Hyperoxemia

This study aims to evaluate whether guidance by the Oxygen Reserve Index (ORi) improves inspiratory oxygen fraction (FiO₂) titration compared with conventional pulse oximetry (SpO₂)-guided oxygen administration in adult patients undergoing surgery in the beach chair position. Oxygen therapy is routinely used during general anesthesia to prevent hypoxemia; however, excessive oxygen administration may result in hyperoxia, which has been associated with adverse cardiovascular and pulmonary effects. Standard pulse oximetry may not adequately detect hyperoxia when oxygen saturation values are high. In this prospective comparative study, patients will receive oxygen titration guided either by SpO₂ alone or by combined ORi and SpO₂ monitoring. The primary outcome is the incidence of intraoperative hyperoxemia, assessed by arterial blood gas analysis. Secondary outcomes include intraoperative oxygenation parameters and hemodynamic variables.

This study aims to better understand how short periods of exposure to 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 strictly necessary, and high blood oxygen levels (hyperoxemia) are very common. However, the immediate effects of short hyperoxic exposures on cerebral circulation and autoregulation remain poorly understood. In this study, patients who already require mechanical ventilation for medical reasons will undergo a brief and controlled increase in the oxygen delivered through the ventilator (FiO₂). During this time, we will continuously monitor blood flow in one of the main brain arteries using a non-invasive ultrasound technique called transcranial Doppler (TCD). The goal is to evaluate how cerebral blood flow, pulsatility, and autoregulatory capacity change during and after a short hyperoxic stimulus. No additional invasive procedures are required beyond standard ICU monitoring, except for the temporary adjustment of the ventilator's oxygen settings and arterial blood gas sampling, which are part of usual care in critically ill patients. Participation does not provide direct clinical benefit but may help improve future oxygen management in ICU patients. The study involves minimal risk, as short hyperoxic exposures are already common in routine care and will be interrupted immediately in case of any adverse event.

The oximeter is used to monitor intensive care patients undergoing oxygen therapy. It indicates pulsed oxygen saturation (SpO2), a reflection of arterial oxygen saturation (SaO2) which enables detection of hypoxemia and hyperoxia, both deleterious state. Current SpO2 recommendations aim to reduce both risk of hypoxemia and hyperoxia. SpO2 is considered the 5th vital sign. Current recommendations for SpO2 targets do not consider the variability of oximeters used in clinical practice. This variability and lack of specification represent an obstacle to an optimal practice of oxygen therapy. Thus, this study aims to compare the SpO2 values of different oximeters (General Electric-GE, Medtronic, Masimo and Nonin) used in clinical practice with the SaO2 reference value obtained by an arterial gas in order to specify the precision and the systematic biases of the oximeters studied. This data will also make it possible to refine the recommendations concerning optimal oxygenation

The oximeter is used to monitor intensive care patients undergoing oxygen therapy. It indicates pulsed oxygen saturation (SpO2), a reflection of arterial oxygen saturation (SaO2) which enables detection of hypoxemia and hyperoxia, both deleterious state. Current SpO2 recommendations aim to reduce both risk of hypoxemia and hyperoxia. SpO2 is considered the 5th vital sign. Current recommendations for SpO2 targets do not consider the variability of oximeters used in clinical practice. This variability and lack of specification represent an obstacle to an optimal practice of oxygen therapy. Thus, this study aims to compare the SpO2 values of different oximeters (Nonin, Masimo, Philips, Nellcor) used in clinical practice with the SaO2 reference value obtained by an arterial gas in order to specify the precision and the systematic biases of the oximeters studied. This data will also make it possible to refine the recommendations concerning optimal oxygenation