Cerebral Oxygenation

Left paratracheal pressure (LPP) has been proposed as an alternative to cricoid pressure to reduce the risk of regurgitation during induction of general anesthesia. Previous studies suggest that LPP can effectively compress the esophagus without significantly reducing left carotid blood flow. However, its effect on cerebral oxygenation has not yet been evaluated. The aim of this prospective randomized crossover study is to assess whether application of LPP affects regional cerebral oxygen saturation measured by near-infrared spectroscopy (NIRS) during general anesthesia. Seventy adult patients undergoing elective surgery under general anesthesia with tracheal intubation will be included. After induction of anesthesia and stabilization, cerebral oxygen saturation will be continuously measured under three conditions: no cervical pressure, left paratracheal pressure at 30 N, and cricoid pressure at 30 N. The order of the two pressure maneuvers will be randomized. The primary objective is to determine the change in left regional cerebral oxygen saturation during LPP compared with baseline without cervical pressure.

This study will enroll children and young adults who are scheduled to undergo planned heart surgery or a heart catheterization procedure while under general anesthesia. Researchers will collect information from a forehead sensor that measures oxygen levels in the body's tissues, along with blood hemoglobin measurements obtained from blood samples that are already being collected as part of routine medical care. The goal of the study is to determine whether a blood hemoglobin monitoring method that has already been cleared by the U.S. Food and Drug Administration (FDA) for use in adults may also work well in pediatric patients.

This prospective randomized controlled trial aims to compare the effects of high-flow nasal oxygen (HFNO) and conventional face mask oxygen therapy on cerebral oxygenation during procedural sedation performed outside the operating room. Adult patients undergoing elective diagnostic or interventional procedures under procedural sedation will be randomly assigned to receive either HFNO or conventional face mask oxygen. Regional cerebral oxygen saturation will be continuously monitored using near-infrared spectroscopy (NIRS), while sedation depth will be assessed using the Patient State Index (PSI, SedLine) and the Modified Observer's Assessment of Alertness/Sedation (MOAA/S) scale. Secondary outcomes include peripheral oxygenation, ventilation parameters, arterial blood gas values, airway interventions, hemodynamic variables, and patient and practitioner satisfaction.

For Patients and Families This study aims to investigate how high-flow oxygen therapy affects oxygen levels, especially brain oxygenation, during cystoscopy procedures performed under sedation. The goal is to improve patient safety and comfort by ensuring better oxygen delivery during the procedure. Different oxygen flow rates will be compared, while patients' breathing, oxygen levels, and vital signs are continuously monitored throughout the procedure. All methods used in the study are consistent with routine anesthesia practices, and patient safety remains the highest priority. For Healthcare Professionals This prospective randomized controlled study evaluates the effects of different high-flow nasal oxygen (HFNO) flow rates on cerebral oxygenation, peripheral oxygenation, and ventilation parameters in patients undergoing cystoscopy under procedural sedation. The primary aim is to determine the contribution of HFNO to sedation safety and to provide clinical evidence regarding the optimal flow rate. In addition, hypoxemia incidence, airway intervention requirements, hemodynamic variables, and sedation depth are being analyzed.

The objective of this study is to compare the effects of manual ventilation and AutoFlow ventilation, administered during the induction of general anesthesia, on cerebral (s-rSO₂) and peripheral (somatic) oxygenation (p-rSO₂) in geriatric patients.

Respiratory distress syndrome (RDS) is common in very preterm infants due to surfactant deficiency. Surfactant replacement therapy is lifesaving, and current guidelines recommend the less invasive surfactant administration (LISA) technique. However, the optimal duration of surfactant instillation during LISA has never been systematically evaluated. Rapid instillation may provoke transient hypoxia and bradycardia, while slower administration might improve physiological stability and cerebral oxygenation. This randomised controlled trial investigates whether the duration of surfactant administration (1 minute versus 5 minutes) affects cerebral and systemic oxygen stability in extremely preterm neonates (\< 28 weeks).

The goal of this observational study is to learn whether the brain's ability to use oxygen during surgery is associated with postoperative delirium in adults aged 65 years and older undergoing general anesthesia. The main question it aims to answer is: \- Does reduced cerebral oxygen consumption responsiveness during surgery increase the risk of postoperative delirium in older patients? Participants who are undergoing elective laparoscopic surgery under general anesthesia as part of their routine medical care will have brain oxygen levels measured during surgery using a non-invasive forehead sensor, and will be assessed for delirium for up to three days after surgery.

