Capnography and CO2 Monitoring

Monitoring the patient’s breathing in emergency situations is of paramount importance. Delivering oxygen ensures the level of oxygen saturation in the blood is maintained, which is sometimes monitored and measured by a pulse oximeter. However, the pulse oximeter does not provide breath-by-breath patient ventilator status.

Capnography is the vital sign of ventilation. By tracking the patient’s expired CO2 clinicians can evaluate the ventilation condition of the patient during critical emergency situations and make the judgment to assess and treat the patient.

Capnography improves patient safety by providing the following vital information:

  • Hypoventiliation and hyperventilation
  • Confirming, maintaining and assisting intubation
  • Return of spontaneous circulation (ROSC)
  • Measuring cardiac output during cardiopulmonary resuscitation (CPR)
  • End-tidal CO2 as a predictor of resuscitation outcome
  • Monitoring sedated patients
  • Perfusion warning sign
  • ETCO2 in asthma, chronic obstructive pulmonary disease (COPD), and congestive heart failure (CHF)

PCO2 Inspiration and Expiration

Phase 1 is the section between A and B, where inhalation has ended and exhalation begins.

Phase 2 is the section between B and C, which represents continued exhalation from the remaining dead space and proximal alveoli.

Phase 3 is the section between C and D, which represents airflow from the alveoli during uniform ventilation (respiratory plateau). D is the end-tidal point where CO2 concentration is highest and where the monitoring of the values is measured.

Phase 4 is the section between D and E, which represents inspiration.