Individualised flow-controlled versus pressure-controlled ventilation in a porcine oleic acid-induced acute respiratory distress syndrome model.

BACKGROUND: A continuous gas flow provided by flow-controlled ventilation (FCV) facilitates accurate dynamic compliance measurement and allows the clinician to individually optimise positive end-expiratory and peak pressure settings accordingly. OBJECTIVE: The aim of this study was to compare the efficiency of gas exchange and impact on haemodynamics between individualised FCV and pressure-controlled ventilation (PCV) in a porcine model of oleic acid-induced acute respiratory distress syndrome (ARDS). DESIGN: Randomised controlled interventional trial conducted on 16 pigs. SETTING: Animal operating facility at the Medical University Innsbruck. INTERVENTIONS: ARDS was induced in lung healthy pigs by intravenous infusion of oleic acid until moderate-to-severe ARDS at a stable Horowitz quotient (PaO 2 FiO 2-1 ) of 80 to 120 over a period of 30 min was obtained. Ventilation was then either performed with individualised FCV ( n  = 8) established by compliance-guided pressure titration or PCV ( n  = 8) with compliance-guided titration of the positive end-expiratory pressure and peak pressure set to achieve a tidal volume of 6 ml kg -1 over a period of 2 h. MAIN OUTCOME MEASURES: Gas exchange parameters were assessed by the PaO 2 FiO 2-1 quotient and CO 2 removal by the PaCO 2 value in relation to required respiratory minute volume. Required catecholamine support for haemodynamic stabilisation was measured. RESULTS: The FCV group showed significantly improved oxygenation [149.2 vs. 110.4, median difference (MD) 38.7 (8.0 to 69.5) PaO 2 FiO 2-1 ; P  = 0.027] and CO 2 removal [PaCO 2 7.25 vs. 9.05, MD -1.8 (-2.87 to -0.72) kPa; P  = 0.006] at a significantly lower respiratory minute volume [8.4 vs. 11.9, MD -3.6 (-5.6 to -1.5) l min -1 ; P  = 0.005] compared with PCV. In addition, in FCV-pigs, haemodynamic stabilisation occurred with a significant reduction of required catecholamine support [norepinephrine 0.26 vs. 0.86, MD -0.61 (-1.12 to -0.09) µg kg -1  min -1 ; P  = 0.037] during 2 ventilation hours. CONCLUSION: In this oleic acid-induced porcine ARDS model, individualised FCV significantly improved gas exchange and haemodynamic stability compared with PCV. TRIAL REGISTRATION: Protocol no.: BMBWF-66.011/0105-V/3b/2019).

Acute respiratory distress syndrome enhances tumor metastasis into lungs: Role of BRD4 in the tumor microenvironment.

Acute respiratory distress syndrome (ARDS) is associated with severe lung inflammation, edema, hypoxia, and high vascular permeability. The COVID-19-associated pandemic ARDS caused by SARS-CoV-2 has created dire global conditions and has been highly contagious. Chronic inflammatory disease enhances cancer cell proliferation, progression, and invasion. We investigated how acute lung inflammation activates the tumor microenvironment and enhances lung metastasis in LPS induced in vitro and in vivo models. Respiratory illness is mainly caused by cytokine storm, which further influences oxidative and nitrosative stress. The LPS-induced inflammatory cytokines made the conditions suitable for the tumor microenvironment in the lungs. In the present study, we observed that LPS induced the cytokine storm and promoted lung inflammation via BRD4, which further caused the nuclear translocation of p65 NF-κB and STAT3. The transcriptional activation additionally triggers the tumor microenvironment and lung metastasis. Thus, BRD4-regulated p65 and STAT3 transcriptional activity in ARDS enhances lung tumor metastasis. Moreover, LPS-induced ARDS might promote the tumor microenvironment and increase cancer metastasis into the lungs. Collectively, BRD4 plays a vital role in inflammation-mediated tumor metastasis and is found to be a diagnostic and molecular target in inflammation-associated cancers.

Comparison of the efficacy of equivalent doses of dexamethasone, methylprednisolone, and hydrocortisone for treatment of COVID-19-related acute respiratory distress syndrome: a prospective three-arm randomized clinical trial.

