Influence of nutrient enrichment on temporal and spatial dynamics of dissolved oxygen within northern temperate estuaries

In temperate estuaries of the southern Gulf of St. Lawrence, intermittent seasonal anoxia coupled with phytoplankton blooms is a regular occurrence in watersheds dominated by agricultural land use. To examine the spatial relationship between dissolved oxygen and phytoplankton throughout the estuary to assist in designing monitoring programs, oxygen depth profiles and chlorophyll measurements were taken bi-weekly from May to December in 18 estuaries. In five of those estuaries, dissolved oxygen data loggers were set to measure oxygen at hourly intervals and at multiple locations within the estuary the subsequent year. The primary hypothesis was that dissolved oxygen in the upper estuary (first 10% of estuary area) is predictive of dissolved oxygen mid-estuary (50% of estuary area). The second hypothesis was that hypoxia/superoxia in the estuary is influenced by temperature and tidal flushing. Oxygen depth profiles conducted in the first year of study provided preliminary support that dissolved oxygen in the upper estuary was related to dissolved oxygen throughout the estuary. However, dissolved oxygen from loggers deployed at 10% and 50% of estuary area did not show as strong a correlation as expected (less than half the variance explained). The strength of the correlation declined towards the end of summer. Spatial decoupling of oxygen within the estuary suggested influence of local conditions. Chlorophyll concentration seemed also to be dependent on local conditions as it appeared to be coupled with the presence of sustained anoxia in the upper estuary with blooms typically occurring within 7 to 14 days of anoxia. The practical implication for oxygen monitoring is that one location within the most severely impacted part of the estuary is not sufficient to fully evaluate the severity of eutrophication effects.

Methods used for Gas Tightness Test and percent Oxygen Monitoring of the NSW Micromegas Detectors of LHC-ATLAS Experiment

In the frame of the LHC-ATLAS Upgrade of phase I, the New Small Wheel detector system is under integration and commissioning at CERN Laboratories. One of the detector type, the Micromegas detectors, during their integration are tested in several stages for gas tightness validation. In particular, the novel method we are using for the gas tightness test, that we called “Flow Rate Loss”, has been realized in several semi-automatic fixed, portable and stand-alone setups for testing either the Micromegas Quads or the final Double Wedges. The obtained measurements up-to-date are presented as well as their obtained statistical distribution. Additionally, during the performance evaluation of the detectors, a percent oxygen monitoring is also performed in 24-hour base. The methods and techniques we developed and used are presented analytically in this work.

Management of oxygen saturation monitoring in preterm newborns in the NICU: the Italian picture

Background Although many studies emphasize the importance of using oxygen saturation (SpO2) targets in the NICUs, there is a wide variability in used saturation ranges among centers. Primary aim was to draw a representative picture on how the management of oxygen monitoring is performed in the Italian NICUs. Second aim was to identify healthcare-professionals related factors associated with oxygen targeting in the preterm population. Methods Cross-sectional study with data collection via an electronic survey form. A questionnaire containing pre-piloted and open questions on monitoring and management of the SpO2 was administered to neonatologists across the network of the Italian Society of Neonatology. The questions focused on: the infrastructure, specific training, healthcare professionals and patients-related factors. The results of the survey were anonymously collected, summarized and analyzed. Results Out of 378 questionnaires, 93 were correctly filled. Thirty-six different SpO2 ranges were observed. Centers using written standard operating procedures on oxygen management and SpO2 monitoring maintained a correct average range of SpO2 90–95%, avoided hyperoxia and reconsidered saturation targets in relation to comorbidities. 39.8% of responders disabled alarms during neonatal care. One center used biomarkers for complete monitoring of neonatal oxygenation status. Conclusions There is considerable variation in SpO2 targets for preterm infants in the Italian NICUs. Standard operating procedures and specific training for health care personnel are the main factors playing a role for the correct maintenance of the recommended oxygen targets in preterms.

Outcomes associated with brain tissue oxygen monitoring in patients with severe traumatic brain injury undergoing intracranial pressure monitoring

OBJECTIVE Brain tissue oxygen monitoring combined with intracranial pressure (ICP) monitoring in patients with severe traumatic brain injury (sTBI) may confer better outcomes than ICP monitoring alone. The authors sought to investigate this using a national database. METHODS The National Trauma Data Bank from 2013 to 2017 was queried to identify patients with sTBI who had an external ventricular drain or intraparenchymal ICP monitor placed. Patients were stratified according to the placement of an intraparenchymal brain tissue oxygen tension (PbtO2) monitor, and a 2:1 propensity score matching pair was used to compare outcomes in patients with and those without PbtO2 monitoring. Sensitivity analyses were performed using the entire cohort, and each model was adjusted for age, sex, Glasgow Coma Scale score, Injury Severity Score, presence of hypotension, insurance, race, and hospital teaching status. The primary outcome of interest was in-hospital mortality, and secondary outcomes included ICU length of stay (LOS) and overall LOS. RESULTS A total of 3421 patients with sTBI who underwent ICP monitoring were identified. Of these, 155 (4.5%) patients had a PbtO2 monitor placed. Among the propensity score–matched patients, mortality occurred in 35.4% of patients without oxygen monitoring and 23.4% of patients with oxygen monitoring (OR 0.53, 95% CI 0.33–0.85; p = 0.007). The unfavorable discharge rates were 56.3% and 47.4%, respectively, in patients with and those without oxygen monitoring (OR 1.41, 95% CI 0.87–2.30; p = 0.168). There was no difference in overall LOS, but patients with PbtO2 monitoring had a significantly longer ICU LOS and duration of mechanical ventilation. In the sensitivity analysis, PbtO2 monitoring was associated with decreased odds of mortality (OR 0.56, 95% CI 0.37–0.84) but higher odds of unfavorable discharge (OR 1.59, 95% CI 1.06–2.40). CONCLUSIONS When combined with ICP monitoring, PbtO2 monitoring was associated with lower inpatient mortality for patients with sTBI. This supports the findings of the recent Brain Oxygen Optimization in Severe Traumatic Brain Injury phase 2 (BOOST 2) trial and highlights the importance of the ongoing BOOST3 trial.

Monitoring deep-tissue oxygenation with a millimeter-scale ultrasonic implant

Deep tissue oxygenation monitoring has many potential applications. Vascular complications after solid organ transplantation, for example, frequently lead to graft ischemia, dysfunction or loss, and can occur months after transplantation. While imaging approaches can provide intermittent assessments of graft perfusion, they require highly skilled practitioners, and fail to directly assess graft oxygenation. Existing tissue oxygen monitoring systems have many drawbacks, including the need for wired connections, the inability to provide real-time data, and, crucially, an operation that is limited to surface tissues. Here, we present the first wireless, minimally-invasive deep tissue oxygen monitoring system that provides continuous real-time data from centimeter-scale depths in a clinically-relevant large animal (sheep) model and demonstrates operation at great depths (up to 10 cm) through ex vivo porcine tissue. The system relies on a millimeter-sized, wireless, battery-free, implantable luminescence oxygen sensor that is powered by ultrasound and capable of bi-directional data transfer with an external transceiver. We present various aspects of system and sensor performance and demonstrate the operation of the system in vitro in distilled water, phosphate-buffered saline (PBS) and undiluted human serum, ex vivo through porcine tissue, and in vivo in a sheep model. We believe this technology represents a new class of diagnostic system particularly suitable for organ monitoring, as well as other surgical or critical care indications.