How reliable/accurate are pulse oximeter results?

Without going into a complicated history which involves my son being diagnosed first with asthma-like problem, then with pneumonia, then with pneumonia+asthma, please tell me if oxigentation measurement done by a pulse oximiter is a reliable indicator of a problem, in the absense of other symptoms. My 4-year old is behaiving fine, eating again, and being playful and energetic. No breathing problems. No wheezing or crackles. Oxigen was shown to be at 93%. This freaked the Dr out and she gave us an inhailer with albuterol. I don't want to use it (my son hates this stuff). I'm puzzled at being confronted with a normally behaving child (who coughs a little) and an oxygen reading which says he needs breathing treatments...

Pulse oximeters are reasonably accurate most of the time. It's important to treat the patient, not the equipment. When in doubt, an arterial blood gas is 100% accurate.

The normal oxygen saturation for a normal healthy person is 95-98%. Even when I was having lots of trouble with asthma when I was first diagnosed, I was always 95% or better.

Sometimes a pulse oximeter doesn't read properly because of movement, light getting to the sensor, plastic nails, anemia, nail polish, poor circulation, aberrant hemoglobins, and there are a few other reasons for a poor reading. If your son was at 93% saturation, that's low but not critical.

Depending on how your doctor diagnoses asthma, she might be very observant and uses all the potential symptoms to see disease. There is a possibility that your doctor thinks a cough and low pulse oximeter reading mean that your son has asthma needing treatment. Depending on the intensity of the cough, I would probably agree. I think the cough is the most important sign of asthma that you have described. If the cough was severe, I think your son would have been prescribed an inhaled steroid for daily use.

If you have an Albuterol inhaler for your son, what does it say to do with it? Use X inhalations, Y or Z times a day as needed? Use X inhalations every four hours? Maybe your doctor was just being prudent and giving you the resources to treat your son if he has an asthma attack.

For some background, I have asthma. I have normal breath sounds, a cough that improves with Albuterol or inhaled steroid (depending on how bad it is), I don't cough anything out, I get short of breath when working hard, I can function just fine in normal activity, my pulse ox runs 95% consistently, my breathing is normal when I am not symptomatic, and you wouldn't be able to tell that I have asthma by looking at me. Sometimes I use a treatment or two a week of Albuterol and sometimes I go on Advair because my cough gets bad. It all depends on the weather, air pollution, stress, and any asthma triggers I am exposed to. I was diagnosed because I had a horrible cough that wouldn't go away.

Oximeter measures the oxygen level in the blood. According to textbooks/other guidelines, the normal level is 96-100% if less, then the patient is indicated as hypoxic (with various level of hypoxia: severe, significant, or just hypoxia). The accuracy of the meter itself is about 98-99%.

Hypoxia has no signs but symptoms--hence no wheezing or crackling, unless hypoxia is due to other disease/disorder.

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