BACKGROUND: This prospective controlled clinical trial aimed to compare the efficacy of methylprednisolone, dexamethasone, and hydrocortisone at equivalent doses in patients with severe COVID-19. METHODS: In total, 106 patients with mild to moderate COVID-19-related acute respiratory distress syndrome (ARDS) were randomized to receive either dexamethasone (6 mg once a day), methylprednisolone (16 mg twice a day), or hydrocortisone (50 mg thrice a day) for up to 10 days. All participants received a standard of care for COVID-19. The primary and secondary efficacy outcomes included all-cause 28-day mortality, clinical status on day 28 assessed using the World Health Organization (WHO) eight-category ordinal clinical scale, number of patients requiring mechanical ventilation and intensive care unit (ICU) care, number of ventilator-free days, length of hospital and ICU stay, change in PaO2:FiO2 ratios during the first 5 days after treatment, and incidence of serious adverse events. P-values below 0.008 based on Bonferroni's multiple-testing correction method were considered statistically significant. RESULTS: According to the obtained results, there was a trend toward more favorable clinical outcomes in terms of needing mechanical ventilation and ICU care, number of ventilator-free days, change in PaO2:FiO2 ratios during the first 5 days after treatment, clinical status score at day 28, length of ICU and hospital stay, and overall 28-day mortality in patients receiving dexamethasone compared to those receiving methylprednisolone or hydrocortisone; however, likely due to the study's small sample size, the difference between groups reached a significant level only in the case of clinical status score on day 28 (p-value = 0.003). There was no significant difference in the incidence of serious adverse events between the study groups. CONCLUSION: Based on the results, severe cases of COVID-19 treated with dexamethasone might have a better clinical status at 28-day follow-up compared to methylprednisolone and hydrocortisone at an equivalent dose. Larger multicenter trials are required to confirm our findings.

Effects of tocilizumab and dexamethasone on the downregulation of proinflammatory cytokines and upregulation of antioxidants in the lungs in oleic acid-induced ARDS.

BACKGROUND: Acute respiratory distress syndrome (ARDS) is a life-threatening disease caused by the induction of inflammatory cytokines and chemokines in the lungs. There is a dearth of drug applications that can be used to prevent cytokine storms in ARDS treatment. This study was designed to investigate the effects of tocilizumab and dexamethasone on oxidative stress, antioxidant parameters, and cytokine storms in acute lung injury caused by oleic acid in rats. METHODS: Adult male rats were divided into five groups: the CN (healthy rats, n = 6), OA (oleic acid administration, n = 6), OA + TCZ-2 (oleic acid and tocilizumab at 2 mg/kg, n = 6), OA + TCZ-4 (oleic acid and tocilizumab at 4 mg/kg, n = 6), and OA + DEX-10 (oleic acid and dexamethasone at 10 mg/kg, n = 6) groups. All animals were euthanized after treatment for histopathological, immunohistochemical, biochemical, PCR, and SEM analyses. RESULTS: Expressions of TNF-α, IL-1ß, IL-6, and IL-8 cytokines in rats with acute lung injury induced by oleic acid were downregulated in the TCZ and DEX groups compared to the OA group (P < 0.05). The MDA level in lung tissues was statistically lower in the OA + TCZ-4 group compared to the OA group. It was further determined that SOD, GSH, and CAT levels were decreased in the OA group and increased in the TCZ and DEX groups (P < 0.05). Histopathological findings such as thickening of the alveoli, hyperemia, and peribronchial cell infiltration were found to be similar when lung tissues of the TCZ and DEX groups were compared to the control group. With SEM imaging of the lung tissues, it was found that the alveolar lining layer had become indistinct in the OA, OA + TCZ-2, and OA + TCZ-4 groups. CONCLUSIONS: In this model of acute lung injury caused by oleic acid, tocilizumab and dexamethasone were effective in preventing cytokine storms by downregulating the expression of proinflammatory cytokines including TNF-α, IL-1ß, IL-6, and IL-8. Against the downregulation of antioxidant parameters such as SOD and GSH in the lung tissues caused by oleic acid, tocilizumab and dexamethasone upregulated them and showed protective effects against cell damage.

Testing oxygenated microbubbles via intraperitoneal and intrathoracic routes on a large pig model of LPS-induced acute respiratory distress syndrome.

