Septic shock can be caused by a variety of mechanisms, including the direct effects of bacterial toxins such as endotoxin. Annually, approximately 5–7 million patients worldwide develop sepsis with very high endotoxin activity in the blood, and more than half die. The term endotoxic septic shock has been used for these patients, but it is important to emphasize that endotoxin may be a factor in all forms of septic shock, including non-bacterial etiologies like COVID-19, since translocation of bacterial products is a common feature of septic shock. A pattern of organ failure including hepatic dysfunction, AKI, and various forms of endothelial dysfunction ranging from disseminated intravascular coagulation to thrombotic microangiopathy characterize endotoxic septic shock. However, while characteristic, the clinical phenotype is not unique to patients with high endotoxin, and the diagnosis relies on the measurement of endotoxin activity in addition to clinical assessment. Therapies for endotoxic septic shock are limited with immune modulating therapies under investigation and extracorporeal blood purification still controversial in many parts of the world [
79]. Early applications of CA in management of sepsis were proposed by Tetta et al., [
80]. They used continuous plasma filtration with sorbent adsorption for the removal of cytokines. The study showed that plasma filtration rather than ultrafiltration significantly increased the clearance of all cytokines, particularly TNF-α. The synthetic Amberlite-type of resin, but not natural uncoated charcoal, could extensively absorb almost 100% of plasma filtered IL-Ra, IL-1β and IL-8, but only 40% of TNF-α. Two protein bands of approximately 400,000 D and 200,000 D were eluted only from Amberchrome resins and immunoprecipitated by anti-human alpha2-macroglobulin and anti-human C3c antibodies, respectively. These studies suggest an efficient removal of cytokines in continuous plasma filtration with sorbent adsorption. The binding of alpha2-macroglobulin, a carrier of cytokines in plasma, might be an additional mechanism in the removal of cytokines from plasma. Song et al., [
81], in an experimental approach with rats found that the adsorption rate of the cytokines onto the polymer beads was concentration-dependent and increased with increasing temperature. The highest adsorption rate was observed at 40°C, followed by 37°C and then 30°C. In addition, the kinetics of adsorption of the cytokines onto the beads was found to be independent of calcium concentration. These results suggest that the adsorbent polymer is an effective and efficient adsorbent for various inflammatory cytokines and that temperature and calcium do not appear to significantly affect the adsorption rate. In an early hemofiltration approaches, Rimmele et al., [
82] discusses the use of a new hemofiltration membrane with enhanced adsorption properties due to a special surface treatment, allowing the adsorption of endotoxins. The study compared this membrane to a standard hemofiltration membrane both in vitro and in 20 sepsis-induced pigs, randomized in two groups. One group was hemofiltered with the treated membrane and the other with the standard hemofiltration membrane during 6-h high volume hemofiltration sessions. At the end of the experiment, mean crystalloids requirements, colloids requirements, lactic acidosis, and pulmonary arterial hypertension were less pronounced when high volume hemofiltration was performed with the treated membrane. In addition, mean ± SD endotoxins levels were lower in the treated membrane group after 1 hour of high volume hemofiltration (1.91 ± 1.19 versus 11.07 ± 10.64 EU/ml, P = 0.035). Cytokines levels were not different between groups except for IL-1β, which was slightly lower in the treated membrane group. The conclusion of the study was that the use of a membrane with enhanced adsorption properties during a 6-h high volume hemofiltration session in septic pigs improves hemodynamics compared to a standard hemofiltration membrane. These results are probably due to an efficient endotoxins and cytokines adsorption. Panagiotou et al., [
83] discusses the role of extracorporeal therapies, such as Sequential Extracorporeal Therapy in treating sepsis. This involves targeting circulating molecules for removal at various stages. The sequence of events and the use of different techniques at different points for specific targets are discussed. Over the years, multiple extracorporeal techniques have evolved, with the intent of influencing the circulating levels of inflammatory mediators like cytokines and chemokines, the complement system, as well as factors of the coagulation system. These include high-volume hemofiltration, use of high cutoff membranes, and systems based on adsorption, such as coupled plasma filtration adsorption and the polymyxin-B column. Hemoperfusion with CytoSorb® is able to efficiently remove cytokines and other medium-sized molecules involved in CRS, thus playing a synergistic effect with CRRT. The paper also discusses the potential role of blood purification in treating sepsis. This approach is proposed as an adjuvant therapy for sepsis, aiming at controlling the associated dysregulation of the immune system. In early experiment with a CA system, Lees et al., [
