Tissue factor pathway inhibitor and interleukin-1 receptor levels in COVID-19

No Abstract.

Clinical practice, decision-making, and use of clinical decision support systems in invasive mechanical ventilation: a narrative review

Invasive mechanical ventilation is a key supportive therapy for patients on intensive care. There is increasing emphasis on personalised ventilation strategies. Clinical decision support systems (CDSS) have been developed to support this. We conducted a narrative review to assess evidence that could inform device implementation. A search was conducted in MEDLINE (Ovid) and EMBASE. Twenty-nine studies met the inclusion criteria. Role allocation is well described, with interprofessional collaboration dependent on culture, nurse:patient ratio, the use of protocols, and perception of responsibility. There were no descriptions of process measures, quality metrics, or clinical workflow. Nurse-led weaning is well-described, with factors grouped by patient, nurse, and system. Physician-led weaning is heterogenous, guided by subjective and objective information, and 'gestalt'. No studies explored decision-making with CDSS. Several explored facilitators and barriers to implementation, grouped by clinician (facilitators: confidence using CDSS, retaining decision-making ownership; barriers: undermining clinician's role, ambiguity moving off protocol), intervention (facilitators: user-friendly interface, ease of workflow integration, minimal training requirement; barriers: increased documentation time), and organisation (facilitators: system-level mandate; barriers: poor communication, inconsistent training, lack of technical support). One study described factors that support CDSS implementation. There are gaps in our understanding of ventilation practice. A coordinated approach grounded in implementation science is required to support CDSS implementation. Future research should describe factors that guide clinical decision-making throughout mechanical ventilation, with and without CDSS, map clinical workflow, and devise implementation toolkits. Novel research design analogous to a learning organisation, that considers the commercial aspects of device design, is required.

Hypoxemia Trajectory of Non-COVID-19 Acute Respiratory Distress Syndrome Patients. An Observational Study Focusing on Hypoxemia Resolver Status

IMPORTANCE

Most studies on acute respiratory distress syndrome (ARDS) group patients by severity based on their initial degree of hypoxemia. However, this grouping has limitations, including inconsistent hypoxemia trajectories and outcomes.

OBJECTIVES

This study explores the benefits of grouping patients by resolver status based on their hypoxemia progression over the first 7 days.

DESIGN SETTING AND PARTICIPANTS

This is an observational study from a large single-center database. Medical Information Mart for Intensive Care (MIMIC)-IV and MIMIC Chest X-ray JPEG databases were used. Mechanically ventilated patients that met the Berlin ARDS criteria were included.

MAIN OUTCOMES AND MEASURES

The primary outcome was the proportion of hypoxemia resolvers vs. nonresolvers in non-COVID-19 ARDS patients. Nonresolvers were defined as those whose hypoxemia worsened or remained moderate or severe over the first 7 days. Secondary outcomes included baseline admission characteristics, initial blood gases and ventilation settings, length of invasive mechanical ventilation, length of ICU stay, and ICU survival rates across resolver groups.

RESULTS

A total of 894 ICU admissions were included in the study. Of these, 33.9% were hypoxemia nonresolvers. The resolver groups showed no significant difference in age, body mass index, comorbidities, or Charlson score. There was no significant difference in the percentage of those with initial severe hypoxemia between the two groups (8.1% vs. 9.2%; p = 0.126). The initial Pao2/Fio2 ratio did not significantly increase the odds ratio (OR) of being a nonresolver (OR, 0.84; 95% CI, 0.65-1.10). Nonresolver mortality was 61.4%, comparable to the survival rates seen in nonresolvers in a previous large COVID-19 ARDS study.

CONCLUSIONS AND RELEVANCE

Our study shows that resolver status is a valuable grouping in ARDS. It has significant advantages over grouping by initial degree of hypoxemia, including better mapping of trajectory and comparable outcomes across other studies. While it may offer insights into disease-specific associations, future studies should include resolver status analysis for more definitive conclusions.

Effects of sleep disturbance on dyspnoea and impaired lung function following hospital admission due to COVID-19 in the UK: a prospective multicentre cohort study

BACKGROUND

Sleep disturbance is common following hospital admission both for COVID-19 and other causes. The clinical associations of this for recovery after hospital admission are poorly understood despite sleep disturbance contributing to morbidity in other scenarios. We aimed to investigate the prevalence and nature of sleep disturbance after discharge following hospital admission for COVID-19 and to assess whether this was associated with dyspnoea.

METHODS

CircCOVID was a prospective multicentre cohort substudy designed to investigate the effects of circadian disruption and sleep disturbance on recovery after COVID-19 in a cohort of participants aged 18 years or older, admitted to hospital for COVID-19 in the UK, and discharged between March, 2020, and October, 2021. Participants were recruited from the Post-hospitalisation COVID-19 study (PHOSP-COVID). Follow-up data were collected at two timepoints: an early time point 2-7 months after hospital discharge and a later time point 10-14 months after hospital discharge. Sleep quality was assessed subjectively using the Pittsburgh Sleep Quality Index questionnaire and a numerical rating scale. Sleep quality was also assessed with an accelerometer worn on the wrist (actigraphy) for 14 days. Participants were also clinically phenotyped, including assessment of symptoms (ie, anxiety [Generalised Anxiety Disorder 7-item scale questionnaire], muscle function [SARC-F questionnaire], dyspnoea [Dyspnoea-12 questionnaire] and measurement of lung function), at the early timepoint after discharge. Actigraphy results were also compared to a matched UK Biobank cohort (non-hospitalised individuals and recently hospitalised individuals). Multivariable linear regression was used to define associations of sleep disturbance with the primary outcome of breathlessness and the other clinical symptoms. PHOSP-COVID is registered on the ISRCTN Registry (ISRCTN10980107).

