General Anesthesia mask is used to ventilate the patient without intubation or before intubation. The mask significantly increases amount of dead space.
These are available in sizes from 0 to 4 numbers. Face mask should be made of antistatic rubber. At the bottom of General Anesthesia mask there is air filled cuff which has soft cushioning effect.
There are other types of General Anesthesia mask that are also available and are made of plastic and are transparent. These masks are better tolerated by the patients because these do not have any bad small like that in the black masks.
Hence the General Anesthesia mask is held tightly only after the patient is induced either through inhalational agents or through Intravenous drugs like Propofol or Thiopentone Sodium.
The disadvantages of ventilation with mask are:
A significant amount of air leaks into esophagus and can easily increase the intragastric pressure
significant enough (>28cm H20) to cause aspiration so bag and mask ventilation with General Anesthesia mask is contra indicated when there are increased chances of aspiration like:
• Full stomach patients.
• Intestinal obstruction.
• Pregnancy.
• Hiatus hernia.
• Conditions like diaphragmatic hernia, trachea esophageal fistula, meconium aspiration syndrome.
Bag and mask ventilation is best avoided in conditions predisposing to aspiration.