This prospective observational study aims to evaluate the effect of glycemic control level on intraoperative cerebral oxygenation measured by near-infrared spectroscopy (NIRS) and postoperative recovery in patients with diabetes mellitus undergoing elective urologic surgery under general anesthesia. Patients will be grouped according to HbA1c levels to assess the relationship between long-term glycemic control and intraoperative regional cerebral oxygen saturation, hemodynamic parameters, and postoperative recovery scores.

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.

The goal of this observational study is to determine the correlation between cerebral oxygenation values measured by near-infrared spectroscopy (NIRS) and other routine monitoring parameters in patients placed in the semi-sitting position. The primary questions investigated are : Do NIRS values correlate with heart rate, invasive mean arterial pressure, and end-tidal carbon dioxide? Do NIRS values reflect changes observed in arterial blood gas analysis? Are cerebral perfusion-related parameters associated with patients' comorbidities such as diabetes, obesity, and hypertension? Researchers will compare routine noninvasive monitoring (heart rate, blood pressure, peripheral oxygen saturation) with invasive arterial monitoring and NIRS to assess whether NIRS provides additional information for evaluating cerebral perfusion. Participants will be monitored for: Heart rate Invasive mean arterial pressure End-tidal carbon dioxide Arterial blood gas changes Cerebral oxygenation with NIRS Patients' comorbidities (e.g., diabetes, obesity, hypertension) will also be recorded, and their association with perfusion-related parameters will be analyzed.

The brain is a metabolic active organ with constant energy demands. Brain oxygen supply is secured via cerebral circulation. Brain tumor surgery is commonly associated with the tumor's underlying pathophysiology including brain swelling or edema. During craniotomy for brain tumor resection maintenance of cerebral hemodynamic stability is of paramount importance. Neuroinflammation is also a normal response to trauma, such as in the case of brain tumor surgery. The role of neuroinflammation in postoperative brain function is well documented and the aim is to limit it through an appropriate anesthetic approach. Anesthetic agents used during surgery affect brain homeostasis. The anesthetic agent of choice for neurosurgery should deliver smooth and hemodynamically stable anesthesia, good operating conditions, and allow early neurological assessment. Also, the ideal anesthetic agent should preserve cerebral perfusion and neuroprotection. The two most common categories of anesthetic agents used nowadays for elective craniotomy are intravenous and inhalational agents. Propofol is the intravenous anesthetic agent of choice. The action of propofol involves a positive modulation of the inhibitory function of the neurotransmitter gamma-aminobutyric acid (GABA). Propofol causes a decrease in cerebral metabolic rate (CMR), intracranial pressure (ICP), cerebral perfusion pressure (CPP), and cerebral blood flow (CBF). It also is known for its antiemetic properties. Volatile agents commonly used in neuroanesthesia clinical practice are sevoflurane and desflurane. Both of these agents decrease CMR while maintaining stable CPP. CBF alteration is dose-dependent. Desflurane evokes a greater cerebral vasodilation effect than sevoflurane. Sevoflurane is a well-known neuroprotective anesthetic agent traditionally used in neurosurgery. Both desflurane and sevoflurane are associated with early emergence. Thus, this study aimed to explore the effect of volatile-based versus total intravenous anesthesia on cerebral homeostasis and neurocognitive function in patients undergoing elective craniotomy for brain tumor excision aiming to provide a basis for clinical rational drug use in patients undergoing craniotomy resection of supratentorial lesions.

This study will be conducted to evaluate the effects of different anesthetic modalities \[sevoflurane with or without intraoperative lidocaine infusion and Propofol total intravenous anesthesia (TIVA)\] on intracranial pressure (ICP) and cerebral oxygenation assessed by non-invasive methods during laparoscopic hysterectomy (LH).

Children undergoing magnetic resonance imaging (MRI) of the brain often need to be sedated to complete the examination, as it is difficult to remain still for a long period, which is required to obtain usable images. During sedation, most patients typically experience a drop in blood pressure, including children. Maintaining an adequate blood pressure under anesthesia is important, as blood pressure is routinely used as a measure to ensure sufficient blood circulation to the body's organs, including the brain. Ensuring adequate blood flow to the brain is one of the cornerstones of all anesthesia, including in children. Therefore, low blood pressure during anesthesia is often treated with standardized interventions, such as blood pressure-raising interventions. These treatments generally restore blood pressure to normal, but how this affects blood flow to the brain in children is not fully known. With the help of modern MRI technology (so-called Arterial Spin Labeling, ASL), blood flow in the brain can be measured quickly and completely safely with high precision. In similar situations with adult patients, it has been observed that while blood pressure-raising interventions successfully normalize low blood pressure, MRI scans show that blood flow to the brain paradoxically decreases despite the increase in blood pressure. It is believed that this may be due to the brain's blood vessels constricting. The investigators now wish to examine this relationship in sedated children undergoing planned brain MRI for certain diagnoses. The investigators hypothesis is that standardized measures intended to raise blood pressure (i.e., the routine treatment used regardless of whether a patient participates in the study or not) normalizes low blood pressure (when deemed necessary to treat according to routine) but does not necessarily lead to improved blood flow to the brain. Primary research question: How does routine treatment of low blood pressure affect cerebral blood flow in sedated children?

