Studying Short-Term Effects of Increased Oxygen Levels on Brain Blood Flow in Adults Receiving Mechanical Ventilation in the ICU

What this Trial Is About

This research aims to better understand how short periods of high oxygen levels affect blood flow in the brain of patients who are intubated and mechanically ventilated in the Intensive Care Unit ICU. Many ICU patients receive more oxygen than necessary, and high blood oxygen levels are common. The study focuses on how these short high oxygen exposures impact cerebral circulation and autoregulation, which are not well understood. Patients will receive one or two brief increases in the oxygen level delivered by the ventilator depending on their baseline oxygen needs. Those with lower baseline oxygen needs will have two steps increasing to 0.5 and then to 1.0 fraction of inspired oxygen FiO2. Those with higher baseline needs will have one step to 1.0 FiO2. Each step includes 5 minutes to stabilize followed by 10 minutes of monitoring with transcranial Doppler ultrasound to assess cerebral blood flow and autoregulation. After the exposure, oxygen levels return to baseline. Participants will be monitored continuously during the procedure, including brain blood flow via ultrasound and arterial blood pressure. Blood gas samples will be collected before, during, and after oxygen adjustments to track oxygen and carbon dioxide levels. Sedation, ventilation, and medication rates will remain stable. Safety is closely observed, and the procedure stops immediately if instability occurs. The main outcome is change in mean flow index Mx during and after hyperoxia, with additional measures of cerebral blood flow and autoregulatory function.

HYPER MIND - Hyperoxia Effects on Cerebral Hemodynamics