An observational study in ENDOBRONCHIAL ULTRASOUND - TRANSBRONCHIAL NEEDLE ASPIRATION, Hypoxemia and Trachea, sponsored by Ankara Ataturk Sanatorium Training and Research Hospital. Not yet recruiting at 1 site in Turkey (Türkiye). Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-11-04.
Sponsored by Ankara Ataturk Sanatorium Training and Research Hospital · Observational
Bronchoscopic procedures performed under endobronchial ultrasound (EBUS) guidance are widely used minimally invasive diagnostic methods for the evaluation of mediastinal lymph nodes. Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration (EBUS-TBNA) is an indicated procedure for the diagnosis, staging, and histopathological characterization of primary or metastatic tumors. The procedure is generally performed under moderate or deep sedation to enhance patient comfort and optimize procedural success. Deep sedation has been shown to be a safe and effective approach in terms of respiratory complications in both younger and elderly patients.
However, hypoxemia may develop during EBUS procedures due to mechanisms such as mechanical airway obstruction, sedation-related ventilatory depression, and ventilation-perfusion mismatch. A decrease in oxygen saturation is frequently observed during bronchoscopic procedures, with reported rates of up to 94%. Studies have also reported a hypoxemia rate of approximately 25% during EBUS, even with the use of a nasopharyngeal oxygen cannula. Therefore, maintaining adequate oxygenation throughout the procedure is of critical importance. In patients receiving sedation under spontaneous respiration, oxygen support is typically provided via low-flow systems such as nasal cannulae, which can generally deliver flows of up to 15 L/min.
It has been reported that a fiberoptic bronchoscope occupies approximately 10% of the tracheal cross-sectional area and about 15% at the level of the cricoid ring, leading to partial obstruction. EBUS endoscopes have a larger outer diameter and, in addition, may exert more pronounced negative effects on respiratory mechanics due to the balloon mechanism used. The outer diameter of EBUS bronchoscopes typically ranges between 6.2 and 6.7 mm, mechanically occupying a significant portion of the tracheal lumen. This may restrict tracheal airflow, leading to partial obstruction and consequently predisposing to hypoxemia. Therefore, identifying objective anatomical predictors that can predict the development of hypoxemia is of clinical importance. However, to the best of our knowledge, no study in the literature has statistically investigated the relationship between tracheal measurements and hypoxemia occurring during EBUS.
In this study, the investigators aim to investigate the relationship between pre-procedural tracheal diameter measured by ultrasonography (USG) and the EBUS outer diameter/tracheal diameter ratio (airway occupancy ratio) with the development of hypoxemia during the procedure in patients undergoing EBUS-TBNA. Additionally, it is aimed to determine the optimal tracheal diameter cutoff value that may predict the development of hypoxemia.
Study Design and Patient Population This study will be conducted in accordance with the Declaration of Helsinki and will be carried out at SBÜ Ankara Atatürk Sanatoryum Training and Research Hospital after obtaining approval from the institutional ethics committee. The study is planned as a prospective observational cohort study. Adult patients scheduled to undergo EBUS-TBNA will be included.
The following parameters will be recorded:
H0: There is no significant association between ultrasonographic tracheal measurements and the development of hypoxemia during Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration (EBUS-TBNA).
H1: There is a significant association between ultrasonographic tracheal measurements and the development of hypoxemia during Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration (EBUS-TBNA).
Ultrasonographic Measurements In this study, tracheal diameter will be measured using a high-frequency linear probe while the patient is in the supine position with the neck in a neutral position. Patients will be instructed to take a deep inspiration, and measurements will be obtained during inspiration at the level just below the cricoid cartilage and at the level of the 2nd-3rd tracheal rings. The narrowest transverse tracheal diameter will be recorded. All ultrasonographic measurements will be performed by the same anesthesiologist.
Sedation Protocol Patients will receive 4 L/min oxygen via nasal cannula along with routine hemodynamic monitoring. Sedation will be administered according to the standard protocol routinely used in our clinic. During the procedure, patients will be maintained under deep sedation corresponding to a Richmond Agitation-Sedation Scale (RASS) score of -4. The total doses of sedative agents used will be recorded.
1,076 studies on the registry are indexed under Hypoxia; 213 are open to participants now.
This study's planned enrollment of 300 is above the median of 79 across 277 observational studies indexed under Hypoxia.
Browse Hypoxia studies →Ankara Ataturk Sanatorium Training and Research Hospital is the lead sponsor of 38 studies on the registry; 15 are open to participants now.
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This study will be conducted in accordance with the Declaration of Helsinki and will be carried out at SBÜ Ankara Atatürk Sanatoryum Training and Research Hospital. In patients aged 18 years and older scheduled to undergo EBUS-TBNA, the narrowest pre-procedural tracheal diameter will be determined. The relationship between tracheal diameter and the development of hypoxemia will be analyzed.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
The anaesthetists’ scale of health before surgery: I is healthy, II has a mild illness that is under control, III a severe one, IV a severe illness that is a constant threat to life. V and VI are used for the critically ill and for organ donors.
From a breathing test (spirometry): how much air you can blow out in the first second. Often given as a percentage of what is expected for your age, height and sex.
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ASA physical status
The anaesthetists’ scale of health before surgery: I is healthy, II has a mild illness that is under control, III a severe one, IV a severe illness that is a constant threat to life. V and VI are used for the critically ill and for organ donors.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
FEV1
From a breathing test (spirometry): how much air you can blow out in the first second. Often given as a percentage of what is expected for your age, height and sex.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
COPD
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
"In patients aged 18 years and older scheduled to undergo EBUS-TBNA, the narrowest pre-procedural tracheal diameter will be determined. The relationship between tracheal diameter and the development of hypoxemia will be analyzed.
Other: TRACHEAL DIAMETER MEASUREMENT · Other: Hypoxemia
"In patients aged 18 years and older scheduled to undergo EBUS-TBNA, the narrowest pre-procedural tracheal diameter will be determined. The relationship between tracheal diameter and the development of hypoxemia will be analyzed.
Hypoxemia will be defined as the presence of at least one of the following criteria: * SpO₂ \< 90% for at least 10 seconds, or * A decrease in SpO₂ of ≥5% from baseline
Hypoxemia
Time frame: Periprocedural
Plan to share: No
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Ankara Ataturk Sanatorium Training and Research Hospital