To give you a better understanding of PowerShell, we should first define what a shell is. No, we're not talking about a turtle's shell. :) In computer science, a shell is a user interface that gives you access to various services of an operating system.
SaO2 can be measured either by ABG analysis or by pulse oximetry. SaO2 refers to the amount of oxygen bound to hemoglobin in arterial blood. SpO2 simply means that the SaO2 was measured using pulse oximetry.aO2 is an invasive measure of the % of Oxyhemoglobin (oxygen saturated hemoglobin) in the blood using lab tests on arterial blood. SpO2 noninvasive measure the % of saturated hemoglobin in the capillary bed and does not identify what is saturating the hemaglobin.
   PaO2 is the Partial pressure (arterial) of oxygen in the blood. That is, if you took the oxygen gas in all the blood, and put it into a box by itself, what pressure would it exert on the walls.  PaO2 is the Partial pressure (arterial) of oxygen in the blood. That is, if you took the oxygen gas in all the blood, and put it into a box by itself, what pressure would it exert on the walls.