防护耳塞和防护筒对听器的防护效果研究

Protective effect of earplug and protective barrel on auditory organs of guinea pig exposed to blast underpressure

目的探讨实验性冲击波负压暴露时防护耳塞和防护筒对豚鼠听器的防护效果。方法防护方法分为给动物佩戴防护耳塞或者将动物全身置于防护筒内。与无防护组豚鼠进行对比,判断防护效果的观察指标有脑干听性反应(ABR)阈值变化、鼓膜和听骨链创伤情况,以及耳蜗外毛细胞缺失率的变化。将防护组动物冲击波负压暴露前后观察结果进行对比,并与未加任何防护的动物进行对比。结果在压力峰值为-64.5^-69.3kPa冲击波负压暴露后,无防护组动物ABR阈值比暴露前明显升高(P<0.001),鼓膜穿孔率达87.5%,负压暴露后14d耳蜗外毛细胞缺失率为(19.46±5.38)%;耳塞防护组和防护筒组动物ABR阈值,在负压暴露后的升高程度明显低于无防护组动物(P<0.01),所有鼓膜均未发生穿孔且听骨链保持完整,外毛细胞缺失率也明显低于无防护组动物(P<0.01),而且防护筒组动物的ABR阈值升高和外毛细胞缺失率,又明显低于耳塞防护组动物(P<0.01)。结论在实验性冲击波负压暴露时,防护耳塞和防护筒均对豚鼠听器有肯定的保护作用,并且防护筒的保护作用优于防护耳塞。

Objective To explore the protective effect of the protective earplug and barrel on auditory organs of guinea pig exposing to experimental blast underpressure（BUP）. Methods The hearing thresholds of the guinea pigs were assessed with auditory brainstem responses（ABR）. The trauma of the tympanic membrane and ossicular chain was observed under the stereo-microscope. The rates of outer hair cells （OHCs） loss were analyzed using a light microscope. The changes of guinea pigs protected with protective barrel and earplug were compared with that of the control group without any protection. Results An important ABR threshold shift of the guinea pigs without any protection was detected from 8h to 14d following exposure to BUP at peak underpressure between -64.5-69.3kPa （P〈0. 01 ）. The perforations occurred in 87.5 % of tympanic membrane and the rate of total OHCs loss was （19.46±5.38）% 14d after exposure. The guinea pigs protected with the barrel and earplug had lower ABR threshold shifts and rate of total OHCs than.the animals without any protection （P〈0.01）. All of the tympanic membranes and ossicular chains of the former animals were integrity. Furthermore, the guinea pigs protected with the barrel had lower ABR threshold shifts and rate of total OHCs than the animals with earplug （P〈0.01）. Conclusion These physiological and morphological results indicate that the protective earplug and protective barrel have protective effects against BUP-induced trauma in the guinea pig auditory organs and that the protective barrel is better than the protective earplug.