With a mortality rate of 46% before the onset of COVID-19, acute respiratory distress syndrome (ARDS) affected 200,000 people in the US, causing 75,000 deaths. Mortality rates in COVID-19 ARDS patients are currently at 39%. Extrapulmonary support for ARDS aims to supplement mechanical ventilation by providing life-sustaining oxygen to the patient. A new rapid-onset, human-sized pig ARDS model in a porcine intensive care unit (ICU) was developed. The pigs were nebulized intratracheally with a high dose (4 mg/kg) of the endotoxin lipopolysaccharide (LPS) over a 2 h duration to induce rapid-onset moderate-to-severe ARDS. They were then catheterized to monitor vitals and to evaluate the therapeutic effect of oxygenated microbubble (OMB) therapy delivered by intrathoracic (IT) or intraperitoneal (IP) administration. Post-LPS administration, the PaO2 value dropped below 70 mmHg, the PaO2 /FiO2 ratio dropped below 200 mmHg, and the heart rate increased, indicating rapidly developing (within 4 h) moderate-to-severe ARDS with tachycardia. The SpO2 and PaO2 of these LPS-injured pigs did not show significant improvement after OMB administration, as they did in our previous studies of the therapy on small animal models of ARDS injury. Furthermore, pigs receiving OMB or saline infusions had slightly lower survival than their ARDS counterparts. The OMB administration did not induce a statistically significant or clinically relevant therapeutic effect in this model; instead, both saline and OMB infusion appeared to lower survival rates slightly. This result is significant because it contradicts positive results from our previous small animal studies and places a limit on the efficacy of such treatments for larger animals under more severe respiratory distress. While OMB did not prove efficacious in this rapid-onset ARDS pig model, it may retain potential as a novel therapy for the usual presentation of ARDS in humans, which develops and progresses over days to weeks.

Long-term ketamine infusion-induced cholestatic liver injury in COVID-19-associated acute respiratory distress syndrome.

BACKGROUND: A higher-than-usual resistance to standard sedation regimens in COVID-19 patients suffering from acute respiratory distress syndrome (ARDS) has led to the frequent use of the second-line anaesthetic agent ketamine. Simultaneously, an increased incidence of cholangiopathies in mechanically ventilated patients receiving prolonged infusion of high-dose ketamine has been noted. Therefore, the objective of this study was to investigate a potential dose-response relationship between ketamine and bilirubin levels. METHODS: Post hoc analysis of a prospective observational cohort of patients suffering from COVID-19-associated ARDS between March 2020 and August 2021. A time-varying, multivariable adjusted, cumulative weighted exposure mixed-effects model was employed to analyse the exposure-effect relationship between ketamine infusion and total bilirubin levels. RESULTS: Two-hundred forty-three critically ill patients were included into the analysis. Ketamine was infused to 170 (70%) patients at a rate of 1.4 [0.9-2.0] mg/kg/h for 9 [4-18] days. The mixed-effects model revealed a positively correlated infusion duration-effect as well as dose-effect relationship between ketamine infusion and rising bilirubin levels (p < 0.0001). In comparison, long-term infusion of propofol and sufentanil, even at high doses, was not associated with increasing bilirubin levels (p = 0.421, p = 0.258). Patients having received ketamine infusion had a multivariable adjusted competing risk hazard of developing a cholestatic liver injury during their ICU stay of 3.2 [95% confidence interval, 1.3-7.8] (p = 0.01). CONCLUSIONS: A causally plausible, dose-effect relationship between long-term infusion of ketamine and rising total bilirubin levels, as well as an augmented, ketamine-associated, hazard of cholestatic liver injury in critically ill COVID-19 patients could be shown. High-dose ketamine should be refrained from whenever possible for the long-term analgosedation of mechanically ventilated COVID-19 patients.

Pirfenidone ameliorates early pulmonary fibrosis in LPS-induced acute respiratory distress syndrome by inhibiting endothelial-to-mesenchymal transition via the Hedgehog signaling pathway.

