A "nasopharyngeal airway" is a soft rubber or plastic tube that is passed through the nose and into the posterior pharynx. Nasopharyngeal airways are produced in various lengths and diameters to accommodate for gender and anatomical variations. Functionally, the device is gently inserted through a patient's nose after careful lubrication with a viscous lidocaine gel. Successful placement will facilitate spontaneous ventilation, masked ventilation, or machine assisted ventilation with a modified nasopharyngeal airway designed with special attachments at the proximal end. Patients generally tolerate NPAs very well. NPAs are preferred over OPAs when the patient's jaw is clenched or if the patient is semiconscious and cannot tolerate an OPA. NPAs, however, are generally not recommended if there is suspicion of a fracture to the base of the skull. In these circumstances, insertion of the NPA can cause neurological damage by entering the cranium during placement. There is no consensus, however, regarding the risk of neurological damage secondary to a basilar skull fracture compared to hypoxia due to insufficient airway management. Other complications of Nasopharyngeal airways use includes laryngospasm, epistaxis, vomiting, and tissue necrosis with prolonged use.