Oxygen Measurements Research Articles

Abstract 371: Physiological Predictors of Cerebral Oxygenation During Hemorrhage in Swine

Introduction: Measurements of cerebral oxygenation (rSO 2 ) using near-infrared spectroscopy (NIRS) have been used to predict survival in retrospective clinical studies. However, the physiology underlying changes in rSO 2 during critical states such as hemorrhage is not completely understood. This analysis examined the effect of blood pressures, intracranial pressure, and heart rate on rSO 2 . Methods: Eight swine were instrumented with invasive pressure catheters in the aorta, right atrium, and cerebrum and underwent a pressure-targeted arterial hemorrhage protocol. Animals were bled at a rate of 20mL/min to a target diastolic pressure of 35 mmHg. Brief periods of increased baseline airway pressure (15 cm H 2 O) were introduced to cause transient drops in arterial blood pressure. The aortic pressure waveform was used to identify individual heartbeats. The first 100 heartbeats represent baseline data, while heart beats 4900-5000 (time from start of bleed; 40±7 min) capture data late into the bleed for all animals. Data from 53,315 heart beats were entered into a regression model: rSO 2 = mean diastolic aortic pressure + mean diastolic right atrial pressure + intracranial pressure + heart rate + animal. Results: The hemorrhage reduced diastolic aortic pressure from 61.7±9.6 (heart beats 1-100) to 35.0±9.2 mmHg (heart beats 4900-5000), increased right atrial pressure from 4.1±3.6 to 4.9±6.9 mmHg, reduced intracranial pressure from 33.6±23.2 mmHg to 16.3±2.5 mmHg, and increased heart rate from 101±14 to 144±40 beats/min. Output from the regression model (Table 1) shows that mean diastolic aortic pressure, but not right atrial pressure, intracranial pressure or heart rate, is a significant predictor of rSO 2 . Conclusions: rSO 2 values are largely driven by arterial blood pressure and may serve as a useful non-invasive tool as a surrogate for arterial blood pressure during hemorrhage. Further work should investigate the use of this technology to provide real-time feedback.

Additive-Free Method for Enhancing the Volume Phase Transition Rate in Light-Responsive Hydrogels: A Study of Micro-Nano Bubble Water on PNIPAM-co-AAc Hydrogels.

Light-responsive hydrogels containing light-thermal convertible pigments have received interest for their possible applications in light-responsive shutters, valves, drug delivery systems, etc. However, their utility is limited by the slow response time. In this study, we investigated the use of micro-nano bubble water as a preparation solvent to accelerate the volume phase transition kinetics of poly(N-isopropylacrylamide-co-acrylic acid) (PNIPAM-co-AAc) hydrogels. The hydrogels were characterized by dynamic light scattering (DLS) and dissolved oxygen (DO) measurements. The mechanical properties, surface morphology, and chemical composition of the hydrogels were analyzed by Young's modulus measurements, scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR) spectroscopy, respectively. The results showed that hydrogels prepared with bubble water changed the volume transition rate by more than two orders of magnitude by simply changing the standing time of the bubble water for only a few hours. The cooperative diffusion coefficients obtained from the light-induced volume transition kinetics correlated linearly with Young's modulus and metastable state swelling ratio. Our results suggest that bubbles act as efficient water channels, thereby modulating the response rate and providing a simple, additive-free method for preparing hydrogels with a wide range of response rates.

Evaluation of placental oxygenation by near-infrared spectroscopy in relation to ultrasound maturation grade in physiological term pregnancies.