Premature babies often require breathing support during their neonatal intensive care unit stay. This is because their lungs are not fully developed to perform the work of breathing on their own. Although breathing support can be provided via a breathing tube, it is preferable to provide breathing support non-invasively from a breathing machine which is then connected to a mask or prongs placed on the baby's nose. In premature babies born under 32 weeks gestation, a commonly used mode of non-invasive breathing support is called Non-Invasive Positive Pressure Ventilation (NIPPV). In this mode, the breathing machine provides 2 levels of support: one is the constant distending pressure to keep the lungs open and the other provides additional 'breaths' on top of that distending pressure. This is to mimic regular breathing. These breaths are set at a fixed rate and pressure. Although NIPPV protects the lungs from injury caused by a breathing tube, the breaths are not in sync with the baby's own breathing effort. Another mode of non-invasive breathing support recently being used in premature infants called Neurally Adjusted Ventilatory Assist (NAVA). When NAVA is provided non-invasively using a mask or prongs similar to NIPPV, it is called Non-invasive NAVA (NIV-NAVA). During NIV-NAVA a special feeding tube is used that detects the baby's own breathing movement from the electrical signal of the baby's diaphragm and feeds back to the machine which then provides a 'top-up' to the baby's own breath. This top-up breath also provides only as much pressure as the baby needs on top on their own breathing effort. Therefore, this is thought to be in sync with the baby's own breathing effort. However, it is not known if this mode of ventilation leads to improved sleep, improved brain oxygen levels, reduced discomfort and improved functioning of the diaphragm. The investigators aim to examine these indices in this research project.

This study investigates whether intermittent hypoxia (IH) and physical activity (PA), either alone or in combination (simultaneously or sequentially), can improve cognitive function and brain health in middle-aged adults (50-65 years old). The hypothesis is that (1) each intervention alone (IHT or PA) provides cognitive benefits and (2) combining IHT with PA may yield additive or synergistic effects, particularly when administered simultaneously rather than sequentially. By comparing these distinct interventions, the study aims to determine which approach best preserves or enhances cognitive performance in middle-aged adults. Findings from this research may inform non-pharmacological strategies to promote healthy aging and reduce the risk of age-related cognitive decline.

The study topic investigates the potential advantages of low-flow anesthesia in terms of physiological protection and resource saving.

Introduction. Initiation of acute kidney replacement therapy (KRT) is common in critically ill adults admitted to the intensive care unit (ICU), and is associated with increased morbidity and mortality. KRT has been linked to poor neurocognitive outcomes, leading to a reduced quality of life, as well as increased utilization of healthcare resources. Adults initiated on dialysis in the ICU may be particularly at risk of neurocognitive impairment, as survivors of critical illness are already predisposed to developing cerebrovascular disease and cognitive dysfunction over the long-term relative to healthy controls. Regional cerebral oxygen saturation (rSO2) may provide a critical early marker of long-term neurocognitive impairment in patients in this population. The INCOGNITO-AKI study aims to understand cerebral oxygenation in patients undergoing KRT, either continuous or intermittent, in the ICU. These findings will be correlated with long-term cognitive and functional outcomes, as well as structural brain pathology. Methods and analysis. 108 patients scheduled to undergo treatment for acute kidney injury with KRT in the Kingston Health Sciences Centre ICU will be recruited into this prospective observational study. Enrolled patients will be assessed with intradialytic cerebral oximetry using near infrared spectroscopy (NIRS). Delirium will be assessed daily with the Confusion Assessment Method-Intensive Care Unit (CAM-ICU) and delirium severity quantified as cumulative CAM-ICU-7 scores. Neurocognitive impairment will be assessed at 3- and 12-months after hospital discharge using the Kinarm and Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Structural brain pathology on MRI will also be measured at the same timepoints. Driving safety, adverse events, and medication adherence will be assessed at 12-months to evaluate the impact of neurocognitive impairment on functional outcomes. Ethics and dissemination. This study has been approved by the Queen's University Health Sciences and Affiliated Teaching Hospitals Research Ethics Board (Approval number: DMED-2424-20). Results will be presented at critical care scientific conferences and a lay summary will be provided to patients and families in their preferred format.