Near Infrared Spectroscopy

Reactive oxygen species (ROS), which include peroxides, are generated in the human body as by-products of cellular metabolism. In small amounts, they fulfill important physiological functions. However, when produced in excess, they can damage cells and tissues. Extremely low gestation age neonates (ELGANs) are particularly vulnerable to such harmful effects because their antioxidant defense systems are immature, and they are exposed to increased ROS levels due to the oxygen therapy required after birth. Fetal hemoglobin (HbF), the primary oxygen carrier in the blood of newborns, plays a crucial role in this context. Compared with adult hemoglobin (HbA), it has a higher oxygen affinity and a more pronounced pseudoperoxidase activity, which helps protect organs during early development from peroxides. In addition to oxygen administration, blood transfusions can also contribute to increased ROS formation. Due to the immature hematopoietic system and the diagnostic blood sampling required, ELGANs frequently receive transfusions with adult red blood cell (A-RBC) concentrates. These lead to a rapid shift from HbF to HbA, further promoting the generation of ROS. Measuring ROS in blood is particularly challenging because these molecules are extremely short-lived. Consequently, reference values for newborns are lacking. Therefore, the investigators aim to establish reference ranges for one ROS, the peroxide in both term and preterm healty neonates from birth event onward and to assess the effects of A-RBC transfusions on this parameter in ELGANs. Furthermore, combining near-infrared spectroscopy-derived measurements of cerebral regional tissue oxygenation with peroxide assessments requiring only minimal blood volumes (0.5 mL per sample) will provide a more comprehensive and quantitatively robust understanding of the physiological changes induced by A-RBC transfusions in ELGANs. Excessive ROS exposure is considered a key risk factor for severe complications of prematurity, including brain injury, retinopathy, and chronic lung disease. With this project, investigators aim to improve the understanding of these risks and promote new evidence-based strategies in transfusion medicine. In the long term, transfusions with HbF-rich red blood cells derived from cord blood could help reduce ROS formation and provide effective protection for particularly vulnerable preterm infants.

The aim of the present study is to test the accuracy and reliability of AI tools in this regard by interpreting NIRS, which we routinely use for monitoring cerebral perfusion in cardiovascular surgery, with AI tools and comparing this interpretation with the interpretations of two clinicians.

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.

This is a prospective, single-center Phase II observational study investigating the predictive value of the "Peripheral(-muscle) Oxygenation and Perfusion Score" (POP-Score), a novel non-invasive composite index, for early detection of infection/inflammation in neonates. The POP-Score combines peripheral muscle oxygenation measured via near-infrared spectroscopy (NIRS) with routinely monitored clinical parameters (heart rate, oxygen saturation, systolic blood pressure, and subcutaneous fat thickness). The study aims to determine the optimal cut-off value of the POP-Score measured within the first 6 hours after birth to predict elevated C-reactive protein (CRP ≥20 mg/L) within 48 hours. Additionally, multi-site NIRS measurements (cerebral, peripheral muscle, intestinal, and flank) will be evaluated to assess their association with inflammation. The study includes term and moderate-to-late preterm neonates (birth weight ≥2000g) with respiratory distress, admitted to the neonatal intensive care unit at the Medical University of Graz.

During major surgical procedures performed under general anesthesia, changes in blood flow and oxygen delivery to tissues may occur due to blood loss, hemodynamic fluctuations, and anesthesia-related physiological effects. These changes can lead to impaired tissue perfusion, which is commonly reflected by increased arterial lactate levels. However, lactate measurements are intermittent and may not detect early perfusion abnormalities. This prospective observational study aims to investigate the relationship between submental tissue oxygenation measured by near-infrared spectroscopy (NIRS), microvascular reactivity assessed by the vascular occlusion test, and arterial lactate levels during major surgery. Adult patients undergoing major abdominal, neurosurgical, or orthopedic procedures will be monitored intraoperatively using non-invasive NIRS techniques, while arterial blood gas analyses will be performed as part of routine clinical care. The study does not involve any changes to standard anesthesia or surgical management. All treatments and clinical decisions will be made by the responsible care team according to routine practice. By evaluating non-invasive indicators of tissue oxygenation and microvascular function, this study aims to improve the understanding of early intraoperative tissue perfusion changes and their association with metabolic markers.

This cross-sectional observational study aims to assess muscle oxygen saturation (SmO2) in the intercostal, quadriceps, and triceps surae muscles using near-infrared spectroscopy (NIRS) during functional exercise tests in breast cancer survivors. Participants will be grouped based on their previous cancer treatment: hormonal therapy only or hormonal therapy combined with chemotherapy. Functional performance will be evaluated through the 6-Minute Walk Test, 30-Second Sit-to-Stand Test, and a submaximal treadmill test. The study will analyze differences in muscle oxygenation and performance between groups and explore associations with other functional and clinical parameters.

Infants with congenital heart disease (CHD) are at increased risk for delayed neurodevelopment. Multiple etiological explanations have been proposed, as there seems to be a multifactorial interplay of both prenatal and perioperative factors. The main goal of this research project is to focus on peri-operative physiological risk factors in infants with CHD which impair functional brain maturation or elicit brain injury, and subsequently creating a risk model and guidelines for standardized developmental follow-up in this population. PART 1: investigation of cerebral autoregulation and neurovascular coupling The homeostasis in cerebral blood supply regardless of perfusion pressure, is called Cerebral autoregulation (CAR). Neurovascular coupling (NVC) is the phenomenon in which blood supply increases as a result of increased brain activity in a specific area. At different times in the perioperative phase, these regulatory mechanisms will be estimated based on Electroencephalography (EEG) and Near Infrared Spectroscopy (NIRS), in addition to hemodynamic parameters. PART 2: cell-free DNA (cfDNA) extraction. Non-invasive monitoring of neuronal degeneration can be performed using cfDNA extraction techniques. Serial measurements of neuronal cfDNA will be used to determine whether and when this neuronal damage has occurred. PART 3: Prognosis and outcome. These risk factors, supplemented with demographic factors and medications administered, will be combined in an Artificial Intelligence-driven model, thus establishing a risk model for neurodevelopmental outcome. This model will be compared to the current standard-of-care, both structural imaging (ultrasound and MRI) and a clinical developmental assessment at 9 and 24 months of age (Bayley Scales of Infant Development-III).

The aim of this study is to evaluate the effects of the steep Trendelenburg position in robotic prostatectomy cases, where anesthesia depth is monitored using BIS and cerebral perfusion is tracked with NIRS, and to determine the incidence of neurocognitive dysfunction using the MoCA test in the postoperative period. Steep Trendelenburg position and CO₂ pneumoperitoneum during robotic radical prostatectomy lead to significant changes in intracranial pressure and cerebral oxygenation, which may contribute to postoperative neurocognitive dysfunction (POCD). Monitoring anesthesia depth with Bispectral Index (BIS) and cerebral perfusion with Near-Infrared Spectroscopy (NIRS) may help detect early neurocognitive changes, and MoCA test assessments will reveal a measurable decline in cognitive function postoperatively.