[DOI] /j.issn Institute of Aviation Medicine, Chinese Air Force, Beijing , China

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1 [ ] 4m 69m 11 (4m ) (69m ) 2 1h 2m/s min 2m/s 4 (4 ) 7 (7 ) 3 (3 ) ( ) 4 (6 ) 3h 24h 11 ( ) 11 (14 ) A (P<.) 3h 24h (P<.) 3h 24h (P<.) 24h [ ] [ ] R81.3 [ ] A [ ] (217)1-7-6 [DOI] 1.118/j.issn Compound effects of inhaling pure oxygen and lifting height on ear baric function in a hypobaric chamber WEN Dong-qing, ZHENG Xue-wen, WANG Gui-you, LIU Xiao-peng, SHI Wei-ru, YU Li-hua, GU Zhao, WU Jianbing, XUE Li-hao, WANG Jie * Institute of Aviation Medicine, Chinese Air Force, Beijing 1142, China * Corresponding author, kjzygdwk@163.com This work was supported by the Major Project of General Logistics Department of PLA (AKJ11J2) [Abstract] Objective To compare the ear baric function between 4m altitude chamber test with inhaling air and 69m altitude chamber test with inhaling pure oxygen. Methods Eleven healthy male volunteers attended two tests as two groups by self-comparison. As the air group the volunteers inhaled air at 4m, while as the pure oxygen group they inhaled pure oxygen at 69m altitude, and the time interval between the two tests was more than two weeks. During the test, the volunteers breathed air or pure oxygen at random for 1h, and then were exposed at a speed of 2m/s to the target altitude for min. Hereafter they were sent back to the ground at the same speed. The changes of subjective symptoms, degree of tympanic congestion, acoustic immitance index and pure-tone auditory threshold were recorded before and after the test. The acoustic impedance index and puretone threshold were statistically analyzed. Results Four volunteers (4 ears) in air group and 7 volunteers (7 ears) in pure oxygen group reported ear pain in altitude chamber exposures, respectively. The pain-triggering altitude was higher in the pure oxygen group. Immediately after tests, there were 3 (3 ears) and volunteers ( ears) with degree congestion of the tympanic membrane in the two groups respectively. Four volunteers (6 ears) developed gradually aggravated hemorrhages after altitude exposure. And the tympanic membrane congestion difference between groups was statistically significant at 3 and 24h after tests (P<.1). The type A tympanogram appeared in 11 ( ears) and 11 (14 ears) volunteers respectively immediately after tests. The increase of static compliance value was significantly greater in pure oxygen group than in air group immediately after tests (P<.), the decrease of middle ear pressure was more significant in pure oxygen group than in air group at 3 and 24h after tests (P<.). Both the two [ ] (AKJ11J2) [ ] [ ] 1142 ( ) [ ] E-mai kjzygdwk@163.com

2 Med J Chin PLA, Vol. 42, No. 1, January 1, altitude exposure tests resulted in eustachian tube dysfunction. At 3 and 24h after the tests, the increase of individual frequency pure-tone threshold was significantly higher in pure oxygen group than in air group (P<.). Conclusion Breathing pure oxygen and lifting height could increase the screening degree of ear baric function test in hypobaric chamber, and have greater influence on degree of tympanic congestion, acoustic immittance and pure-tone auditory threshold in 24 hours. [Key words] barotrauma; hearing test; auditory threshold; questionaires; audiometry, pure-tone [1] [2] [3-4] ~2 6~83kg 167~178cm 3 12~8Hz 2dB HL( hearing level HL) 1.2 ( 2 ) 4m 69m 1.3 ( ) [] F-168 D Madsen ZO91 HBP [6] 1h 2m/s 4m min 2m/s 2m/s 69m min 2m/s ( ) GBZ93-21 [7] A 1~daPa(1daPa=1Pa) B C < 1daPa 12~8Hz GB [8] 1. SPSS 13. x±s t ( ) Pearson χ 2 ( ) P< ( 3h 24h)

3 (m) Tab. 1 Triggered altitude of ear tenderness symptom in the twogroupsofsubjects(m) Subject No. Air group Pure oxygen group " " means the trial was been done A C 24h 4 (4 ) 7 (7 ) 1 (1 ) 3h 24h ( 1) (1 ) 8 (11 ) 3 (3 ) ( ) 4 (6 ) 2 None 2 Slight Mild Moderate Severe 1 1( ) Fig. 1 at different time points after tests (ear) A. during the tests; B. immediately after tests; C. 3 hours after tests; D. 24 hours after tests.. Air group;. Pure oxygen group 2 ( ) Tab. 2 Classification of tympanic congestion in the two groups after tests (ear) Congestion classification Air group Pure oxygen group Immediately after tests 3h after tests 24h after tests Immediately after tests 3h after tests 24h after tests Grade.Nosignofbarotraumas;Grade. Eardrum retraction with redness along the manubrium of malleus and flaccid part; Grade. Sameas grade plus redness around eardrum; Grade. Eardrum retraction with hyperemia of the entire eardrum or the evidence of fluid in the tympanum or hemotympanum B D ( 2) 3h 24h (P<.1)

4 Med J Chin PLA, Vol. 42, No. 1, January 1, ( 3h 24h) 11 ( ) 11 (2 ) 11 (22 ) A 11 (14 ) 11 (17 ) 11 (21 ) A Pearson χ 2 (P>.) 3h 24h ( 4) 3 ( ) Tab. 3 Tympanogram of the two groups after altitude chamber exposure tests (ear) Tympanogram type Air group Pure oxygen group Immediately after tests 3h after tests 24h after tests Immediately after tests 3h after tests 24h after tests A B 4 2 C Type A. Tent shaped curve with a high peak between + and 1daPa (1daPa=1Pa); Type B. Abnormal flat curve; Type C. Negatively shifted curve with peak exceeding 1daPa 4 (x±s n=11) Tab. 4 Middle ear pressure & static compliance at different time points after altitude chamber exposure tests (x±s, n=11) Item Immediately after tests 3h after tests 24h after tests Middle ear pressure (dapa) Air group 9.9± ± ± 2.33 Pure oxygen group.9± ± 64.6 (1) 18.41± 29. (1) Static compliance (ml) Air group.4±.26.7±.12.±.9 Pure oxygen group.14±.2 (1).8±.7.4±.1 (1)P<. compared with air group (4 ) 8 (11 ) 9 (13 ) (7 ) 6 (7 ) 9 (12 ) 7 (1 ) 6 (7 ) 2. 3h Hz 8Hz 24h Hz 1Hz (P<. 2) Difference value of pure-tone threshold immediately after tests (dbhl) Air group Pure oxygen group 2 1 (1) (1) 1 (1) (1) Frequency (Hz) 1 Frequency (Hz) 1 Frequency (Hz) A B C Difference value of pure-tone thresholdat3haftertests(dbhl) 2 (dbhl) Fig. 2 The variable of pure tone threshold in the two groups of subjects after altitude exposure tests (dbhl) A. The variable of pure tone threshold on each frequency immediately after altitude exposure tests; B. The variable of pure tone threshold on each frequency 3h after altitude exposure tests; C. The variable of pure tone threshold on each frequency 24h after altitude exposure tests. (1)P<. compared with air group Difference value of pure-tone threshold at 24h after tests (dbhl) 3 [9]

5 m [1] [11-12] [13-] [16] 24h 24h [17] 24h [17] 24h

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