FINDINGS

2320 of 2468 participants in the PHOSP-COVID study attended an early timepoint research visit a median of 5 months (IQR 4-6) following discharge from 83 hospitals in the UK. Data for sleep quality were assessed by subjective measures (the Pittsburgh Sleep Quality Index questionnaire and the numerical rating scale) for 638 participants at the early time point. Sleep quality was also assessed using device-based measures (actigraphy) a median of 7 months (IQR 5-8 months) after discharge from hospital for 729 participants. After discharge from hospital, the majority (396 [62%] of 638) of participants who had been admitted to hospital for COVID-19 reported poor sleep quality in response to the Pittsburgh Sleep Quality Index questionnaire. A comparable proportion (338 [53%] of 638) of participants felt their sleep quality had deteriorated following discharge after COVID-19 admission, as assessed by the numerical rating scale. Device-based measurements were compared to an age-matched, sex-matched, BMI-matched, and time from discharge-matched UK Biobank cohort who had recently been admitted to hospital. Compared to the recently hospitalised matched UK Biobank cohort, participants in our study slept on average 65 min (95% CI 59 to 71) longer, had a lower sleep regularity index (-19%; 95% CI -20 to -16), and a lower sleep efficiency (3·83 percentage points; 95% CI 3·40 to 4·26). Similar results were obtained when comparisons were made with the non-hospitalised UK Biobank cohort. Overall sleep quality (unadjusted effect estimate 3·94; 95% CI 2·78 to 5·10), deterioration in sleep quality following hospital admission (3·00; 1·82 to 4·28), and sleep regularity (4·38; 2·10 to 6·65) were associated with higher dyspnoea scores. Poor sleep quality, deterioration in sleep quality, and sleep regularity were also associated with impaired lung function, as assessed by forced vital capacity. Depending on the sleep metric, anxiety mediated 18-39% of the effect of sleep disturbance on dyspnoea, while muscle weakness mediated 27-41% of this effect.

INTERPRETATION

Sleep disturbance following hospital admission for COVID-19 is associated with dyspnoea, anxiety, and muscle weakness. Due to the association with multiple symptoms, targeting sleep disturbance might be beneficial in treating the post-COVID-19 condition.

FUNDING

UK Research and Innovation, National Institute for Health Research, and Engineering and Physical Sciences Research Council.

The metabolic cost of inspiratory muscle training in mechanically ventilated patients in critical care

BACKGROUND

Diaphragmatic dysfunction is well documented in patients receiving mechanical ventilation. Inspiratory muscle training (IMT) has been used to facilitate weaning by strengthening the inspiratory muscles, yet the optimal approach remains uncertain. Whilst some data on the metabolic response to whole body exercise in critical care exist, the metabolic response to IMT in critical care is yet to be investigated. This study aimed to quantify the metabolic response to IMT in critical care and its relationship to physiological variables.

METHODS

We conducted a prospective observational study on mechanically ventilated patients ventilated for ≥ 72 h and able to participate in IMT in a medical, surgical, and cardiothoracic intensive care unit. 76 measurements were taken on 26 patients performing IMT using an inspiratory threshold loading device at 4 cmH₂O, and at 30, 50 and 80% of their negative inspiratory force (NIF). Oxygen consumption (VO₂) was measured continuously using indirect calorimetry.

RESULTS

First session mean (SD) VO₂ was 276 (86) ml/min at baseline, significantly increasing to 321 (93) ml/min, 333 (92) ml/min, 351(101) ml/min and 388 (98) ml/min after IMT at 4 cmH₂O and 30, 50 and 80% NIF, respectively (p = 0.003). Post hoc comparisons revealed significant differences in VO₂ between baseline and 50% NIF and baseline and 80% NIF (p = 0.048 and p = 0.001, respectively). VO₂ increased by 9.3 ml/min for every 1 cmH₂O increase in inspiratory load from IMT. Every increase in P/F ratio of 1 decreased the intercept VO₂ by 0.41 ml/min (CI - 0.58 to - 0.24 p < 0.001). NIF had a significant effect on the intercept and slope, with every 1 cmH₂O increase in NIF increasing intercept VO₂ by 3.28 ml/min (CI 1.98-4.59 p < 0.001) and decreasing the dose-response slope by 0.15 ml/min/cmH₂O (CI - 0.24 to - 0.05 p = 0.002).

CONCLUSIONS

IMT causes a significant load-dependent increase in VO₂. P/F ratio and NIF impact baseline VO₂. The dose-response relationship of the applied respiratory load during IMT is modulated by respiratory strength. These data may offer a novel approach to prescription of IMT.

TAKE HOME MESSAGE

The optimal approach to IMT in ICU is uncertain; we measured VO₂ at different applied respiratory loads to assess whether VO₂ increased proportionally with load and found VO₂ increased by 9.3 ml/min for every 1 cmH₂O increase in inspiratory load from IMT. Baseline NIF has a significant effect on the intercept and slope, participants with a higher baseline NIF have a higher resting VO₂ but a less pronounced increase in VO₂ as the inspiratory load increases; this may offer a novel approach to IMT prescription. Trial registration ClinicalTrials.gov, registration number: NCT05101850. Registered on 28 September 2021, https://clinicaltrials.gov/ct2/show/NCT05101850.

