to the patient." (taken from Santa Clara County Protocols).
Really you should discuss with your company what they are comfortable with, review county protocols to see if there is an optional scope of practice for EMTs, or if it's allowed in your county (e.g. your protocols defines stuff like "baseline vital signs: pulse rate, blood pressure, respiratory rate, pulse oximetry" (taken from Santa Clara County protocols), and then in the BLS treatments/algorithms, it says "baseline vitals") and what they (the county) have to say about it. Things are defined at the state level, and then at the county level, so you gotta make sure the two don't contradict. For something that doesn't really offer that very valuable information, it's kind of like playing with fire. I'd prefer to just ask the RN. I think it could be viewed as an non-invasive way to obtain a diagnostic sign, and that you are going above and beyond for your patient buying a personal pulse ox, or that it's a cheap unrealiable/not approved by your company, or by the county medical director, technology that could cause headaches by giving you a false sense of security, or esclating somthing that doesn't require esclation e.g. a patient satting at 85% on your pulse ox, but is asymptommatic.
I usually record the last BGL and SpO2 from the RN, write that in my PCR, and report that to the receiving facility e.g. "1415 SpO2 99% on RA, BGL 120 mg/dL per RN" like that (in my PCRs).