84] discusses the successful use of extracorporeal support and the CA therapy in treating a patient with severe acute respiratory failure, septic, and cardiogenic shock. The case report describes the successful treatment of a 33-year-old patient who developed acute cardiovascular collapse and ARDS secondary to superinfection of Panton-Valentine leukocidin-positive Staphylococcus aureus and H1N1 pneumonia using extracorporeal membrane oxygenation and CA therapy. The patient underwent successful combination therapy for severe sepsis-related cardiomyopathy and respiratory failure using ECMO and CA therapy. This case demonstrates the novel and successful use of ECMO and cytokine removal in severe PVL-S aureus sepsis with ARDS and cardiomyopathy. It adds to the evidence showing CA as a compelling adjuvant therapy in severe sepsis. This case is the first report to our knowledge of the successful use of extracorporeal support and the CA therapy in combination to treat a patient with severe acute respiratory failure, septic, and cardiogenic shock due to PVL-S. aureus superinfection with H1N1. Schädler et al., [
85] suggests that HA therapy is not associated with improved outcomes in septic patients with respiratory failure. Their treatment was found to remove IL-6 from the patient’s blood, but this did not lead to a reduction in plasma IL-6 levels or improved outcomes. The study did find a higher rate of mortality in the treatment group, but this was not statistically significant after adjustment for morbidity and baseline imbalances. Zuccari et al., [
86] suggests that HA with CA may be a promising adjunctive therapy for sepsis in critically ill adult patients. Their findings indicate that it may be able to reduce plasma levels of IL-8 and improve microvascular perfusion, despite no significant variation in macro-hemodynamic parameters. The improvements in microcirculation may lead to an overall improvement in outcome in septic patients. Further research is needed to confirm these findings and to determine the optimal use of this technology in clinical practice. De Rosa et al., [
87] discusses several important aspects of extracorporeal blood purification therapies for managing sepsis and sepsis-associated AKI. Polymyxin B hemadsorption (PMX-HA) has been tested in several experimental and clinical studies for endotoxic shock. The results have shown that PMX-HA can effectively reduce endotoxin and cytokine levels in plasma, improve hemodynamics and oxygenation parameters, and decrease mortality rates in endotoxic animals and patients. However, the optimal timing, frequency, and duration of PMX-HA are still unclear, and the long-term effects of PMX-HA on organ function and quality of life are not well established. The clinical indication for PMX-HA is widely debated in the literature. Some experts suggest that PMX-HA should be initiated as early as possible in patients with suspected or confirmed Gram-negative sepsis who have signs of organ dysfunction or refractory shock. Others propose that PMX-HA should be reserved for patients with confirmed endotoxemia who have high levels of Endotoxin Activity Assay (EAA), a rapid test that measures the biological activity of endotoxins in whole blood. The EAA can be used to monitor the response to PMX-HA and to guide its duration and frequency. Ronco et al., [
88] reviews the use of extracorporeal therapies for sepsis and septic shock has the potential to improve outcomes. However, further research is needed to evaluate the safety, efficacy, and cost-effectiveness of these treatments. In particular, the optimal timing of treatment, the selection of patients who are most likely to benefit from extracorporeal therapies, and the development of new devices that are able to target specific molecules are needed. Furthermore, randomized controlled trials should be conducted to determine whether extracorporeal therapies are superior to conventional treatments. Ricci et al., [
