Ventilators for Nonintensivists. Basic Modes and Breath Types.
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ABSTRACT:
SUBMITTER: Acho M
PROVIDER: S-EPMC8043302 | biostudies-literature | 2020 May
REPOSITORIES: biostudies-literature
Publications
Ventilators for Nonintensivists. Basic Modes and Breath Types.
Acho Megan M Lee Alyson C AC Lee Burton W BW
ATS scholar 20200519 2
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Project description: Not available
| S-EPMC8043300 | biostudies-literature
Project description:Although there has been an increase in bench test evaluation of mechanical ventilators in recent years, a publication gap remains in assessing Pressure Control Continuous Mandatory Ventilation Modes with a set point targeting scheme PC-CMVs. This study evaluates the operational variability in PC-CMVs of eleven transport and emergency ventilators used in ICU units in Brazil during the COVID-19 pandemic. The assessment involved a comprehensive set of test scenarios derived from existing literature and the NBR ISO 80601-2-12:2014 standard. Nine parameters were computed for five consecutive breaths, offering a comprehensive characterization of pressure and flow waveforms. Most ventilators had Inspiratory pressure and PEEP values that fell outside of the tolerance ranges. Notably, three mechanical ventilators failed to reach the target pressures within the specified inspiratory times during test scenarios with a higher time constant (τ). We observed significant differences among emergency and transport ventilators in all assessed parameters, indicating a performance difference in PC-CMVs modes. The current results might help clinicians determine which ventilator models are suitable for specific clinical situations, particularly when unfavorable circumstances compel doctors to use ventilators that may not provide adequate support for patients in intensive care units.
| S-EPMC11439908 | biostudies-literature
Project description:BackgroundNitric oxide (NO) is a strong vasodilator, selectively directed on pulmonary circulation through inhaled administration. In adult intensive care units (ICU), it is mainly used for refractory hypoxemia in mechanically ventilated patients. Several medical delivery devices have been developed to deliver inhaled nitric oxide (iNO). The main purpose of those devices is to guarantee an accurate inspiratory NO concentration, whatever the ventilator used, with NO2 concentrations lower than 0.3 ppm. We hypothesized that the performances of the different available iNO delivery systems could depend on their working principle and could be influenced by the ventilator settings. The objective of this study was to assess the accuracy of seven different iNO-devices combined with different ICU ventilators' flow-by to reach inspiratory NO concentration targets and to evaluate their potential risk of toxicity.MethodsWe tested seven iNO-devices on a test-lung connected to distinct ICU ventilators offering four different levels of flow-by. We measured the flow in the inspiratory limb of the patient circuit and the airway pressure. The nitric oxide/nitrogen (NO/N2) flow was measured on the administration line of the iNO-devices. NO and NO2 concentrations were measured in the test-lung using an electrochemical analyzer.ResultsWe identified three iNO-device generations based on the way they deliver NO flow: "Continuous", "Sequential to inspiratory phase" (I-Sequential) and "Proportional to inspiratory and expiratory ventilator flow" (Proportional). Median accuracy of iNO concentration measured in the test lung was 2% (interquartile range, IQR -19; 36), -23% (IQR -29; -17) and 0% (IQR -2; 0) with Continuous, I-Sequential and Proportional devices, respectively. Increased ventilator flow-by resulted in decreased iNO concentration in the test-lung with Continuous and I-Sequential devices, but not with Proportional ones. NO2 formation measured to assess potential risks of toxicity never exceeded the predefined safety target of 0.5 ppm. However, NO2 concentrations higher than or equal to 0.3 ppm, a concentration that can cause bronchoconstriction, were observed in 19% of the different configurations.ConclusionWe identified three different generations of iNO-devices, based on their gas administration modalities, that were associated with highly variable iNO concentrations' accuracy. Ventilator's flow by significantly impacted iNO concentration. Only the Proportional devices permitted to accurately deliver iNO whatever the conditions and the ventilators tested.
