Geostrophic surface velocity anomalies are used to analyze the annual variations of the large‐scale geostrophic currents and of the eddy kinetic energy (EKE) field of the ocean circulation. The ...underlying geostrophic currents were estimated from the Jason‐1‐TOPEX/Poseidon (JTP) tandem altimetric sea surface height data using the “parallel track approach” with a 10 km along‐track resolution; however, because of the given separation of the tracks of the two satellites only large mesoscale eddies are resolved by the tandem measurements. The analysis covers the entire 3 year period of the tandem mission (109 repeat cycles) from September 2002 to September 2005. The analysis of the seasonal flow changes reveals annual changes of all major current systems, but especially of the zonal flow field in low latitudes, leading to zonal jets on the annual cycle in the southern Pacific, Atlantic, and Indian oceans. In middle and high latitudes, indications of a seasonally modulated strength of the Sverdrup circulation emerge from the analysis. The EKE field also shows changes in its amplitude on the annual period. In low latitudes, those can be rationalized as resulting from seasonally modulated currents. In middle and high latitudes, changes in the wind‐driven barotropic circulation loom large, which are not represented in other altimetric velocity products. Results shown suggest that velocity time series of the JTP tandem mission should be continued through similar constellations, e.g., of Jason‐1 and Jason‐2.
Sea level is a very sensitive index of climate change since it integrates the impacts of ocean warming and ice mass loss from glaciers and the ice sheets. Sea level has been listed as an essential ...climate variable (ECV) by the Global Climate Observing System (GCOS). During the past 25 years, the sea level ECV has been measured from space by different altimetry missions that have provided global and regional observations of sea level variations. As part of the Climate Change Initiative (CCI) program of the European Space Agency (ESA) (established in 2010), the Sea Level project (SL_cci) aimed to provide an accurate and homogeneous long-term satellite-based sea level record. At the end of the first phase of the project (2010–2013), an initial version (v1.1) of the sea level ECV was made available to users (Ablain et al., 2015). During the second phase of the project (2014–2017), improved altimeter standards were selected to produce new sea level products (called SL_cci v2.0) based on nine altimeter missions for the period 1993–2015 (https://doi.org/10.5270/esa-sea_level_cci-1993_2015-v_2.0-201612; Legeais and the ESA SL_cci team, 2016c). Corresponding orbit solutions, geophysical corrections and altimeter standards used in this v2.0 dataset are described in detail in Quartly et al. (2017). The present paper focuses on the description of the SL_cci v2.0 ECV and associated uncertainty and discusses how it has been validated. Various approaches have been used for the quality assessment such as internal validation, comparisons with sea level records from other groups and with in situ measurements, sea level budget closure analyses and comparisons with model outputs. Compared with the previous version of the sea level ECV, we show that use of improved geophysical corrections, careful bias reduction between missions and inclusion of new altimeter missions lead to improved sea level products with reduced uncertainties on different spatial and temporal scales. However, there is still room for improvement since the uncertainties remain larger than the GCOS requirements (GCOS, 2011). Perspectives on subsequent evolution are also discussed.
Mechanical ventilation is a life-saving therapy in several clinical situations, promoting gas exchange and providing rest to the respiratory muscles. However, mechanical ventilation may cause ...hemodynamic instability and pulmonary structural damage, which is known as ventilator-induced lung injury (VILI). The four main injury mechanisms associated with VILI are as follows: barotrauma/volutrauma caused by overstretching the lung tissues; atelectrauma, caused by repeated opening and closing of the alveoli resulting in shear stress; and biotrauma, the resulting biological response to tissue damage, which leads to lung and multi-organ failure. This narrative review elucidates the mechanisms underlying the pathogenesis, progression, and resolution of VILI and discusses the strategies that can mitigate VILI. Different static variables (peak, plateau, and driving pressures, positive end-expiratory pressure, and tidal volume) and dynamic variables (respiratory rate, airflow amplitude, and inspiratory time fraction) can contribute to VILI. Moreover, the potential for lung injury depends on tissue vulnerability, mechanical power (energy applied per unit of time), and the duration of that exposure. According to the current evidence based on models of acute respiratory distress syndrome and VILI, the following strategies are proposed to provide lung protection: keep the lungs partially collapsed (SaO
2
> 88%), avoid opening and closing of collapsed alveoli, and gently ventilate aerated regions while keeping collapsed and consolidated areas at rest. Additional mechanisms, such as subject-ventilator asynchrony, cumulative power, and intensity, as well as the damaging threshold (stress–strain level at which tidal damage is initiated), are under experimental investigation and may enhance the understanding of VILI.
