Buckingham R A, Stuart D R, Geick M R, Girgis S J, McGee T J
Laryngoscope. 1985 Apr;95(4):437-42. doi: 10.1288/00005537-198504000-00012.
The present theory of eustachian tube (ET) function and middle ear (ME) ventilation posits that oxygen absorbed by the ME mucosa causes negative ME pressure which is relieved by periodic opening of the ET during swallowing and yawning. After developing a method to cannulate the ET of mongrel dogs we connected the cannulas hermetically to manometers. This system excluded ET function and tested the oxygen absorption capacity of the ME. When we controlled respiration and maintained blood gas PO2 and PCO2 at normal levels, we were unable to find any manometric evidence of negative pressure of gas absorption in the dog ME. Lowering the PCO2 and raising the PO2 of the blood by hyperventilation caused negative ME pressure which could be measured manometrically. We confirmed these findings with the tympanometer. Raising the PCO2 and lowering the PO2 by hypoventilation caused positive pressure in the ME. There is no evidence in these experiments that O2 absorption occurs or causes negative ME pressure in the dog. To the contrary there is evidence that elevated blood levels of the more diffusible CO2 cause an increase in the ME pressure and lowered CO2 level causes a negative ME pressure.
目前关于咽鼓管（ET）功能和中耳（ME）通气的理论认为，中耳黏膜吸收氧气会导致中耳负压，而在吞咽和打哈欠时咽鼓管的周期性开放可缓解这种负压。在开发出一种将杂种犬的咽鼓管插管的方法后，我们将插管密封连接到压力计上。该系统排除了咽鼓管功能，并测试了中耳的氧气吸收能力。当我们控制呼吸并将血气PO2和PCO2维持在正常水平时，我们未能找到任何关于犬中耳气体吸收负压的压力测量证据。通过过度通气降低血液中的PCO2并提高PO2会导致中耳负压，这可以通过压力测量来检测。我们用鼓室图证实了这些发现。通过通气不足提高PCO2并降低PO2会导致中耳正压。在这些实验中，没有证据表明犬中耳会发生氧气吸收或导致中耳负压。相反，有证据表明，血液中更易扩散的CO2水平升高会导致中耳压力增加，而CO2水平降低会导致中耳负压。
