Pathophysiology of light phenotype SARS-CoV-2 interstitial pneumonia: from histopathological features to clinical presentations

Transbronchial lung cryobiopsy for peripheral pulmonary lesions. A narrative review

An increasing number of peripheral pulmonary lesions (PPLs) requiring tissue verification to establish a definite diagnosis for further individualized management are detected due to the growing adoption of lung cancer screening by chest computed tomography (CT), especially low-dose CT. However, the morphological diagnosis of PPLs remains challenging. Transbronchial lung cryobiopsy (TBLC) that can retrieve larger specimens with more preserved cellular architecture and fewer crush artifacts in comparison with conventional transbronchial forceps biopsy (TBFB), as an emerging technology for diagnosing PPLs, has been demonstrated to have the potential to resolve the clinical dilemma pertaining to currently available sampling devices (e.g., forceps, needle and brush) and become a diagnostic cornerstone for PPLs. Of note, with the introduction of the 1.1 mm cryoprobe that will be more compatible with advanced bronchoscopic navigation techniques, such as radial endobronchial ultrasound (r-EBUS), virtual bronchoscopic navigation (VBN) and electromagnetic navigation bronchoscopy (ENB), the use of TBLC is expected to gain more popularity in the diagnosis of PPLs. While much remains for exploration using the TBLC technique for diagnosing PPLs, it can be envisaged that the emergence of additional studies with larger data accrual will hopefully add to the body of evidence in this field.

Platypnea-Orthodeoxia Syndrome and COVID-19 Successfully Treated With Percutaneous Patent Foramen Ovale Closure: A Report of Two Cases and Literature Review

Platypnea-orthodeoxia syndrome (POS) is a rare clinical condition characterized by positional dyspnea and/or hypoxia. We report two cases of patients with COVID-19 bronchopneumonia with a torpid evolution. Due to clinical suspicion of POS, a diagnostic workup was performed, including a bubble echocardiography, which revealed a patent foramen ovale (PFO) with early and massive passage of bubbles to the left cavities. Both patients underwent percutaneous PFO closure with a resolution of POS. Here, we present the second and third cases of POS associated with PFO successfully closed during the acute phase of COVID-19. This suggests that PFO closure could be a potential treatment option for this condition.

Platypnoea-orthodeoxia syndrome in COVID-19 pneumonia patients: An observational study

This retrospective observational study aimed to assess the clinical characteristics of platypnea-orthodeoxia syndrome in patients with coronavirus disease 2019 (COVID-19) treated using mechanical ventilation or high-flow nasal canula. We analyzed 42 consecutive patients with COVID-19 from January 2020 to March 2022. The primary outcomes were the incidence of platypnea-orthodeoxia syndrome, the time with required long-term oxygen therapy, and short-term prognosis. Additionally, we examined the relationships between platypnea-orthodeoxia syndrome and COVID-19 severity, the time with long-term oxygen therapy, and short-term prognosis. Of the 42 included patients, 15 (35.7 %) had platypnea-orthodeoxia syndrome. Although mortality was not significantly different between both groups, the oxygen withdrawal rate in the platypnea-orthodeoxia syndrome group was significantly lower than that in the group without this syndrome. Clinical staff should be aware of the possibility of platypnea-orthodeoxia syndrome during positional changes in patients with COVID-19. Recognizing POS can improve early detection, countermeasures, and safety during physiotherapy.

Diabetic Pneumopathy- A Novel Diabetes-associated Complication: Pathophysiology, the Underlying Mechanism and Combination Medication

BACKGROUND

The "diabetic lung" has been identified as a possible target organ in diabetes, with abnormalities in ventilation control, bronchomotor tone, lung volume, pulmonary diffusing capacity, and neuroadrenergic bronchial innervation.

OBJECTIVE

This review summarizes studies related to diabetic pneumopathy, pathophysiology and a number of pulmonary disorders including type 1 and type 2 diabetes.