Uncertainty measures for global mean sea level (GMSL) estimates are quantified, resulting from limited (in space and time) along‐track altimetric sampling of the global sea level field by altimetric ...satellite missions. To estimate such sampling‐related uncertainty, sea surface height (SSH) fields simulated by the high‐resolution STORM/NCEP ocean circulation model were subsampled along altimeter tracks for the period 1993–2010 and subsequently processed into global SSH averages using similar techniques to those used by six groups worldwide. Results show that the underlying satellite space‐time sampling has a substantial impact on the accuracy of GMSL estimates. This uncertainty originates primarily from data missing over sea ice‐covered regions; omitted data from shallow seas also contributes. Uncertainties in GMSL estimates result both from interpolation techniques required to fill data gaps such as missing tracks, and the choice of the mean sea surface required to estimate SSH anomalies. Cumulative effects lead to errors in GMSL estimates from ∼0.8 to ∼3.2 mm (root‐mean‐square, RMS), depending on the underlying details of the estimation method. Results suggest that sampling limitations in meridional direction are a fundamental constraint on the accuracy level reachable for any altimetric GMSL estimate, resulting in a systematic Gaussian uncertainty of about 1.2 mm (RMS), 50% of which occurs on monthly time scales, while some fraction occurs on time scales of several years. In all cases, a significant fraction of the error results from a mass exchange between the global ocean and sea ice‐covered polar regions. Contributions from data processing details are measurable but less significant.
Key Points
Meridional sampling limitations due to the satellite orbit inclination are a fundamental constraint on the accuracy level of GMSL estimates
Best GMSL estimates can be derived by a multimission satellite constellation with complete meridional extend, using optimal interpolation
OBJECTIVES:To determine the impact of positive end-expiratory pressure during mechanical ventilation with and without spontaneous breathing activity on regional lung inflammation in experimental ...nonsevere acute respiratory distress syndrome.
DESIGN:Laboratory investigation.
SETTING:University hospital research facility.
SUBJECTS:Twenty-four pigs (28.1–58.2 kg).
INTERVENTIONS:In anesthetized animals, intrapleural pressure sensors were placed thoracoscopically in ventral, dorsal, and caudal regions of the left hemithorax. Lung injury was induced with saline lung lavage followed by injurious ventilation in supine position. During airway pressure release ventilation with low tidal volumes, positive end-expiratory pressure was set 4 cm H2O above the level to reach a positive transpulmonary pressure in caudal regions at end-expiration (best-positive end-expiratory pressure). Animals were randomly assigned to one of four groups (n = 6/group; 12 hr)1) no spontaneous breathing activity and positive end-expiratory pressure = best-positive end-expiratory pressure – 4 cm H2O, 2) no spontaneous breathing activity and positive end-expiratory pressure = best-positive end-expiratory pressure + 4 cm H2O, 3) spontaneous breathing activity and positive end-expiratory pressure = best-positive end-expiratory pressure + 4 cm H2O, 4) spontaneous breathing activity and positive end-expiratory pressure = best-positive end-expiratory pressure – 4 cm H2O.
MEASUREMENTS AND MAIN RESULTS:Global lung inflammation assessed by specific Ffluorodeoxyglucose uptake rate (median 25–75% percentiles, min) was decreased with higher compared with lower positive end-expiratory pressure both without spontaneous breathing activity (0.029 0.027–0.030 vs 0.044 0.041–0.065; p = 0.004) and with spontaneous breathing activity (0.032 0.028–0.043 vs 0.057 0.042–0.075; p = 0.016). Spontaneous breathing activity did not increase global lung inflammation. Lung inflammation in dorsal regions correlated with transpulmonary driving pressure from spontaneous breathing at lower (r = 0.850; p = 0.032) but not higher positive end-expiratory pressure (r = 0.018; p = 0.972). Higher positive end-expiratory pressure resulted in a more homogeneous distribution of aeration and regional transpulmonary pressures at end-expiration along the ventral-dorsal gradient, as well as a shift of the perfusion center toward dependent zones in the presence of spontaneous breathing activity.
CONCLUSIONS:In experimental mild-to-moderate acute respiratory distress syndrome, positive end-expiratory pressure levels that stabilize dependent lung regions reduce global lung inflammation during mechanical ventilation, independent from spontaneous breathing activity.
Background:
Mechanical ventilation (MV) is a life supporting therapy but may also cause lung damage. This phenomenon is known as ventilator-induced lung injury (VILI). A potential pathomechanisms of ...ventilator-induced lung injury may be the stretch-induced production and release of cytokines and pro-inflammatory molecules from the alveolar epithelium. Yes-associated protein (YAP) might be regulated by mechanical forces and involved in the inflammation cascade. However, its role in stretch-induced damage of alveolar cells remains poorly understood. In this study, we explored the role of YAP in the response of alveolar epithelial type II cells (AEC II) to elevated cyclic stretch
in vitro
. We hypothesize that Yes-associated protein activates its downstream targets and regulates the interleukin-6 (IL-6) expression in response to 30% cyclic stretch in AEC II.
