Unexpected tracheal narrowing during general anesthesia in the prone position of Duchenne muscular dystrophy patient -A report of two cases-
A 14 year-old male patient (height 158 cm, weight 50 kg) was scheduled to receive a corrective operation for thoracolumbar scoliosis. He also was diagnosed with DMD in his early childhood. When he was 9 years old, he started a wheelchair life due to muscle weakness. Preoperative evaluation revealed thoracolumbar scoliosis (Cobb's angle 70°) and decreased lung function (FEV1 0.86 liter, FVC 1.37 liter, FEV1/FVC 63%). Except for these findings, all the other tests were in the normal range. He did not report any respiratory problems in his daily life. Anesthesia induction was performed with propofol, remifentanil, and a small dose of a rocuronium. The tracheal intubation was successful with a wire-reinforced tube. Airway pressures during controlled ventilation fell into normal range. But we immediately performed FB and observed a narrowed portion beyond the tip of the tracheal tube until the closing at the carina (). We advanced the tracheal tube along the fiberscope until its tip reached the carina. The sounds of both lung fields were clear. In the volume controlled ventilation mode (expired TV 400 ml, RR 13 per minute, FiO2 0.5), PIP was 18 cmH2O, and EtCO2 was 28 mmHg. After the patient was put into the prone position, we did FB again. It revealed the patency of the tracheal lumen in the prone position. During the operation, PIP maintained at a range of 22-26 cmH2O without CO2 retention. The surgery ended without any problems and at the end of anesthesia, FB confirmed the airway as narrow but acceptable for ventilation with retrieved endotracheal tube. During emergence and in the recovery room, the patient did not suffer from airway problems.