Ventilation Events Research Articles

Advantages of a Data-Capture System with Video to Record Neonatal Resuscitation Interventions

To assess the completeness and accuracy of neonatal resuscitation documentation the electronic medical record (EMR) compared with a data-capture system including video. Retrospective observational study of 226 infants assessed for resuscitation at birth between April 2019 and October 2021 at Sharp Mary Birch Hospital, San Diego. Completeness was defined as the presence of documented resuscitative interventions in the EMR. We assessed the timing and frequency of interventions to determine the accuracy of the EMR documentation using video recordings as an objective record for comparison. Inaccuracy of EMR documentation was scored as missing (not documented), under-reported, or over-reported. Overall, the completeness of resuscitation interventions documented in the EMR was high (85%-100%), but the accuracy of documentation varied between 39% and 100% Modes of respiratory support were accurately captured in 96%-100% of the EMRs. Time to successful intubation (39%) and maximum fraction of inspired oxygen (47%) were the least accurately documented interventions in the EMR. Under-reporting of interventions with several events (eg, number of positive pressure ventilation events and intubation attempts) were also common errors in the EMR. The self-reported modes of respiratory support were accurately documented in the EMR, whereas the timing of interventions was inaccurate when compared with video recordings. The use of a video-capture system in the delivery room provided a more objective record of the timing of specific interventions during neonatal resuscitations.

Climate cyclicity-controlled recurrent bottom-water ventilation events in the aftermath of the Toarcian Oceanic Anoxic Event: the Jenkyns Event

Environmental perturbations of the Toarcian Anoxic Event and its associated carbon isotope excursion (CIE) occurred in a cyclic fashion indicating an orbital control mechanism. Sedimentary strata of the E. elegantulum ammonite subzone in the Lorraine Sub-basin, Luxembourg, exhibit eight sedimentary cycles, most of which postdate the CIE, implying that its termination did not coincide with a full recovery from environmental stress. Sea-level and temperature fluctuations of the Toarcian crisis were linked to a cryosphere demise in the Northern Hemisphere, which modulated stadial versus interstadial phases on the orbital 100 ka eccentricity frequency band. Upon stadial phases, enhanced wind strength in combination with lowered sea level disrupted stratified shelf waters and shifted the storm wave base close to the sea floor. Ventilation of bottom waters interrupted accumulation of laminated and organic-rich black shales, but formed organic-lean and non-laminated gray claystones enriched in terrigenous wax lipids and spores provided via aeolian transport from the hinterland due to the enhanced wind strength. Wind systems are assumed to have been driven by high pressure differences between the cryosphere in the North of the Tethyan shelf and the warmer costal lowland. This distinguishes the atmospheric turbulences after the CIE from the postulated intensification of the cyclones that accompanied the rapid warming at the beginning of the CIE. The deep-water ventilation event following the CIE in the Lorraine Sub-basin was accompanied by a parallel evolution in the SW German Basin, indicating a supraregional driving mechanism in paleobathymetric sub-basins susceptible to lowering of storm wave base. In sub-basins with greater water depth on the NW-Tethyan shelf, post-CIE orbitally driven atmospheric turbulences had a minor or no effect on water column stratification and deposition of organic-rich laminated black shales persisted.Graphical abstract

Clinical trends among patients with asthma hospitalized for COVID-19 based on data from a nationwide database: an observational study

BackgroundWhile the prevalence of severe cases and mortality rate of coronavirus disease 2019 (COVID-19) appear to be reducing, the clinical characteristics and severity of hospitalized patients with asthma and COVID-19 remain largely unknown. This study aimed to examine the association of asthma with COVID-19 severity and mortality risk.MethodsData from the Japanese COVID-19 Registry Database were used to investigate the association between COVID-19 and asthma. This study focused on patients hospitalized for COVID-19 in 690 facilities from January 31, 2020, to December 31, 2022. Multivariate analysis using logistic regression was conducted to assess whether asthma, compared with other conditions, represents a risk factor for mortality and invasive mechanical ventilation after COVID-19.ResultsIn total, 72,582 patients with COVID-19 were included in the analysis, of whom, 3731 were diagnosed with asthma. From January 2020 to June 2021, asthma showed no significant association with an increase in mortality (OR 0.837, 95% CI 0.639–1.080, p = 0.184) or invasive mechanical ventilation events (OR 1.084, 95% CI 0.878–1.326, p = 0.440). An analysis conducted after July 2021 yielded similar results. For patients with asthma, factors such as age, body-mass index, sex, and chronic kidney disease increased the risk of mechanical ventilation. However, non-vaccination status and high blood pressure increased the risk of mechanical ventilation during the second half of the study.ConclusionPatients with asthma did not have an increased risk of mortality or mechanical ventilation due to COVID-19. However, patients with asthma had a higher risk of more severe COVID-19 due to factors such as advancing age, elevated body-mass index, chronic kidney disease, and non-vaccination.

