Capnogram waveform: obstruction

Capnography directly reflects the elimination of CO₂ by the lungs to the anesthesia device. It indirectly reflects the production of CO₂ by tissues and the circulatory transport of CO₂ to the lungs

Capnography Waveform (image needed)

• Phase 0 – Inspiration
• Phase 1 – Represents the CO₂-free gas from the airways (anatomical and apparatus dead space)
• Phase 2 – Mixture of anatomical and alveolar dead space
• Phase 3 – Consists of an alveolar plateau representing CO₂-rich gas from the alveoli
• Alpha Angle – Angle between phase II and III
• Beta Angle – Angle between phase III and descending limb of inspiratory segment

Airway Obstruction (Asthma, Bronchospasm, COPD, Pregnancy, Kinked ET Tube)

• Prolongation or slanting of the expiratory upstroke phase II
• Prolongation of phase III
• Alpha angle is increased