A missed diagnosis of sputum crust with fiberoptic bronchoscope causing extubation failure: a case report

Fiberoptic bronchoscopy (FOB) and bronchoscopic biopsy are the established methods for diagnosing and treating sputum crust. However, sputum crust in concealed locations can sometimes be missed or undiagnosed, even with bronchoscopy.

We present the case of a 44-year-old female patient who experienced initial extubation failure and postoperative pulmonary complications (PPCs) due to the missed diagnosis of sputum crust by FOB and low-resolution bedside chest X-ray. The FOB examination showed no apparent abnormalities prior to the first extubation, and the patient underwent tracheal extubation 2 h after aortic valve replacement (AVR). However, she was reintubated 13 h after the first extubation due to a persistent irritating cough and severe hypoxemia, and a bedside chest radiograph revealed pneumonia and atelectasis. Upon performing a repeat FOB examination prior to the second extubation, we serendipitously discovered the presence of sputum crust at the end of the endotracheal tube. Subsequently, we found that the sputum crust was mainly located on the tracheal wall between the subglottis and the end of the endotracheal tube during the "Tracheobronchial Sputum Crust Removal" procedure, and most of the crust was obscured by the retained endotracheal tube. The patient was discharged on the 20th day following therapeutic FOB.

FOB examination may miss specific areas in endotracheal intubation (ETI) patients, particularly the tracheal wall between the subglottis and distal end of the tracheal catheter, where sputum crust can be concealed. When diagnostic examinations with FOB are inconclusive, high-resolution chest CT can be helpful in identifying hidden sputum crust.