Contourite stratigraphic models linked to the light intermediate versus dense deep Mediterranean water flow regime variations (Alboran Sea, SW Mediterranean)

Several water masses are involved in the circulation of oceans, their bottom layers impacting on sedimentation through contourites. The majority of palaeoceanographic studies on regional contourites are performed for one water mass despite that their joint study would offer relevant clues to understand past ocean and climate interaction. This works presents for the first time a an analysis about the impact of the Light Intermediate Mediterranean (LMW) and Dense Deep Mediterranean (DMW) bottom currents on the sedimentation in the Alboran Sea (SW Mediterranean) and its paleoceanographic significance in response to climatic oscillations from the last glacial period to the Holocene. To do this, an integration of chronostratigraphical, sedimentological, and compositional data is carried out from contourites formed by those water masses. That integration enable us to define three distinct contourite stratigraphic models. (I) The contourite terrace model, characterized by coarse-grained contourites, which is an archive of the interplay between the high-energy Atlantic Water-LMW interface and glacioeustasy from the Younger Dryas (YD) to the Holocene. (II) The contourite drift models, which are archives of rapid ocean-climate coupled fluctuations since 29.5 kyr. They comprise coarse-grained contourites formed by a relatively fast LMW and fine-grained contourites formed by a relatively weak DMW, except for the Heinrich Stadials HS3 to HS1 and YD when coarse-grained contourites were deposited. (III) The contourite/turbidite mixed model represents another archive of DMW and glacioeustasy interplay from the end of the late Pleistocene to Holocene.That contourite stratigraphy allows us to infer for the first time the relative variability of the LMW versus DMW flow regimes, which records differences and similarities. The similarities indicate that the LMW and DMW fluctuations occur in parallel at millennial and centennial time scales. The differences refer to the overall higher velocity of LMW versus DMW; the magnitude changes in velocities that are lower for LMW and higher for DMW; the recognition of three short ventilation events (a, b, c) during HS1 and HS2 for only DMW; and the distinct LMW and DMW responses to the onset of glacial conditions and return to interglacial conditions during the HSs, YD and Holocene cold periods.The proposed contourite stratigraphic models can be applied for other areas in the Mediterranean margins to identify and correlate the LMW and DMW palaeoceanographic events throughout this sea. The findings suggest that the different water masses that make up the water column must be seriously considered to fully understand palaeoceanographic and palaeoclimatic studies based on contourites. This is because their distinct impact on sedimentation may provide new insights into their different palaeoceanographic responses to rapid climatic oscillations and their triggering mechanisms.

Coupling of Carbon and Oxygen in the Pearl River Plume in Summer: Upwelling, Hypoxia, Reoxygenation and Enhanced Acidification

AbstractAcidification and hypoxia are universal environmental issues in coastal seas, especially in large river estuaries such as the Pearl River estuary. In July and August of 2015, two legs of a field survey were conducted in the Pearl River plume. Leg 1 was sampled during the influence of upwelling favorable winds, while Leg 2 was during downwelling favorable winds. During both legs, instead of the typically observed dissolved inorganic carbon (DIC) consumption and dissolved oxygen (DO) over‐saturation, upwelling‐induced high DIC (>2,000 μmol kg−1), low pH (7.7–7.8) and low DO (140–150 μmol kg−1) values were observed in surface waters at the estuary mouth and the area off Hong Kong. In the bottom waters, hypoxia, acidification (pH 7.6–7.8) and DIC accumulation (DIC addition of ∼100–180 μmol kg−1) were observed. Hypoxia was less severe during Leg 2 compared to Leg 1. The stoichiometry of oxygen depletion to DIC addition was 0.89 for bottom water, suggesting remineralization was dominated by marine sourced organic matter. However, a comparison of data from the two legs showed that the stoichiometry of oxygen consumption to DIC accumulation was significantly higher during Leg 2 (0.73 ± 0.03 for Leg 1 vs. 0.80 ± 0.05 for Leg 2), although N/P ratios were the same (13.54 ± 1.93 for Leg 1 vs. 13.51 ± 2.04 for Leg 2). This phenomenon was attributed mainly to enhanced ventilation (re‐oxygenation) under the influence of the downwelling favorable winds during Leg 2. Although ventilation relieves some hypoxia, it might enhance acidification in bottom waters after a short‐term ventilation event. The enhanced acidification after short‐term ventilation is worthy of further study considering that most hypoxia and acidification are found in shallow coastal seas.