METHODS

Electronic searches were conducted on databases such as Pub Med, Wiley Online Library (WOL), Scopus, Elsevier, ScienceDirect, and Google Scholar using standard keywords "diabetes," "diabetes Pneumopathy," "Pathophysiology," "Lung diseases," "lung infection" for review articles published between 1978 to 2023 very few previous review articles based their focus on diabetic pneumopathy and its pathophysiology.

RESULTS

Globally, the incidence of diabetes mellitus has been rising. It is a chronic, progressive metabolic disease. The "diabetic lung" may serve as a model of accelerated ageing since diabetics' rate of respiratory function deterioration is two to three-times higher than that of normal, non-smoking people.

CONCLUSION

Diabetes-induced pulmonary dysfunction has not gained the attention it deserves due to a lack of proven causality and changes in cellular properties. The mechanism underlying a particular lung illness can still only be partially activated by diabetes but there is evidence that hyperglycemia is linked to pulmonary fibrosis in diabetic people.

COVID-19. Biology, pathophysiology, and immunology: a pathologist view

Even if the SARS-CoV-2 pandemic has been declared over, several risks and clinical problems remain to be faced, including long-COVID sequelae and possible outbreaks of pathogenic variants. Intense research on COVID-19 has provided in these few years a striking amount of data covering different fields and disciplines, which can help to provide a knowledge shield against new potential infective spreads, and may also potentially be applied to other fields of medicine, including oncology and neurology. Nevertheless, areas of uncertainty still remain regarding the pathogenic mechanisms that subtend the multifaceted manifestations of the disease. To better clarify the pathogenesis of the disease, a systematic multidisciplinary evaluation of the many mechanisms involved in COVID-19 is mandatory, including clinical, physiological, radiological, immunological and pathological studies. In COVID-19 syndrome the pathological studies have been mainly performed on autopsy cases, and only a few studies are available on biopsies. Nevertheless, these studies have provided relevant information that can substantially contribute to decipher the complex scenario characterizing the different forms of COVID-19 and long-COVID-19. In this review the data provided by pathological investigations are recapitulated and discussed, in the light of different hypothesis and data provided by clinical, physiological and immunological data.

Platypnea-Orthodeoxia Syndrome in Coronavirus Disease 2019 Pneumonia: A Case Report and Literature Review

Platypnea-orthodeoxia syndrome (POS) is a rare disorder associated with coronavirus disease 2019 (COVID-19) pneumonia. However, POS may be underdiagnosed. We report the case of a 59-year-old female patient with POS complicated by pulmonary embolism in COVID-19. Imaging revealed ground-glass opacities predominantly in the lower lobes and a pulmonary embolus in the right upper lobe. She was diagnosed with POS due to marked postural discrepancies between supine and upright oxygen saturations and blood oxygenation. Intracardiac shunt, one of the etiologies of POS, was not detected by bubble contrast echocardiography, and postural de-saturation gradually improved with methylprednisolone and edoxaban administration. In our literature review, only 3 of the 16 patients with POS associated with COVID-19 had cardiac shunting, suggesting that moderate to severe COVID-19 causes POS without cardiac shunts. COVID-19-associated vasculopathy and lower lung lesion predominance in COVID-19 pneumonia may cause ventilation-perfusion mismatch due to gravitational shunting of blood into the poorly ventilated lower lungs in the upright position, which may ultimately cause POS. Hypoxemia impedes rehabilitation, whereas early initiation of supine positioning in bed, with knowledge of the pathophysiology of POS, may have a positive effect.

Clinical, radiological and pathological findings in patients with persistent lung disease following SARS-CoV-2 infection

