Design of medical tympanostomy conduits with selective fluid transport properties

Implantable tubes, shunts, and other medical conduits are crucial for treating a wide range of conditions from ears and eyes to brain and liver but often impose serious risks of device infection, obstruction, migration, unreliable function, and tissue damage. Efforts to alleviate these complications remain at an impasse because of fundamentally conflicting design requirements: Millimeter-scale size is required to minimize invasiveness but exacerbates occlusion and malfunction. Here, we present a rational design strategy that reconciles these trade-offs in an implantable tube that is even smaller than the current standard of care. Using tympanostomy tubes (ear tubes) as an exemplary case, we developed an iterative screening algorithm and show how unique curved lumen geometries of the liquid-infused conduit can be designed to co-optimize drug delivery, effusion drainage, water resistance, and biocontamination/ingrowth prevention in a single subcapillary-length-scale device. Through extensive in vitro studies, we demonstrate that the engineered tubes enabled selective uni- and bidirectional fluid transport; nearly eliminated adhesion and growth of common pathogenic bacteria, blood, and cells; and prevented tissue ingrowth. The engineered tubes also enabled complete eardrum healing and hearing preservation and exhibited more efficient and rapid antibiotic delivery to the middle ear in healthy chinchillas compared with current tympanostomy tubes, without resulting in ototoxicity at up to 24 weeks. The design principle and optimization algorithm presented here may enable tubes to be customized for a wide range of patient needs.

Tympanostomy Tube Placement in Children Using a Single-Pass Tool with Moderate Sedation

Insertion of tympanostomy tubes is a common elective pediatric surgical procedure and is typically performed under general anesthesia. The potential to reduce general anesthetic requirements for young children has led to increased interest in alternatives for tympanostomy tube placement. A tympanostomy tube system, developed to enable tympanostomy tube placement in a single pass on conscious patients under moderate sedation, was evaluated. A prospective study on 128 children and 253 tympanostomy tube placements conducted at 4 centers in the United States demonstrated an 88.3% success rate in performing the procedure under moderate sedation with adverse events within normal rates reported in the literature. The feasibility of completing tympanostomy tube placement under moderate sedation enables avoidance of general anesthesia and provides additional choices to physicians and parents.