Histopathological features in fatal COVID-19 acute respiratory distress syndrome

Background

COVID-19 acute respiratory distress syndrome (ARDS) shares the common histological hallmarks with other forms of ARDS. However, the chronology of the histological lesions has not been well established.

Objective

To describe the chronological histopathological alterations in the lungs of patients with COVID-19 related ARDS.

Design

A prospective cohort study was carried out.

Setting

Intensive Care Unit of a tertiary hospital.

Patients

The first 22 consecutive COVID-19 deaths.

Measurements

Lung biopsies and histopathological analyses were performed in deceased patients with COVID-19 related ARDS. Clinical data and patient course were evaluated.

Results

The median patient age was 66 [63–74] years; 73% were males. The median duration of mechanical ventilation was 17 [8–24] days. COVID-19 induced pulmonary injury was characterized by an exudative phase in the first week of the disease, followed by a proliferative/organizing phase in the second and third weeks, and finally an end-stage fibrosis phase after the third week. Viral RNA and proteins were detected in pneumocytes and macrophages in a very early stage of the disease, and were no longer detected after the second week.

Limitation

Limited sample size.

Conclusions

The chronological evolution of COVID-19 lung histopathological lesions seems to be similar to that seen in other forms of ARDS. In particular, lung lesions consistent with potentially corticosteroid-sensitive lesions are seen.

Histopathological features in fatal COVID-19 acute respiratory distress syndrome

Background

COVID-19 acute respiratory distress syndrome (ARDS) shares the common histological hallmarks with other forms of ARDS. However, the chronology of the histological lesions has not been well established.

Objective

To describe the chronological histopathological alterations in the lungs of patients with COVID-19 related ARDS.

Design

A prospective cohort study was carried out.

Setting

Intensive Care Unit of a tertiary hospital.

Patients

The first 22 consecutive COVID-19 deaths.

Measurements

Lung biopsies and histopathological analyses were performed in deceased patients with COVID-19 related ARDS. Clinical data and patient course were evaluated.

Results

The median patient age was 66 [63–74] years; 73% were males. The median duration of mechanical ventilation was 17 [8–24] days. COVID-19 induced pulmonary injury was characterized by an exudative phase in the first week of the disease, followed by a proliferative/organizing phase in the second and third weeks, and finally an end-stage fibrosis phase after the third week. Viral RNA and proteins were detected in pneumocytes and macrophages in a very early stage of the disease, and were no longer detected after the second week.

Limitation

Limited sample size.

Conclusions

The chronological evolution of COVID-19 lung histopathological lesions seems to be similar to that seen in other forms of ARDS. In particular, lung lesions consistent with potentially corticosteroid-sensitive lesions are seen.

Outcomes of hospitalized patients with SARS-CoV-2 infection previously treated with renin-angiotensin system inhibitors

Background

Renin angiotensin system inhibitors (RASi) are largely prescribed in hypertensive patients. As severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) penetrates respiratory epithelium through angiotensin converting enzyme 2 (ACE2) binding, the association between RASi and poorer outcomes has been questioned.

Purpose

This study aimed to provide insight on the impact of RASi on SARS-CoV-2 outcomes in a population of patients hospitalized for COVID-19.

Methods

This is a retrospective analysis of consecutively hospitalized adult patients with SARS-CoV-2 infection (positive rtPCR) admitted to the University Hospital of Strasbourg from the 25th Feb, 2020 to the 1st Apr, 2020. Patients hospitalized for less than 24 h were excluded and the observation period ended at hospital discharge.

Results

During the study period, 943 COVID-19 patients were hospitalized in our institution, of whom 772 were included in this analysis. Among them, 431 patients had previously known hypertension. The median age was 68 (56–79). The cohort was divided into two subgroups based on RASi treatment on admission: “RASi” (n = 282) and “RASi-free” (n = 490). Both groups had similar clinical presentations and equivalent recourse to endotracheal intubation, high flow nasal oxygen (HFNO) or non-invasive ventilation (NIV). Overall, 220 patients were placed under mechanical ventilation of whom 30% died. Severe pneumonia (defined as either leading to death, and/or requiring intubation, HFNO, NIV and/or requiring an oxygen rate flow ≥ 5l/min) and death occurred more frequently in RASi treated patients (63% vs. 53% and respectively 27.3% versus 18.2%). In a multivariate logistic-regression model, neither severe pneumonia nor death were associated with RASi treatment.

Conclusion

Our study showed no correlation between RASi treatment and death or severe COVID-19 pneumonia.

Venous thromboembolism frequency in patients hospitalized for SARS-CoV-2 infection

Background

SARS-CoV-2 infection was associated with a higher thrombotic risk, partially explained by intense systemic inflammatory reaction, longer hospitalizations and intubations as well as central catheters and extracorporeal membrane oxygenation devices. Intrinsic thrombotic potential is questioned as certain patients had plasma lupus anticoagulant (LAC).