Methods:
The rat lung L2 cell line was exposed to 30% cyclic equibiaxial stretch for 1 or 4 h. Non-stretched conditions served as controls. The cytoskeleton remodeling and cell junction integrity were evaluated by F-actin and Pan-cadherin immunofluorescence, respectively. The gene expression and protein levels of IL-6, Yes-associated protein, Cysteine-rich angiogenic inducer 61 (Cyr61/CCN1), and connective tissue growth factor (CTGF/CCN2) were studied by real-time polymerase chain reaction (RT-qPCR) and Western blot, respectively. Verteporfin (VP) was used to inhibit Yes-associated protein activation. The effects of 30% cyclic stretch were assessed by two-way ANOVA. Statistical significance as accepted at
p
< 0.05.
Results:
Cyclic stretch of 30% induced YAP nuclear accumulation, activated the transcription of Yes-associated protein downstream targets Cyr61/CCN1 and CTGF/CCN2 and elevated IL-6 expression in AEC II after 1 hour, compared to static control. VP (2 µM) inhibited Yes-associated protein activation in response to 30% cyclic stretch and reduced IL-6 protein levels.
Conclusion:
In rat lung L2 AEC II, 30% cyclic stretch activated YAP, and its downstream targets Cyr61/CCN1 and CTGF/CCN2 and proinflammatory IL-6 expression. Target activation was blocked by a Yes-associated protein inhibitor. This novel YAP-dependent pathway could be involved in stretch-induced damage of alveolar cells.
PET imaging with 18F-FDG followed by mathematic modeling of the pulmonary uptake rate (Ki) is the gold standard for assessment of pulmonary inflammation in experimental studies of acute respiratory ...distress syndrome (ARDS). However, dynamic PET requires long imaging and allows the assessment of only 1 cranio-caudal field of view (∼15 cm). We investigated whether static 18F-FDG PET/CT and analysis of SUV or standardized uptake ratios (SURstat, uptake time–corrected ratio of 18F-FDG concentration in lung tissue and blood plasma) might be an alternative to dynamic 18F-FDG PET/CT and Patlak analysis for quantification of pulmonary inflammation in experimental ARDS. Methods: ARDS was induced by saline lung lavage followed by injurious mechanical ventilation in 14 anesthetized pigs (29.5–40.0 kg). PET/CT imaging sequences were acquired before and after 24 h of mechanical ventilation. Ki and the apparent volume of distribution were calculated from dynamic 18F-FDG PET/CT scans using the Patlak analysis. Static 18F-FDG PET/CT scans were obtained immediately after dynamic PET/CT and used for calculations of SUV and SURstat. Mean Ki values of the whole imaged field of view and of 5 ventro-dorsal lung regions were compared with corresponding SUV and SURstat values, respectively, by means of linear regression and concordance analysis. The variability of the 18F-FDG concentration in blood plasma (arterial input function) was analyzed. Results: Both for the whole imaged field of view and ventro-dorsal subregions, Ki was linearly correlated with SURstat (r2 ≥ 0.84), whereas Ki–SUV correlations were worse (r2 ≤ 0.75). The arterial input function exhibited an essentially invariant shape across all animals and time points and can be described by an inverse power law. Compared with Ki, SURstat and SUV tracked the same direction of change in regional lung inflammation in 98.6% and 84.3% of measurements, respectively. Conclusion: The Ki–SURstat correlations were considerably stronger than the Ki–SUV correlations. The good Ki–SURstat correlations suggest that static 18F-FDG PET/CT and SURstat analysis provides an alternative to dynamic 18F-FDG PET/CT and Patlak analysis, allowing the assessment of inflammation of whole lungs, repeated measurements within the period of 18F-FDG decay, and faster data acquisition.
Background
. Global and regional transpulmonary pressure (P
L
) during one-lung ventilation (OLV) is poorly characterized. We hypothesized that global and regional P
L
and driving P
L
(ΔP
L
) ...increase during protective low tidal volume OLV compared to two-lung ventilation (TLV), and vary with body position.
Methods
. In sixteen anesthetized juvenile pigs, intra-pleural pressure sensors were placed in ventral, dorsal, and caudal zones of the left hemithorax by video-assisted thoracoscopy. A right thoracotomy was performed and lipopolysaccharide administered intravenously to mimic the inflammatory response due to thoracic surgery. Animals were ventilated in a volume-controlled mode with a tidal volume (V
T
) of 6 mL kg
−1
during TLV and of 5 mL kg
−1
during OLV and a positive end-expiratory pressure (PEEP) of 5 cmH
2
O. Global and local transpulmonary pressures were calculated. Lung instability was defined as end-expiratory P
L
<2.9 cmH
2
O according to previous investigations. Variables were acquired during TLV (TLVsupine), left lung ventilation in supine (OLVsupine), semilateral (OLVsemilateral), lateral (OLVlateral) and prone (OLVprone) positions randomized according to Latin-square sequence. Effects of position were tested using repeated measures ANOVA.
