A Randomized Controlled Trial to Compare High Flow Nasal Cannula With Standard Nasal Cannula to Prevent Desaturation in Subjects Undergoing Endobronchial Ultrasound Guided Transbronchial Needle Aspiration (EBUS-TBNA)

Endobronchial ultrasound (EBUS)-guided transbronchial needle aspiration (TBNA) is a routine procedure that is performed to sample mediastinal lymph nodes. The procedure is performed either under conscious sedation or using general anaesthesia. At author's center the EBUS-TBNA procedure is performed under conscious sedation using midazolam.During the EBUS procedure, oxygen supplementation is provided to prevent desaturation events. However, despite oxygen supplementation previous studies have reported fall in pulse oximetric saturation (SpO2) below 90%.

The high-flow nasal cannula (HFNC) is a novel device for providing oxygen supplementation. It delivers a flow of 10-70 litres/min of humidified, warmed 100% oxygen through a nasal cannula. The device has been used extensively in intensive care setting in adults with hypoxemic respiratory failure. In a study conducted on patients undergoing EBUS-TBNA, the use of HFNC led to a significant reduction in the number of subjects experiencing clinically significant hypoxemia (SpO2 ≤90%) compared to conventional oxygen supplementation. However, the study conclusions were limited by a small sample size. Another study demonstrated lesser episodes of hypoxemia with HFNC compared to the conventional oxygen supplementation. This study also had a small sample size (n=40). The investigators that the use of HFNC for oxygen supplementation during EBUS would be associated with lesser incidence of clinically significant hypoxemia (SpO2 ≤90%) when compared to conventional nasal cannula. In this study, the authors intend to assess the efficacy of HFNC in reducing the incidence of hypoxemic events in subjects undergoing EBUS under conscious sedation.