The Effect of Microstream® Capnography on Patient Safety in Endobronchial Ultrasonography Applications Under Sedation

Endobronchial ultrasonography (EBUS) is an examination method that has been increasingly used in diagnosing and staging lung cancer, mediastinal lymphadenopathy and masses in recent years. This procedure is performed under anesthesia. General anesthesia or sedation is generally preferred as an anesthesia option. Desaturation may frequently develop during this procedure. Follow-up with standard perioperative monitoring methods (heart rate - HR, respiratory rate - SS, peripheral oxygen saturation - SpO2) is not a proper approach to detecting respiratory depression before desaturation develops.

Capnography is a monitoring method that detects respiratory depression before desaturation develops by making instant end-tidal carbon dioxide (EtCO2) measurements. It has been stated that it significantly reduces the risk of desaturation in many surgical and interventional procedures performed under sedation and general anesthesia. In addition, respiratory disorders such as bronchospasm, apnea or hypopnea can be detected by capnography. However, there is no information about capnography's effect on desaturation development or its contribution to standard monitoring in EBUS cases.

The purpose of this study was to investigate the effects of capnography monitoring in addition to routine monitoring on the development of desaturation and other vital parameters in EBUS cases under moderate sedation according to the Ramsay Sedation Scale (RSS). The primary aim was to compare the groups in terms of the development of desaturation, and the secondary aim was in terms of duration of hypoxemia, development of severe hypoxemia, lowest SpO2 value, development of hypotension, and bradycardia.

150 patients who will undergo elective EBUS procedure, have scores between 1-3 according to the American Society of Anesthesiologists (ASA) classification, are pregnant or not suspected of pregnancy, approve the informed consent form, and are not allergic to the sedation agents to be used, will be included in the study. Patients with an ASA score of 4 and above, pregnant or suspected pregnancy, patients with difficult airway features, and emergency cases will be excluded from the study.

The cases will be divided into two groups of 75 people using the closed envelope method. There will be cases in which capnography monitorization was performed in group 1 (experimental group), and cases in which capnography monitoring was not performed in group 2 (control group). In all cases, age, gender, weight, height, ASA class, doses of applied anesthesia drugs, and smoking history will be recorded. After obtaining informed consent in all cases Standard monitoring and BIS monitoring will be performed before sedation, including HR, SS, SpO2, BP, and 3-lead electrocardiographic analysis. In addition to standard monitoring in patients in Group 1, ETCO2, integrated pulmonary index (IPI) will be measured non-invasively prior to sedation through a nasal cannula (FilterLine®) connected to the capnography device (Capnostream® 20p). Sedation and analgesia will be performed in accordance with the routine sedation-analgesia protocol used by our department in EBUS cases. There will be no changes to the routine protocol. In accordance with this protocol, after the patient is taken to the operating room, 5 ml of 2% lidocaine will be applied with a reservoir mask for topical anesthesia. As a sedative agent, 1-2 mg of midazolam will be administered intravenously. A nasopharyngeal airway will be placed and 5 lt/min oxygen will be given to all patients throughout the operation. In induction, remifentanil will be administered at a level of 0.04 µg/kg/min and Propofol at a level of 0.5-1 mg/kg/hour. The target sedation level will be determined as 60-80 BIS score and will be level 3 (moderate sedation, sleepy but responsive to verbal stimuli) according to the Ramsey Sedation Scale. All parameters measured before sedation in both groups; It will be recorded at 3 minutes, 6 minutes, 9 minutes after sedation, and at 3-minute intervals until the end of the operation.