Hyperoxia

The goal of this observational study is to learn how often high blood oxygen levels (hyperoxemia) occur in adults receiving general anesthesia for planned (elective) neurointerventional procedures, such as brain aneurysm coiling or other catheter-based treatments of brain vessels. It will also look at how well a non-invasive finger sensor measurement called the Oxygen Reserve Index (ORi) reflects arterial oxygen levels. The main questions it aims to answer are: * How often is the arterial oxygen pressure (PaO2) 150 mmHg or higher in blood gas samples taken as part of routine care during these procedures? * How does ORi relate to PaO2, and can ORi help identify high oxygen levels? Participants will: * Receive anesthesia and their procedure exactly as planned by their care team; the study does not change any treatment, oxygen setting, or ventilator setting. * Have a painless ORi sensor placed on a finger, similar to a standard pulse oximeter, during anesthesia. * Have their routine monitoring values and the results of arterial blood gas samples taken for routine clinical care recorded. No extra blood samples will be taken for the study, and ORi values will not be used to guide care.

The goal of this trial is to investigate whether adding a small fraction of hydrogen gas to an oxygen-enriched breathing mixture can reduce pulmonary oxygen toxicity (POT) in healthy and active divers from the Swedish Armed Forces. The main questions it aims to answer are: * Does hydrogen gas reduce oxidative stress and changes in pulmonary function associated with prolonged hyperbaric oxygen exposure? * What are the underlying pathophysiological mechanisms of pulmonary oxygen toxicity? Researchers will compare oxygen-enriched breathing gas with 1-2% hydrogen to oxygen-enriched gas with 1-2% nitrogen (control) to see if hydrogen provides protective effects against POT during hyperbaric exposure. Participants will: * Complete two hyperbaric exposure sessions (hydrogen vs. nitrogen), each lasting 240 minutes at 1.75 ATA * Undergo pulmonary function tests and sampling of blod and urin before and after each session * Serve as their own controls in a double-blind, randomized, crossover study design

The aim of this study is to identify and determine the levels of oxidized lipids and lipid mediators following exposure to oxygen supplementation during mechanical ventilation by oxidative lipidomics. The investigators will include patients with mechanical ventilation and have received FiO2=\>0.5 atleast 90 minutes and collected two sequential mini bronchoalveolar lavage on them 24 hours apart. Mass Spectrometry Lipid chromatography will be conducted and clinical data will be analyzed.