A prospective observational study (ClinicalTrial ID: NCT05771415) was conducted to compare placental oxygenation in low-risk, uncomplicated term pregnancies measured by near-infrared spectroscopy (NIRS) in relation to the placental maturity grade determined by ultrasound assessment according to the Grannum scale. We included 34 pregnancies divided into two groups according to placental maturation. For each pregnancy, measurements were taken at the site above the central part of the placenta (test) and at the site outside of the placenta on the lower abdomen (control). Student's t-test was used to compare tissue oxygenation index (TOI) values among the study groups. The normality of distribution was proven by the Kolmogorov‒Smirnov test. In women with low placental maturity grade, the mean TOI value above the placenta was 70.38 ± 3.72, which was lower than the respective value in women with high placental maturity grade (77.99 ± 3.71; p < 0.001). The TOI values above the placenta and the control site were significantly different in both groups (70.38 ± 3.72 vs 67.83 ± 3.21 and 77.99 ± 3.71 vs 69.41 ± 3.93; p < 0.001). The results offer a new perspective on placental function based on specific non-invasive real-time oxygenation measurements. Unfortunately, and because of technical limitations, NIRS cannot yet be implemented as a routine clinical tool.

Study on the recycling of 100Cr6 powder by plasma spheroidization for Laser Powder Bed Fusion

Additive Manufacturing (AM) of steel parts is crucial in various industries such as medical, energy and transport. Laser Powder Bed Fusion (L-PBF) is a commonly used technique for producing such parts, but it can alter the properties of the unconsumed powder. This study aims to investigate the recycling of oxidized 100Cr6 powder using a plasma spheroidization process, focusing on its physical and chemical properties. The experiments reveal that the powder feed rate during spheroidization has an impact on the physical properties of the recycled powder, an optimized powder feed rate is found. Different washing and drying conditions are applied to the spheroidized powder and their influence on the powder's chemical composition is analysed through oxygen measurement. One of the washing and drying condition led to oxygen content even lower than the commercial powder. Additionally, three different hydrogen ratios in the plasma during the spheroidization process are investigated and it is found that increasing the hydrogen ratio can reduce the oxygen content in the processed powders.

Enhancing Cancer Therapy by Repeated Measurements of Oxygen in Tumors

Enhancing Cancer Therapy by Repeated Measurements of Oxygen in Tumors

A Comparative Study of Ex-Vivo Murine Pulmonary Mechanics Under Positive- and Negative-Pressure Ventilation

Increased ventilator use during the COVID-19 pandemic resurrected persistent questions regarding mechanical ventilation including the difference between physiological and artificial breathing induced by ventilators (i.e., positive- versus negative-pressure ventilation, PPV vs NPV). To address this controversy, we compare murine specimens subjected to PPV and NPV in ex vivo quasi-static loading and quantify pulmonary mechanics via measures of quasi-static and dynamic compliances, transpulmonary pressure, and energetics when varying inflation frequency and volume. Each investigated mechanical parameter yields instance(s) of significant variability between ventilation modes. Most notably, inflation compliance, percent relaxation, and peak pressure are found to be consistently dependent on the ventilation mode. Maximum inflation volume and frequency note varied dependencies contingent on the ventilation mode. Contradictory to limited previous clinical investigations of oxygenation and end-inspiratory measures, the mechanics-focused comprehensive findings presented here indicate lung properties are dependent on loading mode, and importantly, these dependencies differ between smaller versus larger mammalian species despite identical custom-designed PPV/NPV ventilator usage. Results indicate that past contradictory findings regarding ventilation mode comparisons in the field may be linked to the chosen animal model. Understanding the differing fundamental mechanics between PPV and NPV may provide insights for improving ventilation strategies and design to prevent associated lung injuries.

Alteration of cholesterol content and oxygen level in intestinal organoids after infection with Staphylococcus aureus.

The pathogenicity elicited by Staphylococcus (S.) aureus, one of the best-studied bacteria, in the intestine is not well understood. Recently, we demonstrated that S. aureus infection induces alterations in membrane composition that are associated with concomitant impairment of intestinal function. Here, we used two organoid models, induced pluripotent stem cell (iPSC)-derived intestinal organoids and colonic intestinal stem cell-derived intestinal organoids (colonoids), to examine how sterol metabolism and oxygen levels change in response to S. aureus infection. HPLC quantification showed differences in lipid homeostasis between infected and uninfected cells, characterized by a remarkable decrease in total cellular cholesterol. As the altered sterol metabolism is often due to oxidative stress response, we next examined intracellular and extracellular oxygen levels. Three different approaches to oxygen measurement were applied: (1) cell-penetrating nanoparticles to quantify intracellular oxygen content, (2) sensor plates to quantify extracellular oxygen content in the medium, and (3) a sensor foil system for oxygen distribution in organoid cultures. The data revealed significant intracellular and extracellular oxygen drop after infection in both intestinal organoid models as well as in Caco-2 cells, which even 48 h after elimination of extracellular bacteria, did not return to preinfection oxygen levels. In summary, we show alterations in sterol metabolism and intra- and extracellular hypoxia as a result of S. aureus infection. These results will help understand the cellular stress responses during sustained bacterial infections in the intestinal epithelium.