Upcoming and urgent challenges in critical care research based on COVID-19 pandemic experience

While the coronavirus disease 2019 (COVID-19) pandemic placed a heavy burden on healthcare systems worldwide, it also induced urgent mobilisation of research teams to develop treatments preventing or curing the disease and its consequences. It has, therefore, challenged critical care research to rapidly focus on specific fields while forcing critical care physicians to make difficult ethical decisions. This narrative review aims to summarise critical care research -from organisation to research fields- in this pandemic setting and to highlight opportunities to improve research efficiency in the future, based on what is learned from COVID-19. This pressure on research revealed, i.e., i/ the need to harmonise regulatory processes between countries, allowing simplified organisation of international research networks to improve their efficiency in answering large-scale questions; ii/ the importance of developing translational research from which therapeutic innovations can emerge; iii/ the need for improved triage and predictive scores to rationalise admission to the intensive care unit. In this context, key areas for future critical care research and better pandemic preparedness are artificial intelligence applied to healthcare, characterisation of long-term symptoms, and ethical considerations. Such collaborative research efforts should involve groups from both high and low-to-middle income countries to propose worldwide solutions. As a conclusion, stress tests on healthcare organisations should be viewed as opportunities to design new research frameworks and strategies. Worldwide availability of research networks ready to operate is essential to be prepared for next pandemics. Importantly, researchers and physicians should prioritise realistic and ethical goals for both clinical care and research.

Ventilator-Associated Lung Injury

Ventilatory support, while life saving, can also cause or aggravate lung injury through several mechanisms which are encompassed within ventilator-associated lung injury (VALI). The important realizationin the acute respiratory distress syndrome that the “baby” lung resided in non-dependent areas led to the conceptualization of “lung rest” to reduce stress and strain to exposed alveolar units. We discuss concepts and mechanisms within VALI that ultimately induce maladaptive lung responses, as well as, current and future management strategies to detect and mitigate VALI at the bedside.

Secreted Extracellular Cyclophilin A Is a Novel Mediator of Ventilator-induced Lung Injury

Rationale: Mechanical ventilation is a mainstay of intensive care but contributes to the mortality of patients through ventilator-induced lung injury. eCypA (extracellular CypA [cyclophilin A]) is an emerging inflammatory mediator and metalloproteinase inducer, and the gene responsible for its expression has recently been linked to coronavirus disease (COVID-19). Objectives: To explore the involvement of eCypA in the pathophysiology of ventilator-induced lung injury. Methods: Mice were ventilated with a low or high Vt for up to 3 hours, with or without blockade of eCypA signaling, and lung injury and inflammation were evaluated. Human primary alveolar epithelial cells were exposed to in vitro stretching to explore the cellular source of eCypA, and CypA concentrations were measured in BAL fluid from patients with acute respiratory distress syndrome to evaluate the clinical relevance. Measurements and Main Results: High-Vt ventilation in mice provoked a rapid increase in soluble CypA concentration in the alveolar space but not in plasma. In vivo ventilation and in vitro stretching experiments indicated the alveolar epithelium as the likely major source. In vivo blockade of eCypA signaling substantially attenuated physiological dysfunction, macrophage activation, and MMPs (matrix metalloproteinases). Finally, we found that patients with acute respiratory distress syndrome showed markedly elevated concentrations of eCypA within BAL fluid. Conclusions: CypA is upregulated within the lungs of injuriously ventilated mice (and critically ill patients), where it plays a significant role in lung injury. eCypA represents an exciting novel target for pharmacological intervention.

Natural history, trajectory, and management of mechanically ventilated COVID-19 patients in the United Kingdom

PURPOSE

The trajectory of mechanically ventilated patients with coronavirus disease 2019 (COVID-19) is essential for clinical decisions, yet the focus so far has been on admission characteristics without consideration of the dynamic course of the disease in the context of applied therapeutic interventions.

METHODS

We included adult patients undergoing invasive mechanical ventilation (IMV) within 48 h of intensive care unit (ICU) admission with complete clinical data until ICU death or discharge. We examined the importance of factors associated with disease progression over the first week, implementation and responsiveness to interventions used in acute respiratory distress syndrome (ARDS), and ICU outcome. We used machine learning (ML) and Explainable Artificial Intelligence (XAI) methods to characterise the evolution of clinical parameters and our ICU data visualisation tool is available as a web-based widget ( https://www.CovidUK.ICU ).

