Renal replacement therapy (RRT) is one of the key treatment modalities for critically ill patients in the intensive care unit (ICU). Recently, the results from several large randomized controlled trials on the optimal timing of RRT initiation became available. Most of these results showed no significant merit in early initiation of RRT when they defined “early” treatment depending on serum creatinine value and urine amount. However, there is less evidence on the optimal timing of discontinuing RRT. Each ICU physician has to decide when to stop RRT according to several indicators, including urine amount, other clinically available biomarkers, and overall patient status. In this narrative review, we summarized the previous studies on these topics. We also quoted the result of our recent multi-centered observational study on patients with continuous RRT in seven university-affiliated ICUs across Japan. This study validated three clinical biomarkers: urinary neutrophil gelatinase-associated lipocalin (NGAL), serum interleukin-6 (IL-6), and serum high mobility group box 1. Consequently, higher urinary NGAL and serum IL-6 levels at RRT initiation were significantly correlated with subsequent mortality. Meanwhile, lower urinary NGAL level at RRT discontinuation was significantly correlated with successful RRT discontinuation in the following seven days. Future larger studies should focus on implementing these biomarkers to decide when to start and stop RRT in ICU.

The effect of polymyxin B-immobilized fiber column-direct hemoperfusion (PMX-DHP) for managing coronavirus disease (COVID-19) pneumonia has been previously reported. We performed PMX-DHP for 29 patients with COVID-19 pneumonia. Blood test results revealed significantly lower interleukin-6 and C-reactive protein levels after treatment than before treatment (p＝0.022 and p＝0.033, respectively). All 21 cases (72.4%) with decreased oxygen requirement after PMX-DHP survived regardless of disease severity, but 6 of 8 cases with increased oxygen requirement died. PMX-DHP may contribute to cytokine adsorption and improvement of respiratory status in COVID-19 pneumonia. Twelve cases developed blood circuit coagulation during PMX-DHP; in six cases, PMX-DHP was interrupted owing to circuit coagulation, suggesting the existence of coagulation disorder due to COVID-19 pneumonia. Future studies are necessary to evaluate the effectiveness of PMX-DHP in managing COVID-19 pneumonia.

[Purpose] Infants/neonates tend to develop hypothermia during continuous blood purification therapy (CBP) in critical care. Blood purification device in critical care are provide either substitution fluid warming or blood warming, with ACH-Σ^® (A) is the substitution fluid warming device and Prismacomfort^® (PC) is the blood warming device. The warming performance of A and PC were compared in water system study using children circuits.［Methods］Tap water was recirculated in a constant-temperature water bath at 37.5℃ under the following conditions: continuous hemodialysis (CHD); without water removal; dialysate flow rate, 400 mL/h; and blood flow (Q_W): 10, 20, 30 mL/min. Water temperature at the outlet for blood return was measured when the warmer in A was set at off (A off) or 40℃ (A40), when PC was set at off (PC off) , 40℃ (PC40) or 43℃ (PC43), and when PC set at 43℃ was installed in the blood return circuit in A40 (hereinafter, A40 + PC43). [Results] Water temperature at the outlet for blood return was significantly higher in PC43, followed by PC40, A40 + PC43 and A40, in that order, for all values of Q_W. [Conclusion] In water system study using children circuits, the blood warming device showed better warming performance than the substitution fluid warming devices.

We report a case of a 71-year-old female with a history of angina pectoris, abdominal aortic aneurysm, right hydronephrosis. 【Present history】The patient was admitted to the emergency room due to loss of consciousness. The next morning, she presented ventricular fibrillation (VF) , hence, she underwent chest compressions and electrical defibrillation. She was admitted to the intensive care unit (ICU) after the return of spontaneous circulation. We diagnosed that the VF was caused by hyperkalemia due to post-renal acute kidney injury (AKI) and initiated high volume high flow (HVHF)-continuous hemodialysis (CHD) . In addition, she was treated for septic shock due to urinary tract infection, the CHD column was changed to AN69ST, and she underwent polymyxin B-immobilized fiber column (PMX) treatment.【Conclusion】This study concluded that a patient with septic shock due to urinary tract infection following VF caused by post-renal AKI-associated hyperkalemia was discharged from the ICU after recovery from shock and renal function using HVHF-CHD and PMX in combination with catecholamine regulation based on detailed circulatory monitoring.

Background: In rhabdomyolysis, there is a significant relationship between the development of an acute kidney injury (AKI) and serum creatine phosphokinase (CK) levels. It has been reported that blood purification therapy such as hemodialysis (HD), hemodiafiltration dialysis (HDF), and plasma exchange is useful in patients with severe renal dysfunction. However, the selection criteria for these blood purification therapies remains unclear. Case report: A 73-year-old man with a history of schizophrenia and diabetes mellitus was brought to the emergency room with generalized weakness. The serum CK and creatine (Cr) were elevated to 283,500 U/L and 2.53 mg/dL, respectively. He was admitted with a diagnosis of rhabdomyolysis and AKI. Although intravenous fluids and diuretics were started, serum Cr increased to 7.11 mg/dL on the third day and the patient became anuric. Therefore, HDF with medium cut-off membranes was started on the fourth day and was performed six times until the 14th day. On the 15th day, serum CK was 90 U/L and rhabdomyolysis had resolved. On the 16th day, a switch from HDF to HD was made and HD therapy was completed on the 32nd day. Conclusion: In a patient who had AKI and rhabdomyolysis with marked serum CK elevation, use of HDF with medium cut-off membranes in the beginning followed by a switch to HD could result in improvement.