Future climate-induced changes in mixing and deep oxygen content of a caldera lake with hydrothermal heat and salt inputs

Vertical profiles of temperature, salinity and dissolved oxygen in Crater Lake, a caldera lake in the Oregon Cascade Range that receives hydrothermal inputs of heat and salt, were simulated with a 1-dimensional model. Twelve Global Circulation Models and two Representative Concentration Pathways (RCPs) were used to develop boundary conditions from 1950 to 2099. The model simulated the ventilation of deep water initiated by reverse stratification and subsequent thermobaric instability. All models predicted a reduction in the frequency of deep ventilation events, from an ensemble median frequency of 5.4 winters decade−1 during 1950–2005 to 4.3 (RCP4.5) or 2.5 (RCP8.5) winters decade−1 during 2045–2099. Favorable conditions for thermobaric instability-induced mixing currently occur infrequently and will become rare in the future. The salinity gradient resulting from hydrothermal inputs presents an additional barrier to thermobaric instability that will continue through 2099. A redistribution of salt to the deep lake may prevent ventilation all the way to the bottom in the future. Hypolimnetic dissolved oxygen percent saturation remained above 75% within the 21st century, consistent with oligotrophy and very small oxygen demands. The rate of change in all variables accelerated approaching 2099, coincident with elimination of winter reverse stratification. Historically, about half of the hydrothermal heat added to Crater Lake has been vented to the atmosphere. In the RCP8.5 scenario, the hydrothermal heat will cease to be vented to the atmosphere by the end of the 21st century, and then the temperature of the deep waters will increase rapidly.

Effectiveness of Casirivimab and Imdevimab Antibody Combination in Immunocompromised Hospitalized Patients With Coronavirus Disease 2019: A Post Hoc Analysis in a Phase 1/2/3 Double-Blind Trial.

Individuals who are immunocompromised (IC) are at high risk for severe coronavirus disease 2019 (COVID-19). Post hoc analyses of a double-blind trial conducted prior to Omicron (June 2020-April 2021), in hospitalized patients with COVID-19 assessed viral load, clinical outcomes, and safety of casirivimab plus imdevimab (CAS + IMD) versus placebo in IC versus overall study patients. Ninety-nine of 1940 (5.1%) patients were IC. IC versus overall patients were more frequently seronegative for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies (68.7% vs 41.2%) and had higher median baseline viral loads (7.21 vs 6.32 log10 copies/mL). On placebo, IC versus overall patients had slower viral load declines. CAS + IMD reduced viral load in IC and overall patients; least-squares mean difference versus placebo in time-weighted average change from baseline viral load at day 7 was -0.69 (95% confidence interval [CI], -1.25 to -.14) log10 copies/mL for IC patients and -0.31 (95% CI, -.42 to -.20) log10 copies/mL for overall patients. For IC patients, the cumulative incidence of death or mechanical ventilation at day 29 was lower with CAS + IMD (11.0%) versus placebo (17.2%), consistent with overall patients (15.7% CAS + IMD vs 18.3% placebo). IC and overall patients receiving CAS + IMD exhibited similar rates of treatment-emergent adverse events (30.4% and 26.6%, respectively), grade ≥2 hypersensitivity or infusion-related reactions (1.4% and 2.5%), and deaths (8.7% and 12.2%). IC patients were more likely to exhibit high viral loads and be seronegative at baseline. For susceptible SARS-CoV-2 variants, CAS + IMD reduced viral load and resulted in fewer death or mechanical ventilation events in IC and overall study patients. There were no new safety findings among IC patients. Clinical Trials Registration. NCT04426695.

