A simple method for confirming correct endotracheal intubation in mice.

Endotracheal intubation in mice is both a common and important technique. However, it is a difficult procedure because of the small orotracheal size and the success rate is variable. There have been many reports of refined techniques that facilitate intubation but only a few reports have proposed how to verify the proper placement of the endotracheal tube. We describe a novel, safe and reliable method to confirm endotracheal intubation in mice using an extension tube for intravenous infusion. One drop of water was instilled in the extension tube and connected to the end of the catheter used as an endotracheal tube. When the catheter was inserted correctly into the trachea, the water in the extension tube oscillated in synchrony with the movement of the mouse's thorax, indicating correct placement of the catheter. This method was simple, reliable and use materials that are routinely available. This method is helpful for experimental mouse models that require airway access.