Acute Respiratory Failure

Bone marrow mesenchymal stem cells-derived exosomes ameliorate LPS-induced acute lung injury by miR-223-regulated alveolar macrophage M2 polarization

Numerous studies have shown that the M2 polarization of alveolar macrophages (AM) plays a protective role in acute lung injury (ALI). Mesenchymal stem cells (MSCs) secreted exosomes have been reported to be involved in inflammatory diseases by the effects of polarized M1/M2 macrophage populations. However, whether bone marrow mesenchymal stem cells (BMMSCs) derived exosomes could protect from ALI and its mechanisms are still unclear. Here, we explored the role of exosomes from BMMSC in rat AM polarization and the lipopolysaccharide- (LPS-) induced ALI rat model. Furthermore, the levels of exosomal miR-223 in BMMSCs were measured by RT-qPCR. Additionally, miR-223 mimics and its inhibitors were used to verify the vital role of miR-223 of BMMSCs-derived exosomes in the polarization of M2 macrophages. The results showed that BMMSCs-derived exosomes were taken up by the AM. Exosomes derived from BMMSCs promoted M2 polarization of AM in vitro. BMMSCs exosomes effectively mitigated pathological injuries, lung edema, and the inflammation of rats from LPS-induced ALI, accompanied by an increase of M2 polarization of AM in lung tissue. Interestingly, we also found that miR-223 was enriched in BMMSCs-derived exosomes, and overexpression of miR-223 in BMMSCs-derived exosomes promoted M2 polarization of AM while depressing miR-223 showed opposite effects in AM. The present study demonstrated that BMMSCs-derived exosomes triggered alveolar M2 polarization to improve inflammation by transferring miR-223, which may provide new therapeutic strategies in ALI.

Toward microfluidic integration of respiratory and renal organ support in a single cartridge

BACKGROUND

Extracorporeal organ assist devices provide lifesaving functions for acutely and chronically ill patients suffering from respiratory and renal failure, but their availability and use is severely limited by an extremely high level of operational complexity. While current hollow fiber-based devices provide high-efficiency blood gas transfer and waste removal in extracorporeal membrane oxygenation (ECMO) and hemodialysis, respectively, their impact on blood health is often highly deleterious and difficult to control. Further challenges are encountered when integrating multiple organ support functions, as is often required when ECMO and ultrafiltration (UF) are combined to deal with fluid overload in critically ill patients, necessitating an unwieldy circuit containing two separate cartridges.

METHODS

We report the first laboratory demonstration of simultaneous blood gas oxygenation and fluid removal in single microfluidic circuit, an achievement enabled by the microchannel-based blood flow configuration of the device. Porcine blood is flowed through a stack of two microfluidic layers, one with a non-porous, gas-permeable silicone membrane separating blood and oxygen chambers, and the other containing a porous dialysis membrane separating blood and filtrate compartments.

RESULTS

High levels of oxygen transfer are measured across the oxygenator, while tunable rates of fluid removal, governed by the transmembrane pressure (TMP), are achieved across the UF layer. Key parameters including the blood flow rate, TMP and hematocrit are monitored and compared with computationally predicted performance metrics.

CONCLUSIONS

These results represent a model demonstration of a potential future clinical therapy where respiratory support and fluid removal are both realized through a single monolithic cartridge.

Prolonged Mechanical Ventilation in Pediatric Trauma Patients in a Combat Zone

OBJECTIVES

It is well known that polytrauma can lead to acute lung injury. Respiratory failure has been previously observed in combat trauma, but not reported in children, who account for over 11% of bed days at deployed Military Treatment Facilities (MTFs) using significant resources. We seek to identify risk factors associated with prolonged mechanical ventilation (PMV) which is important in resource planning and allocation in austere environments.

DESIGN

Retrospective review of prospectively collected data within the United States Department of Defense Trauma Registry.

SETTING

Deployed U.S. MTFs in Iraq and Afghanistan from 2007 to 2016.

PATIENTS

All pediatric subjects who required at least 1 day of mechanical ventilation, excluding patients who died on day 0.

INTERVENTIONS

PMV was defined using the Youden index for mortality. A multivariable logistic regression model was then performed to identify factors associated with PMV.

