Acute blood purification therapy may originate from chronic dialysis or intensive care. It was found that the mainly participating nephrologists and intensive care physicians had different educational backgrounds and lacked communication. However, in recent years, the barriers have decreased due to the activities of KDIGO guidelines in the world and the Japanese Society for Blood Purification in Critical Care in Japan. The basis of blood purification therapy is based on renal replacement therapy, and many acute blood purification are derived from it. This paper considers the development of acute blood purification from the historical development of chronic dialysis.

Vascular access (VA) is essential for blood purification therapy by means of an extracorporeal circulation technique. The non-cuffed type of vascular catheter is most useful in creating vascular access for acute blood purification therapy, associated with continuous renal replacement therapy (CRRT). The advantage of using a non-cuffed vascular catheter is that it may be inserted quickly, and blood purification therapy may be started immediately. A non-cuffed catheter may also be utilized as a central venous line for the administration of drugs and fluid. A non-cuffed catheter is required to have the following capacities as a medical device: operability during insertion, placement and fixation, safety during the attachment or detachment of the circuit, smooth blood transfer performance, minimal invasiveness to the vessel wall, and antibacterial attributes. However, even if a catheter has sufficient capacities, it is humans who handle it. In other words, when using a non-cuffed catheter, it is important to understand its characteristics and to know how to handle it appropriately. In this review, we summarized the evidence regarding effective and safe techniques for using a non-cuffed catheter for CRRT in the field of emergency and critical-care medicine. The qualities of the ideal device for blood purification therapy were also explored.

COVID-19 patients with BMI 30 or higher are more likely to become severely ill and are at increased risk of requiring ECMO. In addition, although the incidence of severe AKI in non-ECMO cases is not high, patients with ECMO are often complicated with severe AKI, requiring combination therapy with CRRT. It has been pointed out that cytokine storms are involved as a factor in the severity of the disease, and when performing CRRT, a hemofilter that has adsorptive properties for inflammatory cytokines could be selected. However, fibrinogen/fibrin degradation products and D-dimer tend to increase, and the CRRT treatment membrane tends to generate clot formation, which cause a shortening of life-time. It is necessary to monitor APTT etc. to adjust the dose of anticoagulant. If CRRT or HD is not possible due to equipment problem, it is necessary to consider treatment with high-flow RRT. In addition, in order to prevent infection of medical staffs, it is necessary to pay close attention and ingenuity to the management of drainage from CRRT and the equipment used.

Patients with COVID-19 may present with severe symptoms, and develop acute respiratory distress syndrome, septic shock, and multiple organ failure requiring extracorporeal life support. In particular, renal function is affected in a variety of ways, from mild proteinuria to acute kidney injury, and continuous kidney replacement therapy (CKRT) may need to be performed in some cases. Severe patients may also exhibit clinical features similar to those of cytokine storm syndrome, in which cases blood purification using a cytokine-adsorbing hemofilter (e.g., AN69ST and PMMA membranes) becomes an option. This also requires measures to prevent circuit coagulation, especially given the possibility of hypercoagulation. Patients with severe pneumonia may be treated with mechanical ventilation in prone position or extracorporeal membrane oxygenation (ECMO), with attention to complications and combined CKRT. Management strategies involve consideration for membrane selection, anticoagulation, infection control (equipment and CKRT effluent), and combined ECMO and CKRT, with infection control for medical staff being of utmost importance.

Continuous renal replacement therapy (CRRT) is the mainstay of blood purification therapy in the critical care setting. CRRT machines are used to ensure precision and safety during CRRT. The improvement of CRRT-specific machines started with the refinement of the flow control of each pump. Currently, the machines have evolved to include various safety features. European and American machines are capable of performing pre-dilution continuous hemofiltration (CHF), and are also equipped with innovative air-drip chambers and heating systems, while Japanese machines have not been able to perform pre-diluted CHF. However, the TR-2020 (Toray Medical Inc.) is now available and can perform pre-dilution CHF safely. While CRRT machines might not be able to make progress in the future, improvements can be expected in the development of a mode to reduce power consumption in case of disasters and in downsizing and transportability. If such a machine can be developed, the range of applications of CRRT will expand further.

