Ungar Omer J, Dadia Solomon, Yahav Oron, Handzel Ophir, Fliss Dan M, Cavel Oren
Department of Otolaryngology Head and Neck Surgery and Maxillofacial Surgery, Tel-Aviv Sourasky Medical Center, 6 Weizman Street, 6423906, Tel Aviv, Israel.
Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
Eur Arch Otorhinolaryngol. 2018 Nov;275(11):2627-2632. doi: 10.1007/s00405-018-5117-y. Epub 2018 Sep 3.
Ventilation tubes (VT) in the tympanic membrane expose the middle ear (ME) to the external auditory canal and its content. It carries the risk of penetration of contaminated material and could provide a pathway for the delivery of drugs into the ME. The aim of this study was to use a printed 3D-model of the external auditory canal (EAC) and ME to assess the permeability of various VTs to different fluids.
CT scan of the external and ME was 3D-reconstructed and printed. Five different types of VT were inserted in the model's tympanic membrane and the minimal pressure for penetration to the ME was measured. Liquids with different viscosities, including commonly used ear drops, were tested.
Water passed through the standard 1.14 mm diameter VTs after filling the EAC with a volume of 2 ml and through a narrower grommet or a T-tube after filling the canal with 2.5 ml. Soapy-water had the highest penetration in all VTs (1-2 ml). The initial volume of dexamethasone needed for penetration was 2.5 ml in the standard tubes. It did not pass at any volume through the narrow grommet or the T-tube.
In the printed 3D-model, the volume of most solutions, including water, required to provide enough pressure in order to pass through the VTs was as high as the EAC volume or exceeded it. Soapy water had the highest penetrance while Dexamethasone needed volume of 2.5 ml to pass through the VT, questioning its reliability as a passive drug delivery channel to the ME.
鼓膜置管使中耳暴露于外耳道及其内容物。这存在被污染物质侵入的风险，并且可能为药物进入中耳提供一条途径。本研究的目的是使用外耳道和中耳的打印3D模型来评估各种鼓膜置管对不同液体的通透性。
对外耳道和中耳的CT扫描进行3D重建并打印。将五种不同类型的鼓膜置管插入模型的鼓膜中，并测量穿透至中耳的最小压力。测试了包括常用耳滴剂在内的不同粘度的液体。
在向外耳道注入2毫升液体后，水可通过标准直径为1.14毫米的鼓膜置管；在注入2.5毫升液体后，水可通过较窄的鼓膜通气管或T形管。肥皂水在所有鼓膜置管中穿透性最高（1 - 2毫升）。在标准管中，地塞米松穿透所需的初始液体量为2.5毫升。在任何液体量下，它都无法通过窄鼓膜通气管或T形管。
在打印的3D模型中，大多数溶液（包括水）为了产生足够压力以通过鼓膜置管所需的液体量与外耳道容积一样高或超过外耳道容积。肥皂水的穿透性最高，而地塞米松需要2.5毫升液体量才能通过鼓膜置管，这质疑了其作为向中耳被动给药通道的可靠性。
