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

Introduction Despite advances in diagnosis and treatment, foreign body aspiration remains a common and clinically relevant health problem among children. The mortality rate associated with foreign body aspiration in children has been reported to range from 1% to 5%. Diagnostic bronchoscopy remains the gold standard for confirming the diagnosis of foreign body aspiration and providing definitive treatment. In clinical practice, indications for bronchoscopy are determined based on the history provided by the family, physical examination findings, and radiological investigations. However, 16%-57% of bronchoscopies performed in children with suspected foreign body aspiration may result in negative exploration. Furthermore, among children presenting to the emergency department with a history suggestive of foreign body aspiration, 27% have no respiratory symptoms and 20% have no abnormal physical examination findings. During bronchoscopy performed under general anesthesia for foreign body aspiration, respiratory distress and oxygenation problems may also occur because of inflammation, secretions, or granulation tissue caused by the foreign body. Consequently, post-bronchoscopy respiratory complications requiring intensive care monitoring may develop in 6.3% of patients. Given these risks, the use of scoring systems based on preprocedural physical examination and radiological findings to determine bronchoscopy indications remains an active area of research.

For these reasons, in addition to determining the indication for bronchoscopy based on the available clinical and radiological findings, predicting potential intraoperative complications appears to be important in children with suspected foreign body aspiration. Accordingly, assessing both the likelihood of a positive bronchoscopy and the adequacy of ventilation before the procedure may improve the safety of bronchoscopy in these patients.

Capnography enables the noninvasive assessment of ventilation by measuring end-tidal carbon dioxide levels in intubated patients receiving mechanical ventilation. Nasal capnography is used particularly during procedures performed under sedation and analgesia in which spontaneous breathing is maintained, allowing respiratory depression and associated hypercapnia to be detected and thereby improving procedural safety. A particular advantage of nasal capnography is its ability to identify mild hypercapnia that may not be reflected by pulse oximetry, as well as to facilitate the early detection of serious respiratory compromise. Therefore, preprocedural nasal capnographic assessment in patients scheduled to undergo diagnostic bronchoscopy for suspected foreign body aspiration may help predict potential intraoperative complications and facilitate appropriate preparation for interventions such as respiratory support. Taken together, these considerations suggest that the noninvasive assessment of ventilatory status using nasal capnography before bronchoscopy may be a clinically relevant parameter for both improving procedural safety and predicting positive bronchoscopic findings in children with suspected foreign body aspiration.

This study aimed to evaluate the associations of preprocedural nasal capnographic assessment with positive and negative bronchoscopic exploration findings and with intraoperative complications in children undergoing bronchoscopy for suspected foreign body aspiration.

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

Children aged 0-18 years who are scheduled to undergo rigid bronchoscopy for suspected foreign body aspiration at the Department of Pediatric Surgery of Mersin University Hospital during the specified study period are planned to be included. Patients undergoing procedures performed by Assoc. Prof. Caner İsbir, Dr. Hatice Büyüköztürk Çolak, or Dr. Mert Jundi during the data collection period will be considered for inclusion. Data collection will be conducted with the participation of all investigators. The collected data will be analyzed by Assoc. Prof. Caner İsbir and Dr. Hatice Büyüköztürk Çolak.

Patients presenting with suspected foreign body aspiration whose legal guardians decline rigid bronchoscopy, those whose legal guardians do not sign the informed consent forms prepared for the study, and those whose nasal capnographic measurements cannot be recorded because of technical problems will be excluded from the study.

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

The variables to be evaluated will include age, sex, body weight, weight-for-age percentile, preoperative pulse oximetry values, preoperative clinical symptoms, physical examination findings, radiological findings, and postoperative complications following bronchoscopy. Patients will be divided into three age groups: 0-6, 6-12, and 12-18 years. In addition, the associations between nasal capnographic measurements and positive or negative bronchoscopic exploration findings, intraoperative complications, and postoperative complications will be investigated.

The associations of positive or negative bronchoscopic exploration findings and intraoperative/postoperative complications with preoperative capnographic assessment results will be analyzed using the independent-samples t test and chi-square test, as appropriate. Furthermore, logistic regression analysis will be performed to evaluate the associations between nasal capnographic measurements in the specified age groups and positive or negative bronchoscopic exploration findings, as well as intraoperative and postoperative complications.