Oxygen Saturation or Tissue Oxygen Determinations on Skin Whose Viability is at Risk.

The triad of ischaemia, neuropathy, and infection are among the principal causes of lower extremity wounds that are commonly prevalent in patients with diabetic foot (DF) a condition in which peripheral arterial disease commonly co-exists. The prevalence of this condition is increasing globally and with it, the mounting costs of its management. One aspect of management is saving limbs and or digits, a crucial part of this process is assessing tissue viability of skin which is a focus of this review: there are other aspects which are well described in the literature. Amputations are offered to limit the damage resulting from acute/chronic ischaemia. Holstein measured skin perfusion pressure using a radioisotope clearance technique to describe critically ischaemic skin; he found 30 mm Hg as the threshold above which healing may reliably be expected. Recent advances in vascular surgery and related technology have informed evidence-based advice to revascularize and save limbs; in practice, this may leave a wound in the distal skin unhealed; managing these raises questions of tissue viability. Much effort has been made to manage, prevent and to better understand these lower extremity wounds using measurements of tissue oxygen, oxygen saturation and skin imaging. The measurement techniques and their relevant merits are examined in this article. Advances in wound management systems and protocols can also facilitate the repair processes, and those which can have a particular impact on restoring or maintaining tissue perfusion are also discussed in the article.

Proposed synergies between oceanography and metrology

Accurate and traceable measurements are required to understand ocean processes, to address pressing societal challenges, such as climate change and to sustainably manage marine resources. Although scientific and engineering research has resulted in advanced methods to measure Essential Ocean Variables (EOVs) there is a need for cross comparison of the techniques and traceability to recognized standards. Metrological laboratories are experienced in accredited methods and assessment of methodology. An EU INFRAIA-02-2020: Integrating Activities for Starting Communities project MINKE (Metrology for Integrated marine maNagement and Knowledge-transfer nEtwork https://minke.eu) brings European marine science and metrology Research Infrastructures together to identify synergies and create an innovative approach to Quality Assurance of oceanographic data. Quality depends both on the accuracy (that can be provided through the metrology component) and the completeness of the data sets. The collaboration between different Marine Research Infrastructures (RIs) places a fundamental role on assuring the completeness of the datasets, particularly at global scales. The MINKE project encourages enhancement through collaboration of national metrology laboratories and the oceanographic community. Metrological assessment of the accuracy and uncertainties within multidisciplinary ocean observations will provide data that are key to delivering policy information. Objectives across all the RIs are to facilitate ocean observation and build wider synergies. MINKE will investigate these synergies, then introduce metrology to the core of various EOV measurements. Currently the marine RIs cover laboratory and field operations, from the surface seafloor, coastal waters to deep sea, fixed ocean stations to ship and autonomous vehicle operations to ships of opportunity, and flux stations focusing on carbonate system variables. The nexus of these operations is the focal point for coordinated improvement of ocean observing methods. Measurement intercomparisons, traceability and uncertainty assessments should be at the core of the scientific observations. Specifically, MINKE will work with RIs and Metrology Institutes to improve the quality of dissolved oxygen, carbonate system, chlorophyll-fluorescence, ocean sound and current meter measurements, through access to metrology laboratories, Transnational Access and intercomparison studies across existing marine consortia and RIs. MINKE will also promote the development of absolute salinity observation, and improvements in marine litter measurements.

Prediction of pseudoprogression in post-treatment glioblastoma using dynamic susceptibility contrast-derived oxygenation and microvascular transit time heterogeneity measures.