High-resolution characterization of the development and decay of seasonal hypoxia in the Gulf of Riga, Baltic Sea

The Gulf of Riga is a shallow basin in the eastern Baltic Sea connected to the Central Baltic Sea via shallow straits. Seasonal oxygen depletion occurs in the deep layer of the gulf. We conducted hourly measurements of dissolved oxygen, temperature, and salinity in the deep layer (50 m) of the gulf and observed the full cycle of development and relaxation of hypoxia in 2021. Hypoxia (<2.9 mg l-1) first occurred on 27 June and was observed for 71 days until its complete decay on 22 October. Average oxygen decline of 0.10 mg l-1 d-1 from saturation in mid-April until mid-July and 0.04 mg l-1 d-1 onwards until the end of August were observed. This seasonal pattern was superimposed by short-term variability in time scales from hours to days and was probably caused by inertial oscillations, (sub)mesoscale processes, deep layer currents, and pycnocline movements. Ventilation events with a relatively low impact and duration of up to ten days occurred in the deep layer due to the inflows of the saltier water from the Central Baltic. The inflowed water originated from the upper layer in winter and the thermocline in summer and was almost saturated in oxygen. Mostly mixing with existing oxygen-depleted water in the Gulf of Riga, but also local consumption declined the oxygen levels in the inflow water before it arrived at the observing station. Monthly standard deviations in oxygen varied from 0.3 to 2.8 mg l-1 and illustrated the added value of Eulerian measurements to complement the conventional monitoring.

“PEEP-ZEEP” Maneuver for Airway Clearance in Mechanically Ventilated Patients: A Scoping Review

Abstract A mechanical ventilator is the standard care to manage airways in intensive care unit (ICU). The inherent complications associated with mechanical ventilation are easy to prevent and control. Ventilator events, including ventilator-associated pneumonia, are crucial issues to manage in critically ill patients. Secretion retention due to compromised mucociliary function and altered lung internal milieu plays a significant concern in ICU outcomes. Physiotherapy involved in ICU plays an essential role in maintaining lung hygiene. Conventional chest physiotherapy is an extrapulmonary technique to remove secretion and maintain bronchial hygiene. Manual hyperinflation and suctioning are the methods that are highly at risk of transmitting lung infection. Generating flow bias through modification in various ventilator parameters is recently in trend to prevent bronchial hygiene-related complications. PEEP-ZEEP maneuver causes the expiratory flow bias by increasing peak expiratory flow. The present scoping review explores the safety and efficacy of the PEEP-ZEEP maneuver for airway clearance in mechanically ventilated patients. The current scoping review aims to identify the use and safety of the PEEP-ZEEP maneuver applied in mechanically ventilated patients for airway clearance. The five databases, i.e., PubMed, PEDro, Google Scholar, Cochrane, and Web of Science, have been searched till October 2022. The published experimental studies included in the review was searched using Boolean operators (“AND” and “OR”) and keywords, i.e., PEEP-ZEEP, Mechanical Ventilator, and Airway Clearance technique. PEEP-ZEEP is a safe and efficient for airway clearance in mechanically ventilated patients, with the need to explore further with a larger sample size and more defined outcomes and population.

Enrichment of mercury in the Lower Cambrian sedimentary successions by submarine hydrothermal venting

• Widespread sedimentary Hg enrichments in the Early Cambrian can be attributed to periodic hydrothermal ventilation. • Prevailing hydrothermal ventilation was an important source of Hg in sediments in the Early Cambrian. • The accumulation of Hg in sediments may be more effective in euxinic environments. Although extremely high Hg contents are known in the Lower Cambrian sedimentary successions, the extent and spatial-temporal distribution of sedimentary Hg anomalies in these successions remain unclear. Here, we report concentrations of Hg, total organic carbon (TOC), total sulfur (TS), and major and rare earth elements of the Lower Cambrian (∼525 Ma) sedimentary rocks at the Dongxihe section in the interior of the Yangtze Platform, South China. We investigated the sedimentary Hg enrichment mechanism and the spatial-temporal fluctuations of Hg in the Lower Cambrian and compiled published Hg (Hg/TOC) data from the Upper Neoproterozoic to the Lower Cambrian to trace the potential Hg sources. Our study verified that hydrothermal vents provide an excess Hg source for the sedimentary Hg enrichment in the Dongxihe section, which is supported by the positive Eu anomaly and major element. The major elements show more Fe and Mn enrichment in the upper part than the lower part, indicating more hydrothermal contribution in the upper part. Additionally, the records of the spatial-temporal distribution of Hg show that most of the sections (including shelf, slope, and basin) in South China show strong sedimentary Hg enrichment, which can be attributed to widespread hydrothermal venting. By reconstructing fluctuations of Hg during the Late Neoproterozoic to the Early Cambrian, we proposed that in the context of the Gondwana continent assembly, the prevalent hydrothermal ventilation event during the Early Cambrian not only induced the abnormal enrichment of sedimentary Hg but also played a crucial role in shaping the marine environment and ecosystem during this period.