| S-EPMC11339004 | biostudies-literature
Project description:The definition of a new case is a vital step in incidence studies in both epidemiology and pharmacoepidemiology, although with significant differences in methodology between the fields. We define and apply a framework for two different types of new cases of drug use, first-ever and recurrent, and show how the associated misclassifications related to length of run-in period can be expressed by the positive predictive value (PPV). In the study, we consider individual-level dispensations of statins 2006-2019 for 1,017,058 individuals with at least one dispensation in 2019 in Sweden. The incidence proportion for statins for both sexes of all ages in Sweden 2019 varied from 17.4/1000 with a run-in of 8 months, 9.45/1000 with 5 years and 8.4/1000 with 10 years. The PPV was 49% with 8 months and 89% for 5 years using 10 years as gold standard. We conclude that the interpretation of incidence and thus the selection of an appropriate run-in period, in pharmacoepidemiology, depends on whether first-ever use, recurrent treatment or both together (new cases) is the focus of the research question studied. At least five different misclassifications can be introduced depending on how incidence is defined.
| S-EPMC9320840 | biostudies-literature
Project description:In preparing for influenza pandemics, public health agencies stockpile critical medical resources. Determining appropriate quantities and locations for such resources can be challenging, given the considerable uncertainty in the timing and severity of future pandemics. We introduce a method for optimizing stockpiles of mechanical ventilators, which are critical for treating hospitalized influenza patients in respiratory failure. As a case study, we consider the US state of Texas during mild, moderate, and severe pandemics. Optimal allocations prioritize local over central storage, even though the latter can be deployed adaptively, on the basis of real-time needs. This prioritization stems from high geographic correlations and the slightly lower treatment success assumed for centrally stockpiled ventilators. We developed our model and analysis in collaboration with academic researchers and a state public health agency and incorporated it into a Web-based decision-support tool for pandemic preparedness and response.
| S-EPMC5443432 | biostudies-literature
Project description:BackgroundThe performance of high-frequency oscillatory ventilators (HFOV) differs by the waveform generation mode and circuit characteristics. Few studies have described the performance of piston-type HFOV. The present study aimed to compare the amplitude required to reach the target high-frequency tidal volume ([Formula: see text]); determine the relationship between the settings and actual pressure in amplitude or mean airway pressure ([Formula: see text]); and describe the interaction among compliance, frequency, and endotracheal tube (ETT) inner diameter in 4 HFOV models, including Humming X, Vue (a piston type ventilator commonly used in Japan), VN500 (a diaphragm type), and SLE5000 (a reverse jet type).MethodsThe oscillatory ventilators were evaluated by using a 50-mL test lung with 0.5 and 1.0 mL/cm H2O compliance, [Formula: see text] of 10 cm H2O, frequency of 12 and 15 Hz, and ETT inner diameters 2.0, 2.5, and 3.5 mm. At each permutation of compliance, frequency, and ETT, the target high-frequency [Formula: see text] was increased from 0.5 to 3.0 mL. The change in [Formula: see text] from the ventilator (ventilator [Formula: see text]) to Y-piece (Y [Formula: see text]) and alveolar pressure (alveolar [Formula: see text]) and the change in amplitude from the ventilator (ventilator amplitude) to Y-piece (Y amplitude) and alveolar pressure (alveolar amplitude) were determined at high-frequency [Formula: see text] of 1.0 and 3.0 mL.ResultsTo achieve the target high-frequency [Formula: see text], the Humming X and Vue required a higher amplitude than did the SLE5000, but the maximum amplitude in the VN500 was unable to attain a larger high-frequency [Formula: see text]. Ventilator [Formula: see text] and alveolar pressure decreased at the Y-piece with the Humming X and Vue but increased with the SLE5000. The ventilator [Formula: see text] in the VN500 decreased remarkably at a frequency of 15 Hz. The ventilator amplitude in all 4 ventilators decreased while temporarily increasing at the Y-piece in the VN500.ConclusionsThe actual measured value, such as alveolar [Formula: see text] and high-frequency [Formula: see text], varied according to the type of HFOV system and the inner diameter of the ETT, even with identical settings. Clinicians should therefore determine the setting appropriate to each HFOV model.