To evaluate the added value of MR dynamic susceptibility contrast (DSC)-perfusion-weighted imaging (PWI)-derived tumour microvascular and oxygenation information with cerebral blood volume (CBV) to distinguish pseudoprogression from true progression (TP) in post-treatment glioblastoma. This retrospective single-institution study included patients with isocitrate dehydrogenase (IDH) wild-type glioblastoma and a newly developed or enlarging measurable contrast-enhancing mass within 12 weeks after concurrent chemoradiotherapy. CBV, capillary transit time heterogeneity (CTH), oxygen extraction fraction (OEF), and cerebral metabolic rate of oxygen (CMRO2) were obtained from DSC-PWI. Predictors were selected using univariable logistic regression, and performance was measured with adjusted diagnostic odds with tumour volume and area under the curve (AUC) of receiver operating characteristics analysis. A total of 103 patients were included (mean age, 59.6 years; 59 women), with 67 cases of TP and 36 cases of pseudoprogression. Pseudoprogression exhibited higher CTH (4.0 vs. 3.4, p= .019) and higher OEF (12.7 vs. 10.7, p= .014) than TP, but a similar CBV (1.48 vs. 1.53, p= .13) and CMRO2 (7.7 vs. 7.3s, p= .598). Independent of tumour volume, both high CTH (adjusted odds ratio [OR] 1.52; 95% confidence interval [CI]: 1.11-2.09, p= .009) and high OEF (adjusted OR 1.17; 95% CI:1.03-1.33, p= .016) were predictors of pseudoprogression. The combination of CTH, OEF, and CBV yielded higher diagnostic performance (AUC 0.71) than CBV alone (AUC 0.65). High intratumoural capillary transit heterogeneity and high oxygen extraction fraction derived from DSC-PWI have enhanced the diagnostic value of CBV in pseudoprogression of post-treatment IDH-wild type glioblastoma. In the early post-treatment stage of glioblastoma, pseudoprogression exhibited both high oxygen extraction fraction and high capillary transit heterogeneity and these dynamic susceptibility contrast-perfusion weighted imaging derived parameters have added value in cerebral blood volume-based noninvasive differentiation of pseudoprogression from true progression. • Capillary transit time heterogeneity and oxygen extraction fraction can be measured noninvasively through processing of dynamic susceptibility contrast imaging. • Pseudoprogression exhibited higher capillary transit time heterogeneity and higher oxygen extraction fraction than true progression. • A combination of cerebral blood volume, capillary transit time heterogeneity, and oxygen extraction fraction yielded the highest diagnostic performance (area under the curve 0.71).

Physiological oxygen measurements in vitro-Schrödinger's cat in 3D cell biology.

After the development of 3D cell culture methods in the middle of the last century and the plethora of data generated with this culture configuration up to date, it could be shown that a three-dimensional arrangement of cells in most of the cases leads to a more physiological behavior of the generated tissue. However, a major determinant for an organotypic function, namely, the dissolved oxygen concentration in the used in vitro-system, has been neglected in most of the studies. This is due to the fact that the oxygen measurement in the beginning was simply not feasible and, if so, disturbed the measurement and/or the in vitro-system itself. This is especially true for the meanwhile more widespread use of 3D culture systems. Therefore, the tissues analyzed by these techniques can be considered as the Schrödinger's cat in 3D cell biology. In this perspective paper we will outline how the measurement and, moreover, the regulation of the dissolved oxygen concentration in vitro-3D culture systems could be established at all and how it may be possible to determine the oxygen concentration in organoid cultures and the respiratory capacity via mito stress tests, especially in spheroids in the size range of a few hundred micrometers, under physiological culture conditions, without disturbances or stress induction in the system and in a high-throughput fashion. By this, such systems will help to more efficiently translate tissue engineering approaches into new in vitro-platforms for fundamental and applied research as well as preclinical safety testing and clinical applications.

