Quote from dirtyhippiegirl
Background: ventilated burn patient. No real medical history per family. (So don't know if this is reliable or not.)
saO2 is reading 86%-88%. It's reliable -- same in every conceivable extremity, good waveform, heart rate is matching his leads. However, this guy's ABGs are all within normal limits with his sO2 between 98%-100%. His CBC was also normal.
Any thoughts on what could cause this?
SaO2 is the measured value and the "a" stands for arterial. If you are moving a pulse ox probe around and looking at a waveform you are measuring the SpO2.
If you are looking at SO2 on the ABG then you are looking at a calculated value. It is calculated from the pH and PaO2 with an algorithm which assumes normal O2 affinity, normal 2,3-diphosphoglycerate concentratons and no dyshomglobins or hemoglobinsopathies.
If it is a true SaO2 reading from a co-oximeter machine you will have the most accurate number.
Someone with severe carboxyhemoglobin or MethHb may have a very normal ABG if it is not ran with a co-oximeter.
Many labs will run the co-oximeter values with the ABG but will only report what is ordered. The exception might be a Respiratory Therapist ran lab but then they will have to get an order to place it in the chart. Usually they have no problem writing a standing protocol order for that.