Pulmonary vascular endothelial dysfunction is a key pathogenic mechanism in acute respiratory distress syndrome (ARDS), resulting in fibrosis in lung tissues, including in the context of COVID-19. Pirfenidone (PFD) has become a novel therapeutic agent for treating idiopathic pulmonary fibrosis (IPF) and can improve lung function, inhibit fibrosis and inhibit inflammation. Recently, endothelial-to-mesenchymal transition (EndMT) was shown to play a crucial role in various respiratory diseases. However, the role of PFD in the course of EndMT in LPS-induced ARDS remains poorly understood. The purpose of this study was to explore the anti-EndMT effects of PFD on pulmonary fibrosis after LPS-induced ARDS. First, we determined that PFD significantly reduced LPS-induced ARDS, as shown by significant pathological alterations, and alleviated the oxidative stress and inflammatory response in vitro and in vivo. Furthermore, PFD decreased pulmonary fibrosis in LPS-induced ARDS by inhibiting EndMT and reduced the expression levels of Hedgehog (HH) pathway target genes, such as Gli1 and α-SMA, after LPS induction. In summary, this study confirmed that inhibiting the HH pathway by PFD could decrease pulmonary fibrosis by downregulating EndMT in LPS-induced ARDS. In conclusion, we demonstrate that PFD is a promising agent to attenuate pulmonary fibrosis following ARDS in the future.

Two Cases of Miliary and Disseminated Coccidioidomycosis Following Glucocorticoid Therapy and Literature Review.

A 49-year-old man with no significant past medical history received dexamethasone as part of his treatment for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Less than 3 weeks later, the patient developed acute respiratory distress syndrome. Radiological and serological testing led to a diagnosis of acute hypoxic miliary coccidioidomycosis. A 52-year-old man with a past medical history of chronic kidney disease (CKD) was treated with prednisone for focal segmental glomerulosclerosis (FSGS). Within 2 weeks, this patient developed bilateral lower extremity weakness. Radiology, serology, and lumbar puncture proved a diagnosis of reactivated coccidioidomycosis with miliary pattern and coccidioidomycosis meningoencephalitis with arachnoiditis. Whether treatment with glucocorticoids caused reactivation of coccidioidomycosis is discussed in this case series.

Acute respiratory distress syndrome precipitated by granulocyte colony-stimulating factor in undiagnosed Pneumocystis jirovecii pneumonia.

We present the case of a 62-year-old man with rheumatoid arthritis who developed a leukaemoid reaction and acute respiratory distress syndrome (ARDS) following granulocyte colony-stimulating factor (G-CSF) administration that had been given to treat neutropenia secondary to methotrexate and leflunomide toxicity. Later it was established that he had Pneumocystis jirovecii pneumonia, which was treated to complete resolution with a course of corticosteroids and antibiotics. This case highlights the potential risk of G-CSF administration in an immune compromised individual in the midst of bone marrow recovery in the context of active infection. Recognition of immune escape syndromes is vital and requires an understanding of potential triggers and risk factors.

Elastase Inhibitor Cyclotheonellazole A: Total Synthesis and In Vivo Biological Evaluation for Acute Lung Injury.

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) is one of the most common complications in COVID-19. Elastase has been recognized as an important target to prevent ALI/ARDS in the patient of COVID-19. Cyclotheonellazole A (CTL-A) is a natural macrocyclic peptide reported to be a potent elastase inhibitor. Herein, we completed the first total synthesis of CTL-A in 24 linear steps. The key reactions include three-component MAC reactions and two late-stage oxidations. We also provided seven CTL-A analogues and elucidated preliminary structure-activity relationships. The in vivo ALI mouse model further suggested that CTL-A alleviated acute lung injury with reductions in lung edema and pathological deterioration, which is better than sivelestat, one approved elastase inhibitor. The activity of CTL-A against elastase, along with its cellular safety and well-established synthetic route, warrants further investigation of CTL-A as a candidate against COVID-19 pathogeneses.

Inhibition of Prostaglandin F2α Receptors Exaggerates HCl-Induced Lung Inflammation in Mice.

