大气压变化对咽鼓管通气阻力的影响及耳气压伤的预防

目的探讨咽鼓管通气阻力(VRET)是否随大气压变化而变化,并了解呼气压大于咽鼓管通气阻力的正压呼吸能否预防耳气压伤。方法8名健康男性,咽鼓管通气阻力<6kPa,在海拔28m和1180m高度的大气压条件下,用咽鼓管通气阻力测量仪测量VRET,比较其相对值和绝对值。另在压力舱内做增压试验:每2人一组,互为试验者和对照者。试验组经面罩予以6kPa的呼气正压,对照组正常呼吸。高压舱以0.5kPa/s增压速率增压至5kPa,两组均不进行其他任何主动或被动开放咽鼓管的措施,测鼓室腔压力。以同样速率增压至50kPa,试验组条件不变,对照组可进行主动或被动开放咽鼓管的措施,测鼓室压。结果在海拔28m,测量的VRET相对值是3.7kPa(27.75mmHg);在1180m高度,测量的VRET相对值是3.8kPa(28.50mmHg)。经t检验,两地高度VRET的相对值差异无显著性意义,高压舱增压至5kPa时,试验组和对照组鼓室压差值162.1±75.4daPa(P<0.01)。增压至50kPa时,试验组和对照组鼓室压差值2.86±6.19daPa(P>0.05)。结论当人体的环境气压发生变化时,VRET相对值无显著变化。经面罩提供大于VRET的压力,可以使咽鼓管被动开放,预防耳气压伤。

The effect of the atmospheric pressure change on the ventilative resistance of the eustachian tube and the prevention of the barotrauma

Objective To investigate whether the ventilative resistance of the eustachian tube (VRET) changed with the atmospheric pressure, and whether barotrauma can be prevented by positive pressure breathing (PPB) with exhalation pressure >VRET. Methods Eight healthy male with VRET <6 kPa served as subjects. The VRET was determined by a self-developed testing system at 28 m and 1180 m altitude above the sea level. Pressure chamber tests were performed as follows: each 2 men as a group, one acted as testee, anther as collator. During pressurizing, testee underwent PPB (6.0 kPa) while collator breathed ambient air without taking any measure for opening eustachian tube. Pressure chamber was pressurized to 5 kPa at the rate of 0.5 kPa/s, the pressure of the tympanic cavity was measured. Then the pressure chamber was pressurized to 50 kPa, the collator was allowed to open eustachian tube actively or passively, the pressure of the tympanic cavity was measured. Results At 28 m, the average relative VRET were 3.7 kPa (27.75 mm Hg). At 1180 m, the average relative VRET was 3.8 kPa (28.50 mm Hg). After pressurized to 5 kPa, the difference between the tympanic cavity pressure of the testee group and the collator group was significant (P<0.01). After pressurized to 50 kPa, the difference between the testee group and the collator group was non-significant. Conclusions It is suggested that VRET at various altitudes is relatively stable, and PPB with pressure higher than the VRET can prevent the barotrauma of ear.