Study on trauma of tympanic membrane and ossicular chain of guinea pigs exposed to experimental blast underpressure

Objective To probe into the characteristics of traumatic effect of blast underpressure (BUP) on tympanic membrane and ossicular chain of guinea pigs exposed to blast underpressure. Methods The guinea pigs were exposed to experimental BUP generated by the underpressure generator and their tympanic membranes and auditory ossicules were observed with stereo-microscope.Results Most of the tympanic membranes in 72 guinea pigs (141 ears) presented with traumatic changes,such as engorgement,haemorrhage,epidermic desquamation and perforation,combined with fracture of ossicles in some guinea pigs.The traumatic severity of the tympanic membranes and auditory ossicules was related to the peak and the declinating duration of BUP.The minimum peak of the underpressure inducing perfo- ration was between-22.4kPa and-23.9kPa and the minimum peak inducing perforation of all the tym- panic membranes was between-83.1kPa and-87.2kPa.Conclusion The tympanic membrane in guinea pigs exposed to BUP changed traumatically,such as engorgement,haemorrhage,epidermic des- quamation,perforation and fracture of ossicles.The traumatic severity of the tympanic membranes and au- ditory ossicules is related to the peak and declinating duration of BUP.