Measurement of acidity or alkalinity of solution . The normal range is 7.35 to 7.45
pH > 7.45 = alkalosis
pH< 7.35 = acidosis
The partial pressure of oxygen that is dissolved in the<unk>  serum that is not carried by hemoglobin. The normal range is 80 to 100 mm Hg.
Used to assess alveolar-arterial (A-a) gradient, or [[PaO2/FiO2 ratio]].
Used to assess alveolar-arterial (A-a) gradient, or [[PaO2/FiO2 ratio]].
The<unk>  oxygen saturation
The normal range is 95% to 100%.
The amount of carbon dioxide dissolved in<unk><unk> 
The normal range is 35 to 45 mm Hg.
pCO2 >45 = primary respiratory acidosis
pCO2 <35 = primary respiratory alkalosis
The calculated value of the amount of bicarbonate in the<unk> stream
The normal range is 22 to 26 mEq/liter
HCO3 > 26 = alkalosis
HCO3 < 22 = acidosis
The base excess indicates the amount of excess or insufficient level of bicarbonate in the system.
The normal range is -2 to +2 mEq/liter.
A negative base excess indicates a base deficit in the<unk> .
Arterial blood gas analysis
Venous blood gas
Cardiac ultrasound
ECG 
Pulmonary artery catheter
Age adjusted D-dimer
Initial mechanical ventilation settings 
Initial mechanical ventilation settings