Cost-effectiveness of remdesivir plus usual care versus usual care alone for hospitalized patients with COVID-19: an economic evaluation as part of the Canadian Treatments for COVID-19 (CATCO) randomized clinical trial.

Background:The role of remdesivir in the treatment of hospitalized patients with COVID-19 remains ill-defined. We conducted a cost-effectiveness analysis alongside the Canadian Treatments for COVID-19 (CATCO) open-label, randomized clinical trial evaluating remdesivir.Methods:Patients with COVID-19 in Canadian hospitals from Aug. 14, 2020, to Apr. 1, 2021, were randomly assigned to receive remdesivir plus usual care versus usual care alone. Taking a public health care payer’s perspective, we collected in-hospital outcomes and health care resource utilization alongside estimated unit costs in 2020 Canadian dollars over a time horizon from randomization to hospital discharge or death. Data from 1281 adults admitted to 52 hospitals in 6 Canadian provinces were analyzed.Results:The total mean cost per patient was $37 918 (standard deviation [SD] $42 413; 95% confidence interval [CI] $34 617 to $41 220) for patients randomly assigned to the remdesivir group and $38 026 (SD $46 021; 95% CI $34 480 to $41 573) for patients receiving usual care (incremental cost −$108 [95% CI −$4953 to $4737], p > 0.9). The difference in proportions of in-hospital deaths between remdesivir and usual care groups was −3.9% (18.7% v. 22.6%, 95% CI −8.3% to 1.0%, p = 0.09). The difference in proportions of incident invasive mechanical ventilation events between groups was −7.0% (8.0% v. 15.0%, 95% CI −10.6% to −3.4%, p = 0.006), whereas the difference in proportions of total mechanical ventilation events between groups was −5.7% (16.4% v. 22.1%, 95% CI −10.0% to −1.4%, p = 0.01). Remdesivir was the dominant intervention (but only marginally less costly, with mildly lower mortality) with an incalculable incremental cost effectiveness ratio; we report results of incremental costs and incremental effects separately. For willingness-to-pay thresholds of $0, $20 000, $50 000 and $100 000 per death averted, a strategy using remdesivir was cost-effective in 60%, 67%, 74% and 79% of simulations, respectively. The remdesivir costs were the fifth highest cost driver, offset by shorter lengths of stay and less mechanical ventilation.Interpretation:From a health care payer perspective, treating patients hospitalized with COVID-19 with remdesivir and usual care appears to be preferrable to treating with usual care alone, albeit with marginal incremental cost and small clinical effects. The added cost of remdesivir was offset by shorter lengths of stay in the intensive care unit and less need for ventilation. Study registration:ClinicalTrials. gov, no. NCT04330690

Comparative study between BAP65 score and DECAF score in assessment of acute exacerbation of chronic obstructive pulmonary disease

