Crimping of a Laser Tube Resulting in Hypoxemia 

To the Editor:

—Laryngeal surgery involving a laser often necessitates the use of special endotracheal tubes (ETTs) to avoid an airway fire. 1,2Many companies, including Rüsch (Duluth, GA), manufacture these tubes. We describe an anesthetic complication with a laser ETT constructed from rubber, wrapped with foil, and overwrapped with fabric. 3 

The patient was a 90-kg, 170-cm, 65-yr-old male smoker who was scheduled for direct laryngoscopy and vocal cord laser therapy. After uneventful induction of general anesthesia and paralysis, the patient was intubated via  direct laryngoscopy with a 6.0-mm ID Rüsch Lasertubus (lot #CE0124) without difficulty. The patient had bilateral clear breath sounds, arterial oxygen saturation was 100%, and end-tidal CO²was demonstrated. The ETT was secured with 1-inch silk tape at 23 cm at the lips. The operating room table was then turned away from the anesthesia machine, and the surgeons extended the neck and head to position the patient for the surgical procedure. Within 30 s, the peak inspiratory pressures began to increase, and both the ET^CO2and Sp^O2started to decrease. No devices had been inserted into the patient's mouth, and there was no tension on the circuit or ETT. The patient's head was returned to the neutral position, but bilateral auscultation showed minimal to no breath sounds bilaterally. The patient was hand-ventilated with 100% oxygen, and the sevoflurane was increased to 8%. Sp^O2decreased to 70%, and no ET^CO2was evident by capnography. Immediate direct laryngoscopy confirmed correct ETT placement. Because inspection of the ETT showed no kinks or obvious obstructions, working diagnoses included the presence of either bronchospasm or a mucus plug in the tube. The patient received an inhaled β-agonist and subcutaneous terbutaline without improvement. We attempted to pass a suction catheter through the tube but met resistance at approximately 20 cm. Because initial intubation was easy and the patient was not responding to medical therapy, we decided to exchange the ETT for a PVC Portex (Keane, New Hampshire) Softseal 7.0-mm ID (nonlaser tube), which was inserted to 23 cm. Ventilation was achieved, and within 10 breaths, the patient's Sp^O2returned to 100%. Surgery proceeded, and it was decided that the laser portion of the operation was not necessary. Emergence and extubation were uneventful.

We inspected the Lasertubus and found the tube crimped under the tape (fig. 1). Although this was only a small defect not obvious to cursory inspection, it resulted in complete obstruction to airflow when tested with the breathing circuit. Experimenting with unused tubes showed that after bending the Lasertubus, a weakness within the wall of the tube remained, predisposing to crimping with minimal force and complete obstruction to airflow. All anesthesia providers need to be aware of this potential complication.