The Impact of Preoperative Nasal Capnography on Clinical Management in Patients Undergoing Diagnostic Bronchoscopy for Suspected Foreign Body Aspiration

Introduction Despite advances in medical care, foreign body aspiration remains a common and ongoing health concern in children. Diagnostic bronchoscopy is the gold standard for confirming the diagnosis and providing definitive treatment. However, bronchoscopy performed for suspected foreign body aspiration in children yields negative findings in 16-57% of cases. Furthermore, oxygenation problems may occur during bronchoscopy performed under general anesthesia for foreign body aspiration. Respiratory complications requiring intensive care monitoring may develop in 6.3% of patients following bronchoscopy. These risks underscore the importance of preoperative assessment. In children with suspected foreign body aspiration, preoperative nasal capnography may complement clinical and radiological findings in determining the indications for bronchoscopy and predicting potential intraoperative complications.

Capnography assesses oxygenation status by measuring end-tidal carbon dioxide concentrations. Nasal capnography is used particularly during sedation and analgesia when spontaneous breathing is maintained. In patients scheduled for diagnostic bronchoscopy for suspected foreign body aspiration, preoperative capnographic assessment may help predict complications occurring during and after the procedure.

This study aims to evaluate the association of preoperative nasal capnographic measurements with positive and negative bronchoscopic findings and potential intraoperative complications in children with foreign body aspiration.

Methods Ethical approval was obtained from the Mersin University Health Sciences Ethics Committee (2026/556). The study, including data collection, is planned to be completed within 12 months of ethical approval. The ethics application stated that an application for project funding would be submitted to the Mersin University Scientific Research Projects (BAP) Unit. The study period was specified in the ethics application as one year following approval by the BAP Unit. Data collection will commence after the nasal capnography device has been procured through the project.

Children aged 0-18 years undergoing rigid bronchoscopy for foreign body aspiration at the Department of Pediatric Surgery, Mersin University Hospital, during the specified study period will be eligible for inclusion. Patients operated on by Associate Professor Caner İsbir, Dr. Hatice Büyüköztürk Çolak, or Dr. Mert Jundi will be included. All investigators will participate in data collection, and the collected data will be analyzed by Associate Professor Caner İsbir and Dr. Hatice Büyüköztürk Çolak.

Patients presenting with foreign body aspiration during the study period will be excluded if they decline rigid bronchoscopy, if their legal guardians do not sign the study-specific informed consent forms, or if nasal capnographic measurements cannot be recorded because of technical difficulties.

In patients admitted to the pediatric surgery ward with suspected foreign body aspiration, end-tidal carbon dioxide (ETCO₂) will be measured using a capnography device connected to a nasal cannula during preoperative preparation on the ward, before rigid bronchoscopy. Measurements will be recorded numerically for each patient. ETCO₂ values will also be classified into two groups: values up to and including the 35-45 mmHg range and values above this range.

The following variables will be assessed: age, sex, body weight, weight percentiles, preoperative pulse oximetry readings, preoperative clinical symptoms, physical examination findings, radiological findings, and postoperative complications following bronchoscopy. Patients will be categorized into three age groups: 0-6, 6-12, and 12-18 years.

The associations between nasal capnographic measurements and positive or negative bronchoscopic findings, as well as intraoperative and postoperative complications, will be examined. Independent-samples t-tests and chi-square tests will be used to assess the associations of preoperative capnographic measurements with bronchoscopic findings and intraoperative and postoperative complications. Logistic regression analysis will additionally be used to examine the associations of nasal capnographic measurements within the specified age groups with positive or negative bronchoscopic findings and intraoperative and postoperative complications.