| S-EPMC10984598 | biostudies-literature
Project description:BASIC: Biology, Affect, Stress, Imaging and Cognition in pregnancy
| PRJEB62678 | ENA
Project description:Spontaneous activity of the human brain provides a window to explore intrinsic principles of functional organization. However, most studies have focused on interregional functional connectivity. The principles underlying rich repertoires of instantaneous activity remain largely unknown. We apply a recently proposed eigen-microstate analysis to three resting-state functional MRI datasets to identify basic modes that represent fundamental activity patterns that coexist over time. We identify five leading basic modes that dominate activity fluctuations. Each mode exhibits a distinct functional system-dependent coactivation pattern and corresponds to specific cognitive profiles. In particular, the spatial pattern of the first leading basis mode shows the separation of activity between the default-mode and primary and attention regions. Based on theoretical modelling, we further reconstruct individual functional connectivity as the weighted superposition of coactivation patterns corresponding to these leading basic modes. Moreover, these leading basic modes capture sleep deprivation-induced changes in brain activity and interregional connectivity, primarily involving the default-mode and task-positive regions. Our findings reveal a dominant set of basic modes of spontaneous activity that reflect multiplexed interregional coordination and drive conventional functional connectivity, furthering the understanding of the functional significance of spontaneous brain activity.
| S-EPMC10471630 | biostudies-literature
Project description:N-methyl-d-aspartate receptors (NMDARs) are profound regulators of glutamate neurotransmission and behavior. To coordinate components of the limbic system, the dorsal and ventral striatum integrate cognitive and emotional information towards the execution of complex behaviors. Striatal outflow is conveyed by medium spiny neurons (MSNs), which can be dichotomized by expression of dopamine receptor subtype 1 (D1) or adenosine receptor subtype 2A (A2A). To examine how striatal NMDAR function modulates reward-related behaviors, we generated D1- and A2A-specific genetic deletions of the obligatory GluN1 subunit. Interestingly, we observed no differences in any GluN1-/- genotype in reward learning as assessed by acquisition or extinction of cocaine conditioned place preference (CPP). Control and A2A-GluN-/- mice exhibited robust cocaine-primed reinstatement, however this behavior was markedly absent in D1-GluN-/- mice. Interestingly, dual D1-/A2A-GluN-/- mice displayed an intermediate reinstatement phenotype. Next, we examined models of exploration, anxiety, and despair, states often associated with relapse to addiction-related behavior, to determine NMDAR contribution in D1 and A2A cell types to these behaviors. D1-GluN1-/- mice displayed aberrant exploratory locomotion in a novel environment, but the phenotype was absent in dual D1/A2A-GluN1-/- mice. In contrast A2A-GluN1-/- mice displayed a despair-resistant phenotype, and this phenotype persisted in dual D1/A2A-GluN-/- mice. These data support the hypothesis that cell type-specific NMDAR signaling regulates separable behavioral outcomes related to locomotion, despair, and relapse. This article is part of the Special Issue entitled 'Ionotropic glutamate receptors'.
| S-EPMC5031515 | biostudies-literature
Project description:Histone H2A (1-10 microg/ml) added to Ehrlich ascite cell suspensions promoted: (i) Ca2+ influx, but no apparent intracellular Ca2+ mobilization; (ii) plasma-membrane depolarization and Na+ influx in Ca2+-free medium, which were recovered by Ca2+ readmission; (iii) influx of other cations such as Ba2+, Mn2+, choline+ and N-methyl-d-glucamine+, but not of propidium+, ethidium bromide and Trypan Blue. H2A-induced Ca2+ influx and cell depolarization were: (i) blocked by La3+ and Gd3+, but not by various inhibitors of receptor-activated Ca2+-influx pathways/channels; (ii) mimicked by various basic polypeptides, with Mr>4000; (iii) prevented or reversed by polyanions such as polyglutamate or heparin; (iv) present in other cell types, such as Jurkat, PC12 and Friend erythroleukaemia cells, but virtually absent from rat hepatocytes and thymocytes. We conclude that cationic proteins/polypeptides, by interacting in a cell-specific manner with the cell surface, can activate in those cells putative non-selective Ca2+ channels and membrane depolarization.
| S-EPMC1219397 | biostudies-other