Purpose

This study aimed to evaluate the frequency of venous thromboembolism (VTE) among adult patients hospitalized for COVID-19.

Methods

This is a retrospective analysis of consecutively hospitalized adult patients with SARS-CoV-2 infection (positive rtPCR) admitted to the University Hospital of Strasbourg from the 25th Feb, 2020 to the 1st Apr, 2020. Patients hospitalized for less than 24 h were excluded and the observation period ended at hospital discharge.

Results

During the study period, 943 COVID-19 patients were hospitalized in our institution, of whom 772 were included in this analysis. The median age was 68 (56–79) years old and 58 patients had previously known VTE. Overall, VTE occurred in 60 patients (7.8%): 43 pulmonary embolisms (PE), 15 isolated deep vein thrombosis and 2 superficial vein thrombosis. Of note, 81% of patients had been prescribed an anticoagulant treatment on admission. VTE incidence was higher in patients with more severe forms of pneumonia defined as either leading to death, and/or requiring intubation/high flow nasal oxygen/non-invasive ventilation (21% versus 2%, P < 0.001). Overall mortality was 21% and death rate was higher in patients that presented a VTE event (35% versus 20%, P = 0.012). Among VTE patients, a search for LAC was performed in 72% of them and came back positive in 88% of cases. Overall, 33 major bleeding complications (4.3%) were observed of which 42% were intracranial.

Conclusion

Our study showed that in-hospital VTE occurred more frequently in case of severe COVID-19 pneumonia and was associated with higher death rates.

Outbreak of psittacosis in a group of women exposed to Chlamydia psittaci-infected chickens

Eight cases of psittacosis due to Chlamydia psittaci were identified in May 2013 among 15 individuals involved in chicken gutting activities on a mixed poultry farm in France. All cases were women between 42 and 67 years-old. Cases were diagnosed by serology and PCR of respiratory samples. Appropriate treatment was immediately administered to the eight hospitalised individuals after exposure to birds had been discovered. In the chicken flocks, mainly C. gallinacea was detected, a new member of the family Chlamydiaceae, whereas the ducks were found to harbour predominantly C. psittaci, the classical agent of psittacosis. In addition, C. psittaci was found in the same flock as the chickens that the patients had slaughtered. Both human and C. psittaci-positive avian samples carried the same ompA genotype E/B of C. psittaci, which is widespread among French duck flocks. Repeated grassland rotations between duck and chicken flocks on the farm may explain the presence of C. psittaci in the chickens. Inspection by the veterinary service led to temporary closure of the farm. All birds had to be euthanised on site as no slaughterhouses accepted processing them. Farm buildings and grasslands were cleaned and/or disinfected before the introduction of new poultry birds.

Resistive Index or color-Doppler semi-quantitative evaluation of renal perfusion by inexperienced physicians: results of a pilot study

BACKGROUND

Doppler-based renal resistive index (RI) calculation may help in the early detection of acute kidney injury (AKI). Its feasibility and reproducibility by inexperienced operators remain unknown. The main objective of this study was to compare performances of junior and senior operators in assessing renal perfusion using both the semiquantitative color-Doppler scale and RI calculation.

METHODS

Prospective cohort study performed in 3 ICUs. Inexperienced juniors physicians attended a half-day course on renal perfusion assessment using RI calculation and color-Doppler (from 0, absence of renal perfusion; to 3, renal vessels identifiable in the entire field of view). Junior and senior operators used both methods in 69 mechanically ventilated patients, in blind fashion.

RESULTS

Failure to obtain RI occurred for a junior operator in a single patient. RI and color-Doppler semi-quantitative values obtained by operators were correlated (r²=0.64 and r²=0.61, respectively). Systematic bias across operators as assessed using Bland-Altman plots was negligible (-0.001 and -0.29, respectively), although precision was limited (95% confidence intervals, +0.105 to -0.107 and +0.98 to -1.04, respectively). RI calculation and semi-quantitative assessment performed well for diagnosing persistent AKI (area under the receiver-operating characteristic curve, 0.84 [95% confidence interval, 0.73-0.97] and 0.87 [0.77-0.97], respectively).

CONCLUSION

A brief course on renal Doppler allowed inexperienced operators to assess effectively renal perfusion with a good reliability when compared to senior operators. In addition, our results suggest the good diagnostic performance of both Doppler-based RI and semi-quantitative renal perfusion assessment in predicting short-term renal dysfunction reversibility.