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are severe respiratory disorders that are caused by aspiration, sepsis, trauma, and pneumonia. A clinical feature of ALI/ARDS is the acute onset of severe hypoxemia, and the mortality rate, which is estimated at 38-50%, remains high. Although prostaglandins (PGs) are detected in the bronchoalveolar lavage fluid of patients with ALI/ARDS, the role of PGF2α in ALI remains unclear. We aimed to clarify the role of PGF2α/PGF2α receptor (FP) signaling in acid-induced ALI using an FP receptor antagonist, AL8810. Intratracheal injection of hydrochloric acid (HCl) increased neutrophil migration into the lungs, leading to respiratory dysfunction. Pre-administration of AL8810 further increased these features. Moreover, pre-treatment with AL8810 enhanced the HCl-induced expression of pro-inflammatory cytokines and neutrophil migratory factors in the lungs. Administration of HCl decreased the gene expression of lung surfactant proteins, which was further reduced by co-administration of AL8810. Administration of AL8810 also increased lung edema and reduced mRNA expression of epithelial sodium channel in the lungs, indicating that AL8810 reduced fluid clearance. Furthermore, AL8810 also increased lipopolysaccharide-induced expression of adhesion molecules such as intracellular adhesion molecule-1 and E-selectin in human umbilical vein endothelial cells. These results indicate that inhibition of FP receptors by AL8810 exacerbated HCl-induced ALI.

A randomised, double-blind, placebo-controlled, pilot trial of intravenous plasma purified alpha-1 antitrypsin for SARS-CoV-2-induced Acute Respiratory Distress Syndrome: a structured summary of a study protocol for a randomised, controlled trial.

