Final answer:
The nasopharyngeal airway should not be used if a head injury is suspected due to the risk of further injury through a possible skull fracture. It is otherwise used in cases of airway constriction or difficulty in breathing.
Step-by-step explanation:
You should never use the nasopharyngeal airway when you suspect a head injury. This is because the presence of a head injury may mean that the base of the skull is fractured and inserting a tube could cause further injury by passing through the fracture into the brain tissue. The nasopharyngeal airway is typically used to secure an airway when there is constriction and tightening of the airway, a situation that might be due to causes such as a swollen throat or the sensation of a lump in your throat that makes it difficult to breathe. These symptoms can lead to shock, with a severe drop in blood pressure, a rapid pulse, dizziness, lightheadedness or loss of consciousness, and in such scenarios, securing the airway is critical. It is also important to note that the nasopharynx is not involved in digestion and that the laryngopharynx is composed partially of cartilage. Intubation is another procedure that might be required in emergency situations where the respiratory system is blocked.