RESULTS

Data for 633 adults with COVID-19 who underwent IMV between 01 March 2020 and 31 August 2020 were analysed. Overall mortality was 43.3% and highest with non-resolution of hypoxaemia [60.4% vs17.6%; P < 0.001; median PaO2/FiO2 on the day of death was 12.3(8.9-18.4) kPa] and non-response to proning (69.5% vs.31.1%; P < 0.001). Two ML models using weeklong data demonstrated an increased predictive accuracy for mortality compared to admission data (74.5% and 76.3% vs 60%, respectively). XAI models highlighted the increasing importance, over the first week, of PaO2/FiO2 in predicting mortality. Prone positioning improved oxygenation only in 45% of patients. A higher peak pressure (OR 1.42[1.06-1.91]; P < 0.05), raised respiratory component (OR 1.71[ 1.17-2.5]; P < 0.01) and cardiovascular component (OR 1.36 [1.04-1.75]; P < 0.05) of the sequential organ failure assessment (SOFA) score and raised lactate (OR 1.33 [0.99-1.79]; P = 0.057) immediately prior to application of prone positioning were associated with lack of oxygenation response. Prone positioning was not applied to 76% of patients with moderate hypoxemia and 45% of those with severe hypoxemia and patients who died without receiving proning interventions had more missed opportunities for prone intervention [7 (3-15.5) versus 2 (0-6); P < 0.001]. Despite the severity of gas exchange deficit, most patients received lung-protective ventilation with tidal volumes less than 8 mL/kg and plateau pressures less than 30cmH2O. This was despite systematic errors in measurement of height and derived ideal body weight.

CONCLUSIONS

Refractory hypoxaemia remains a major association with mortality, yet evidence based ARDS interventions, in particular prone positioning, were not implemented and had delayed application with an associated reduced responsiveness. Real-time service evaluation techniques offer opportunities to assess the delivery of care and improve protocolised implementation of evidence-based ARDS interventions, which might be associated with improvements in survival.

Right ventricular dysfunction in critically ill COVID-19 ARDS

Aims

Comprehensive echocardiography assessment of right ventricular (RV) impairment has not been reported in critically ill patients with COVID-19. We detail the specific phenotype and clinical associations of RV impairment in COVID-19 acute respiratory distress syndrome (ARDS).

Methods

Transthoracic echocardiography (TTE) measures of RV function were collected in critically unwell patients for associations with clinical, ventilatory and laboratory data.

Results

Ninety patients (25.6% female), mean age 52.0 ± 10.8 years, veno-venous extracorporeal membrane oxygenation (VVECMO) (42.2%) were studied. A significantly higher proportion of patients were identified as having RV dysfunction by RV fractional area change (FAC) (72.0%,95% confidence interval (CI) 61.0–81.0) and RV velocity time integral (VTI) (86.4%, 95 CI 77.3–93.2) than by tricuspid annular plane systolic excursion (TAPSE) (23.8%, 95 CI 16.0–33.9), RVS’ (11.9%, 95% CI 6.6–20.5) or RV free wall strain (FWS) (35.3%, 95% CI 23.6–49.0). RV VTI correlated strongly with RV FAC (p ≤ 0.01). Multivariate regression demonstrated independent associations of RV FAC with NTpro-BNP and PVR. RV-PA coupling correlated with PVR (univariate p < 0.01), as well as RVEDAi (p < 0.01), and RVESAi (p < 0.01), and was associated with P/F ratio (p 0.026), PEEP (p 0.025), and ALT (p 0.028).

Conclusions

Severe COVID-19 ARDS is associated with a specific phenotype of RV radial impairment with sparing of longitudinal function. Clinicians should avoid interpretation of RV health purely on long-axis parameters in these patients. RV-PA coupling potentially provides important additional information above standard measures of RV performance in this cohort.

Respiratory follow-up of patients with COVID-19 pneumonia

The COVID-19 pandemic has led to an unprecedented surge in hospitalised patients with viral pneumonia. The most severely affected patients are older men, individuals of black and Asian minority ethnicity and those with comorbidities. COVID-19 is also associated with an increased risk of hypercoagulability and venous thromboembolism. The overwhelming majority of patients admitted to hospital have respiratory failure and while most are managed on general wards, a sizeable proportion require intensive care support. The long-term complications of COVID-19 pneumonia are starting to emerge but data from previous coronavirus outbreaks such as severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) suggest that some patients will experience long-term respiratory complications of the infection. With the pattern of thoracic imaging abnormalities and growing clinical experience, it is envisaged that interstitial lung disease and pulmonary vascular disease are likely to be the most important respiratory complications. There is a need for a unified pathway for the respiratory follow-up of patients with COVID-19 balancing the delivery of high-quality clinical care with stretched National Health Service (NHS) resources. In this guidance document, we provide a suggested structure for the respiratory follow-up of patients with clinicoradiological confirmation of COVID-19 pneumonia. We define two separate algorithms integrating disease severity, likelihood of long-term respiratory complications and functional capacity on discharge. To mitigate NHS pressures, virtual solutions have been embedded within the pathway as has safety netting of patients whose clinical trajectory deviates from the pathway. For all patients, we suggest a holistic package of care to address breathlessness, anxiety, oxygen requirement, palliative care and rehabilitation.

Dual-Energy CT Pulmonary Angiography (DECTPA) Quantifies Vasculopathy in Severe COVID-19 Pneumonia

BACKGROUND

The role of dual energy computed tomographic pulmonary angiography (DECTPA) in revealing vasculopathy in coronavirus disease 2019 (COVID-19) has not been fully explored.

PURPOSE

To evaluate the relationship between DECTPA and disease duration, right ventricular dysfunction (RVD), lung compliance, D-dimer and obstruction index in COVID-19 pneumonia.

MATERIALS AND METHODS

This institutional review board approved this retrospective study, and waived the informed consent requirement. Between March-May 2020, 27 consecutive ventilated patients with severe COVID-19 pneumonia underwent DECTPA to diagnose pulmonary thrombus (PT); 11 underwent surveillance DECTPA 14 ±11.6 days later. Qualitative and quantitative analysis of perfused blood volume (PBV) maps recorded: i) perfusion defect 'pattern' (wedge-shaped, mottled or amorphous), ii) presence of PT and CT obstruction index (CTOI) and iii) PBV relative to pulmonary artery enhancement (PBV/PAenh); PBV/PAenh was also compared with seven healthy volunteers and correlated with D-Dimer and CTOI.