Results
. End-expiratory P
L
and ΔP
L
were higher during OLVsupine than TLVsupine. During OLV, regional end-inspiratory P
L
and ΔP
L
did not differ significantly among body positions. Yet, end-expiratory P
L
was lower in semilateral (ventral: 4.8 ± 2.9 cmH
2
O; caudal: 3.1 ± 2.6 cmH
2
O) and lateral (ventral: 1.9 ± 3.3 cmH
2
O; caudal: 2.7 ± 1.7 cmH
2
O) compared to supine (ventral: 4.8 ± 2.9 cmH
2
O; caudal: 3.1 ± 2.6 cmH
2
O) and prone position (ventral: 1.7 ± 2.5 cmH
2
O; caudal: 3.3 ± 1.6 cmH
2
O), mainly in ventral (
p
≤ 0.001) and caudal (
p
= 0.007) regions. Lung instability was detected more often in semilateral (26 out of 48 measurements;
p
= 0.012) and lateral (29 out of 48 measurements,
p
< 0.001) as compared to supine position (15 out of 48 measurements), and more often in lateral as compared to prone position (19 out of 48 measurements,
p
= 0.027).
Conclusion
. Compared to TLV, OLV increased lung stress. Body position did not affect stress of the ventilated lung during OLV, but lung stability was lowest in semilateral and lateral decubitus position.
A promising therapeutic option for the treatment of critical-size mandibular defects is the implantation of biodegradable, porous structures that are produced patient-specifically by using additive ...manufacturing techniques. In this work, degradable poly(DL-lactide) polymer (PDLLA) was blended with different mineral phases with the aim of buffering its acidic degradation products, which can cause inflammation and stimulate bone regeneration. Microparticles of CaCO
, SrCO
, tricalcium phosphates (α-TCP, β-TCP), or strontium-modified hydroxyapatite (SrHAp) were mixed with the polymer powder following processing the blends into scaffolds with the Arburg Plastic Freeforming 3D-printing method. An in vitro degradation study over 24 weeks revealed a buffer effect for all mineral phases, with the buffering capacity of CaCO
and SrCO
being the highest. Analysis of conductivity, swelling, microstructure, viscosity, and glass transition temperature evidenced that the mineral phases influence the degradation behavior of the scaffolds. Cytocompatibility of all polymer blends was proven in cell experiments with SaOS-2 cells. Patient-specific implants consisting of PDLLA + CaCO
, which were tested in a pilot in vivo study in a segmental mandibular defect in minipigs, exhibited strong swelling. Based on these results, an in vitro swelling prediction model was developed that simulates the conditions of anisotropic swelling after implantation.
Oxygen is one of the most commonly used drugs by anesthesiologists. The World Health Organization (WHO) gave recommendations regarding perioperative oxygen administration, but the practice of oxygen ...use in anesthesia, critical emergency, and intensive care medicine remains unclear.
We conducted an online survey among members of the European Society of Anaesthesiology and Intensive Care (ESAIC). The questionnaire consisted of 46 queries appraising the perioperative period, emergency medicine and in the intensive care, knowledge about current recommendations by the WHO, oxygen toxicity, and devices for supplemental oxygen therapy.
Seven hundred ninety-eight ESAIC members (2.1% of all ESAIC members) completed the survey. Most respondents were board-certified and worked in hospitals with > 500 beds. The majority affirmed that they do not use specific protocols for oxygen administration. WHO recommendations are unknown to 42% of respondents, known but not followed by 14%, and known and followed by 24% of them. Respondents prefer inspiratory oxygen fraction (FiO
) ≥80% during induction and emergence from anesthesia, but intraoperatively < 60% for maintenance, and higher FiO
in patients with diseased than non-diseased lungs. Postoperative oxygen therapy is prescribed more commonly according to peripheral oxygen saturation (SpO
), but shortage of devices still limits monitoring. When monitoring is used, SpO
≤ 95% is often targeted. In critical emergency medicine, oxygen is used frequently in patients aged ≥80 years, or presenting with respiratory distress, chronic obstructive pulmonary disease, myocardial infarction, and stroke. In the intensive care unit, oxygen is mostly targeted at 96%, especially in patients with pulmonary diseases.
The current practice of perioperative oxygen therapy among respondents does not follow WHO recommendations or current evidence, and access to postoperative monitoring devices impairs the individualization of oxygen therapy. Further research and additional teaching about use of oxygen are necessary.
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