Hydrochemical Characteristics and Self-Purification Potential of Iyiechu Stream in Okigwe Area, Southeastern Nigeria

Iyiechu stream is a small tropical urban stream that receives both domestic and industrial wastes. The self-purification potential of the stream was determined by evaluating its deoxygenation and reaeration rate coefficients. The methods of study used include dissolved oxygen (DO) measurements, biochemical oxygen demand (BOD) and chemical oxygen demand (COD) tests as well as measurements of hydrological parameters. Deoxygenation rate of 0.20 to 0.42/day were obtained indicating very swift depletion of oxygen in the stream probably as a result of domestic sewage input. The reaeration rate coefficients ranged from 0.01 to 0.84 day and these values suggest deep and slow moving streams. The measured DO values are quite low, indicating high deoxygenation reaction in the stream and minimal dissolved oxygen contribution from other sources such as algal photosynthesis. Spatially, about 66.66% of the stream is dominated by deoxygenation reaction. The chemical oxygen demand ranged from 20 to 40 mg/l. These values are relatively high and show that the process may be partly responsible for the low dissolved oxygen levels in the stream. However, the stream is capable of re-attaining its optimum dissolved oxygen level within a flow time of 0.84 day (20hrs 16minutes) in the rainy season. Thus, a flow time much greater than 0.84 day (20hrs 16minutes) would be required during the dry season. These flow times suggest that the stream has poor self-purification potential.

THU597 Po2-guided Adrenal Vein Sampling In Primary Aldosteronism

Abstract Disclosure: K. Omata: None. Y. Tezuka: None. Y. Ono: None. F. Satoh: None. Background: Accurate laterality diagnosis of adrenal aldosterone over-secretion is crucial in determining specific treatment for primary aldosteronism. Although adrenal vein sampling (AVS) is considered as the gold standard method for lateralization, successful canulation to right adrenal vein (RAV) has been reported to be difficult since RAV usually empties directly into inferior vena cava (IVC). In addition, the entrance of RAV is close to that of hepatic vein (HV) or opens to a common trunk with HV in up to 20% of the patients with PA. Cortisol step-up and other proposed indices are not always available during the procedure. Method: AVS was performed in confirmed PA patients between January 2021 and March 2022 at Tohoku University Hospital. During AVS, a small portion (0.3mL) of the sampled veins (RAV, IVC and HV) were analyzed with a blood gas analyzer for partial pressure of oxygen (pO2) measurement. Result: A total of 113 AVS was performed. After excluding inappropriate samples, further analyzed were 113 samples of IVC, 100 of RAV, 109 of HV before cosyntropin stimulation, and 113 samples of IVC, 110 of RAV, 108 of HV after cosyntropin stimulation. We observed an average of 22 mmHg increase of pO2 in RAV than IPV, and 27 mmHg increase than HV before stimulation. The difference between RAV and IPV was 15 mmHg in average and that of RAV and HV was 21 mmHg after stimulation. Similar pO2 step-up was also observed between left adrenal vein and left inferior phrenic vein. Discussion: Here we first describe prominent pO2 step-up in both adrenal veins compared to neighboring non-adrenal veins and peripheral blood. pO2 measurement is easier, faster, less expensive, and requires a very small amount of sample, can be performed by routine equipments in angiography suite, compared to other selectivity indices of successful canulation in AVS. This could also contribute to reducing unnecessary blood sampling, radiation exposure and repeat AVS. pO2 step-up in adrenal vein suggests low oxygen consumption in adrenal glands, which potentially contributes to survival advantage in systemic hypoxic conditions. We propose the novel pO2-guided AVS especially in patients with difficult RAV anatomy and in unexperienced centers. Presentation: Thursday, June 15, 2023

In vitro oxygen imaging of acellular and cell-loaded beta cell replacement devices

