Bronchofiberoscopy is a widespread invasive intervention in clinical practice with a number of diagnostic and therapeutic indications. The Clinic of Pulmonary Medicine in Debrecen carries out nearly 2000 examinations a year. The intervention is guided by the recommendation of the Vocational College for Pulmonary Medicine in 2005, but it does not contain a clear recommendation on the oxygen therapy used during the intervention. The Hungarian recommendation states that pulsoximetry is mandatory in bronchoscopy, but it does not contain information on the indications and the implementation of oxygen suplementation. The British Thoracic Society Guideline 2013 deals with the issue and makes the following statements:

• patients should be monitored for oxygen saturation under bronchofiberoscopy
• oxygen supplementation during the test is recommended if the patient's desaturation is significant (greater than 4% or less than 90%) and is over 1 minute
• during the bronchoscopy, the occurrence of oxygen saturation decreases depending on the level of initial oxygen saturation, respiratory function, co-morbidity, sedation and the course of intervention.

The aim of our study is to investigate the frequency with which systemic hypoxia occurs during bronchoscopy, what factors may contribute to its development and how the level of cerebral oxygen saturation changes with systemic desaturation (in the case of NIRS, a 20% reduction from baseline is considered significant).

: Consecutive patients admitted to Bronchology Laboratory of Department of Pulmonology, University of Debrecen for flexible bronchoscopy were asked to participate in the study. After explaining the procedure in detail, all patients gave written informed consent.

The indication of flexible bronchoscopy was based in all cases on the results of medical history, physical examination, chest X-ray and/or chest CT scan, lung function tests and laboratory parameters including hemoglobin concentration, hemostasis variables as well as blood gas analysis when necessary.

Bronchoscopy (PENTAX EB-1975K) was performed after an at least 4-hour fasting period. The procedure was performed either in sitting or supine position after a topical administration of lidocaine 2% solution. Routine monitoring consisted of ECG, non-invasive blood pressure measurement, pulse oxymetry (finger probe). As an additional monitoring tool, near infrared monitoring sensor was placed to the forhead of the dominant hemisphere of patients for monitoring cerebral oxygen saturation. INVOS 5100 C cerebral oximeter (Covidien llc, 15 Hampshire Street, Mansfield, MA 02048 USA) was used for cerebral near infrared spectroscopy measurements.

Inclusion Criteria:

inclusion criteria: adult patients (over 18 years) going elective bronchoscopy

Exclusion Criteria:

age under 18 years

Consecutive patients admitted to Bronchology Laboratory of Department of Pulmonology, University of Debrecen for flexible bronchoscopy were asked to participate in the study. After explaining the procedure in detail, all patients gave written informed consent.