Respiratory Stabilization in Chronic Acidosis Before Bronchofiberoscopy & Non-Invasive Ventilation Effectivenes

Bronchofiberoscopy (FOB) is a minimally invasive and safe procedure performed for diagnostic and therapeutic purposes. FOB frequently impairs respiratory function, which may lead to possible exacerbation of respiratory failure. Currently, the most frequent respiratory support is passive oxygen therapy, but non-invasive ventilation (NIV) and high flow nasal cannula (HFNC) are increasingly attempted, however the optimal setting and indications for NIV and HFNC in patients undergoing FOB with respiratory acidosis, haven't been determined yet. Methods: The study protocol describes a prospective, multicenter, two- armed randomized controlled trial (RCT). The investigators aim to study two patients groups, based on FOB indications and the type of respiratory acidosis: 1\) Diagnostic FOB; patients with chronic respiratory acidosis (pH ≥7.35; pCO2 \> 45mmHg and/or HCO3- \>27 mmol/l); 1. randomized to: passive oxygen, NIV, HFNC; 2. total number of participants: 210 Randomization: two-step randomization (1st randomization :a or b; 2nd randomization: i- iii method of respiratory support): a. Stabilization of respiratory parameters before FOB (pH 7.35-7.45; pCO2 35-45 mmHg; HCO3- \>27 mmol/l) i. NIV ii. HFNC iii. Passive oxygen therapy b. FOB right away (pH 7.35-7.45; pCO2 \>45 mmHg; HCO3- \> 27 mmol/l) i. NIV ii. HFNC Before FOB, both groups will undergo arterial blood gas analysis (ABG). During FOB there will be a continuous monitoring of vital signs as in: SpO2, FiO2, TcCO2, ECG, and Heart Rate. After FOB, the investigators are going to perform another ABG, mark endpoints, and complications, if any arise. Results: Based on the selected endpoints, or any complication related to FOB the investigators hope to determine which of the respiratory methods: passive oxygen, NIV, HFNC or IMV provides the best support, leading to a lower number of complications and overall a better tolerance of FOB by the patient. Additionally, our aim is to find the optimal settings for NI