89] reviews HP as a process that has been studied and applied in the treatment of various medical conditions, such as sepsis, liver failure, and kidney failure. Recent randomized controlled trials have shown that HP may be beneficial in the treatment of septic shock and multi-organ failure. In these trials, HP was found to reduce the levels of proinflammatory cytokines in the blood and improve clinical outcomes. In addition, the use of HP was found to be safe and well tolerated by patients. Despite the promising results of these trials, more research is needed to further evaluate the efficacy and safety of HP in the treatment of septic shock and multi-organ failure. Future studies should focus on the potential benefits of using it in combination with other treatments, such as antibiotics, to further improve the prognosis of patients with sepsis and multi-organ failure. Furthermore, more research is needed to elucidate the mechanisms of action of HP and to identify other potential indications for its use. Forin et al., [
90] analyzes a single center, retrospective, observational web-based database (extracted from the EUPHAS2 registry) of critically ill patients admitted to the ICU between January 2016 and May 2021 who were affected by endotoxic shock. From January 2016 to May 2021, 61 patients were treated with PMX-HA out of 531 patients diagnosed with septic shock and of these, fifty patients (82%) developed AKI during their ICU stay. The most common source of infection was secondary peritonitis (36%), followed by community-acquired pneumonia (29%). Fifty-five (90%) out of 61 patients received a second PMX-HA treatment, with a statistically significant difference between the two groups (78% of the Pre-F vs. 100% of the Post-F group, p = 0.005). In both groups, between T0 and T120, the EAA decreased, while the SOFA score, MAP, and Vasoactive Inotropic Score improved with no statistically significant difference. Furthermore, when performing a propensity score matching analysis to compare mortality between the two groups, statistically significant lower ICU and 90-day mortalities were observed in the Post-F group [p = 0.016]. Although in this experienced center data registry, PMX-HA was associated with organ function recovery, hemodynamic improvement, and current EAA level reduction in critically ill patients with endotoxic shock. Following propensity score-matched analysis, ICU mortality and 90-day mortalities were lower in the diagnostic-therapeutic flowchart group when considering two temporal groups based on strict patient selection criteria and timing to achieve PMX-HA. In a pilot study that Friesecke et al., [
91] conducted a study on 17 patients with refractory septic shock. Hemodynamic measurements and laboratory tests were performed before and after each HP session. The results showed that CA HP significantly decreased levels of pro-inflammatory cytokines and improved hemodynamic parameters such as MAP and cardiac index. Moreover, the study revealed a decrease in markers of oxidative stress, suggesting that the technique may have beneficial effects on the metabolic aspects of septic shock. Overall, the results of this pilot study suggest CA is a promising approach for the treatment of refractory septic shock. Kogelmann et al., [
92] evaluates the impact of a new HA device, CytoSorb®, used as adjunctive therapy on hemodynamics and clinically relevant outcome parameters in 26 critically ill patients with septic shock who needed CRRT. Treatment of these patients with septic shock was associated with hemodynamic stabilization and a reduction in blood lactate levels. Actual mortality in the overall patient population was lower than mortality predicted by Acute Physiology and Chronic Health Evaluation II (APACHE II). The effects seem to be more pronounced in patients in whom therapy started within 24 hours of sepsis diagnosis. A delay in the start of therapy was associated with a poor response to therapy in terms of reduction of catecholamine demand and survival. Treatment using the CytoSorb® device was safe and well-tolerated with no device-related adverse events during or after the treatment sessions. Hemoadsorption using CytoSorb® resulted in rapid hemodynamic stabilization and increased survival, particularly in patients in whom therapy was started early. Kogelmann et al., [
93] shows that their septic shock dynamic scoring system (DSS) can be used to identify patients with a high risk of death and in our cohort with a DSS score >4.4 that was associated with a mortality rate of >30%, indicating a clear cut-off for the initiation of adjunctive CA therapy. Furthermore, a delay of more than 12 h between the onset of septic shock and the start of CA therapy was associated with a worse outcome, in terms of mortality and length of stay. This suggests that the earlier a patient is treated, the better the outcome. These findings support the use of the DSS as a tool to identify patients with refractory septic shock who might benefit from adjunctive CA treatment. The results of this analysis are in line with the results of recent studies, which suggest that the early initiation of adjunctive CA therapy might be beneficial for patients with septic shock. De Rosa et al., [