RESULTS

Amorphous (n=21), mottled (n=4), and wedge-shaped (n=2) perfusion defects were observed (M=20; mean age=56 ±8.7 years). Mean extent of perfusion defects=36.1%±17.2. Acute PT was present in 11/27(40.7%) patients. Only wedge-shaped defects corresponded with PT (2/27, 7.4%). Mean CTOI was 2.6±5.4 out of 40. PBV/PAenh (18.2 ±4.2%) was lower than in healthy volunteers (27 ±13.9%, p = 0.002). PBV/PAenh correlated with disease duration (β = 0.13, p = 0.04), and inversely correlated with RVD (β = -7.2, p = 0.001), persisting after controlling for confounders. There were no linkages between PBV/PAenh and D-dimer or CTOI.

CONCLUSION

Perfusion defects and decreased PBV/PAenh are prevalent in severe COVID-19 pneumonia. PBV/PAenh correlates with disease duration and inversely correlates with RVD. PBV/PAenh may be an important marker of vasculopathy in severe COVID-19 pneumonia even in the absence of arterial thrombus.

Pulmonary Angiopathy in Severe COVID-19: Physiologic, Imaging, and Hematologic Observations

Rationale: Clinical and epidemiologic data in coronavirus disease (COVID-19) have accrued rapidly since the outbreak, but few address the underlying pathophysiology.Objectives: To ascertain the physiologic, hematologic, and imaging basis of lung injury in severe COVID-19 pneumonia.Methods: Clinical, physiologic, and laboratory data were collated. Radiologic (computed tomography (CT) pulmonary angiography [n = 39] and dual-energy CT [DECT, n = 20]) studies were evaluated: observers quantified CT patterns (including the extent of abnormal lung and the presence and extent of dilated peripheral vessels) and perfusion defects on DECT. Coagulation status was assessed using thromboelastography.Measurements and Results: In 39 consecutive patients (male:female, 32:7; mean age, 53 ± 10 yr [range, 29-79 yr]; Black and minority ethnic, n = 25 [64%]), there was a significant vascular perfusion abnormality and increased physiologic dead space (dynamic compliance, 33.7 ± 14.7 ml/cm H2O; Murray lung injury score, 3.14 ± 0.53; mean ventilatory ratios, 2.6 ± 0.8) with evidence of hypercoagulability and fibrinolytic "shutdown". The mean CT extent (±SD) of normally aerated lung, ground-glass opacification, and dense parenchymal opacification were 23.5 ± 16.7%, 36.3 ± 24.7%, and 42.7 ± 27.1%, respectively. Dilated peripheral vessels were present in 21/33 (63.6%) patients with at least two assessable lobes (including 10/21 [47.6%] with no evidence of acute pulmonary emboli). Perfusion defects on DECT (assessable in 18/20 [90%]) were present in all patients (wedge-shaped, n = 3; mottled, n = 9; mixed pattern, n = 6).Conclusions: Physiologic, hematologic, and imaging data show not only the presence of a hypercoagulable phenotype in severe COVID-19 pneumonia but also markedly impaired pulmonary perfusion likely caused by pulmonary angiopathy and thrombosis.

Monocytes mediate homing of circulating microvesicles to the pulmonary vasculature during low-grade systemic inflammation

Microvesicles (MVs), a plasma membrane-derived subclass of extracellular vesicles, are produced and released into the circulation during systemic inflammation, yet little is known of cell/tissue-specific uptake of MVs under these conditions. We hypothesized that monocytes contribute to uptake of circulating MVs and that their increased margination to the pulmonary circulation and functional priming during systemic inflammation produces substantive changes to the systemic MV homing profile. Cellular uptake of i.v.-injected, fluorescently labelled MVs (J774.1 macrophage-derived) in vivo was quantified by flow cytometry in vascular cell populations of the lungs, liver and spleen of C57BL6 mice. Under normal conditions, both Ly6C^high and Ly6C^low monocytes contributed to MV uptake but liver Kupffer cells were the dominant target cell population. Following induction of sub-clinical endotoxemia with low-dose i.v. LPS, MV uptake by lung-marginated Ly6C^high monocytes increased markedly, both at the individual cell level (~2.5-fold) and through substantive expansion of their numbers (~8-fold), whereas uptake by splenic macrophages was unchanged and uptake by Kupffer cells actually decreased (~50%). Further analysis of MV uptake within the pulmonary vasculature using a combined model approach of in vivo macrophage depletion, ex vivo isolated perfused lungs and in vitro lung perfusate cell-based assays, indicated that Ly6C^high monocytes possess a high MV uptake capacity (equivalent to Kupffer cells), that is enhanced directly by endotoxemia and ablated in the presence of phosphatidylserine (PS)-enriched liposomes and β3 integrin receptor blocking peptide. Accordingly, i.v.-injected PS-enriched liposomes underwent a redistribution of cellular uptake during endotoxemia similar to MVs, with enhanced uptake by Ly6C^high monocytes and reduced uptake by Kupffer cells. These findings indicate that monocytes, particularly lung-marginated Ly6C^high subset monocytes, become a dominant target cell population for MVs during systemic inflammation, with significant implications for the function and targeting of endogenous and therapeutically administered MVs, lending novel insights into the pathophysiology of pulmonary vascular inflammation.