MEASUREMENTS AND MAIN RESULTS

The Youden index identified greater than or equal to 6 days as the cutoff for PMV. Of the 859 casualties included in the analysis, 154 (17.9%) had PMV. On univariable analysis, age, severe injury to the thorax and skin, 24-hour volume/kg administration of crystalloids, colloids, platelets, plasma, and packed RBCs was associated with PMV. In the multivariable model, odds ratios (95% CI) associated with PMV were crystalloids 1.04 (1.02-1.07), colloids 1.24 (1.04-1.49), platelets 1.03 (1.01-1.05), severe injury to the thorax 2.24 (1.41-3.48), and severe injury to the skin 4.48 (2.72-7.38). Model goodness-of-fit r2 was 0.14.

CONCLUSIONS

In this analysis of factors associated with PMV in pediatric trauma patients in a combat zone, in addition to severe injury to skin and thorax, we found that administration of crystalloids, colloids, and platelets was independently associated with greater odds of PMV. Our findings will help inform resource planning and suggest potential resuscitation strategies for future studies.

Oxygen Management During Collective Aeromedical Evacuation of 36 COVID-19 Patients With ARDS

OBJECTIVE

The ongoing coronavirus disease-2019 pandemic leads to the saturation of critical care facilities worldwide. Collective aeromedical evacuations (MEDEVACS) might help rebalance the demand and supply of health care. If interhospital transport of patients suffering from ARDS is relatively common, little is known about the specific challenges of collective medevac. Oxygen management in such context is crucial. We describe our experience with a focus on this resource.

METHODS

We retrospectively analyzed the first six collective medevac performed during the coronavirus disease-2019 pandemic by the French Military Health Service from March 17 to April 3, 2020. Oxygen management was compliant with international guidelines as well as aeronautical constraints and monitored throughout the flights. Presumed high O2 consumers were scheduled to board the last and disembark the first.

RESULTS

Thirty-six mechanically ventilated patients were successfully transported within Europe. The duration of onboard ventilation was 185 minutes (145-198.5 minutes), including the flight, the boarding and disembarking periods. Oxygen intake was 1,650 L per patient per flight (1,350-1,950 L patient per flight) and 564 L per patient per hour (482-675 L per patient-1 per hour) and surpassed our anticipation. As anticipated, presumed high O2 consumers had a reduced ventilation duration onboard. The estimations of oxygen consumptions were frequently overshot, and only two hypoxemia episodes occurred.

CONCLUSION

Oxygen consumption was higher than expected, despite anticipation and predefined oxygen management measures, and encourages to a great caution in the processing of such collective medevac missions.

Aloin suppresses lipopolysaccharide-induced acute lung injury by inhibiting NLRP3/NF-κB via activation of SIRT1 in mice

OBJECTIVE

The purpose of this study was to explore the protective effects and potential mechanisms of aloin on lipopolysaccharide (LPS)-induced acute lung injury (ALI).

METHODS

Mice were pretreatment with aloin 1 h before LPS administration. The number of inflammatory cells and the levels of TNF-α and IL-1β was detected. The lung histopathological changes, wet/dry ratio, MPO activity, GSH, MDA, SOD, and the expression of NF-κB and NLRP3 inflammasome were measured.

RESULTS

The results showed that aloin significantly inhibited the number of total cells, neutrophils, and macrophages, as well as the levels of TNF-α and IL-1β in BALF induced by LPS. In addition, pretreatment with aloin also inhibited LPS-induced lung histopathological injuries, lung wet/dry ratio, MPO activity, and MDA content. The levels of GSH and SOD were decreased by LPS and treatment of aloin could increase the levels of GSH and SOD. To study the protective mechanisms of alion on LPS-induced ALI, the expression of SIRT1, NF-κB and NLRP3 inflammasome were tested. We found that aloin significantly inhibited the activation of NF-κB and NLRP3 inflammasome in ALI induced by LPS. Meanwhile, aloin was found to increase the expression of SIRT1 and inhibition of SIRT1 by EX-527 reversed the protective effects of aloin.

CONCLUSIONS

These results suggest that aloin exerts its protective effects on LPS-induced ALI by activation SIRT1, which subsequently results in the suppression of NF-κB and NLRP3 inflammasome.