UMEM Educational Pearls

Category: Critical Care

Title: Critical Care Monitoring - End-Tidal CO2

Keywords: end-tidal CO2, capnography, status asthmaticus, increased intracranial pressure (PubMed Search)

Posted: 12/18/2007 by Mike Winters, MD (Updated: 7/10/2020)
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Critical Care Monitoring - End-Tidal CO2

  • End-tidal CO2 (ETCO2) monitoring is used to verify ETT placement, monitor procedural sedation, traumatic brain injury, and to estimate prognosis during cardiopulmonary resuscitation
  • ETCO2 concentration typically underestimates PaCO2 by 4-5 mmHg in healthy non-intubated patients
  • This relationship is less reliable in critically ill patients secondary to shunt, altered alveolar dead space, and inadequate ventilation
  • While a low ETCO2 value is less useful in the critically ill, a high value almost always correlates with an equal or higher PaCO2 value
  • This can be useful when monitoring conditions such as status asthmaticus, CHF, or increased ICPs in which a high ETCO2 may signal the need for additional aggressive treatment