94] describes the successful management of a 49-year-old man who presented in the emergency department with a 5-day history of cough, fever, and dysuria and was admitted to the intensive care unit due to septic shock. An endotoxic shock was suspected and the patient was initially treated with PMX-HA alternate with high-volume hemofiltration sessions, which resulted in a marked decrease in the serum endotoxin level. However, due to the progression of circulatory insufficiency, veno-arterial extracorporeal membrane oxygenation (VA-ECMO) was initiated for circulation assistance on day 3 from admission. CA was incorporated into the VA-ECMO circuit for 48 h without a considerable improvement. Subsequently, a 72-h continuous veno-venous HD session was started in which a high cutoff filter was used. Tachycardia and myocardial dysfunction improved, and VA-ECMO was withdrawn on the tenth day. Nutrition management and rehabilitation were then performed, and the patient was discharged from our hospital on day 113. This case highlights the importance of sequential extracorporeal therapy when concomitant with circulatory assistance in severe cases of septic shock. David et al., [
95] tests the effects of CA on a 32-year-old female patient with septic shock and accompanying AKI. The study analyzed the endothelial phenotype in vitro before and after extracorporeal cytokine removal and found that there were severe alterations in cell-cell contact and the cytoskeletal architecture as well as profound functional permeability changes. However, the endothelial barrier was protected from these adverse effects when challenged with septic shock serum that was collected after extracorporeal cytokine removal. This suggests that beneficial observations of extracorporeal cytokine removal in septic shock patients might be promoted via protection of vascular barrier function. In a 70-year-old male patient who presented with severe sepsis due to S. aureus bacteremia, complicated by ARDS, septic shock, and multiorgan failure. Bruenger et al., [
96]. describes the successful management of patient that had been admitted to the intensive care unit and was initially stabilized using conventional supportive care, including antibiotics, fluids and vasopressors. However, his condition deteriorated and he developed severe hypotension, increased lactate levels, and metabolic acidosis. The team started left ventricular assist device support, ECMO, CVVH, and CA. The patient responded well to the combined therapy, with improved organ perfusion, normalization of lactate levels, and resolution of metabolic acidosis. The patient was weaned off ECMO and left ventricular assist device support. He was subsequently discharged from the hospital in good condition. This case report demonstrates that the combined use of left ventricular assist device, ECMO, CVVH, and CA is a viable option for management of severe sepsis in critically ill patients. The combination of devices provided effective organ support and improved the patient’s clinical outcome. The combination of devices could be a reasonable approach for management of sepsis in patients with multiple organ dysfunction, especially when conventional supportive care is not sufficient. Linden et al., [
97] performs CA HA as a therapy for patients with refractory septic shock to improve hemodynamic stability and reduce the need for vasopressors. A patient with septic shock and multi-organ failure who was treated with CA HA for five consecutive days. Following the treatment, the patient experienced a significant reduction in the need for vasopressors and a marked improvement in the clinical status. Their results suggest that CA HA may be a viable and effective therapeutic option in the management of refractory septic shock. Netti et al., [
98] investigates the therapeutic efficacy of LPS removal in decreasing albuminuria through the reduction of CD80 expression, a co-stimulatory molecule, in podocytes, which are specialized cells that form the filtration barrier in the kidney. CD80 expression in podocytes can cause proteinuria, or the leakage of protein into the urine, which is a sign of kidney damage and a risk factor for CKD. To elucidate the possible relationship between LPS-induced renal damage, proteinuria, and CD80 expression in Gram sepsis, a swine model of LPS-induced AKI was set up. The treatment with CPFA significantly reduced serum cytokines, CRP, procalcitonin, and endotoxin levels in patients with Gram-negative sepsis-induced AKI. CPFA treatment also significantly lowered proteinuria and albuminuria levels, along with CD80 urinary excretion. The study suggests that selective removal of LPS reduces albuminuria and CD80 expression both in the experimental and clinical settings and propose a possible role of this therapeutic approach in preventing the increased risk of progressive chronic kidney disease (CKD) in patients with septic AKI. Li et al., [