Background Chronic obstructive pulmonary disease (COPD) exacerbations is common, but accurate expectation of hospitalized patients in exacerbation state has been difficult for a long time. Dyspnea, eosinopenia, consolidation, acidemia, and atrial fibrillation (DECAF) score was evaluated in this study for prediction of mortality and ventilation need in patients with acute exacerbation of COPD admitted to ICU or chest department. This novel score was compared with the BAP65 scoring system. Patients and methods A total of 50 patients were included in this comparative study. They were admitted with COPD exacerbation from our ER to the chest department or ICU. BAP65 and DECAF scores were collected on admission for each patient. The patients were followed up during the hospital stay. Death or ventilation events was recorded. Data analysis was done using SPSS, version 22. Results DECAF and BAP65 scores had a good prediction of in-hospital mortality, with 100% sensitivity for both, whereas the specificity was 87% for DECAF score and 91% BAP65 score. The accuracy in mortality prediction for DECAF and BAP65 score was 88 and 92%, respectively. The sensitivity of DECAF and BAP65 scores for prediction of mechanical ventilation need was 93 and 87%, respectively, whereas the specificity was 74 and 60%, respectively, with 80% accuracy in DECAF score and 68% accuracy in BAP65 score. A positive linear relationship with a significant correlation was found between DECAF score and BAP65 score on the Pearson’s graph (r=0.604, P<0.001). Conclusion BAP65 and DECAF are feasible scores that can be calculated by usually available data. They also have a good prediction for mortality and ventilation need during acute exacerbation of COPD.

67 Transient Dysphagia After Burn Injury in Children: An Under-identified Problem

IntroductionSeverely burn injured pediatric patients are at risk of dysphagia (difficulty swallowing) due to prolonged intubation or tracheostomy placement. To improve the early identification and treatment of dysphagia, we implemented a swallowing assessment protocol. We hypothesized that the swallowing assessment protocol is effective for identifying and treating dysphagia after prolonged intubation.MethodsBetween October 2016 and December 2020, pediatric burn patients with facial burn injuries, prolonged mechanical ventilation, tracheostomy, inhalation injury and/or anoxic events were placed on the swallowing protocol. The protocol included a Transitional Swallow Screen (TSS) performed within 24 hours after extubation or decanulation by an advanced practice swallow occupational therapist. If signs of dysphagia were noted, recommendations on diet consistency and treatment for positioning and feeding were implemented. Regular reassessments continued until the patient was determined to have regained premorbid swallowing function. Data on patient demographics, burn characteristics, dysphagia, treatment and outcome were collected. Descriptive statistics were used to describe the population, treatments and outcome.ResultsA total of 33 pediatric burn patients were included. Mean age was 8.1±5.9 years and TBSA was 48.1±26.8%. Median time from injury to swallow assessment was 45 (21-81) days. The majority of patients suffered from flame burns (70%). Almost all of the patients were intubated (97%) and 85% underwent a tracheostomy. Patients had a facial burn (73%), inhalation injury (24%) or anoxic injury (15%). Transient dysphagia was diagnosed in 79% of patients. Subsequent therapeutic procedures as a result of the TSS included: neurologic re-education (30%), swallow therapy exercises (55%), desensitization (42%), and patient/ family training and supervision (79%). All patients eventually returned to normal swallow and regular diet. This occurred at an average of 72.5+46.7 days post injury and 8.2+18.0 days post swallow assessment.ConclusionsPediatric patients with substantial burn injury may not only be at risk for aspiration but also have other forms of dysphasia that require intervention. Implementation of a swallowing protocol can identify patients who required further therapeutic intervention and can guide the recovery of safe swallowing and functional oral intake.

Validation of CFD fire model pressure predictions for modern residential style structures

Controlled gas burner experiments were conducted in single- and two-story residential style structures instrumented with pressure transducers, thermocouples, and bi-directional probes throughout the structures. Exterior doors and window openings were vented in a controlled sequence to investigate the effect of the resulting flow paths on fire-induced flow dynamics and thermal conditions in the structures. The data collected in these experiments provides validation cases for the fire modeling community which currently lacks full-scale data from experiments in realistic residential style structures. The Fire Dynamics Simulator was used to model each scenario in a validation exercise that also investigated the sensitivity of the pressure predictions to the model parameters. The model was capable of predicting the qualitative changes in pressure measurements due to ventilation events as well as the apparent elevation of the neutral plane. Peak pressures were predicted to within 6% on average and quasi-steady static pressures were predicted to within 24% on average. The mean instantaneous error between the experimental pressures and those predicted with the “Localized Leakage” method was approximately 53% compared to 67% with the “Pressure Zone Leakage” method prior to the first ventilation event.

Dynamics of PM2.5 pollution in the vicinity of the old municipal solid waste dumpsite.

