A 74-year-old female (156 cm, 50 kg) with vertebral osteomyelitis was scheduled for an extreme lateral interbody fusion in the lateral decubitus position followed by posterior fixation in the prone positions. In the operating room, standard monitoring including electrocardiography, noninvasive blood pressure, invasive radial artery pressure, percutaneous oxygen saturation, bispectral index, and tympanic temperature was applied. Motor-evoked potential monitoring via transcranial electrical stimulation was planned for the procedure. General anesthesia was induced with propofol and remifentanil. Endotracheal intubation with a cuffed reinforced endotracheal tube with an inner diameter of 7.0 mm was performed following muscle relaxation with rocuronium. The endotracheal tube was secured at a depth of 21 cm on the right side of the mouth with the cuff pressure gauge indicating a cuff pressure of 28 cmH2O, and no cuff leak was detected on auscultation. Anesthesia was maintained with propofol, remifentanil, and oxygen-in-air gas mixture. Mechanical ventilation was administered using pressure control ventilation-volume guaranteed with a set tidal volume of 450 mL and a respiratory rate of 10 breaths/min. The patient was placed in the right lateral decubitus position for the extreme lateral interbody fusion. To provide supplemental lighting during surgery, a fiber-optic light attached to a 300-W xenon lamp was utilized as part of the surgical illuminator (ProXenon 350™, Welch Allyn, Inc., New York, USA). The fiber-optic light source intensity was set at 100% (200,000 lx of illumination) throughout the surgery but was stored in a polyethylene electrosurgical safety holster when not in active use. Approximately 1 h into the surgery, we noted a sudden decrease in the tidal volume and airway pressure to less than 50 ml and 5 cmH2O, respectively. While ensuring no displacement or obstruction of the endotracheal tube, an intact respiratory circuit, and no malfunction of equipment failure, we suspected air leakage around the endotracheal tube cuff; however, no decrease was detected.

The cuff pressure gauge was maintained at 28 cmH2O, consistent with the level immediately after intubation. Despite the normal cuff pressure, we decided to inject a small amount of air which led to a significant increase in the cuff pressure. Upon careful inspection of the endotracheal tube, we discovered that the pilot balloon tubing was damaged as a result of thermal energy emitted by the illuminated end of the fiber-optic light (Fig. 1A). This energy burned the bottom of the electrosurgical safety holster in which the fiberoptic light was stored, subsequently igniting the surgical drape beneath the holster (Fig. 1A, B) and leading to damaging the pilot balloon tubing. More specifically, the pilot balloon tubing was partially severed in which the section proximal to the endotracheal tube cuff was burned and punctured, causing the cuff leak (Fig. 1C). Meanwhile, the section proximal to the pilot balloon had melted and occluded the lumen, resulting in a falsely normal cuff pressure reading followed by an elevated cuff pressure when a small amount of air was injected into the pilot balloon during troubleshooting (Fig. 1C).

Thermal damage induced by the fiber-optic light. A A diagram illustrating thermal damage caused by the fiber-optic light. The thermal energy emitted from the illuminated end of the fiber-optic light burned the bottom of the electrosurgical safety holster in which the fiber-optic light was stored, subsequently igniting the surgical drape beneath the holster and leading to damage of the pilot balloon tubing. B The damaged holster and surgical drape caused by thermal damage from the fiber-optic light. An inset image highlights the damaged section of the electrosurgical safety holster. The arrowhead and arrow indicate the holes in the surgical drape and the holster, respectively. C The damaged pilot balloon tubing caused by thermal damage from the fiber-optic light. The upper panel shows the damaged pilot balloon tubing, and the lower panel provides a schematic representation of the damage. The pilot balloon tubing was partially severed in which the section proximal to the endotracheal tube cuff was burned and punctured, causing the cuff leak. Meanwhile, the section proximal to the pilot balloon had melted and occluded the lumen, resulting in a falsely normal cuff pressure reading followed by an elevated cuff pressure when a small amount of air was injected into the pilot balloon during troubleshooting

Appropriate ventilation was resumed after extubation and re-intubation with a new endotracheal tube. Subsequently, the surgery was successfully completed, with no burns observed on the patient’s body. The postoperative course was uneventful, and the patient was discharged on postoperative day 21. This case was reviewed by the Medical Safety Promotion Department of our institution, and relevant departments were notified.