72] discusses the use of endotoxin and CA-CRRT in managing septic shock after liver transplantation. The study reports a case of a 35-year-old man with a 20-year history of hepatitis B who developed septic shock after liver transplantation. The patient was immediately treated with endotoxin and CA CRRT (oXiris hemofilter) along with tigecycline, caspofungin, and ganciclovir as anti-infectives. After 48 hours on CRRT, the patient’s blood pressure gradually stabilized, the Consortium Acute-on-Chronic Liver Failure score decreased from 63 to 43, and procalcitonin, endotoxin, and the inflammatory factors IL-6 and IL-10 also decreased gradually. The patient’s liver and kidney functions were completely restored. This suggests that oXiris CRRT combined with antibacterial therapy could be an effective treatment for septic shock after liver transplantation. Ankawi et al., [
99] reviews the role of various extracorporeal techniques in treating sepsis, since diffferent extracorporeal techniques have been studied in recent years in the hope of maximizing the effect of CRRT in modulating the exaggerated host inflammatory response, including the use of high volume hemofiltration, high cut-off (HCO) membranes, adsorption alone, and CPFA. These strategies are not widely utilized in practice, depending on resources and local expertise. Monard et al., [
100] reviews several important aspects of extracorporeal blood purification therapies for managing sepsis and sepsis-associated AKI. They describe the use of the oXiris® membrane that has a unique 4-in-1 device that combines cytokine and endotoxin removal properties, renal replacement function, and antithrombogenic properties. oXiris® treatment in septic patients enables optimization of hemodynamic status, clears inflammatory mediators such as TNF-α, IL-6, IL-8, and interferon-γ, and ultimately improves prognosis. This membrane has attracted attention due to its ability to remove both endotoxins and cytokines, which are mediators released by microorganisms and injured cells involved in the pathogenic mechanisms of organ dysfunction, including sepsis-associated AKI. Ricci et al., [
89] reviews the use of CA as a process in which blood is circulated through a device containing a biomaterial in order to remove molecules from the flowing blood. The process involves binding of molecules, such as endotoxins and proinflammatory cytokines, to the biomaterial surface. The biomaterial can be in the form of a resin or a membrane, and is tailored to bind the specific molecules in order to remove them from circulation. This process has been studied and applied in the treatment of various medical conditions, such as sepsis, liver failure, and kidney failure. Recent randomized controlled trials have shown that HP may be beneficial in the treatment of septic shock and multi-organ failure. In these trials, HP was found to reduce the levels of proinflammatory cytokines in the blood and improve clinical outcomes. In addition, the use of HP was found to be safe and well tolerated by patients. Despite the promising results of these trials, more research is needed to further evaluate the efficacy and safety of HP in the treatment of septic shock and multi-organ failure. Future studies should focus on the potential benefits of using it in combination with other treatments, such as antibiotics, to further improve the prognosis of patients with sepsis and multi-organ failure. Ankawi et al., [
101] reviews the use of polysulfone adsorption column with an adsorption capacity of up to 6,000 g/L. It has been demonstrated to be an effective technique in the removal of endotoxins, cytokines, myeloperoxidase, and other pro-inflammatory mediators. It has been used in clinical studies for the treatment of sepsis and septic shock, as well as for other acute inflammatory conditions, such as AKI, ARDS, and post-CPB syndrome. The most common method of use is CVVH with CA. The potential advantages of using CA for the treatment of acute inflammatory conditions include the removal of high concentrations of mediators in a short period of time. This can potentially lead to a faster resolution of symptoms and improved outcome. Additionally, the use of this adsorption column has been shown to be safe and well tolerated, with no reports of adverse reactions. The evidence supporting the use of CA for the treatment of acute inflammatory conditions is still limited, and further studies are required to confirm its efficacy. Additionally, further studies are needed to explore the potential of this technique for other clinical applications. Nevertheless, CA has demonstrated potential efficacy and safety in the treatment of acute inflammatory conditions, and should be considered as a potential therapeutic option. Ruegg et al., [