The present study explored the effect of local meteorology on the dispersion of PM2.5 from a 30-year open municipal solid waste (MSW) dumpsite in Chennai, India. The spatial monitoring was conducted in and around the dumpsite to understand the impacts of dumpsite activities on the nearby residential area. Results showed that dumpsite activities are responsible for deteriorating local air quality. The 24-h average PM2.5 concentrations were 50, 43.7, and 34µgm-3 during stagnation, recirculation, and ventilation events, respectively. Spearman's correlation showed an inverse relationship between PM2.5 and temperature; wind speed indicated dispersion of fine aerosols. The observed inverse relationship between PM2.5 and relative humidity indicated the hygroscopic growth of fine aerosols in the study area. We used AERMOD to simulate the dispersion of 1-h, 8-h, and 24-h PM2.5 emissions from open waste burning in the dumpsite. The 1-h, 8-h, and 24-h simulated results showed the maximum concentration of 247, 136, and 53.4µgm-3 in the dumpsite, and concentration levels ranged between 50-60, 30-50, and 10-20µgm-3 were observed in the nearby residential area. The AERMOD predictions indicated that open waste burning could be a significant contributor to high PM2.5 concentration in an adjacent residential area of the dumpsite.

Comparison of Confirmation of Placement of Laryngeal Mask Airway by Fiberoptic Laryngoscope and Ultrasound Examination

Abstract Background: The laryngeal mask airway (LMA) is widely used as an effective and safe airway adjunct in the routine practice of anesthesia. There are various methods to assess the correct placement, the gold standard being fiberoptic visualization through the LMA. Ultrasound (USG) is a noninvasive, readily available diagnostic tool and has been used with increased frequency for airway examination. The aim of our study was comparison of fiberoptic and USG evaluation for the confirmation of placement of LMA. Patients and Methods: This was a cross-sectional observational study conducted on 250 patients of American Society of Anesthesiologists Grade 1 and 2, in the age group of 18–65 years undergoing elective surgery under general anesthesia with LMA. The position of the LMA cuff was confirmed by USG and reconfirmed with fiberoptic laryngoscopy (FOL). Results: We observed that the USG Grade 1 was seen in 76.8% of patients as compared to FOL Grade 1 seen in 81.6%. The frequency of LMA misplacement (i.e., Grades 2–4) noted with USG was 23.2% and with FOL was 18.4%. The Bland–Altman scatter plot showed insignificant differences between the two grading systems (near-zero mean: 0.05), with small limits of agreement (−0.509 to +0.609). Conclusion: USG can replace fiberoptic examination for confirmation of the correct placement of an LMA. USG can further give insight into the grading of LMA placement and the cause of airway and ventilation events, which can be corrected and prevented.

Evidence for influx of Atlantic water masses to the Labrador Sea during the Last Glacial Maximum

The Last Glacial Maximum (LGM, 23–19,000 year BP) designates a period of extensive glacial extent and very cold conditions on the Northern Hemisphere. The strength of ocean circulation during this period has been highly debated. Based on investigations of two marine sediment cores from the Davis Strait (1033 m water depth) and the northern Labrador Sea (2381 m), we demonstrate a significant influx of Atlantic-sourced water at both subsurface and intermediate depths during the LGM. Although surface-water conditions were cold and sea-ice loaded, the lower strata of the (proto) West Greenland Current carried a significant Atlantic (Irminger Sea-derived) Water signal, while at the deeper site the sea floor was swept by a water mass comparable with present Northeast Atlantic Deep Water. The persistent influx of these Atlantic-sourced waters entrained by boundary currents off SW Greenland demonstrates an active Atlantic Meridional Overturning Circulation during the LGM. Immediately after the LGM, deglaciation was characterized by a prominent deep-water ventilation event and potentially Labrador Sea Water formation, presumably related to brine formation and/or hyperpycnal meltwater flows. This was followed by a major re-arrangement of deep-water masses most likely linked to increased overflow at the Greenland-Scotland Ridge after ca 15 kyr BP.

