Improved Methodology for Liquid Delivery to the Mouse Lung: Intubation using a Consumer Otoscope

Consistent delivery of liquids, including potential therapies, to the lungs is critical for modeling pulmonary disease and pre-clinical therapeutic development. However, current methods used in mice -such as oropharyngeal aspiration by the tongue-pull method- can result in variable delivery. Here, we describe the use of an affordable, mobile phone-linked, lighted otoscope to visualize the glottis and permit direct inoculation into the airway. We detail an optimized staging technique with adequate lighting and positioning aids. How intubation can be reliably conducted using a 20 G flexible catheter with or without a fiberoptic light is also described. This technique greatly reduces variance in intrapulmonary delivery and increases the volume of delivered liquid that reaches the lungs. Due to reduced variance, smaller animal cohort sizes can be used when employing this method instead of oropharyngeal instillation by the tongue-pull method. What follows is a method for effective, rapid, and consistent intubation of mice and delivery to the lungs, including robust confirmation of endotracheal tube placement. With this improved methodology, consistent, safe intubation and replicable, efficient delivery to the lungs are within reach.