<unk>  measures the amount of exhaled CO2
ETCO2 of 35-45mmHg is considered normal
<35mmHg = Hypocapnia or Hyperventilation
>45mmHg = Hypercapnia or Hypoventilation
Directly measure the function of ventilation (not oxygenation)
ETCO2 ≥ PCO2
Indirectly measures overall metabolism (or lack there of in cardiac arrest)
<35mmHg = Hypocapnia or Hyperventilation
>45mmHg = Hypercapnia or Hypoventilation
ETCO2 ≥ PCO2

Exhalation will first expel dead space air (Phase I)
Then a rapid rise in CO2 rich air is noted (Phase II)
This is followed by a more gradual increase in CO2 (Phase III)
The curve peaks at the end of Phase III which is noted as the End-Tidal CO2 measurement
Inhalation follows (Phase 0 or IV)
Capnography
Compartment pressure measurement
Thromboelastography 
Glasgow-Blatchford Bleeding Score
Tourniquet
Tourniquet 
Age adjusted D-dimer
D-dimer