Some patients experience pulmonary sequelae after SARS-CoV-2 infection, ranging from self-limited abnormalities to major lung diseases. Morphological analysis of lung tissue may help our understanding of pathogenic mechanisms and help to provide consistent personalised management. The aim of this study was to ascertain morphological and immunomolecular features of lung tissue. Transbronchial lung cryobiopsy was carried out in patients with persistent symptoms and computed tomography suggestive of residual lung disease after recovery from SARS-CoV-2 infection. 164 patients were referred for suspected pulmonary sequelae after COVID-19; 10 patients with >5% parenchymal lung disease underwent lung biopsy. The histological pattern of lung disease was not homogeneous and three different case clusters could be identified, which was mirrored by their clinical and radiological features. Cluster 1 ("chronic fibrosing") was characterised by post-infection progression of pre-existing interstitial pneumonias. Cluster 2 ("acute/subacute injury") was characterised by different types and grades of lung injury, ranging from organising pneumonia and fibrosing nonspecific interstitial pneumonia to diffuse alveolar damage. Cluster 3 ("vascular changes") was characterised by diffuse vascular increase, dilatation and distortion (capillaries and venules) within otherwise normal parenchyma. Clusters 2 and 3 had immunophenotypical changes similar to those observed in early/mild COVID-19 pneumonias (abnormal expression of STAT3 in hyperplastic pneumocytes and PD-L1, IDO and STAT3 in endothelial cells). This is the first study correlating histological/immunohistochemical patterns with clinical and radiological pictures of patients with post-COVID lung disease. Different phenotypes with potentially different underlying pathogenic mechanisms have been identified.

Unbalanced IDO1/IDO2 Endothelial Expression and Skewed Keynurenine Pathway in the Pathogenesis of COVID-19 and Post-COVID-19 Pneumonia

Despite intense investigation, the pathogenesis of COVID-19 and the newly defined long COVID-19 syndrome are not fully understood. Increasing evidence has been provided of metabolic alterations characterizing this group of disorders, with particular relevance of an activated tryptophan/kynurenine pathway as described in this review. Recent histological studies have documented that, in COVID-19 patients, indoleamine 2,3-dioxygenase (IDO) enzymes are differentially expressed in the pulmonary blood vessels, i.e., IDO1 prevails in early/mild pneumonia and in lung tissues from patients suffering from long COVID-19, whereas IDO2 is predominant in severe/fatal cases. We hypothesize that IDO1 is necessary for a correct control of the vascular tone of pulmonary vessels, and its deficiency in COVID-19 might be related to the syndrome’s evolution toward vascular dysfunction. The complexity of this scenario is discussed in light of possible therapeutic manipulations of the tryptophan/kynurenine pathway in COVID-19 and post-acute COVID-19 syndromes.

Platypnea-Orthodeoxia Syndrome after SARS-CoV-2 interstitial pneumonia: an overview and an update on our patient

Platypnea-Orthodeoxia Syndrome (POS) is a clinical entity defined as positional dyspnoea (platypnea) and arterial desaturation (orthodeoxia) that occurs when sitting or standing up and usually resolves by lying down. Up to April 25th 2021, eleven cases of POS after SARS-CoV-2 pneumonia have been reported on Pubmed. Accordingly, SARS-CoV-2 infection may be considered as an emergent cause of POS due to an increase in ventilation/perfusion (V/Q) mismatch. In this article we provide an update on the patient with POS after fibrotic evolution of SARS-CoV-2 interstitial pneumonia, which we previously reported and we discuss the case reports of POS due to SARS-CoV-2 infection.

Platypnoea-Orthodeoxia Syndrome in COVID-19

Platypnoea-orthodeoxia syndrome (POS) is a rare disorder and its pathophysiology has puzzled clinicians for years. Few cases of POS are described in COVID-19 patients in the literature, with a high variability of conditions related to the syndrome. In this article, we report the case of a patient admitted to our hospital for SARS-CoV-2 interstitial pneumonia, who developed POS during the hospitalization.

LEARNING POINTS

Platypnoea-orthodeoxia syndrome (POS) is a possible and rare condition associated with SARS-CoV-2 pneumonia.A prompt diagnosis of POS is important in order to start careful and adequate oxygen supplementation.Clinical data on COVID-19 evolution in patients with POS and possible therapeutic and rehabilitative strategies are not available in the literature.

