Different ways of estimating ETCO2:
|Normal Capnograph (Adults)|
|SpO2 and ETCO2|
|Normal capnograph wave|
|Increasing ETCO2 (Ex. Hypoventilation during procedural sedation)|
- Airway management: To confirm the ET tube placement, also for continuous confirmation of the airway
- Monitoring CPR efficacy: Target ETCO2 >20 during CPR
- Estimates prognosis during CPR: An end-tidal CO2 value < 10 mm Hg after 20 min of resuscitation has been shown to be very accurate in predicting death
- Confirming ROSC without stopping chest compressions: With ROSC ETCO2 shows as a sudden increase
- Monitoring PaCo2 in a Traumatic Brain Injury/ Post Cardiac Arrest care
- Guide to ventilation during procedural sedation: Shows hypoventilation i.e increasing ETCO2 at least 60 seconds prior to hypoxia
- Fluid responsiveness (5% or greater increase in ETCO2 following a passive leg raise is a non invasive way of predicting fluid responsiveness)
- Diagnosing other pathologies (PE, DKA)
|On Muscle relaxants|
- ETCO2 is a surrogate marker for arterial CO2. If increased, it confirms hypercapnia.
- ETCO2 changes immediately with changes in the amount of CO2 in the airway (unlike SpO2 that shows a lag)
- When using waveform capnography, look at the ETCO2 numeric value as well as the waveform.
- Eliminate pulse checks during CPR, use ETCO2 instead.
- Heradstveit BE, Heltne JK. PQRST - A unique aide-memoire for capnography interpretation during cardiac arrest. Resuscitation 2014; 85:1619-20.
- Monnet, X. et al. ETCO2 is better than arterial pressure for predicting volume responsiveness by PLRT. Intensive Care Med. 2013 Jan;39 (1): 93-100