Sonographic follow-up of diaphragm function in COVID-19: an exploratory study

Introduction

Survivors of COVID-19 frequently endure chronic disabilities. We hypothesize that diaphragm function has a long recovery time after COVID-19 hospitalization, and may play a role in post-COVID syndrome. The aim of this study was to assess diaphragm function during COVID-19 hospitalization and during recovery.

Methods

We conducted a prospective single-center cohort study in 49 patients enrolled, of which 28 completed one-year follow-up. Participants were evaluated for diaphragm function. Diaphragm function was assessed using ultrasound measuring of diaphragm thickening fraction (TF) within 24 h after admission, after 7 days of admission or at discharge, whichever came first, and three and twelve months after hospital admission.

Results

Estimated mean TF increased from 0.56 (95% CI 0.46–0.66) on admission to 0.78 (95% CI 0.65–0.89) at discharge or seven days after admission, to 1.05 (95% CI 0.83–1.26) three months after admission to 1.54 (95% CI 1.31–1.76) twelve months after admission. The improvements from admission to discharge, 3 months and 12 months were all significant (linear mixed modeling; p=0.020, p<0.001, and p<0.001, respectively) and the improvement from discharge to three months follow-up was borderline significant (p<0.1).

Conclusion

Diaphragm function was impaired during hospitalization for COVID-19. During recovery in hospital and up to one-year follow-up, diaphragm TF improved, suggesting a long recovery time of the diaphragm. Diaphragm ultrasound may be a valuable modality in the screening and follow-up of (post-)COVID-19 patients for diaphragm dysfunction.

The value of thymus and activation related chemokine immunohistochemistry in classic Hodgkin lymphoma diagnostics

AIMS

Classic Hodgkin lymphoma (cHL) should be distinguished from its wide variety of histological mimics, including reactive conditions and mature B and T cell neoplasms. Thymus and activation-related chemokine (TARC) is produced in extremely high quantities by the Hodgkin/Reed-Sternberg (HRS) tumour cells and is largely responsible for the attraction of CD4⁺ T cells into the cHL tumour micro-environment. In the current study we evaluated the diagnostic potential of TARC immunohistochemistry in daily practice in a tertiary referral centre in the Netherlands.

METHODS AND RESULTS

A total of 383 cases, approximately half of which were cHL mimics, were prospectively evaluated in the period from June 2014 to November 2020. In 190 cHL cases, 92% were TARC-positive and the majority of cases showed strong and highly specific staining in all HRS cells (77%). In most cases, TARC could discriminate between nodular lymphocyte-predominant and lymphocyte-rich Hodgkin lymphoma. HRS-like cells in mature lymphoid neoplasms were rarely positive (6.4%) and there was no TARC staining at all in 64 reactive lymphadenopathies.

CONCLUSIONS

TARC immunohistochemistry has great value in differentiating between cHL and its mimics, including nodular lymphocyte-predominant Hodgkin lymphoma, reactive lymphadenopathies and mature lymphoid neoplasms with HRS-like cells.

[Non-invasive respiratory support in acute respiratory distress]

Conventional oxygen therapy could be delivered via nasal prongs, face mask, venturi mask, or non-rebreather mask. High flow nasal cannula (HFNC) produces a higher flow of FiO2. This higher flow creates a positive pressure on the higher respiratory tract. Collapsed alveoli could be opened due to this positive pressure and CO2 would be eliminated. This improves the oxygenation and reduces the total work of breathing. Continuous positive pressure support (CPAP) realizes a continuous positive expiratory pressure to the respiratory tract, which opens the alveoli and reduces the pre-load by reducing the venous return. Non-invasive ventilation (NIV) improves ventilation and reduces the work of breathing. Initiating use of HFNC, CPAP or NIV can prevent intubation but the response should be carefully evaluated after 1-2 hours to not delay intubation.

Pemphigus--paradigm of autoantibody-mediated autoimmunity

Pemphigus encompasses a group of life-threatening autoimmune blistering diseases due to a loss of adhesion between keratinocytes, called acantholysis, which is caused by autoantibodies (AAb) against intercellular adhesion structures of epidermal keratinocytes. In pemphigus vulgaris (PV), the blisters are located in the suprabasal layer whereas in pemphigus foliaceus (PF), a clinically less severe disease, the blisters occur within the upper layers of the epidermis. In PV and PF, the AAb target the extracellular portions of desmoglein 3 (Dsg3) and Dsg1, respectively. AAb production in PV and PF is polyclonal and most AAb are of the IgG4 subclass in acute onset or active disease while patients in remission have mainly AAb of the IgG1 subtype. Evidence for the pathogenicity of these circulating AAb is provided by the observations that (1) the activity of pemphigus correlates with AAb titers, (2) newborns of mothers with active pemphigus temporarily exhibit blisters due to the transplacentar transfer of maternal AAb and (3) pemphigus-like lesions are induced in neonatal mice by transfer of IgG from PV patients. Clinically, pemphigus is characterized by extensive cutaneous blisters and erosions of the mucous membranes (PV). Patients with untreated pemphigus are prone to infections, loss of body fluids and proteins and to weight loss due to painful oral and esophageal erosions. The major therapeutic strategy in pemphigus is chronic immunosuppressive therapy with glucocorticosteroids in combination with immunosuppressive adjuvants.

Calcium and insulin-like growth factor I stimulation of sodium-dependent phosphate transport and proliferation of cultured rat osteoblasts

Calcium (Ca) stimulates proliferation of osteoblasts in vitro, an effect proposed to be mediated by IGF I. Addition of 1 mM Ca or of 1 nM IGF I to the medium (0.3 mM Ca) of a rat bone-derived cell line, PyMS, stimulated not only DNA synthesis but also sodium-dependent (Nad) phosphate (Pi) uptake, the latter, within 2 h. These cells barely express and produce IGF I. IGF binding protein-3 which inhibits IGF action decreased neither basal nor Ca-stimulated but IGF I-stimulated NadPi transport and DNA synthesis, indicating that Ca stimulated NadPi transport and DNA synthesis independently of IGF I. The effects of Ca and IGF I on DNA synthesis were additive. 1 microM nifedipine blocked IGF I- and Ca-stimulated DNA synthesis but not NadPi transport, suggesting that Ca influx is not mediating the NadPi transport-enhancing IGF I signal but is required for IGF I-induced osteoblast proliferation.