Intracranial Hemorrhage and Early Mortality in Patients Receiving Extracorporeal Membrane Oxygenation for Severe Respiratory Failure

Intracranial hemorrhage (ICH) is a serious complication in patients receiving veno-venous extracorporeal membrane oxygenation (VV-ECMO) and is associated with high mortality. It is unknown whether ICH may be a consequence of the ECMO or of an underlying disease. The authors first aimed to assess the incidence of ICH at initiation and during the course of VV-ECMO and its associated mortality. The second aim was to identify clinical and laboratory measures that could predict the development of ICH in severe respiratory failure. Data were collected from a total number of 165 patients receiving VV-ECMO from January, 2012 to December, 2016 in a single tertiary center and treated according to a single protocol. Only patients who had a brain computed tomography within 24 hours of initiation of ECMO (n = 149) were included for analysis. The prevalence and incidence of ICH at initiation and during the course of VV-ECMO (at median 9 days) were 10.7% (16/149) and 5.2% (7/133), respectively. Thrombocytopenia and reduced creatinine clearance (CrCL) were independently associated with increased risk of ICH on admission; odds ratio (95% confidence interval): 22.6 (2.6-99.5), and 10.8 (5.6-16.2). Only 30-day (not 180-day) mortality was significantly higher in patients with ICH on admission versus those without (37.5% [6/16] vs 16.4% [22/133]; p = 0.03 and 43.7% [7/16] vs 26.3% [35/133]; p = 0.15, respectively). Reduced CrCL and thrombocytopenia were associated with ICH at initiation of VV-ECMO. The higher incidence of ICH at initiation suggests it is more closely related to the severity of the underlying lung injury than to the VV-ECMO itself. ICH at VV-ECMO initiation was associated with early mortality.

Inhibition of TNF Receptor p55 By a Domain Antibody Attenuates the Initial Phase of Acid-Induced Lung Injury in Mice

BACKGROUND

Tumor necrosis factor-α (TNF) is strongly implicated in the development of acute respiratory distress syndrome (ARDS), but its potential as a therapeutic target has been hampered by its complex biology. TNF signals through two receptors, p55 and p75, which play differential roles in pulmonary edema formation during ARDS. We have recently shown that inhibition of p55 by a novel domain antibody (dAb™) attenuated ventilator-induced lung injury. In the current study, we explored the efficacy of this antibody in mouse models of acid-induced lung injury to investigate the longer consequences of treatment.

METHODS

We employed two acid-induced injury models, an acute ventilated model and a resolving spontaneously breathing model. C57BL/6 mice were pretreated intratracheally or intranasally with p55-targeting dAb or non-targeting "dummy" dAb, 1 or 4 h before acid instillation.

RESULTS

Acid instillation in the dummy dAb group caused hypoxemia, increased respiratory system elastance, pulmonary inflammation, and edema in both the ventilated and resolving models. Pretreatment with p55-targeting dAb significantly attenuated physiological markers of ARDS in both models. p55-targeting dAb also attenuated pulmonary inflammation in the ventilated model, with signs that altered cytokine production and leukocyte recruitment persisted beyond the very acute phase.

CONCLUSION

These results demonstrate that the p55-targeting dAb attenuates lung injury and edema formation in models of ARDS induced by acid aspiration, with protection from a single dose lasting up to 24 h. Together with our previous data, the current study lends support toward the clinical targeting of p55 for patients with, or at risk of ARDS.

Synthesis and Physico-Chemical Properties of Polycyanurates of 2-(N,N-Diphenylhydrazino)4,6-Dichloro-s-Triazine with Various Aromatic Diols

Various polycynaurates were synhesised by stirred interfacial polycondensation of 2-(N.N-diphenynhydrazino)-4,6-dichloro-s-triaziae (DPHDCT) with each of the aromatic diols: bisphenol-A (BPA); bisphenol-C (BPC); bisphenol-S (BPS); phenolphthalein (Ph); catechol; resorcinol; 1,5and 2.7-dihydroxynaphthalene (DHN-1,5 and DHN-2,7) and 1,8-dihydroxyanthraquinone (DHA-1,8). Interfacial polycondensation of DPHDCT with BPA was investigated in detail in order to select optimum reaction conditions. The yield of polycyanurates varies from 6 I% to 79%. The polycyanurates are soluble in chlorinated solvents such as chloroform, dichloroethane. dichloromethane and chlorobenzene. The reduced viscosity for polycyanurates, determined with a 1 g disolution in chloroform at 25 + 3°C was found to be in the range 0.50-0.68 dl g. All the polycyanurates were characterized by IR spectra. The densities of the polycyanurates, determined using the suspension method at 25 3°C, range between 1.196 and 1.330 g cm. The overall reactivity of diols, based on reduced viscosity values, was found to decrease in the following order: PCBPA> PCPh> PCBPC> PCR>PCDHN-2,7 > PCDHN-I,5 > PCC > PCDHA-1.8 > PCBPS. The thermal stability of polycyanurates, derived from various temperature characteristics, was found to decrease in the following order: PCBPA> PCBPS> PCBPC > PCC PCR> PCDHN-2,7 PCDHN-.l 5 > PCDHA-1,8 > PCPh.