Type 1 diabetes (T1D) is an autoimmune disease that leads to the loss of insulin-producing beta cells. Bioartificial pancreas (BAP) or beta cell replacement strategies have shown promise in curing T1D and providing long-term insulin independence. Hypoxia (low oxygen concentration) that may occur in the BAP devices due to cell oxygen consumption at the early stages after implantation damages the cells, in addition to imposing limitations to device dimensions when translating promising results from rodents to humans. Finding ways to provide cells with sufficient oxygenation remains the major challenge in realizing BAP devices’ full potential. Therefore, in vitro oxygen imaging assessment of BAP devices is crucial for predicting the devices’ in vivo efficiency. Electron paramagnetic resonance oxygen imaging (EPROI, also known as electron MRI or eMRI) is a unique imaging technique that delivers absolute partial pressure of oxygen (pO2) maps and has been used for cancer hypoxia research for decades. However, its applicability for assessing BAP devices has not been explored. EPROI utilizes low magnetic fields in the mT range, static gradients, and the linear relationship between the spin–lattice relaxation rate (R1) of oxygen-sensitive spin probes such as trityl OX071 and pO2 to generate oxygen maps in tissues. With the support of the Juvenile Diabetes Research Foundation (JDRF), an academic-industry partnership consortium, the “Oxygen Measurement Core” was established at O2M to perform oxygen imaging assessment of BAP devices originated from core members’ laboratories. This article aims to establish the protocols and demonstrate a few examples of in vitro oxygen imaging of BAP devices using EPROI. All pO2 measurements were performed using a recently introduced 720 MHz/25 mT preclinical oxygen imager instrument, JIVA-25™. We began by performing pO2 calibration of the biomaterials used in BAPs at 25 mT magnetic field since no such data exist. We compared the EPROI pO2 measurement with a single-point probe for a few selected materials. We also performed trityl OX071 toxicity studies with fibroblasts, as well as insulin-producing cells (beta TC6, MIN6, and human islet cells). Finally, we performed proof-of-concept in vitro pO2 imaging of five BAP devices that varied in size, shape, and biomaterials. We demonstrated that EPROI is compatible with commonly used biomaterials and that trityl OX071 is nontoxic to cells. A comparison of the EPROI with a fluorescent-based point oxygen probe in selected biomaterials showed higher accuracy of EPROI. The imaging of typically heterogenous BAP devices demonstrated the utility of obtaining oxygen maps over single-point measurements. In summary, we present EPROI as a quality control tool for developing efficient cell transplantation devices and artificial tissue grafts. Although the focus of this work is encapsulation systems for diabetes, the techniques developed in this project are easily transferable to other biomaterials, tissue grafts, and cell therapy devices used in the field of tissue engineering and regenerative medicine (TERM). In summary, EPROI is a unique noninvasive tool to experimentally study oxygen distribution in cell transplantation devices and artificial tissues, which can revolutionize the treatment of degenerative diseases like T1D.

Fast deployable real-time bioelectric dissolved oxygen sensor based on a multi-source data fusion approach

Commercially available dissolved oxygen (DO) sensors are hardly suitable for stereoscopic and precise DO monitoring due to their design, high cost and susceptibility to matrix effects. Here, we have developed a DO biosensor based on an integrated chamber-free microbial fuel cell (DOMFC) as the core and a Raspberry Pi microcomputer as the data acquisition system. This biosensor is low cost, readily available and compact in configuration. To this end, stable microbial biofilms with oxygen gradients were established on bioaffinity aluminum foam as anode. The DOMFC sensor has a low internal resistance (9.62 Ω) that can respond to DO changes in less than one minute and produce a reliable voltage signal to record DO (0.15–9.5 mg/L) under challenging conditions. After training the GA-BPNN model with multidimensional data by automatically applying a data fusion strategy from multiple sources, accurate DO predictions (R2 = 0.997, RMSE = 0.0447, MAE = 0.0401) were obtained. The DOMFC sensor and the prediction model showed excellent agreement (R2 = 0.954) in complex natural applications (different pH values, conductivities, water temperatures, etc.), covering a wide range of applications. Since the sensor mini-monitoring system is inexpensive and easy to make and use on a large scale, it is a promising alternative for oxygen measurements in both natural and artificial waters.

Evaluation of a New Telemedicine System for Early Detection of Cardiac Instability in Patients With Chronic Heart Failure: Real-Life Out-of-Hospital Study.