Hyperammonemia associated with inborn errors of metabolism in newborns causes non-specific neurological abnormalities, so it is necessary to remove blood ammonia promptly, and blood purification therapy by extracorporeal circulation is indicated. Therefore, we report an example of devising continuous renal replacement therapy and adjusting treatment conditions for acute hyperammonemia. The case was a boy with OTC deficiency, the target value of ammonia was 150 μg/dL or less from the second day after birth (day 0), and the osmotic pressure was measured by CT at any time to confirm that there was no cerebral edema and continuous renal replacement. The therapy was started. The serum ammonia level before the start of treatment was 3,426 μg/dL, and after the start of treatment, the improvement was slight, so the dialysate flow rate was gradually increased to 300 mL/hr. No abnormal findings were found on the head CT due to the fine adjustment of dialysis efficiency and the adjustment of osmotic pressure by medication. On the 5th day of illness, continuous renal replacement therapy was withdrawn, and on the 19th day of illness, he was transferred to the referral hospital.

In continuous renal replacement therapy (CRRT), hemofilter clotting is one of the frequent troubles. Polysulfone (PS) membranes with polyvinylpyrrolidone (PVP) as a hydrophilic agent are widely used as hemofilters for CRRT. Recently, Toray Medical Co., Ltd. developed a new PS membrane hemofilter that uses NV polymer as a hydrophilic agent. They claim that the NV polymer has better hydrophilic properties than the PVP polymer. In this study, we retrospectively analyzed whether the difference of these two hydrophilic agents (PVP and NV polymer) will affect hemofilter lifetime. The subjects were 20 individuals who met all of the following conditions: they are maintenance hemodialysis patients who underwent CRRT after cardiac surgery, the CRRT mode was via continuous hemofiltration, and the anticoagulant used was nafamostat mesilate. We compared the achievement ratio of the hemofilter lifetime for 48 hours for the two groups (PS membrane with NV polymer (NV group; 11 cases) vs PS membrane with PVP polymer (PVP group; 9 cases)). Results showed that the hemofilter lifetime achievement rate for 48 hours was significantly higher in the NV group than in the PVP group (45.4% vs 0%, p = 0.038). In the context of CRRT for maintenance hemodialysis patients after cardiac surgery, the antithrombotic performance of the PS hemofilter coated with NV polymer is better than that coated with PVP polymer.

Treatment of acute kidney injury (AKI) in older patients is difficult and time-consuming. Furthermore, patients experience a serious problem in terms of decline in activities of daily living (ADL) after treatment. In this study, we investigated the effectiveness of the treatment of AKI using a tunneled cuffed catheter (TCC) in older patients while administering blood purification therapy for AKI. This study included six patients (mean age: 83.7 ± 3.7 years, four males and two females) who received treatment with TCC during blood purification therapy for AKI between January 2018 and June 2020. The vascular access for initiating blood purification therapy involved a direct puncture, non-cuffed catheter, and TCC in one, four, and one of the six patients, respectively. However, five non-TCC patients were also shifted to treatment using TCC. Finally, all patients were on ambulatory maintenance hemodialysis while receiving treatment with TCC. Because of its structural characteristics, TCC presents high safety with few restrictions and can be managed on an outpatient basis. Treatment with TCC for AKI in older patients could shorten the hospitalization duration, prevent deterioration of ADLs, and facilitate outpatient maintenance hemodialysis.

[Introduction] In our institution, continuous hemofiltration (CHF) with AN69ST hemofilter (AN69ST-CHF) is performed using ACH-Σ and Prismaflex console. In this study, we retrospectively investigated the occurrence of circuit coagulation during AN69ST-CHF using ACH-Σ (Σgroup) and Prismaflex (P group). [Methods]Patients who underwent AN69ST-CHF at a total nafamostat mesylate dose rate of 30 mg/h (dispensed dose method in group Σ and pre-filtered dose method in group P) were selected. We defined goal attainment as the ability to perform CHF for more than 22 h with one filter and compared the target attainment rates and coagulation sites for each CHF procedure. [Results] There was no difference in the rate of CHF goal attainment between the two groups (group Σ: 72.7% (16/22) vs. group P: 77.3% (17/22) , p = 0.73) , and there was significantly lesser V-chamber coagulation in group P than in group Σ (group Σ: 5/6 vs. group P: 1/5, p＜0.05) . [Conclusion] When AN69ST-CHF was performed, there was no difference in the rate of goal attainment between the two groups. The incidence of V-chamber coagulation was significantly lower in the P group.