Journal of Artificial Organs最新文献

Purpose: We developed a method to measure the extracellular and intracellular fluid volumes using the kinetics of uric acid in the bodies of Japanese patients undergoing dialysis. In this research, we aimed to assess the prognosis of vascular events using this uric acid kinetic model method.

Methods: We conducted a retrospective cohort study of 1,298 patients who were undergoing hemodialysis or predilution online hemodiafiltration at the end of December 2019 at 13 institutions in Japan. Information on vascular events was acquired in 2020. Vascular event prognosis was defined as the new incidence of one or more of the following four types of vascular events: myocardial infarction, cerebral infarction, cerebral hemorrhage, or limb amputation. We measured the extracellular fluid volume and intracellular fluid volume after dialysis using the uric acid kinetic model method and determined the association between ECV, ICV, and vascular event risk.

Results: A high extracellular volume was substantially linked to an increased risk of vascular events. In addition, while a crude analysis revealed that a high intracellular volume was associated with a low risk of vascular events, this was not statistically significant after multifactorial adjustment. This result was partly affected by the low measurement accuracy of the serum urea nitrogen level used for the intracellular volume calculation.

Conclusions: Extracellular volume calculated using the uric acid kinetic model method is a prognostic factor for vascular events in patients undergoing hemodialysis.

High-efficiency plasma skimming is hopeful to prevent hemolysis inside spiral groove bearings (SGBs) because it can exclude red blood cells from the ridge gap with a high shear force. However, no study reveals the shape design of SGBs to improve plasma skimming. Therefore, this study proposed and applied a groove design strategy to designing an optimal SGB for enhancing plasma skimming in a rotary blood pump (RBP). Initially, we proposed the design strategy that the shape of the groove for enhancing plasma skimming corresponds to the direction of blood flow in the ridge gap. Second, we visualized the cell flow in a specially designed experimental RBP to determine the direction of blood flow, which was helpful in the subsequent SGB design. Then, we created an SGB to provide superior plasma skimming and applied it to the experimental RBP. We evaluated the plasma skimming effect of SGB at rotational speeds ranging from 2400 to 3000 rpm and hematocrit conditions between 1% and 40%. At a 1% hematocrit, the plasma skimming efficiency for the entire SGB was greater than 95%. In all hematocrit conditions, the efficiency at the inner ridges of the SGB was greater than 80%. The results showed the designed SGB successfully induced excellent plasma skimming within ridge gaps. This study is the first to propose and apply a shape design strategy to generate excellent plasma skimming within an SGB. This study may contribute to the prevention of SGB hemolysis inside SGB for use in RBPs.

A 72-year-old female with type 1 diabetes, a history of interstitial pneumonia, and diabetic ketoacidosis was admitted to our hospital with dysphagia. Endoscopy revealed a circumferential neoplastic lesion in the upper to middle esophagus, and a biopsy revealed squamous cell carcinoma. Computed tomography revealed invasion of the left main bronchus, and induction chemotherapy was initiated with a diagnosis of unresectable locally advanced esophageal cancer. After one course of induction chemotherapy, the tumor size reduced, bronchial invasion improved, and thoracoscopic esophagectomy was performed. During surgery and until 3 days after surgery, the patient's blood glucose level was controlled using an artificial pancreas, and the target blood glucose range was set at 140-180 mg/dL. On the fourth postoperative day, the patient was managed using a sliding scale. Mean blood glucose was 186.7 ± 70.0 mg/dL for 3 days before surgery, 190.5 ± 25.0 mg/dL during artificial pancreas therapy from the surgery to the next day, 169.8 ± 22.0 mg/dL during artificial pancreas therapy on the second to third postoperative days, and 174.5 ± 25.0 mg/dL during sliding scale therapy for 4-15 days after surgery. No hypoglycemia or ketoacidosis was noted.

Heart transplantation is considered to be the best treatment for severe heart failure refractory to medical therapy, improving patients' survival and quality of life (QOL). However, the number of donors is smaller than the number of registered applicants for heart transplantation, which increases every year, and the waiting period for heart transplantation has been extended to more than 1700 days by 2022. Since 2011, reimbursement for the implantable left ventricular assist device (iLVAD) was established. The numbers of the iLVAD patients have been increasing year by year. Patients are managed at home with an iLVAD and can live with their families and even return to work, depending on the situation. On the other hand, self-management at home, including caregivers, is important for a safe life. Home management beyond 5 years is becoming more common due to long waiting time for transplant. This article outlines the important aspects of patient management for long-term support. This review was created based on a translation of the Japanese review written in the Japanese Journal of Artificial Organs in 2023 (Vol. 52, No. 1, pp. 62-66), with some modifications.

We report a case in which excessive negative pressure may have been applied to the proximal side hole of a drainage cannula during venovenous extracorporeal membrane oxygenation (V-V ECMO), resulting in abnormal stenosis of the drainage cannula. V-V ECMO was introduced in a 71-year-old male patient who was transferred from another hospital for severe respiratory failure associated with varicella pneumonia and acute respiratory distress syndrome. Drainage was performed using a PCKC-V™ 24Fr (MERA, Japan) cannula via the right femoral vein with the tip of the cannula near the level of the diaphragm under fluoroscopy. Reinfusion was performed via the right internal jugular vein. Due to poor systemic oxygenation, the drainage cannula was withdrawn caudally and refixed to reduce the effect of recirculation. Two days later, drainage pressure dropped rapidly, and frequent ECMO flow interruption occurred due to poor drainage. An abdominal X-ray revealed abnormal stenosis of the proximal side hole site of the drainage cannula. We diagnosed that the drainage cannula was damaged, and it was replaced with another, namely a Medtronic Bio-Medicus™ 25 Fr (GETINGE, Sweden) cannula. However, the removed drainage cannula was not damaged, suggesting that the cannula was temporarily stenosed by momentary excessive negative pressure. In a multi-stage drainage cannula, the main drainage site is the proximal side hole, with little negative pressure applied at the apical foramen in a mock experimental ex vivo drainage test in a water tank. Hence, improvement of a multi-stage drainage cannula is recommended, such as adequate reinforcement of the side hole site with a wire.

