Some forums threads suggest another solution to fix the gray out iPhone 4S Wifi issue: placing the iPhone 4S in a refrigerator or freezer for several minutes, for they considered the 4S WiFi issue after iOS 7 update is caused by the heating issues.
An ABG test uses blood drawn from an artery, where the oxygen and carbon dioxide levels can be measured before they enter body tissues. Partial pressure of oxygen (PaO2). This measures the pressure of oxygen dissolved in the blood and how well oxygen is able to move from the airspace of the lungs into the blood.
Why It Is Done. An arterial blood gas (ABG) test is done to: 1  Check for severe breathing problems and lung diseases, such as asthma, cystic fibrosis, or chronic obstructive pulmonary disease (COPD) . 2  See how well treatment for lung diseases is working.3  Find out if you need extra oxygen or help with breathing (mechanical ventilation).s blood passes through your lungs, oxygen moves into the blood while carbon dioxide moves out of the blood into the lungs. An ABG test uses blood drawn from an artery, where the oxygen and carbon dioxide levels can be measured before they enter body tissues. An ABG measures: 1  Partial pressure of oxygen (PaO2).