Recruitment maneuvers in acute respiratory distress syndrome: The safe way is the best way

Acute respiratory distress syndrome(ARDS) represents a serious problem in critically ill patients and is associated with in-hospital mortality rates of 33%-52%. Recruitment maneuvers(RMs) are a simple, low-cost, feasible intervention that can be performed at the bedside in patients with ARDS. RMs are characterized by the application of airway pressure to increase transpulmonary pressure transiently. Once non-aerated lung units are reopened, improvements are observed in respiratory system mechanics, alveolar reaeration on computed tomography, and improvements in gas exchange(functional recruitment). However, the reopening process could lead to vascular compression, which can be associated with overinflation, and gas exchange may not improve as expected(anatomical recruitment). The purpose of this review was to discuss the effects of different RM strategies- sustained inflation, intermittent sighs, and stepwise increases of positive end-expiratory pressure(PEEP) and/or airway inspiratory pressure- on the following parameters: hemodynamics, oxygenation, barotrauma episodes, and lung recruitability through physiological variables and imaging techniques. RMs and PEEP titration are interdependent events for the success of ventilatory management. PEEP should be adjusted on the basis of respiratory system mechanics and oxygenation. Recent systematic reviews and meta-analyses suggest that RMs are associated with lower mortality in patients with ARDS. However, the optimal RM method(i.e., that providing the best balance of benefit and harm) and the effects of RMs on clinical outcome are still under discussion, and further evidence is needed.

Ligand-binding properties of three odorant-binding proteins of the diamondback moth Plutella xylostella

Strategies for insect population control are currently targeting chemical communication at the molecular level. The diamondback moth Plutella xylostella represents one of the most serious pests in agriculture, however detailed information on the proteins mediating olfaction in this species is still poor. This species is endowed with a repertoire of a large number of olfactory receptors and odorant binding proteins（OBPs）. As a contribution to map the specificities of these chemical sensors in the moth and eventually unrave l the complexity of chemodetection, we have measured the affinities of three selected OBPs to a series of potential odorants. Three proteins are highly divergent in their amino acid sequences and show markedly different expression profiles. In fact, PxylOBP3 is exclusively expressed in the antennae of both sexes, PxylOBP9 is male specific and present only in antennae and reproductive organs, while PxylOBP19, an unusual OBP with nine cysteines, is ubiquitously present in all the organs examined. Such expression pattern suggests that the last two proteins may be involved in non-chemosensory functions. Despite such differences, the three OBPs exhibit similar binding spectra, together with high selectivity. Among the 26 natural compounds tested, only two proved to be good ligands, retinol and coniferyl aldehyde. This second compound is particularly interesting being part of the chemical pathway leading to regeneration of lignin, one of the defense strategies of the plant against insect attack, and might find applications as a repellent for P. xylostella and other pests.

Immunomodulatory effects of anesthetics in obese patients

Anesthesia and surgery have an impact on inflammatory responses, which influences perioperative homeostasis. Inhalational and intravenous anesthesia can alter immune-system homeostasis through multiple processes that include activation of immune cells(such as monocytes, neutrophils, and specific tissue macrophages) with release of pro-or anti-inflammatory interleukins, upregulation of cell adhesion molecules, and overproduction of oxidative radicals. The response depends on the timing of anesthesia, anesthetic agents used, and mechanisms involved in the development of inflammation or immunosuppression. Obese patients are at increased risk for chronic diseases and may have the metabolic syndrome, which features insulin resistance and chronic low-grade inflammation. Evidence has shown that obesity has adverse impacts on surgical outcome, and that immune cells play an important role in this process. Understanding the effects of anesthetics on immune-system cells in obese patients is important to support proper selection of anesthetic agents, which may affect postoperative outcomes. This review article aims to integrate current knowledge regarding the effects of commonly used anesthetic agents on the lungs and immune response with the underlying immunology of obesity. Additionally, it identifies knowledge gaps for future research to guide optimal selection of anesthetic agents for obese patients from an immunomodulatory standpoint.

