Video-Assisted Orotracheal Intubation in Rats Using a Low-Cost Smartphone-Connected Otoscope

Reliable endotracheal intubation is essential for experimental procedures in rats that require controlled ventilation, particularly during thoracic and cardiovascular surgeries. However, airway management in rats remains technically challenging due to anatomical constraints and limited accessibility of available intubation techniques. The goal of this protocol is to describe a simple, low-cost method for orotracheal intubation in rats using video-assisted direct laryngoscopy successfully applied in a cohort of 50 rats. This protocol uses a commercially available video otoscope with an integrated light source and wireless smartphone connectivity to provide real-time visualization of the upper airway. The method does not require device modification or specialized imaging systems. Adult rats are anesthetized with xylazine and isoflurane, positioned on an inclined intubation platform, and intubated under continuous visual guidance using a flexible guide and an endotracheal tube. Correct tube placement is defined by bilateral thoracic expansion, stable oxygen saturation (SpO₂), and a consistent end-tidal CO₂ (capnography) waveform. Following intubation, mechanical ventilation is initiated without positive end-expiratory pressure, and the tidal volume was set at 7.5 mL/kg. In this cohort, the technique enabled rapid intubation with a high first-attempt success rate and was associated with a low incidence of peri-procedural complications. Continuous visualization may reduce the risk of esophageal intubation and airway trauma. These findings support the feasibility of this approach under the conditions tested, without extrapolation beyond this experimental setting.