capnography

1. Capnography
MONITORING VENTILATION IN CLINICAL SETTINGS

2. Introduction
 • What is Capnography?
 Capnography is the monitoring of CO in
₂
respiratory gases.
 • Why is it important?
 It provides real-time feedback on ventilation.

3. Physiology of CO₂
 • CO is a byproduct of metabolism
₂
 • Transported via bloodstream to the lungs
 • Exhaled through the respiratory system
 • Measured as End-Tidal CO (EtCO )
₂ ₂

4. Capnography Components
 1. Sampling system – gathers exhaled gas
 2. Analyzer – detects and measures CO₂
 3. Display – shows waveform and values

5. Types of Capnography
 • Mainstream – Sensor at airway
 • Sidestream – Gas sampled via a tube
 • Microstream – Low flow, high accuracy

6. The Capnogram
 • Graph of CO concentration over time
₂
 • Phases:
 1. Baseline (inhalation)
 2. Expiratory upstroke
 3. Alveolar plateau
 4. End-tidal point (EtCO )
₂

7. Normal Values
 • EtCO : 35–45 mmHg
₂
 • Waveform: Smooth, square
 • Indicates adequate ventilation

8. Clinical Uses
 • Confirm endotracheal tube placement
 • Monitor sedation and anesthesia
 • Detect respiratory depression
 • Early warning in cardiac arrest

9. Abnormal Capnograms
 • Hypoventilation: High EtCO₂
 • Hyperventilation: Low EtCO₂
 • Obstructive diseases: Slanted waveform
 • Apnea/disconnection: Flatline

10. Advantages of Capnography
 • Non-invasive
 • Immediate feedback
 • Continuous monitoring
 • Helps prevent complications

11. Limitations
 • Affected by movement
 • Requires calibration
 • Not a direct measure of blood CO₂

12. Summary
 • Vital for monitoring ventilation
 • Used in ICU, ER, OR, pre-hospital
 • Pattern recognition guides care

13. References
 • Miller’s Anesthesia
 • ACLS Guidelines
 • UpToDate
 • AANA Journal