Clinicopathological evaluation of non-parasitic dermatoses in canines

Aim:

The present study has been carried out to detect non-parasitic dermatoses in canines brought at the Nandini Veterinary Hospital, Surat.

Materials and Methods:

The current investigation was carried out on skin scrapping, skin biopsy specimens, blood, and serum samples of 210 freshly registered cases of dogs with dermatological afflictions. Dogs found healthy on clinical examination were used as control animals (n=15). The incidence of non-parasitic dermatoses has been recorded as per age, breed, and sex of dogs. For bacterial isolation, the pus/exudates samples were collected from 40 cases of pyoderma and streaked onto brain-heart infusion agar while 13 skin scrapping samples were inoculated on Sabouraud’s dextrose agar with chloramphenicol for isolation of fungi. The organisms were identified on the basis of gross and microscopic observation of cultural growth on media. The blood and sera samples were also collected to note alteration in hematology and biochemical parameters, respectively. Tissue samples from lesions were collected and subsequently preserved in 10% neutral buffered formalin for histopathology.

Results:

Out of 210 cases of dermatoses, 60 cases were of non-parasitic dermatoses, i.e., 28.57%. Of these, bacterial skin infections (pyoderma) were found to be the predominant at 80.00%, followed by other non-parasitic dermatological disorders, i.e., 11.67% and fungal skin infection, i.e., 8.33%. The dogs belonging to age group 1-3 years showed greater susceptibility to non-parasitic dermatological conditions. Breed wise incidence of pyoderma was found more in the Pomeranian breed (20.83%), whereas fungal skin affections were found to be higher in mongrel breed (60.00% and 42.86%, respectively). Male dogs showed greater involvement in bacterial, fungal, and other non-parasitic dermatoses. Bacteriological culture examination of 40 pus swabs resulted in the growth of 39 bacterial isolates. Mycological culture of skin scrapings from 13 suspected cases of fungal dermatoses resulted in the recovery of five fungal isolates. Hematological and serum biochemical parameters revealed a significant difference in all cases of non-parasitic dermatoses.Histopathological study revealed characteristic changes like infiltration of neutrophils with perifolliculitis, hyperkeratosis, and rafts of acantholytic cells. Histochemical staining revealed purple or magenta color fungal elements.

Conclusion:

Based on current experiment it has been concluded that among non-parasitic dermatoses bacterial and fungal skin infections are the main ailments, followed by nutritional and other causes in adult and male dogs which can be diagnosed by cultural inoculation, microscopic examination of skin scrapings, and dermatohistopathology along with hematology and biochemistry.

In vivo compartmental analysis of leukocytes in mouse lungs

The lung has a unique structure consisting of three functionally different compartments (alveolar, interstitial, and vascular) situated in an extreme proximity. Current methods to localize lung leukocytes using bronchoalveolar lavage and/or lung perfusion have significant limitations for determination of location and phenotype of leukocytes. Here we present a novel method using in vivo antibody labeling to enable accurate compartmental localization/quantification and phenotyping of mouse lung leukocytes. Anesthetized C57BL/6 mice received combined in vivo intravenous and intratracheal labeling with fluorophore-conjugated anti-CD45 antibodies, and lung single-cell suspensions were analyzed by flow cytometry. The combined in vivo intravenous and intratracheal CD45 labeling enabled robust separation of the alveolar, interstitial, and vascular compartments of the lung. In naive mice, the alveolar compartment consisted predominantly of resident alveolar macrophages. The interstitial compartment, gated by events negative for both intratracheal and intravenous CD45 staining, showed two conventional dendritic cell populations, as well as a Ly6C^lo monocyte population. Expression levels of MHCII on these interstitial monocytes were much higher than on the vascular Ly6C^lo monocyte populations. In mice exposed to acid aspiration-induced lung injury, this protocol also clearly distinguished the three lung compartments showing the dynamic trafficking of neutrophils and exudative monocytes across the lung compartments during inflammation and resolution. This simple in vivo dual-labeling technique substantially increases the accuracy and depth of lung flow cytometric analysis, facilitates a more comprehensive examination of lung leukocyte pools, and enables the investigation of previously poorly defined “interstitial” leukocyte populations during models of inflammatory lung diseases.

TNF-induced death signaling triggers alveolar epithelial dysfunction in acute lung injury

The ability of the alveolar epithelium to prevent and resolve pulmonary edema is a crucial determinant of morbidity and mortality in acute lung injury (ALI). TNF has been implicated in ALI pathogenesis, but the precise mechanisms remain undetermined. We evaluated the role of TNF signaling in pulmonary edema formation in a clinically relevant mouse model of ALI induced by acid aspiration and investigated the effects of TNF p55 receptor deletion, caspase-8 inhibition, and alveolar macrophage depletion on alveolar epithelial function. We found that TNF plays a central role in the development of pulmonary edema in ALI through activation of p55-mediated death signaling, rather than through previously well-characterized p55-mediated proinflammatory signaling. Acid aspiration produced pulmonary edema with significant alveolar epithelial dysfunction, as determined by alveolar fluid clearance (AFC) and intra-alveolar levels of the receptor for advanced glycation end-products. The impairment of AFC was strongly correlated with lung caspase-8 activation, which was localized to type 1 alveolar epithelial cells by flow cytometric analysis. p55-deficient mice displayed markedly attenuated injury, with improved AFC and reduced caspase-8 activity but no differences in downstream cytokine/chemokine production and neutrophil recruitment. Caspase-8 inhibition significantly improved AFC and oxygenation, whereas depletion of alveolar macrophages attenuated epithelial dysfunction with reduced TNF production and caspase-8 activity. These results provide in vivo evidence for a novel role for TNF p55 receptor-mediated caspase-8 signaling, without substantial apoptotic cell death, in triggering alveolar epithelial dysfunction and determining the early pathophysiology of ALI. Blockade of TNF-induced death signaling may provide an effective early-phase strategy for ALI.

