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目的比较低压舱内4000m吸空气和6900m吸纯氧对耳气压功能的影响。方法 11名男性健康志愿者采用自身对照方法,均参加空气组(4000m暴露呼吸空气)和纯氧组(6900m暴露呼吸纯氧)两组试验,两次试验间隔2周以上。志愿者在地面高度分别吸空气或纯氧1h,然后在低压舱内以20m/s的速度上升至目标高度停留5min,再以20m/s的速度下降至地面高度。记录两组志愿者试验前后不同时间点主观症状、鼓膜充血程度、声导抗和纯音听阈等指标的变化,并对声导抗指标和听阈变化进行统计学分析。结果检查过程中空气组和纯氧组分别有4人(4耳)和7人(7耳)主诉发生耳痛,且纯氧组发生压痛的高度较高。出舱即刻两组分别有3人(3耳)和5人(5耳)鼓膜Ⅲ度充血,试验后纯氧组有4人(6耳)充血程度随时间延长而加重,出舱3h及24h两组鼓膜充血程度差异有统计学意义。出舱即刻两组分别有11人(15耳)和11人(14耳)为正常的A型鼓室图。纯氧组出舱即刻静态声顺值的增加量明显高于空气组(P<0.05),出舱3h和24h中耳压的减少量明显高于空气组(P<0.05)。两组试验均可致咽鼓管功能下降。出舱3h和24h时纯氧组个别频率纯音听阈的增加量明显高于空气组(P<0.05)。结论吸入纯氧并增加高度可提高低压舱耳气压功能检查的筛选度,且对24h内的鼓膜充血程度、声导抗和纯音听阈有较大影响。
Objective To compare the effects of 4000m suction air and 6900m suction pure oxygen on the pressure function of the ear in low pressure cabin. Methods Eleven male healthy volunteers were enrolled in two groups of tests: air group (4000m exposed to breathing air) and pure oxygen group (6900m exposed to breathing pure oxygen), with two tests more than two weeks. Volunteers inhaled air or pure oxygen at ground level for 1 h, then ramped them to the target altitude for 5 min at a speed of 20 m / s in the low-pressure cabin and then dropped to the ground level at a speed of 20 m / s. The changes of subjective symptoms, hyperemia of the tympanic membrane, acoustic impedance and pure tone threshold were recorded before and after the two groups of volunteers were tested. The changes of acoustic impedance index and hearing threshold were statistically analyzed. Results During the examination, 4 (4 ears) and 7 (7 ears) patients complained of earache in the air group and the pure oxygen group, respectively, and had a higher tenderness in the pure oxygen group. Immediately after extubation, there were 3 (3 ears) and 5 (5 ears) tympanic membrane third degree hyperemia respectively in the two groups. After the test, 4 people (6 ears) in pure oxygen group increased congestion with time, The two groups of tympanic membrane congestion were statistically significant. Immediately out of the two groups were 11 (15 ears) and 11 (14 ears) for the normal A-type tympanogram. In the pure oxygen group, the increase of static acoustic compliance immediately after outgassing was significantly higher than that of the air group (P <0.05). The reduction of middle ear pressure at 3h and 24h was significantly higher than that of the air group (P <0.05). Two groups of tests can cause eustachian tube function decline. At 3 h and 24 h, the increment of pure tone audiometry threshold of pure oxygen group was significantly higher than that of air group (P <0.05). Conclusion Inhaling pure oxygen and increasing height can improve the screening function of low pressure cabin air pressure, and it has a significant effect on tympanic membrane hyperemia, acoustic impedance and pure tone hearing threshold within 24h.