Is High Flow Nasal Oxygenation a Game Changer in Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration: A pilot study

Objectives: A pilot observational study was done to compare High Flow Nasal Oxygen (HFNO) and supraglottic airway device (SAD) technique in patients undergoing endobronchial ultrasound (EBUS) and transbronchial needle aspiration procedures (TBNA) with an objective to evaluate the efficacy of HFNO  in oncological patients. Methods:  The study was conducted in a tertiary cancer center in Muscat, Sultanate of Oman from May 2022 to March 2023.  Consecutive patients undergoing EBUS TBNA under moderate sedation were quasi-randomized into HFNO and SAD groups. The episodes and duration of hypoxia and the lowest level of oxygen saturation were the primary outcome measured. Results: A total of twenty-four patients were taken into the study of which 10 were in the HFNO group and 14 were in the SAD group with an equal number of males and females.  The duration of the procedure in both the groups was similar (45±20 mins in HFNO vs 44±17 in the SAD group). Mean lowest oxygen saturation in the HFNO group was (93.5%±4), which was statistically significant in comparison to the SAD group (90±6). In both groups, the maximum hypoxia occurred during the early phase of the procedure. However, both the groups were similar for the cumulative duration of hypotension (140 secs in HFNO vs 55 secs in SAD) and bradycardia (25 secs in HFNO vs. 40 secs in SAD). Conclusion: HFNO can be a good alternative to the SAD and could be used safely and efficiently in the cohort of population in patients undergoing EBUS TBNA. Keywords: High flow nasal oxygenation; Endobronchial Ultrasound-guided Transbronchial Needle Aspiration; Supraglottic airway devices

Short-Term Time-Series Observations of Phytoplankton Light-Absorption and Productivity in Prydz Bay, Coastal Antarctica

The optical characteristics of coastal Antarctic waters exhibit complexity due to the dynamic hydrography influenced by meltwater intrusion, which alters nutrient levels, thermohaline structure, and optically active substances (OAS) regimes. Studies on bio-optical variability and its implications on phytoplankton productivity (PP) are scanty in coastal polar regions. On this backdrop, time-series measurements (72 h at 6 h intervals) of bio-optical properties such as phytoplankton biomass (chlorophyll-a), absorption (aph), and total suspended matter (TSM) concurrently with PP were measured to understand their interplay and variability in relation to the ambient physicochemical settings in the under-sampled Prydz Bay, coastal Antarctica. Our findings revealed thermohaline stratification within the bay, likely attributed to the inflow of less saline meltwater from nearby glaciers and minimal wind activity. The consistent presence of sub-surface chlorophyll maximum (SCM) beneath the stratified layer underscored the light-acclimatization response of shade-adapted phytoplankton. Surface waters exhibited higher TSM compared to deeper layers, indicating glacial melt influence, while the depth of the sunlit layer remained relatively stable, suggesting limited water mass movement and/or variability in OAS at the study site. An inverse relation between chlorophyll-a and chlorophyll-a-specific phytoplankton light absorption (a*ph(λ)) manifested ‘pigment package effect’ within the prevailing phytoplankton community, implying reduced light-absorption efficiency and consequent lower PP. Compared to chlorophyll-a, the phytoplankton light absorption (aph(λ)) emerged as a better proxy for explaining PP variability. Nutrient availability was not limiting, which was conducive to micro (large) phytoplankton growth. Classification of phytoplankton size classes (micro, nano, and pico) based on the B/R ratio (aph at Blue (443 nm)/Red (676 nm) region) confirmed the dominance of larger (micro) phytoplankton that are more susceptible to package effect, thus have implications on reduced PP potential of this polar marine ecosystem