102] demonstrates the potential of CA to improve hemodynamics and metabolism in refractory septic shock. The study analyze septic shock patients who received CytoSorb® in addition to CCRT. This group was compared to a matched control group. The baseline comparability between the two groups was high, with differences mainly in higher initial SOFA scores and requirements of norepinephrine equivalents in the CytoSorb® group. The requirement for catecholamines decreased to 0.26 microg/kg/min within 24 hours after the initiation of CytoSorb® therapy, while it remained fairly constant in the control group. The in-hospital mortality was significantly lower in the CytoSorb® group (35.7% vs. 61.9%). Within the CytoSorb® group, high lactate levels and low thrombocyte counts prior to initiation were identified as risk factors for mortality. A cut-off value of 7.5 mmol/L lactate predicted mortality with high specificity (88.9%). High lactate levels may indicate absent benefits when confronted with septic shock patients considered eligible for CytoSorb® therapy. These findings suggest that HA with CytoSorb® could potentially reduce catecholamine requirements and in-hospital mortality in septic shock patients. Mariano et al., [
103] evaluates the efficacy and safety of CPFA in severe burn patients with septic shock and AKI needing CRRT. The study was conducted between January 2001 and December 2017, and it included 39 severe burn patients who were treated with CPFA (CPFA group) and 87 patients who were treated with RRT but not CPFA (control group). The study found that the observed mortality rate was 51.3% in the CPFA group and 77.1% in the control group (p 0.004). The SOFA score on the first day of CPFA resulted significant in the multivariate analysis logistic model. The study also collected data regarding CPFA safety (hemorrhagic episodes, catheter associated-complications, hypersensitivity reactions) and efficiency (number and duration of CPFA sessions, plasma treated amount, plasma processed dose). Reis et al., [
104] emphasizes the need for a new classification of solutes of interest in chronic kidney disease and HD. It highlights that the retention of solutes is already detected in the early stages of the disease when patients are pauci-symptomatic or asymptomatic. The role of therapies to retard the loss of kidney function in patients with chronic kidney disease (e.g., modulators of the renin-angiotensin-aldosterone system, sodium-glucose cotransporter inhibitors) in reducing uremic toxins is poorly understood. In the past 2 decades, blood purification strategies with enhanced convective properties, such as high-volume online hemodiafiltration and expanded HD, have considerably amplified the ability to mechanically extract middle molecules (molecular weight >0.5 kDa) from the blood compartment. However, the role of therapies to retard the loss of kidney function in patients with chronic kidney disease in reducing uremic toxins is still poorly understood. De Rosa et al., [
105] reviews several important aspects of Sepsis-Associated AKI (SA-AKI), a life-threatening condition leading to high morbidity and mortality in critically ill patients. Over the past decades, several extracorporeal blood purification therapies have been developed for both sepsis and sepsis-associated AKI management. Despite the widespread use of these therapies, it is still unclear when to start this kind of treatment and how to define its efficacy. Several questions on SA-AKI and extracorporeal blood purification therapy still remain unresolved, including the indications and timing of CRRT in patients with septic vs. non-septic AKI, the optimal dialysis dose for CRRT modalities in SA-AKI patients, and the rationale for using these therapies in septic patients without AKI. Dubler et al., [
106] assesses the outcome relevance of adequately treated putative invasive pulmonary aspergillosis (pIPA) in a cohort of critically ill patients with and without solid organ transplantation. The study included data from 121 surgical critically ill patients with pIPA (n = 30) or non-pIPA (n = 91). the adequately treated putative invasive pulmonary aspergillosis (pIPA) did not increase the risk of death or an unfavorable outcome. Instead, a higher SOFA score and evidence of bacteraemia were identified as risk factors for mortality and unfavorable outcomes. Adequately treated pIPA did not increase the risk of death or an unfavorable outcome in this mixed cohort of critically ill patients with or without solid organ transplantation, whereas higher disease severity and bacteraemia negatively affected the outcome..