Witter H L, Deka R C, Lipscomb D M, Shambaugh G E
Am J Otol. 1980 Apr;1(4):227-32.
Human subjects and chinchilla breathed either Carbogen or compressed air prior to high level sound stimulation. Following stimulation, threshold shifts and recovery to prestimulation thresholds were monitored. Behavioral audiometry was used for human subjects and electrocochleography was utilized to measure noise-induced threshold shifts in the animals. Results were similar for both human and animal subjects in that preinhalation of Carbogen (05 percent 02 and 5 percent CO2) was seen to decrease the amount of temporary threshold shift (TTS) and to increase recovery rate. Further, histologic study of a limited sample of the experimental animals suggested a notable reduction in the amount of sensory cell damage in subjects that breathed Carbogen before sound stimulation. To follow up on this encouraging indication, an additional experiment was conducted to investigate any differences between Carbogen-treated and non-Carbogen-treated animals with respect to histologically observable high level noise exposure damage. The follow-up experiment resulted in strong evidence that Carbogen inhalation prior to intense sound stimulation decreases the susceptibility to hair cell damage. Carbogen-treated chinchilla sustained cochlear sensory cell damage ranging between 1.1 percent and 1.5 percent, whereas non-Carbogen-treated, noise-exposed chinchilla were found to have between 1.6 percent and 4.6 percent sensory cell damage. The use of Carbogen in prophylactic treatment for unavoidable or accidental noise exposure is discussed.
在进行高强度声音刺激之前，人类受试者和龙猫分别吸入卡波金或压缩空气。刺激后，监测阈值变化以及恢复到刺激前阈值的情况。人类受试者采用行为测听法，动物则利用电耳蜗图来测量噪声引起的阈值变化。人类和动物受试者的结果相似，即吸入卡波金（5%氧气和5%二氧化碳）可减少暂时性阈值偏移（TTS）的量并提高恢复率。此外，对有限数量的实验动物样本进行的组织学研究表明，在声音刺激前吸入卡波金的受试者感觉细胞损伤量显著减少。为跟进这一令人鼓舞的迹象，又进行了一项实验，以研究经卡波金处理和未经卡波金处理的动物在组织学上可观察到的高强度噪声暴露损伤方面的差异。后续实验提供了有力证据，表明在强烈声音刺激前吸入卡波金可降低对毛细胞损伤的易感性。经卡波金处理的龙猫耳蜗感觉细胞损伤率在1.1%至1.5%之间，而未经卡波金处理、暴露于噪声中的龙猫感觉细胞损伤率在1.6%至4.6%之间。本文还讨论了卡波金在不可避免或意外噪声暴露的预防性治疗中的应用。