Since the introduction of hemodialysis for renal failure patients in the 20th century, acute blood purification has been applied to treat various critical illnesses. Here, we introduce the recently revised guidelines focusing on acute kidney injury (AKI), sepsis, and new coronavirus infections (coronavirus disease 2019: COVID-19). Regarding AKI, Kidney Disease Improving Global Outcomes (KDIGO) discussed the guidelines revision, recommending smooth communication with patients and the provision of renal replacement therapy (RRT) tailored to their condition. The Japanese sepsis guidelines have also been revised mainly about the timing of the introduction of RRT. As for COVID-19, various organizations have provided recommendations on RRT prescriptions, infection control, and circuit coagulation.

The new definition of sepsis emphasizes the development of organ dysfunction. Hypercytokinemia plays an important role in the excessive inflammatory response; blood purification to modulate the response is conducted. The efficacy of blood purification using hemofilter membranes with high cytokines absorption capabilities has been reported. However, as pointed out in the various guidelines, there are still few studies with a high level of evidence. A recent study focusing on Interleukin-6 (IL-6), a pro-inflammatory cytokine, has clarified the association between hypercytokinemia and acute kidney injury as well as multiple organ dysfunction. Early blood purification may be effective in modulating the pathophysiology of sepsis to prevent organ dysfunction. Therefore, it is mandatory to measure useful biomarkers such as serum IL-6 and perform cytokine-based therapies, to generate high-quality evidence in this area.

Reports reveal that continuous renal replacement therapy (CRRT) circuit lifetime significantly lengthens in patients treated with disseminated intravascular coagulation (DIC) drugs. However, the relationship between a circuit lifetime and DIC drugs is unclear. Therefore, we conducted a retrospective observational study comparing the effectiveness of recombinant human soluble thrombomodulin (rhTM) with that of danaparoid sodium (DS) on circuit lifetime in patients undergoing CRRT. We compared the circuit patency rates between the two groups: TM group (administration of rhTM, n=33) and the DS group (administration of DS, n=65) at 48 and 72 hours. The TM group had a significantly higher result than the DS group at 48 hours. Data obtained was analyzed by matched pair analysis of the two groups with background items that may affect circuit lifetime (83.4% vs 54.7%). However, there was no significant difference at 72 hours (62.4% vs 54.7%). The results indicate that rhTM prevents coagulation in the CRRT circuit compared to DS when circuit replacement period is 48 hours.

Nafamostat mesilate (NM) was a first-choice drug used as an anticoagulant in continuous hemodiafiltration (CHDF) in our hospital. Activated clotting time (ACT) is an index of the dose of NM. The standard value of ACT is undecided, and blood coagulation in the circuit is occasionally observed. The purpose of this study was to investigate the optimal ACT value for continuous hemodiafiltration using NM. Forty-seven adult patients with scheduled CHDF using NM were included in this study. The ACT value of the outlet site (H-ACT) in the circuit of the hemofiltration device and the ACT value of arterial blood (A-HCT) were measured. There are significant differences (P＜ 0.001) in the H-ACT values between the group (346±94.1s) that continued hemodiafiltration for more than 48 hours and the group（261±92.5s）that stopped hemodiafiltration within 48 hours due to occlusion in the dialysis circuit. These results suggest that a higher H-ACT value lowers the risk of occlusion in the circuit. As analyzed by receiver operating characteristic (ROC) analysis, the cut-off value for the achievement of CHDF was 271 sec (specificity 69.6%, sensitivity 85.1%). These results suggest that H-ACT values of more than 271 sec are appropriate.

A woman in her 40s ingested a cresol soap solution several hours prior to transportation to the hospital, resulting in emesis, loss of consciousness, respiratory failure and hypotension. Physical examination showed chemical burns due to the cresol to approximately 50% of the head and neck, and blood tests showed a creatinine level of 0.97mg/dL. Continuous hemodialysis (CHD) was started from the first day of admission because of hyperkalemia. We maintained a mean blood pressure of 65mmHg or higher and a proper fluid volume. Oliguria was observed on the 3rd day. CHD was changed to intermittent hemodialysis on the 11th day. After 13 days of oliguria and anuria, the urine volume recovered and hemodialysis was discontinued on the 21st day. The serum creatinine level recovered to 0.76mg/dL 9 months from the time of admission. Cresol poisoning can cause multiple organ failure including acute kidney injury (AKI). In particular, cases of percutaneous absorption can increase the risk of AKI than oral ingestion, because cresol is not metabolized by the first-pass effect in the liver. For cresol poisoning with percutaneous absorption, attention should be paid to the onset of AKI and treatment should be performed with a view to renal prognosis.

