Therapeutic Rationale for Endotoxin Removal with Polymyxin B Immobilized Fiber Column (PMX) for Septic Shock.

Endotoxin removal therapy with polymyxin B immobilized fiber column (PMX) has been clinically applied for sepsis and septic shock patients since 1994. The effectiveness and usefulness of this therapy have been demonstrated for more than a quarter of a century. However, a documented survival benefit has not yet been demonstrable in a large, multicenter, randomized and controlled trial. Following the findings derived from a large sepsis clinical trial with PMX in North America, a new trial is ongoing to determine if PMX has a long-term survival benefit when administered to septic patients. Another approach to support a survival benefit from intervention with PMX is to utilize a detailed analysis available from a large clinical data base. The endotoxin adsorption capacity of PMX columns in vitro and the effectiveness of PMX columns can be further demonstrable in animal models. The capability of PMX and details of its mechanism of action to intervene in the sepsis cascade and impede organ dysfunction in septic patients is not fully understood. The surface antigen expression in monocytes and neutrophils are improved after PMX therapy. Immunomodulatory effects as a result of endotoxin removal and/or other mechanisms of action have been suggested. These effects and other potential immune effects may explain some of the improved effects upon organ dysfunction of sepsis and septic shock patients. Endotoxemia may be involved in the pathophysiology of other diseases than sepsis. A rapid diagnostic method to detect and target endotoxemia could allow us to practice precision medicine and expand the clinical indications of endotoxin removal therapy.

Direct hemoperfusion using a polymyxin B-immobilized polystyrene column for COVID-19.

OBJECTIVE: To evaluate the efficacy and safety of direct hemoperfusion using a polymyxin B-immobilized polystyrene column (PMX-DHP) in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-positive pneumonia patients. METHODS: This study was a case series conducted at a designated infectious diseases hospital. Twelve SARS-CoV-2-positive patients with partial pressure of arterial oxygen/percentage of inspired oxygen (P/F) ratio < 300 were treated with PMX-DHP on two consecutive days each during hospitalization. We defined day 1 as the first day when PMX-DHP was performed. PMX-DHP efficacy was assessed on days 7 and 14 after the first treatment based on eight categories. Subsequently, improvement in P/F ratio and urinary biomarkers on days 4 and 8, malfunctions, and ventilator and extracorporeal membrane oxygenation avoidance rates were also evaluated. RESULTS: On day 14 after the first treatment, disease severity decreased in 58.3% of the patients. P/F ratio increased while urine ß2-microglobulin decreased on days 4 and 8. Cytokine measurement pre- and post-PMX-DHP revealed decreased levels of interleukin-6 and the factors involved in vascular endothelial injury, including vascular endothelial growth factor. Twenty-two PMX-DHPs were performed, of which seven and five PMX-DHPs led to increased inlet pressure and membrane coagulation, respectively. When the membranes coagulated, the circuitry needed to be reconfigured. Circuit problems were usually observed when D-dimer and fibrin degradation product levels were high before PMX-DHP. CONCLUSIONS: Future studies are expected to determine the therapeutic effect of PMX-DHP on COVID-19. Because of the relatively high risk of circuit coagulation, coagulation capacity should be assessed beforehand.