 The vast majority of tracheal <unk> involve the use of a viewing instrument of one type or another . The modern conventional laryngoscope consists of a handle containing batteries that power a light and a set of interchangeable blades , which are either straight or curved . This device is designed to allow the laryngoscopist to directly view the larynx . Due to the widespread availability of such devices , the technique of blind intubation of the trachea is rarely practiced today , although it may still be useful in certain emergency situations , such as natural or man @-@ made disasters . In the prehospital emergency setting , digital intubation may be necessitated if the patient is in a position that makes direct laryngoscopy impossible . For example , digital intubation may be used by a paramedic if the patient is entrapped in an inverted position in a vehicle after a motor vehicle collision with a prolonged extrication time . 