For a decade, despite results from many studies, telemedicine systems have suffered from a lack of recommendations for chronic heart failure (CHF) care because of variable study results. Another limitation is the hospital-based architecture of most telemedicine systems. Some systems use an algorithm based on daily weight, transcutaneous oxygen measurement, and heart rate to detect and treat acute heart failure (AHF) in patients with CHF as early on as possible. The aim of this study is to determine the efficacy of a telemonitoring system in detecting clinical destabilization in real-life settings (out-of-hospital management) without generating too many false positive alerts. All patients self-monitoring at home using the system after a congestive AHF event treated at a cardiology clinic in France between March 2020 and March 2021 with at least 75% compliance on daily measurements were included retrospectively. New-onset AHF was defined by the presence of at least 1 of the following criteria: transcutaneous oxygen saturation loss, defined as a transcutaneous oxygen measurement under 90%; rise of cardiac frequency above 110 beats per minute; weight gain of at least 2 kg; and symptoms of congestive AHF, described over the phone. An AHF alert was generated when the criteria reached our definition of new-onset acute congestive heart failure (HF). A total of 111 consecutive patients (n=70 men) with a median age of 76.60 (IQR 69.5-83.4) years receiving the telemonitoring system were included. Thirty-nine patients (35.1%) reached the HF warning level, and 28 patients (25%) had confirmed HF destabilization during follow-up. No patient had AHF without being detected by the telemonitoring system. Among incorrect AHF alerts (n=11), 5 patients (45%) had taken inaccurate measurements, 3 patients (27%) had supraventricular arrhythmia, 1 patient (9%) had a pulmonary bacterial infection, and 1 patient (9%) contracted COVID-19. A weight gain of at least 2 kg within 4 days was significantly associated with a correct AHF alert (P=.004), and a heart rate of more than 110 beats per minute was more significantly associated with an incorrect AHF alert (P=.007). This single-center study highlighted the efficacy of the telemedicine system in detecting and quickly treating cardiac instability complicating the course of CHF by detecting new-onset AHF as well as supraventricular arrhythmia, thus helping cardiologists provide better follow-up to ambulatory patients.

Oxygen saturation levels and retinopathy of prematurity in extremely preterm infants - a case control study

PurposeTo investigate the association of risk factors, including oxygen exposure, for developing retinopathy of prematurity (ROP) in preterm infants at increased risk of ROP.MethodsA case-control study was conducted where each infant born at < 28 weeks gestation with ROP was matched with another without ROP over five years (July 2015 – June 2020). Clinical information about the infants was collected from electronic medical records, including method of oxygen delivery, oxygen saturation (SpO2), fraction of inspired oxygen (FiO2) and mean airway pressure (MAP) measurements. MATLAB was used for a time-averaged analysis. Stata/SE 16.0 was used for statistical analysis.Results123 ROP/non-ROP pairs were included in this study. The time-averaged SpO2 analysis showed non-ROP group spent more time in hyperoxia than the ROP group (p < 0.001). The non-ROP group had lower respiratory severity scores and analysis when FiO2 > 21% showed that were was no difference in SpO2 between the two groups when the infants were receiving oxygen support. Conditional logistic regressions showed neonatal surgery significantly increased the risk of ROP (OR = 1.4347, p = 0.010), while the influence of birthweight (odds ratio of 0.9965, p = 0.001) and oxygen exposure (OR = 0.9983, p = 0.012) on ROP outcome was found to be negligible as their odds ratios indicated no influence.ConclusionsAt times when infants were receiving respiratory support (FiO2 > 21%) the SpO2 data indicated no difference in SpO2 between the ROP and non-ROP groups. Analysis of clinical variables found that neonatal surgery increased the odds of developing ROP.