Development and validation of a reinforcement learning algorithm to dynamically optimize mechanical ventilation in critical care

The aim of this work was to develop and evaluate the reinforcement learning algorithm VentAI, which is able to suggest a dynamically optimized mechanical ventilation regime for critically-ill patients. We built, validated and tested its performance on 11,943 events of volume-controlled mechanical ventilation derived from 61,532 distinct ICU admissions and tested it on an independent, secondary dataset (200,859 ICU stays; 25,086 mechanical ventilation events). A patient “data fingerprint” of 44 features was extracted as multidimensional time series in 4-hour time steps. We used a Markov decision process, including a reward system and a Q-learning approach, to find the optimized settings for positive end-expiratory pressure (PEEP), fraction of inspired oxygen (FiO2) and ideal body weight-adjusted tidal volume (Vt). The observed outcome was in-hospital or 90-day mortality. VentAI reached a significantly increased estimated performance return of 83.3 (primary dataset) and 84.1 (secondary dataset) compared to physicians’ standard clinical care (51.1). The number of recommended action changes per mechanically ventilated patient constantly exceeded those of the clinicians. VentAI chose 202.9% more frequently ventilation regimes with lower Vt (5–7.5 mL/kg), but 50.8% less for regimes with higher Vt (7.5–10 mL/kg). VentAI recommended 29.3% more frequently PEEP levels of 5–7 cm H2O and 53.6% more frequently PEEP levels of 7–9 cmH2O. VentAI avoided high (>55%) FiO2 values (59.8% decrease), while preferring the range of 50–55% (140.3% increase). In conclusion, VentAI provides reproducible high performance by dynamically choosing an optimized, individualized ventilation strategy and thus might be of benefit for critically ill patients.

Prevalence and consequences of Gastroesophageal Reflux Disease on COPD

Background The main determinants for COPD exacerbations are previous history of exacerbation, the severity of the disease, and the presence of comorbidities. However, the role of GER in this setting remains unclear. Aim To assess the impact of GER on COPD severity and exacerbation frequency. Methods Stable COPD patients were included.Diagnosis of GER was done by GERD questionnaire.Patients were classified into two groups (COPD with GERD & COPD without GERD). Associations of GERD with degree of airway obstruction, frequency of exacerbation ,ICU admission and mechanical ventilation in the previous year were assessed. Factors associated with exacerbation were analysed by regression analysis Results The current study included 233 COPD patients and were classified into two groups;Group A: COPD with GERD including 56 patients (24%) and Group B : COPD without GERD including 177 patients (76%).Group A had more ICU admission and mechanical ventilation events in the last year (P= 0.01&0.009 respectively).COPD patients with GERD had more severe degree of airway obstruction measured by FEV1 % (56% versus 62% in COPD patients without GERD.When comparing rate of COPD exacerbation in the last year before inclusion, 60% of COPD patients with GERD gave history of two or more exacerbations while in those without GERD, only 33% were exacerbators. . Current smoking, GERD and Severity of airway obstruction were the three independent predictors of excaerbation in the studied population. Conclusions The frequency of GER in COPD was 24%.COPD with GERD had lower FEV1%, more exacerbation and mechanical ventilation than those without GERD.

Elevated marine productivity triggered nitrogen limitation on the Yangtze Platform (South China) during the Ordovician-Silurian transition

The Ordovician-Silurian transition (OST) coincided with global environmental and biological changes, including perturbations of the carbon and sulfur cycles, oceanic redox changes, and a mass extinction event, but their effects on the contemporaneous marine nitrogen cycle remain poorly known. In this study, we measured bulk nitrogen isotopes in the Datianba and Shuanghe OST sections of South China, which accumulated in the semi-restricted inner Yangtze Sea. The uniformly low δ15Nbulk (mostly –1 to +1 ‰) of Wufeng and Longmaxi Formation black shales (representing the pre- and post-Hirnantian intervals) imply large losses of bioavailable nitrogen (i.e., nitrate and ammonium) via denitrification/anammox as well as strong nitrogen fixation by diazotrophs. Persistence of low δ15Nbulk values within the Guanyinqiao Bed (representing the Hirnantian glacial interval) indicates that denitrification/anammox remained strong even during this major glacio-eustatic fall and deep-ocean ventilation event. We hypothesize that elevated primary productivity caused by upwelling was a key factor producing a shallow redoxcline in the inner Yangtze Sea. By comparing our nitrogen data with records from other cratons, we suggest that oceanic anoxia was prevalent globally during the Late Katian to early Rhuddanian, and that ocean-redox conditions were spatially heterogeneous during the Hirnantian glaciation. These considerations imply that bioavailable nitrogen was the limiting factor on marine primary productivity during the OST, and that oceanic anoxia may have contributed to the Late Ordovician mass extinction, especially on the Yangtze Platform.