Oxygen therapy in severe asthma

This study is for people who come to the emergency department with a severe asthma attack. Standard practice is to give all asthma patients high-flow oxygen, but this study questions whether that is always the right approach. High-flow oxygen may actually be harmful in some cases. This trial compares high-flow oxygen to a 'controlled' approach where oxygen levels in the blood are monitored and the amount of oxygen given is adjusted accordingly — known as titrated oxygen therapy. You may be eligible if: - You are between 18 and 65 years old - You have a history of asthma - You are attending the emergency department with a severe asthma attack - Your lung function (FEV1) is 50% or less of what is expected for you You may NOT be eligible if: - You have been diagnosed with COPD or emphysema - Your asthma is so severe that you need a breathing machine (mechanical ventilation) - You are unconscious, unable to speak, or unable to do a breathing test when you arrive - You have a known chronic breathing condition caused by nerve or muscle disease, chest wall problems, or obesity Talk to your doctor about whether this trial might be right for you.