Sadé J
Department of Biomedical Engineering, Faculty of Engineering, Sackler School of Medicine, Tel-Aviv University, Israel.
Am J Otol. 2000 Jan;21(1):20-3.
To measure the middle ear (ME) volume displaced when the pars tensa (PT) retracts during conditions of atelectasis (AT).
Measurements were carried out on AT tympanic membrane (TM).
Measurements were carried out on ambulatory patients in a private clinic.
Thirty-nine patients treated for otologic disorders who came for a routine follow-up.
Quantitative assessment of ME volume displaced by retraction of the PT was achieved by measuring the amount of fluid needed to fill up the retracted part of a TM. The fluid-3% aqueous boric acid solution was colored with gentian violet.
Retraction of the PT may prevent formation of high ME negative pressure by reducing the ME volume. Retraction of the PT acts as a pressure buffer according to Boyls law, in which volume x pressure = constant.
Direct correlation was found between the degree of AT and the ME volume displaced by the AT. Measurements of 12 AT ears grade I showed them to have a volume of 5 microL to 31 microL (average, 19.5 microL) and ten AT ears grade II had a volume of 15 microL to 87 microL (average, 39.5 microL). Eight AT ears grade III had a volume of 26 microL to 67 microL (average, 54.3 microL), and nine AT ears grade IV had 80 microL to 200 microL (average, 130.6 microL).
Retraction of the PT may counteract an important potential negative ME pressure (up to several hundred millimeters of water) depending on the degree of retraction and the extent of mastoid pneumatization.
测量在肺不张（AT）情况下紧张部鼓膜（PT）回缩时中耳（ME）移位的容积。
对AT鼓膜（TM）进行测量。
在一家私人诊所对门诊患者进行测量。
39例因耳科疾病接受治疗并前来进行常规随访的患者。
通过测量填充TM回缩部分所需的液体量，对PT回缩引起的ME容积移位进行定量评估。液体为3%的硼酸水溶液，并加入了龙胆紫进行染色。
PT回缩可能通过减少ME容积来防止形成高ME负压。根据波义耳定律（容积×压力=常数），PT回缩起到压力缓冲作用。
发现AT程度与AT引起的ME容积移位之间存在直接相关性。对12只I级AT耳的测量显示，其容积为5微升至31微升（平均19.5微升）；10只II级AT耳的容积为15微升至87微升（平均39.5微升）。8只III级AT耳的容积为26微升至67微升（平均54.3微升），9只IV级AT耳的容积为80微升至200微升（平均130.6微升）。
PT回缩可能抵消重要的潜在ME负压（高达几百毫米水柱），这取决于回缩程度和乳突气化程度。
