- To breathe for a patient during surgery when anesthetics are used
- Neurological deficit (Narcosis, drug overdose, spinal cord injury, Grullain-Barre,
- Muscular deficit ( myasthenia gravis, poliomyelitis, malnutrition, )
- Protect the airway from aspiration (as in a drug overdose, lack of gag reflex).
- Relieve Airway obstruction (laryngeal edema, epiglottitis, bronchospasm, etc.)
General discussion will come later.