Models of urea kinetics facilitate a mechanistic understanding of urea transfer and provide a tool for optimizing dialysis efficacy. Dual-compartment models have largely replaced single-compartment models as they are able to accommodate the urea rebound on the cessation of dialysis. Modeling the kinetics of urea and other molecular species is frequently regarded as a rarefied academic exercise with little relevance at the bedside. We demonstrate the utility of System Dynamics in creating multi-compartment models of urea kinetics by developing a dual-compartment model that is efficient, intuitive, and widely accessible to a range of practitioners. Notwithstanding its simplicity, we show that the System Dynamics model compares favorably with the performance of a more complex volume-average model in terms of calibration to clinical data and parameter estimation. Its intuitive nature, ease of development/modification, and excellent performance with real-world data may make System Dynamics an invaluable tool in widening the accessibility of hemodialysis modeling.

Purpose: Hemi-resurfacing arthroplasty (Hemi) and metal-on-metal hip resurfacing arthroplasty (HR) were proposed as alternatives to conventional total hip arthroplasty (THA) for patients with osteonecrosis of the femoral head (ONFH). Long-term results were evaluated.

Methods: Twenty-three hips with ONFH were treated, using Hemi in 12 and HR in 11. Mean follow-up was 15 years in the Hemi group and 10 years in the HR group. Long-term outcomes were reviewed retrospectively.

Results: In the Hemi group, 8 hips showed acetabular protrusion and were revised to THA. One of the 8 hips showed femoral loosening. In the HR group, pseudotumor was detected in 4 hips (36%), and 1 hip was revised due to symptomatic pseudotumor. No evidence of any femoral or acetabular loosening was seen in the HR group. Ten-year survival rates were 64.2% and 90.9% in the Hemi and HR groups, respectively. Survival rate in the Hemi group dropped to 22.9% at 15 years.

Conclusions: Long-term results of Hemi for patients with ONFH were very poor, and Hemi should not continue to be used. Although HR had a concern of pseudotumor, it could offer attractive indications for 10 years.

Implantable ventricular assist device (VAD) has enabled patients with severe heart failure to be discharged from the hospital and to continue their care at home. The presence of caregivers is essential to maintain home care of patients with VAD. The caregivers are mainly the family members who live with the patient with VAD. The caregivers need to be trained (1) VAD device management, (2) disinfection of driveline skin punctures, (3) medication management, and (4) responding to sudden changes. The caregivers' lifestyle is also forced to change. In this article, we discuss the role of caregivers in the VAD era, where long-term support beyond 5 years is now possible. This review was created based on a translation of the Japanese review written in the Japanese Journal of Artificial Organs in 2023 (Vol. 52, No. 1, pp. 81-84), with some modifications.

Collaboration between the implantation centers, management centers, and regional core hospitals is a key factor in securing long-term implantable ventricular assist device (VAD) management. In Kyushu, a management system for patients with implantable VADs has been established at the prefectural and regional levels. Presently, six implantable VAD implantation centers and seven management centers exists in the eight prefectures of Kyushu and Okinawa, with at least one specialized VAD centers in each prefecture. This collaborative management system allows patients with VADs to receive seamless treatment based on the same management concept wherever they live. In fact, approximately half of the present outpatients treated at our center reside outside the prefecture and are managed in collaboration with management centers and regional core hospitals. Among our patients, there were no significant differences in survival or rehospitalization-free rates between patients with VADs in and out of the prefecture, suggesting that the place of residence did not affect the outcome. With the increase in the number of patients with VADs and the diversification of patients, patient management has become more complex. Mutual collaboration between the implantation centers, management centers, and regional core hospitals, is essential to improve the quality of VAD management. This review was created based on a translation of the Japanese review written in the Japanese Journal of Artificial Organs in 2023 (Vol. 52, No. 1, pp. 85-88), with some modifications.

Periprosthetic joint infection (PJI) is a catastrophic complication after total hip arthroplasty. A new drug-loaded carbon fiber-reinforced polymer (CFRP) prosthesis with a sustained drug-release mechanism is being developed for one-stage surgery. We aimed to examine the diffusion dynamics of vancomycin from vancomycin paste-loaded CFRP implants. The differences in the in vitro diffusion dynamics of vancomycin paste were investigated using the elution test by varying parameters. These included the mixing ratio of vancomycin and distilled water (1:0.8, 1:1.2, and 1:1.4) for vancomycin paste, and hole diameter (1 mm and 2 mm) on the container. The in vivo diffusion dynamics were investigated using a rabbit model with vancomycin-loaded CFRP implants placed subcutaneously. The in vitro experiments showed that the diffusion effect of vancomycin was highest in the parameters of vancomycin paste with distilled water mixed in a ratio of 1:1.4, and with a 2 mm hole diameter. The in vivo experiments revealed diffusion dynamics similar to those observed in the in vitro study. The drug diffusion effect tended to be high for vancomycin paste with a large water ratio, and a large diameter of holes. These results indicate that the drug diffusion dynamics from a CFRP implant with holes can be adjusted by varying the water ratio of the vancomycin paste, and the hole size on the CFRP implant.