Microparticles and infectious diseases

Membrane shedding with microvesicle (MV) release after membrane budding due to cell stimulation is a highly conserved intercellular interplay. MV can be released by micro-organisms or by host cells in the course of infectious diseases. Host MVs are divided according to cell compartment origin in microparticles (MPs) from plasma membrane and exosomes from intracellular membranes. MPs are cell fragments resulting from plasma membrane reorganization characterized by phosphatidylserine (PhtdSer) content and parental cell antigens on membrane. The role of MPs in physiology and pathophysiology is not yet well elucidated; they are a pool of bioactive molecules able to transmit a pro-inflammatory message to neighboring or target cells. The first acknowledged function of MP was the dissemination of a procoagulant potential via PhtdSer and it is now obvious than MPs bear tissue factor (TF). Such MPs have been implicated in the coagulation disorders observed during sepsis and septic shock. MPs have been implicated in the regulation of vascular tone and cardiac dysfunction in experimental sepsis. Beside a non-specific role, pathogens such as Neisseria meningitidis and Ebola Virus can specifically activate blood coagulation after TF-bearing MPs release in the bloodstream with disseminated intravascular coagulopathy and Purpura fulminans. The role of MPs in host-pathogen interactions is also fundamental in Chagas disease, where MPs could allow immune evasion by inhibiting C3 convertase. During cerebral malaria, MPs play a complex role facilitating the activation of brain endothelium that contributes to amplify vascular obstruction by parasitized erythrocytes. Phagocytosis of HIV induced MPs expressing PhtdSer by monocytes/macrophages results in cellular infection and non-inflammatory response via up-regulation of TGF-β.

Vascular hyporesponsiveness to vasopressors in septic shock: from bench to bedside

PURPOSE

To delineate some of the characteristics of septic vascular hypotension, to assess the most commonly cited and reported underlying mechanisms of vascular hyporesponsiveness to vasoconstrictors in sepsis, and to briefly outline current therapeutic strategies and possible future approaches.

METHODS

Source data were obtained from a PubMed search of the medical literature with the following MeSH terms: Muscle, smooth, vascular/physiopathology; hypotension/etiology; shock/physiopathology; vasodilation/physiology; shock/therapy; vasoconstrictor agents.

RESULTS

Nitric oxide (NO) and peroxynitrite are crucial components implicated in vasoplegia and vascular hyporeactivity. Vascular ATP-sensitive and calcium-activated potassium channels are activated during shock and participate in hypotension. In addition, shock state is characterized by inappropriately low plasma glucocorticoid and vasopressin concentrations, a dysfunction and desensitization of alpha-receptors, and an inactivation of catecholamines by oxidation. Numerous other mechanisms have been individualized in animal models, the great majority of which involve NO: MEK1/2-ERK1/2 pathway, H(2)S, hyperglycemia, and cytoskeleton dysregulation associated with decreased actin expression.

CONCLUSIONS

Many therapeutic approaches have proven their efficiency in animal models, especially therapies directed against one particular compound, but have otherwise failed when used in human shock. Nevertheless, high doses of catecholamines, vasopressin and terlipressin, hydrocortisone, activated protein C, and non-specific shock treatment have demonstrated a partial efficiency in reversing sepsis-induced hypotension.

Origin and Biological Significance of Shed-Membrane Microparticles

Microparticles (MPs) are small vesicles released from the membrane surface during eukaryotic cell activation or apoptosis. They originate from various cell types, displaying the typical surface cell proteins and cytoplasmic components of their cell origin. Their procoagulant properties are linked to phosphatidylserine exposed at their surface. Numerous reports have shown that MPs are able to mediate long-range signaling, acting on different targets from those of their own cellular origin. MPs-mediated binding to other cells occurs by integration into the membrane, by adhesion to the cell surface or by ligand-receptor interaction. Elevated levels of circulating MPs have been detected in cardiovascular and immune-mediated diseases. Despite extensive studies of the procoagulant and pro-inflammatory properties of MPs, little is known about their effect on vascular function. MPs accumulate in atherosclerotic plaques and injured vascular wall. Circulating MPs from patients with myocardial infarction induce endothelial dysfunction by impairing the endothelial nitric oxide (NO) pathway, without causing changes in endothelial NO-synthase (eNOS) expression. However, MPs from T-cells may induce endothelial dysfunction, altering gene expression of eNOS and caveolin-1. Moreover, MPs may promote the expression of pro-inflammatory proteins implicated in vascular contractility alterations. This review describes the origin of MPs and their biological role in physiological conditions and in various pathological states, with special reference to the possible linkage between their pro-inflammatory and procoagulant properties and vascular dysfunction.

Fatal allergic vasculitis associated with celecoxib

We report on the occurrence of a rare and as yet unforseeable adverse reaction to treatment with celecoxib, a cyclooxygenase-2 (COX-2) selective, non-steroidal, anti-inflammatory drug. A previously healthy adult suffered fatal acute multiple organ failure presumably after diffuse allergic vasculitis with diffuse necrotic purpura. Although no conclusive proof is available, such a reaction could have been triggered by at least one of two mechanisms: an allergic reaction linked to the chemical structure of celecoxib; or an interaction of the drug with synthesis of endothelial eiconasoids leading to an imbalance between vasoactive end products, resulting in widespread rise to local thrombosis.