Prevalence and prognostic value of cardiac troponin in elderly patients hospitalized for COVID-19

BACKGROUND Increases in cardiac troponin(cTn)in coronavirus disease 2019(COVID19)have been associated with worse prognosis.Nonetheless,data about the significance of cTn in elderly subjects with COVID19 are lacking.METHODS From a registry of consecutive patients with COVID19 admitted to a hub hospital in Italy from 25/02/2020 to 03/07/2020,we selected those≥60 yearold and with cTnI measured within three days from the molecular diagnosis of SARSCoV2 infection.When available,a second cTnI value within 48 h was also extracted.The relationship between increased cTnI and allcause inhospital mortality was evaluated by a Cox regression model and restricted cubic spline functions with three knots.RESULTS Of 343 included patients(median age:75.0(68.0−83.0)years,34.7%men),88(25.7%)had cTnI above the upperreference limit(0.046μg/L).Patients with increased cTnI had more comorbidities,greater impaired respiratory exchange and higher inflammatory markers on admission than those with normal cTnI.Furthermore,they died more(73.9%vs.37.3%,P<0.001)over 15(6−25)days of hospitalization.The association of elevated cTnI with mortality was confirmed by the adjusted Cox regression model(HR=1.61,95%CI:1.06−2.52,P=0.039)and was linear until 0.3μg/L,with a subsequent plateau.Of 191(55.7%)patients with a second cTnI measurement,49(25.7%)had an increasing trend,which was not associated with mortality(univariate HR=1.39,95%CI:0.87−2.22,P=0.265).CONCLUSIONS In elderly COVID19 patients,an initial increase in cTn is common and predicts a higher risk of death.Serial cTn testing may not confer additional prognostic information.

Ten golden rules for individualized mechanical ventilation in acute respiratory distress syndrome

Considerable progress has been made over the last decades in the management of acute respiratory distress syndrome(ARDS).Mechanical ventilation(MV)remains the cornerstone of supportive therapy for ARDS.Lung-protective MV minimizes the risk of ventilator-induced lung injury(VILI)and improves survival.Several parame-ters contribute to the risk of VILI and require careful setting including tidal volume(V_(T)),plateau pressure(P_(plat)),driving pressure(ΔP),positive end-expiratory pressure(PEEP),and respiratory rate.Measurement of energy and mechanical power allows quantification of the relative contributions of various parameters(V_(T),P_(plat),ΔP,PEEP,respiratory rate,and airflow)for the individualization of MV settings.The use of neuromuscular blocking agents mainly in cases of severe ARDS can improve oxygenation and reduce asynchrony,although they are not known to confer a survival benefit.Rescue respiratory therapies such as prone positioning,inhaled nitric oxide,and extracorporeal support techniques may be adopted in specific situations.Furthermore,respiratory weaning protocols should also be considered.Based on a review of recent clinical trials,we present 10 golden rules for individualized MV in ARDS management.

Ventilation practices in burn patients—an international prospective observational cohort study

Background:It is unknown whether lung-protective ventilation is applied in burn patients and whether they benefit from it.This study aimed to determine ventilation practices in burn intensive care units(ICUs)and investigate the association between lung-protective ventilation and the number of ventilator-free days and alive at day 28(VFD-28).Methods:This is an international prospective observational cohort study including adult burn patients requiring mechanical ventilation.Low tidal volume(V_(T))was defined as V_(T)≤8 mL/kg predicted body weight(PBW).Levels of positive end-expiratory pressure(PEEP)and maximum airway pressures were collected.The association between V_(T) and VFD-28 was analyzed using a competing risk model.Ventilation settings were presented for all patients,focusing on the first day of ventilation.We also compared ventilation settings between patients with and without inhalation trauma.Results:A total of 160 patients from 28 ICUs in 16 countries were included.Low V_(T) was used in 74%of patients,median V_(T) size was 7.3[interquartile range(IQR)6.2–8.3]mL/kg PBW and did not differ between patients with and without inhalation trauma(p=0.58).Median VFD-28 was 17(IQR 0–26),without a difference between ventilation with low or high V_(T)(p=0.98).All patients were ventilated with PEEP levels≥5 cmH_(2)O;80%of patients had maximum airway pressures<30 cmH_(2)O.Conclusion:In this international cohort study we found that lung-protective ventilation is used in the majority of burn patients,irrespective of the presence of inhalation trauma.Use of low V_(T) was not associated with a reduction in VFD-28.Trial registration:Clinicaltrials.gov NCT02312869.Date of registration:9 December 2014.