We examined the association between neutrophil adsorption to the column of polymyxin B-immobilized fiber-direct hemoperfusion (PMX-DHP) and improvement of respiratory condition in a case of exacerbated interstitial pneumonia treated with PMX-DHP. An 81-year-old male was admitted to the ICU for acute exacerbation of interstitial pneumonia. PMX-DHP was used to improve the respiratory condition with the first performance for 22 hours and the second one for 28 hours. The PaO₂/FiO₂ (P/F) ratio improved from 96.3 to 165 through the first PMX-DHP treatment, however, it dropped down to 98.6 after the second PMX-DHP. The changes in the number of neutrophil counts were as follows: at 1h; -32.5%, 2h; -1.1％, and 6h; 1.8% of the first PMX-DHP: at 1h; -21.4%, 2h; -13.9％, and 6h; 0% of the second PMX-DHP. The P/F ratio was temporarily improved by PMX-DHP, however, no association was found between neutrophil adsorption and improvement of respiratory condition.

The patient was a 63-year-old woman who had a common bile duct stone, which was removed by endoscopic retrograde cholangiopancreatography, followed by endoscopic retrograde biliary drainage. She subsequently developed acute pancreatitis, which did not improve with pancreatic enzyme inhibitor treatment. The patient developed sepsis and underwent polymyxin B-immobilized fiber column direct hemoperfusion (PMX-DHP). Urinary L-type fatty acid binding protein (L-FABP) was raised (485.2μg/g Cre) before PMX-DHP, suggesting that acute kidney injury was inevitable. Therefore, continuous hemodiafiltration was performed using PMMA membrane. Urinary L-FABP decreased to 364.7μg/g Cre after the first PMX-DHP, and decreased from 177.7μg/g Cre to 5.4μg/g Cre after the second PMX-DHP. Acute pancreatitis improved and the renal function did not worsen (serum creatinine: 0.4mg/dL). In this patient, serum creatinine was normal, but urinary L-FABP was high and proximal tubular injury was observed. Therefore, acute kidney injury may be avoided by early renal replacement therapy. Additionally, urinary L-FABP may be used for early diagnosis of acute kidney injury.

While the asymmetric triacetate (ATA) membrane, a novel hemofilter, has the potential to achieve an extended membrane lifetime given its high biocompatibility, this has not been investigated in clinical settings. The present study aimed to determine the stability of internal circuit pressure and membrane lifetime of the ATA membrane in clinical use with a retrospective case-control design. Patients who underwent continuous renal replacement therapy (CRRT) after cardiac surgery due to acute kidney injury for more than 24 hours were divided into two groups based on the type of membrane used: the ATA group (n=15) and the cellulose triacetate (CTA) group (n=14). Patient characteristics, intra-circuit pressure variations, and membrane lifetime at 4, 8, 12, and 24 hours from the start of CRRT were compared between the two groups. There was no significant difference in patient characteristics except hematocrit. The rate of change in TMP at 24 hours from the start of CRRT were significantly higher in the CTA group. There was no significant difference in membrane lifetime. These results suggest that the ATA membrane has more stable circuit pressure compared to the CTA membrane in clinical use. A future study will be necessary to observe and compare these membranes for more than 24 hours.

This study was aimed to enable remote monitoring and real-time evaluation of pressure changes during blood purification by constructing a network system that can continuously extract various data from the blood purification devices. We developed an application that obtains operation history by communicating with each blood purification device. An authorized computer was allowed to extract data and transmit it to Network Attached Storage, Network HDD, and NAS. With this system, it was possible to calculate the rate of change of various circuit pressures and create a trend graph. By using NAS on the hospital network, the obtained information and the analyzed data were available in various places of the hospital. This new system can accumulate and aggregate the data from the blood purification devices in real time enabled remote monitoring in various places and is expected to contribute to improving the quality of blood purification device management.