Myth: ETCO2=PaCO2, in fact it’s EtCO2 = PaCO2 AND Deadspace in Lungs (from poor perfusion/Cardiac Output), so basically the deadspace in the lungs will lower the overall EtCO2 (by diluting the PaCO2)
What does this mean? EtCO2 < PaCO2, so if EtCO2 ~ 60 means we need increased ventilation, but EtCO2 ~20 means what exactly? NOTHING! PaCO2 could be 22 or 105.So when is it helpful?
1. ET tube confirmation2. If spike in EtCO2 during cardiac arrest (like 12 → 48), check pulse! (remember its Cardiac Output as well!). On flipside, if EtCO2 is <10 at 20min mark, chance of survival is low.3. Procedural Sedation
If supplemental O2 used, SpO2 (pulse ox) is USELESS for measuring ventilatory status (won’t desat until they’ve been apenic for a while)
Can see when patient is apneic4. Brain trauma (TBI)
Intubated patient has EtCO2 of 50, means PaCO2 is at least 50, need to increase ventilation (lowers CO2 → vasoconstriction in brain -->decreased swelling). Again, if 20, means nothing?? So wait until EtCO2 is lower than 35 before sending blood gas!5 Intubation with Acidosis (DKA, aspirin)
See baseline EtCO2, then don’t let it rise during intubation
During RSI, bag, then after tubed immediately to get EtCO2 to at least your baseline pre-intubation.
Maybe drip bicarb in before intubation, anyone remember how to correctly do that?Where is it NOT helpful
Can’t use to estimate respiratory status (aka what is the PaCO2), since it measures CO and PaCO2.What about color change devices??
Quickest/easiest way to confirm tube in non-cardiac arrest patient
Needs to stay yellow after 6 breaths, not 2.
Vomit gives false positive
Epi in ET tube will change it yellow
Doesn’t work in Cardiac Arrest (use direct laryngoscopy or use quantitative device) (edited)