OBJECTIVES: The primary objective is to demonstrate that, in patients with PCR-confirmed SARS-CoV-2 resulting in Acute Respiratory Distress Syndrome (ARDS), administration of 120mg/kg of body weight of intravenous Prolastin®(plasma-purified alpha-1 antitrypsin) reduces circulating plasma levels of interleukin-6 (IL-6). Secondary objectives are to determine the effects of intravenous Prolastin® on important clinical outcomes including the incidence of adverse events (AEs) and serious adverse events (SAEs). TRIAL DESIGN: Phase 2, randomised, double-blind, placebo-controlled, pilot trial. PARTICIPANTS: The study will be conducted in Intensive Care Units in hospitals across Ireland. Patients with a laboratory-confirmed diagnosis of SARS-CoV-2-infection, moderate to severe ARDS (meeting Berlin criteria for a diagnosis of ARDS with a PaO2/FiO2 ratio <200 mmHg), >18 years of age and requiring invasive or non-invasive mechanical ventilation. All individuals meeting any of the following exclusion criteria at baseline or during screening will be excluded from study participation: more than 96 hours has elapsed from onset of ARDS; age < 18 years; known to be pregnant or breastfeeding; participation in a clinical trial of an investigational medicinal product (other than antibiotics or antivirals) within 30 days; major trauma in the prior 5 days; presence of any active malignancy (other than nonmelanoma skin cancer) which required treatment within the last year; WHO Class III or IV pulmonary hypertension; pulmonary embolism prior to hospital admission within past 3 months; currently receiving extracorporeal life support (ECLS); chronic kidney disease receiving dialysis; severe chronic liver disease with Child-Pugh score > 12; DNAR (Do Not Attempt Resuscitation) order in place; treatment withdrawal imminent within 24 hours; Prisoners; non-English speaking patients or those who do not adequately understand verbal or written information unless an interpreter is available; IgA deficiency. INTERVENTION AND COMPARATOR: Intervention: Either a once weekly intravenous infusion of Prolastin® at 120mg/kg of body weight for 4 weeks or a single dose of Prolastin® at 120mg/kg of body weight intravenously followed by once weekly intravenous infusion of an equal volume of 0.9% sodium chloride for a further 3 weeks. Comparator (placebo): An equal volume of 0.9% sodium chloride intravenously once per week for four weeks. MAIN OUTCOMES: The primary effectiveness outcome measure is the change in plasma concentration of IL-6 at 7 days as measured by ELISA. Secondary outcomes include: safety and tolerability of Prolastin® in the respective groups (as defined by the number of SAEs and AEs); PaO2/FiO2 ratio; respiratory compliance; sequential organ failure assessment (SOFA) score; mortality; time on ventilator in days; plasma concentration of alpha-1 antitrypsin (AAT) as measured by nephelometry; plasma concentrations of interleukin-1ß (IL-1ß), interleukin-8 (IL-8), interleukin-10 (IL-10), soluble TNF receptor 1 (sTNFR1, a surrogate marker for TNF-α) as measured by ELISA; development of shock; acute kidney injury; need for renal replacement therapy; clinical relapse, as defined by the need for readmission to the ICU or a marked decline in PaO2/FiO2 or development of shock or mortality following a period of sustained clinical improvement; secondary bacterial pneumonia as defined by the combination of radiographic findings and sputum/airway secretion microscopy and culture. RANDOMISATION: Following informed consent/assent patients will be randomised. The randomisation lists will be prepared by the study statistician and given to the unblinded trial personnel. However, the statistician will not be exposed to how the planned treatment will be allocated to the treatment codes. Randomisation will be conducted in a 1:1:1 ratio, stratified by site and age. BLINDING (MASKING): The investigator, treating physician, other members of the site research team and patients will be blinded to treatment allocation. The clinical trial pharmacy personnel and research nurses will be unblinded to facilitate intervention and placebo preparation. The unblinded individuals will keep the treatment information confidential. The infusion bag will be masked at the time of preparation and will be administered via a masked infusion set to maintain blinding. NUMBERS TO BE RANDOMISED (SAMPLE SIZE): A total of 36 patients will be recruited and randomised in a 1:1:1 ratio to each of the trial arms. TRIAL STATUS: In March 2020, version 1.0 of the trial protocol was submitted to the local research ethics committee (REC), Health Research Consent Declaration Committee (HRCDC) and the Health Products regulatory Authority (HPRA). REC approval was granted on April 1st 2020, HPRA approval was granted on April 24th 2020 and the HRCDC provided a conditional declaration on April 17th 2020. In July 2020 a substantial amendment (version 2.0) was submitted to the REC, HRCDC and HPRA. Protocol changes in this amendment included: the addition of trial sites; extending the duration of the trial to 12 months from 3 months; removal of inclusion criteria requiring the need for vasopressors; amendment of randomisation schedule to stratify by age only and not BMI and sex; correction of grammatical error in relation to infusion duration; to allow for inclusion of subjects who may have been enrolled in a clinical trial involving either antibiotics or anti-virals in the past 30 days; to allow for inclusion of subjects who may be currently enrolled in a clinical trial involving either antibiotics or anti-virals; to remove the need for exclusion based on alpha-1 antitrypsin phenotype; removal of mandatory isoelectric focusing of plasma to confirm Pi*MM status at screening; removal of need for mandatory echocardiogram at screening; amendment on procedures around plasma analysis to reflect that this will be conducted at the central site laboratory (as trial is multi-site and no longer single site); wording amended to reflect that interim analysis of cytokine levels taken at 7 days may be conducted. HRCDC approved version 2.0 on September 14th 2020, and HPRA approved on October 22nd 2020. REC approved the substantial amendment on November 23rd. In November 2020, version 3.0 of the trial protocol was submitted to the REC and HPRA. The rationale for this amendment was to allow for patients with moderate to severe ARDS from SARS-CoV-2 with non-invasive ventilation. HPRA approved this amendment on December 1st 2020 and the REC approved the amendment on December 8th 2020. Patient recruitment commenced in April 2020 and the last patient will be recruited to the trial in April 2021. The last visit of the last patient is anticipated to occur in April 2021. At time of writing, patient recruitment is now complete, however follow-up patient visits and data collection are ongoing. TRIAL REGISTRATION: EudraCT 2020-001391-15 (Registered 31 Mar 2020). FULL PROTOCOL: The full protocol (version 3.0 23.11.2020) is attached as an additional file accessible from the Trials website (Additional file 1). In the interest in expediting dissemination of this material, the familiar formatting has been eliminated; this Letter serves as a summary of the key elements of the full protocol. The study protocol has been reported in accordance with the Standard Protocol Items: Recommendations for Clinical Interventional Trials (SPIRIT) guidelines (Additional file 2).

Characterization of Secondary Bacterial Infections and Antibiotic Use in Mechanically Ventilated Patients With COVID-19 Induced Acute Respiratory Distress Syndrome.