Characteristics of COVID-19 Pneumonia Survivors With Resting Normoxemia and Exercise-Induced Desaturation

BACKGROUND

Survivors of coronavirus disease 2019 (COVID-19) associated pneumonia may show exercise-induced desaturation. We wondered whether these individuals show physiologic and symptom characteristics similar to individuals with chronic respiratory diseases with exercise-induced desaturation, namely COPD or interstitial lung diseases (ILD). We evaluated lung function, exercise capacity, and symptoms in these individuals compared with individuals with COPD or ILD and exercise-induced desaturation.

METHODS

Survivors of COVID-19 associated pneumonia (study individuals), normoxemic at rest with exercise-induced desaturation, underwent assessment of dyspnea, dynamic lung volumes, carbon monoxide diffusion capacity, and the 6-min walk test. Data of individuals with COPD or with ILD and exercise-induced desaturation were also retrospectively analyzed.

RESULTS

FVC was lower in individuals with COVID-19 or ILD than in those with COPD. Individuals who had COVID-19 walked < 70% of predicted and, as a whole, had a 6-min walk test performance similar to individuals with ILD but walked significantly less, showed more severe leg fatigue and dyspnea during exercise, and more exercise-induced desaturation than individuals with COPD.

CONCLUSIONS

Survivors of COVID-19 associated pneumonia, who were normoxemic at rest with exercise-induced desaturation, had alterations in lung function, exercise capacity, and symptoms similar to individuals with ILD but more severe than individuals with COPD and exercise-induced desaturation.

Extension of Collagen Deposition in COVID-19 Post Mortem Lung Samples and Computed Tomography Analysis Findings

Lung fibrosis has specific computed tomography (CT) findings and represents a common finding in advanced COVID-19 pneumonia whose reversibility has been poorly investigated. The aim of this study was to quantify the extension of collagen deposition and aeration in postmortem cryobiopsies of critically ill COVID-19 patients and to describe the correlations with qualitative and quantitative analyses of lung CT. Postmortem transbronchial cryobiopsy samples were obtained, formalin fixed, paraffin embedded and stained with Sirius red to quantify collagen deposition, defining fibrotic samples as those with collagen deposition above 10%. Lung CT images were analyzed qualitatively with a radiographic score and quantitatively with computer-based analysis at the lobe level. Thirty samples from 10 patients with COVID-19 pneumonia deceased during invasive mechanical ventilation were included in this study. The median [interquartile range] percent collagen extension was 6.8% (4.6-16.2%). In fibrotic compared to nonfibrotic samples, the qualitative score was higher (260 (250-290) vs. 190 (120-270), p = 0.036) while the gas fraction was lower (0.46 (0.32-0.47) vs. 0.59 (0.37-0.68), p = 0.047). A radiographic score above 230 had 100% sensitivity (95% confidence interval, CI: 66.4% to 100%) and 66.7% specificity (95% CI: 41.0% to 92.3%) to detect fibrotic samples, while a gas fraction below 0.57 had 100% sensitivity (95% CI: 66.4% to 100%) and 57.1% specificity (95% CI: 26.3% to 88.0%). In COVID-19 pneumonia, qualitative and quantitative analyses of lung CT images have high sensitivity but moderate to low specificity to detect histopathological fibrosis. Pseudofibrotic CT findings do not always correspond to increased collagen deposition.

Respiratory care for the critical patients with 2019 novel coronavirus

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is transmitted through respiratory droplets, aerosols and close contact. Cross infections occur because viruses spread rapidly among humans. Nineteen percent (19%) of the infected patients developed severe pneumonia and acute respiratory distress syndrome (ARDS). Hypoxemia usually occurs and patients may require oxygen therapy or mechanical ventilation (MV) support. In this article, recently published clinical experience and observational studies were reviewed. Corresponding respiratory therapy regarding different stages of infection is proposed. Infection control principles and respiratory strategies including oxygen therapy, non-invasive respiratory support (NIRS), intubation evaluation, equipment preparation, ventilator settings, special maneuvers comprise of the prone position (PP), recruitment maneuver (RM), extracorporeal membrane oxygenation (ECMO), weaning and extubation are summarized. Respiratory equipment and device disinfection recommendations are worked up. We expect this review article could be used as a reference by healthcare workers in patient care while minimizing the risk of environmental contamination.