Resolution of acute lung injury and inflammation: a translational mouse model

Previous animal models of acute lung injury (ALI) are limited as they only reproduce part of the complex pathobiology of clinical ALI. Here we develop a translational mouse model of ALI, which not only reflects the major clinical and pathological features but also enables investigation into ALI resolution. Anaesthetised mice underwent orotracheal instillation of hydrochloric acid. During the immediate period after instillation, mice were carefully maintained with supplemental oxygen to avoid mortality. At specified time-points, lung injury was assessed by analysis of blood gases, respiratory mechanics, bronchoalveolar lavage fluid, alveolar fluid clearance and lung histology. Animals exhibited significant weight loss, decreased oxygenation, increased respiratory elastance and pulmonary inflammation (intra-alveolar leukocyte influx/cytokine levels and histological injury scores). Moreover, mice displayed alveolar-capillary barrier dysfunction/epithelial injury as reflected by increased alveolar protein, lung wet/dry weight ratio and soluble receptor for advanced glycation end-products, as well as reduced alveolar fluid clearance. These injury parameters peaked between days 1 and 3, followed by almost complete recovery over days 5-10. Histology showed evidence of fibrosis on day 10. The results indicate that this resolving model of acid aspiration represents a powerful experimental tool to investigate the injurious, inflammatory, fibrotic, and resolving and reparative processes of ALI.

Sources of alveolar soluble TNF receptors during acute lung injury of different etiologies

Elevated soluble tumor necrosis factor-α receptor (sTNFR) levels in bronchoalveolar lavage fluid (BALF) are associated with poor patient outcome in acute lung injury (ALI). The mechanisms underlying these increases are unknown, but it is possible that pulmonary inflammation and increased alveolar epithelial permeability may individually contribute. We investigated mechanisms of elevated BALF sTNFRs in two in vivo mouse models of ALI. Anesthetized mice were challenged with intratracheal lipopolysaccharide or subjected to injurious mechanical ventilation. Lipopolysaccharide instillation produced acute intra-alveolar inflammation, but minimal alveolar epithelial permeability changes, with increased BALF sTNFR p75, but not p55. Increased p75 levels were markedly attenuated by alveolar macrophage depletion. In contrast, injurious ventilation induced substantial alveolar epithelial permeability, with increased BALF p75 and p55, which strongly correlated with total protein. BALF sTNFRs were not increased in isolated buffer-perfused lungs (devoid of circulating sTNFRs) subjected to injurious ventilation. These results suggest that lipopolysaccharide-induced intra-alveolar inflammation upregulates alveolar macrophage-mediated production of sTNFR p75, whereas enhanced alveolar epithelial permeability following mechanical ventilation leads to increased BALF p75 and p55 via plasma leakage. These data provide new insights into differential regulation of intra-alveolar sTNFR levels during ALI and may suggest sTNFRs as potential markers for evaluating the pathophysiology of ALI.

Adherence and persistence of single-pill ARB/CCB combination therapy compared to multiple-pill ARB/CCB regimens

OBJECTIVE

To evaluate the impact of angiotensin receptor blocker (ARBs)/dihydropyridine calcium channel blockers (CCBs) single-pill combination (SPC) on adherence to antihypertensive treatment in comparison to free combination of ARBs and CCBs.

RESEARCH DESIGN AND METHODS

A retrospective data analysis was performed using pharmacy claims data from a national pharmacy benefit management company. The study included patients who were newly initiated on ARB/CCB treatment between 01/01/2007 and 08/31/2008, aged ≥ 18 years, and continuously enrolled in the same health plan for 12 months prior to and 13 months after starting ARB/CCB treatment. Outcome variables were persistence, defined as time to discontinuation of therapy, and adherence, defined as proportion of days covered (PDC)  ≥ 0.80. Propensity score weighting was used to balance the characteristics of the two groups.

RESULTS

The final sample contained 2312 patients in the free-combination group and 2213 patients in the SPC group. Patients in the SPC group and the free-combination group were different in age, gender, type of insurance, history of antihypertensive therapy and co-morbidities. These differences were largely normalized after propensity score adjustment. Multivariate logistic model regression showed that patients in the SPC group had a 90% greater odds of being adherent to index therapy compared to patients in the free-combination group (odds ratio [OR] 1.90, 95% confidence interval [CI] 1.75-2.08, p< 0.001). A Cox proportional hazards model showed that patients in the SPC group were less likely to discontinue ARB/CCB SPC therapy compared to patients in the free-combination group (hazard ratio [HR] 0.66, 95% CI 0.63-0.70, p < 0.001). In both models, higher copayment (copayment $50 and above) was associated with worse persistence and adherence in comparison to patients who had a lower copayment ($0-$5): HR = 1.23, p < 0.001 and OR = 0.67, p < 0.001.

CONCLUSION

Patients using SPC ARB/CCB therapy were more likely to be persistent and adherent to treatment compared to patients taking free-combination therapy.