Oxygen therapy and Interpretation of blood gases

Oxygen therapy

• Different modes of O₂ therapy

-          nasal prongs

-          face mask

-          venturi mask

-          ET tube/LMA

• Ordinary face mask provides a FiO₂ of about 35%
• Addition of an reservoir bag can increase the FiO₂> 70% 
• Venturi mask can provide a FiO₂ up to about 60%
• Anaesthetic circuit can provide a FiO₂ close to 100%