Which device provides real-time evidence of ventilation by measuring CO2 during exhalation?

Which device provides real-time evidence of ventilation by measuring CO2 during exhalation?

• A. Pulse Oximetry
• B. Capnography
• C. Spirometry
• D. Auscultation

Answer: (B)

Capnography provides real-time evidence of ventilation by measuring carbon dioxide in exhaled air and displaying it as a capnogram. The key value, end-tidal CO2 (EtCO2), reflects how well air is being moved out of the lungs at the end of expiration. This gives immediate feedback on ventilation: you can see if the patient is actually ventilating, detect apnea or hypoventilation, and verify that an airway device is functioning properly (for example, confirming correct placement of an endotracheal tube). Normal EtCO2 is typically about 35–45 mmHg in a healthy adult, and changes in the waveform or value signal problems such as disconnection, obstruction, or rebreathing in real time. By contrast, pulse oximetry only tracks oxygen saturation, not ventilation; spirometry measures lung volumes and airflow but isn’t a continuous CO2 monitor; auscultation can suggest issues but doesn’t provide quantitative, real-time ventilation data.

Capnography provides real-time evidence of ventilation by measuring carbon dioxide in exhaled air and displaying it as a capnogram. The key value, end-tidal CO2 (EtCO2), reflects how well air is being moved out of the lungs at the end of expiration. This gives immediate feedback on ventilation: you can see if the patient is actually ventilating, detect apnea or hypoventilation, and verify that an airway device is functioning properly (for example, confirming correct placement of an endotracheal tube). Normal EtCO2 is typically about 35–45 mmHg in a healthy adult, and changes in the waveform or value signal problems such as disconnection, obstruction, or rebreathing in real time. By contrast, pulse oximetry only tracks oxygen saturation, not ventilation; spirometry measures lung volumes and airflow but isn’t a continuous CO2 monitor; auscultation can suggest issues but doesn’t provide quantitative, real-time ventilation data.