Development and in-vivo validation of a portable phosphorescence lifetime-based fiber-optic oxygen sensor

Oxygenation is a crucial indicator of tissue viability and function. Oxygen tension (hbox {pO}_2), i.e. the amount of molecular oxygen present in the tissue is a direct result of supply (perfusion) and consumption. Thus, measurement of hbox {pO}_{{2}} is an effective method to monitor tissue viability. However, tissue oximetry sensors commonly used in clinical practice instead rely on measuring oxygen saturation (hbox {StO}_2), largely due to the lack of reliable, affordable hbox {pO}_2 sensing solutions. To address this issue we present a proof-of-concept design and validation of a low-cost, lifetime-based oxygen sensing fiber. The sensor consists of readily-available off-the shelf components such as a microcontroller, a light-emitting diode (LED), an avalanche photodiode (APD), a temperature sensor, as well as a bright in-house developed porphyrin molecule. The device was calibrated using a benchtop setup and evaluated in three in vivo animal models. Our findings show that the new device design in combination with the bright porphyrin has the potential to be a useful and accurate tool for measuring hbox {pO}_2 in tissue, while also highlighting some of the limitations and challenges of oxygen measurements in this context.

Prefrontal oxygenation varies as a function of response inhibition performance in healthy participants but not in youth with non-suicidal self-injury.

Non-suicidal self-injury (NSSI), a highly prevalent symptom in adolescence, has been associated with impulsivity. Behavioral measures of response inhibition in combination with the recording of brain activity potentially improve the understanding of the etiology of the behavior. We therefore investigated prefrontal cortex (PFC) oxygenation during a response inhibition task using functional near-infrared spectroscopy (fNIRS) in n=152 adolescents with NSSI and n=47 healthy controls. We compared groups regarding behavioral performance and PFC oxygenation and tested whether the association between task performance and PFC oxygenation differed between groups. PFC oxygenation was slightly higher in adolescents with NSSI than in controls. Further, there was evidence for a group by performance interaction: In healthy controls, higher oxygenated hemoglobin was associated with better task performance, which was not the case in the NSSI group. We did not find evidence of associations between PFC oxygenation and clinical measures. Our study provides preliminary evidence of altered brain functional correlates of response inhibition in adolescents with NSSI potentially reflecting deficient top-down regulation of limbic regions through prefrontal regions. Due to methodological limitations of the current study, findings must be interpreted with caution and future studies should optimize task designs for fNIRS processing.

Abstract 002: PO 2 -guided Adrenal Vein Sampling In Primary Aldosteronism

Background: Accurate diagnosis of laterality of adrenal aldosterone over-secretion is crucial in determining specific treatment for primary aldosteronism (PA). Although adrenal vein sampling (AVS) is considered as the gold standard method for lateralization, successful canulation to right adrenal vein (RAV) has been reported to be challenging since RAV usually empties directly into inferior vena cava (IVC). In addition, the entrance of RAV is close to that of hepatic vein (HV) or opens to a common trunk with HV in up to 20% of the patients with PA. Cortisol step-up and other proposed indices are not always available during the procedure. Method: AVS was performed in confirmed PA patients between January 2021 and April 2022 at Tohoku University Hospital. During AVS, a small portion (0.3mL) of the sampled veins (RAV, IVC and HV) were analyzed with a blood gas analyzer for partial pressure of oxygen (pO 2 ) measurement. Result: A total of 120 AVS was performed. After excluding inappropriate samples, further analyzed were 120 samples of IVC, 107 of RAV, 116 of HV before cosyntropin stimulation, and 120 samples of IVC, 117 of RAV, 115 of HV after cosyntropin stimulation. We observed an average of 22 mmHg increase of pO 2 in RAV than IPV, and 28 mmHg increase than HV before stimulation. The difference between RAV and IPV was 15 mmHg in average and that of RAV and HV was 22 mmHg after stimulation. Similar pO 2 step-up was also observed between left adrenal vein and left inferior phrenic vein. Discussion: Here we describe prominent pO 2 step-up in both adrenal veins compared to neighboring non-adrenal veins and peripheral blood. pO 2 measurement is easier, faster, less expensive, and requires a very small amount of sample, can be performed by routine equipments in angiography suite, compared to other selectivity indices for successful cannulation in AVS. This would also contribute to reducing unnecessary blood sampling, radiation exposure and repeat AVS. pO 2 step-up in adrenal vein suggests low oxygen consumption in adrenal glands, which potentially contributes to survival advantage in systemic hypoxic conditions. We propose novel pO 2 -guided AVS especially in patients with difficult RAV anatomy and in unexperienced centers.