BACKGROUND: COVID-19 has a widely variable clinical syndrome that is difficult to distinguish from bacterial sepsis, leading to high rates of antibiotic use. Early studies indicate low rates of secondary bacterial infections (SBIs) but have included heterogeneous patient populations. Here, we catalogue all SBIs and antibiotic prescription practices in a population of mechanically ventilated patients with COVID-19 induced acute respiratory distress syndrome (ARDS). METHODS: This was a retrospective cohort study of all patients with COVID-19 ARDS requiring mechanical ventilation from 3 Seattle, Washington hospitals in 2020. Data were obtained via electronic and manual review of the electronic medical record. We report the incidence and site of SBIs, mortality, and antibiotics per day using descriptive statistics. RESULTS: We identified 126 patients with COVID-19 induced ARDS during the study period. Of these patients, 61% developed clinical infection confirmed by bacterial culture. Ventilator associated pneumonia was confirmed in 55% of patients, bacteremia in 20%, and urinary tract infection (UTI) in 17%. Staphylococcus aureus was the most commonly isolated bacterial species. A total of 97% of patients received antibiotics during their hospitalization, and patients received nearly one antibiotic per day during their hospital stay. CONCLUSIONS: Mechanically ventilated patients with COVID-19 induced ARDS are at high risk for secondary bacterial infections and have extensive antibiotic exposure.

A Potent Leukocyte Transmigration Blocker: GT-73 Showed a Protective Effect against LPS-Induced ARDS in Mice.

We recently developed a molecule (GT-73) that blocked leukocyte transendothelial migration from blood to the peripheral tissues, supposedly by affecting the platelet endothelial cell adhesion molecule (PECAM-1) function. GT-73 was tested in an LPS-induced acute respiratory distress syndrome (ARDS) mouse model. The rationale for this is based on the finding that the mortality of COVID-19 patients is partly caused by ARDS induced by a massive migration of leukocytes to the lungs. In addition, the role of tert-butyl and methyl ester moieties in the biological effect of GT-73 was investigated. A human leukocyte, transendothelial migration assay was applied to validate the blocking effect of GT-73 derivatives. Finally, a mouse model of LPS-induced ARDS was used to evaluate the histological and biochemical effects of GT-73. The obtained results showed that GT-73 has a unique structure that is responsible for its biological activity; two of its chemical moieties (tert-butyl and a methyl ester) are critical for this effect. GT-73 is a prodrug, and its lipophilic tail covalently binds to PECAM-1 via Lys536. GT-73 significantly decreased the number of infiltrating leukocytes in the lungs and reduced the inflammation level. Finally, GT-73 reduced the levels of IL-1ß, IL-6, and MCP-1 in bronchoalveolar lavage fluid (BALF). In summary, we concluded that GT-73, a blocker of white blood cell transendothelial migration, has a favorable profile as a drug candidate for the treatment of ARDS in COVID-19 patients.

Monitoring lung injury with particle flow rate in LPS- and COVID-19-induced ARDS.

In severe acute respiratory distress syndrome (ARDS), extracorporeal membrane oxygenation (ECMO) is a life-prolonging treatment, especially among COVID-19 patients. Evaluation of lung injury progression is challenging with current techniques. Diagnostic imaging or invasive diagnostics are risky given the difficulties of intra-hospital transportation, contraindication of biopsies, and the potential for the spread of infections, such as in COVID-19 patients. We have recently shown that particle flow rate (PFR) from exhaled breath could be a noninvasive, early detection method for ARDS during mechanical ventilation. We hypothesized that PFR could also measure the progress of lung injury during ECMO treatment. Lipopolysaccharide (LPS) was thus used to induce ARDS in pigs under mechanical ventilation. Eight were connected to ECMO, whereas seven animals were not. In addition, six animals received sham treatment with saline. Four human patients with ECMO and ARDS were also monitored. In the pigs, as lung injury ensued, the PFR dramatically increased and a particular spike followed the establishment of ECMO in the LPS-treated animals. PFR remained elevated in all animals with no signs of lung recovery. In the human patients, in the two that recovered, PFR decreased. In the two whose lung function deteriorated while on ECMO, there was increased PFR with no sign of recovery in lung function. The present results indicate that real-time monitoring of PFR may be a new, complementary approach in the clinic for measurement of the extent of lung injury and recovery over time in ECMO patients with ARDS.