Therapeutic plasma exchange: A potential therapeutic modality for critically ill adults with severe acute respiratory syndrome coronavirus 2 infection

Therapeutic plasma exchange accelerates immune cell recovery in severe COVID-19

Background

Immunological disturbances (anti-type I IFN auto-antibody production, cytokine storm, lymphopenia, T-cell hyperactivation and exhaustion) are responsible for disease exacerbation during severe COVID-19 infections.

Methods

In this study, we set up a prospective, randomised clinical trial (ClinicalTrials.gov ID: NCT04751643) and performed therapeutic plasma exchange (TPE) in severe COVID-19 patients in order to decrease excess cytokines and auto-antibodies and to assess whether adding TPE to the standard treatment (ST, including corticosteroids plus high-flow rate oxygen) could help restore immune parameters and limit the progression of acute respiratory distress syndrome (ARDS).

Results

As expected, performing TPE decreased the amount of anti-type I IFN auto-antibodies and improved the elimination or limited the production of certain inflammatory mediators (IL-18, IL-7, CCL2, CCL3, etc.) circulating in the blood of COVID-19 patients, compared to ST controls. Interestingly, while TPE did not influence changes in ARDS parameters throughout the protocol, it proved more effective than ST in reversing lymphopenia, preventing T-cell hyperactivation and reducing T-cell exhaustion, notably in a fraction of TPE patients who had an early favourable respiratory outcome. TPE also restored appropriate numbers of CD4+ and CD8+ T-cell memory populations and increased the number of circulating virus-specific T cells in these patients.

Conclusion

Our results therefore indicate that the addition of TPE sessions to the standard treatment accelerates immune cell recovery and contributes to the development of appropriate antiviral T-cell responses in some patients with severe COVID-19 disease.

Study on the clinical characteristics, treatment, and outcome influencing factors of severe pneumonia complicated with ARDS

To investigate the clinical characteristics, treatment methods, and factors influencing the prognosis of patients with severe pneumonia complicated by Acute Respiratory Distress Syndrome (ARDS), aiming to provide references for clinical decision-making and improve patient outcomes. A retrospective analysis was conducted on 118 patients with severe pneumonia complicated by ARDS treated at our hospital from June 2018 to December 2022. Based on treatment outcomes, patients were divided into a death group (n = 75) and a survival group (n = 43). General data and clinical laboratory indicators, including blood urea nitrogen, serum creatinine, C-reactive protein, procalcitonin, arterial partial pressure of oxygen, and arterial partial pressure of carbon dioxide, were collected and compared between the 2 groups to identify independent factors affecting prognosis. Among the 118 patients, the mortality rate was 63.56%. Patients in the death group had a significantly higher average age (57.15 ± 13.38 years) and a higher proportion of severe ARDS (66.67%) compared to the survival group (40.02 ± 11.41 years, 30.23%, P < .001). The death group had significantly lower white blood cell counts (8.10 ± 1.64 × 109/L), oxygenation index (19.82 ± 2.29), and duration of mechanical ventilation (7.79 ± 2.11 days) compared to the Survival group (8.92 ± 1.22 × 109/L, 13.42 ± 1.82, 12.23 ± 3.05 days, P < .05). Conversely, the death group had significantly higher levels of blood urea nitrogen (6.87 ± 1.80 mmol/L), C-reactive protein (130.55 ± 50.28 mg/L), procalcitonin (5.50 ± 2.11 ng/mL), arterial partial pressure of carbon dioxide (41.12 ± 5.56 mm Hg), and a higher proportion of viral infections (48.00%) compared to the survival group (5.90 ± 1.72 mmol/L, 101.77 ± 55.56 mg/L, 3.98 ± 1.15 ng/mL, 35.59 ± 6.22 mm Hg, 27.91%, P < .05). Logistic regression analysis revealed that age (odds ratios [OR] = 1.990, 95% confidence interval [CI]: 1.306-3.033, P < .001), oxygenation index (OR = 1.426, 95% CI: 1.123-1.649, P < .001), and duration of mechanical ventilation (OR = 0.694, 95% CI: 0.557-0.864, P < .001) were independent factors influencing patient prognosis. This indicates that an increase in age and a decrease in oxygenation index are associated with a significantly higher risk of mortality, while shorter mechanical ventilation duration is related to poorer prognosis. Advanced age, lower oxygenation index, and shorter duration of mechanical ventilation are unfavorable prognostic factors in patients with severe pneumonia complicated by ARDS. These findings aid clinicians in identifying high-risk patients, optimizing treatment plans, and improving patient prognosis.

Therapeutic Plasma Exchange to Reverse Plasma Failure in Multiple Organ Dysfunction Syndrome

Plasma plays a crucial role in maintaining health through regulating coagulation and inflammation. Both are essential to respond to homeostatic threats such as traumatic injury or microbial infection; however, left unchecked, they can themselves cause damage. A well-functioning plasma regulatory milieu controls the location, intensity, and duration of the response to injury or infection. In contrast, plasma failure can be conceptualized as a state in which these mechanisms are overwhelmed and unable to constrain coagulation and inflammation appropriately. This dysregulated state causes widespread tissue damage and multiple organ dysfunction syndrome. Unlike plasma derangements caused by individual factors, plasma failure is characterized by a heterogeneous set of plasma component deficiencies and excesses. Targeted therapies such as factor replacement or recombinant antibodies are thus inadequate to restore plasma function. Therapeutic plasma exchange offers the unique ability to remove harmful factors and replete exhausted components, thereby reestablishing appropriate regulation of coagulation and inflammation.

Plasmapheresis in the ICU

Therapeutic plasma exchange (TPE) is a treatment paradigm used to remove harmful molecules from the body. In short, it is a technique that employs a process that functions partially outside the body and involves the replacement of the patient's plasma. It has been used in the ICU for a number of different disease states, for some as a first-line treatment modality and for others as a type of salvage therapy. This paper provides a brief review of the principles, current applications, and potential future directions of TPE in critical care settings.

The efficacy of therapeutic plasma exchange in COVID-19 patients on endothelial tightness in vitro is hindered by platelet activation

Coronavirus disease (COVID)-19 is characterised in particular by vascular inflammation with platelet activation and endothelial dysfunction. During the pandemic, therapeutic plasma exchange (TPE) was used to reduce the cytokine storm in the circulation and delay or prevent ICU admissions. This procedure consists in replacing the inflammatory plasma by fresh frozen plasma from healthy donors and is often used to remove pathogenic molecules from plasma (autoantibodies, immune complexes, toxins, etc.). This study uses an in vitro model of platelet-endothelial cell interactions to assess changes in these interactions by plasma from COVID-19 patients and to determine the extent to which TPE reduces such changes. We noted that exposure of an endothelial monolayer to plasmas from COVID-19 patients post-TPE induced less endothelial permeability compared to COVID-19 control plasmas. Yet, when endothelial cells were co-cultured with healthy platelets and exposed to the plasma, the beneficial effect of TPE on endothelial permeability was somewhat reduced. This was linked to platelet and endothelial phenotypical activation but not with inflammatory molecule secretion. Our work shows that, in parallel to the beneficial removal of inflammatory factors from the circulation, TPE triggers cellular activation which may partly explain the reduction in efficacy in terms of endothelial dysfunction. These findings provide new insights for improving the efficacy of TPE using supporting treatments targeting platelet activation, for instance.