Strong association between insufficient plasma exchange and fatal outcomes in Japanese patients with immune-mediated thrombotic thrombocytopenic purpura.

Plasma exchange (PEX) using fresh frozen plasma has considerably reduced the mortality rate in patients with immune-mediated thrombotic thrombocytopenic purpura (iTTP). However, some patients still do not survive even with treatment, but little information is available regarding which treatment these patients received. This study was conducted to obtain this information in 240 patients who met the current iTTP diagnostic criteria and completed at least 30 days of follow-up except for deceased cases. These patients were divided into three groups: survivors (n = 195), TTP-related deaths (n = 32), and other cause of death (n = 13). In the TTP-related death group, 26 of 32 patients experienced sudden death, mostly following radical hypotension and bradycardia. The median follow-up time after admission was 5.0 days, and the median number of PEX sessions was 2.5. Nine patients underwent autopsy and had cardiac microvascular thrombi in arterioles. Levels of lactate dehydrogenase, total bilirubin, serum creatinine, and D-dimer were significantly higher in the TTP-related death group than in the survivors group. Frequent PEX (> 20 sessions) was not associated with TTP-related death. In the acute phase of iTTP, patients with substantial organ damage caused by microthrombi have a greater mortality risk, even after just a few PEX sessions.

Current Status of Clinical Engineer Anesthesia Assistants and Their Effect on Labor Task Shifting in Japan: A Prospective Observational Study in a Single Institute.

INTRODUCTION: Anesthesiologists are in short supply across the world, resulting in perpetually long working hours. To reduce the burden on anesthesiologists, tasks that can be performed by non-physicians must be shifted to other medical staff. In hospitals, clinical engineers can work as anesthesia assistants and perform some of the duties of anesthesiologists. This study aimed to evaluate the effect of task shift performed by clinical engineer anesthesia assistants (CEAAs). METHODS: This was a 1-month prospective observational study that included 33 anesthesiologists (11 fellows and 22 certified anesthesiologists) and 11 CEAAs. The total activity and anesthesia times were extracted from the attendance record as indices of the anesthesiologists' work status. The CEAAs recorded the duration of work performed on behalf of the anesthesiologists as task shift time. The task shift rate was evaluated as follows: task shift time/(task shift time + total activity time) and task shift time/(task shift time) + (total anesthesia time). RESULTS: The study period consisted of 19 weekdays. The average daily activity time of the anesthesiologists was 10.1 h, and the average anesthesia time was 8.5 h. The CEAAs performed a total of 546.8 h of task shift. The defined task shift rate was 20.1% when the total activity time was the denominator and 23.1% when the anesthesia time was the denominator. CONCLUSIONS: CEAAs might be effective in reducing the working hours of anesthesiologists through task shift. Their taking over a portion of the anesthesiologists' duties may allow the anesthesiologists to work more efficiently.

Hemolysis and von Willebrand factor degradation in mechanical shuttle shear flow tester.

Chronic blood trauma caused by the shear stresses generated by mechanical circulatory support (MCS) systems is one of the major concerns to be considered during the development of ventricular assist devices. Large multimers with high-molecular-weight von Willebrand factor (VWF) are extended by the fluid forces in a shear flow and are cleaved by ADAMTS13. Since the mechanical revolving motions in artificial MCSs induce cleavage in large VWF multimers, nonsurgical bleeding associated with the MCS is likely to occur after mechanical hemodynamic support. In this study, the shear stress (~ 600 Pa) and exposure time related to hemolysis and VWF degradation were investigated using a newly designed mechanical shuttle shear flow tester. The device consisted of a pair of cylinders facing the test section of a small-sized pipe; both the cylinders were connected to composite mechanical heads with a sliding-sleeve structure for axial separation during the withdrawing motion. The influence of exposure time, in terms of the number of stress cycles, on hemolysis and VWF degradation was confirmed using fresh goat blood, and the differences in the rates of dissipation of the multimers were established. The plasma-free hemoglobin levels showed a logarithmic increase corresponding to the number of cycles, and the dissipation of large VWF multimers occurred within a few seconds under high shear stress flow conditions.

Management of a COVID-19 Patient during ECMO: Paying Attention to Acquired von Willebrand Syndrome.

Patients with severe COVID-19 often experience complications including coagulopathy and fatal thrombosis. COVID-19 pneumonia sometimes leads to acute respiratory distress syndrome, requiring extracorporeal membrane oxygenation (ECMO), during which thrombosis and bleeding are major causes of death. Anticoagulation such as heparin is essential for COVID-19 patients on ECMO; however, bleeding might be caused by not only heparin, but also acquired von Willebrand syndrome (AVWS). To date, no study has examined ECMO-related bleeding and AVWS in COVID-19 patients.We report a COVID-19 patient who experienced bleeding from AVWS in addition to disseminated intravascular coagulation (DIC) during ECMO. The level of high-molecular weight VWF multimers decreased during ECMO therapy, and these findings promptly improved after discontinuation of ECMO. Plasma levels of VWF antigen were extremely high, probably due to endothelial cell damage caused by COVID-19. On the other hand, plasma levels of ADAMTS13 activity were moderately reduced, to 20-30% of normal. The patient was successfully treated with cryoprecipitate in bleeding during ECMO without a reduction in heparin, which might have induced thromboembolism. Bleeding found in this patient might be caused by AVWS and DIC.Severe COVID-19 patients are in a thrombotic state and need to receive anticoagulant therapy. However, once they receive ECMO therapy, bleeding symptoms could be observed. In such cases, physicians should think of AVWS in addition to the side effect of heparin and DIC.

Changes in the reference lumen size of target lesions before and after coronary stent implantation: Evaluation with frequency domain optical coherence tomography.

OBJECTIVE: In optical coherence tomography (OCT)-guided percutaneous coronary intervention (PCI), stent size is usually determined according to the pre-PCI lumen size of either the distal or proximal reference site. However, the effect of the OCT imaging catheter crossing the target lesion on the reference lumen measurements has not been studied. We evaluated changes in the reference lumen size before and after PCI using frequency domain OCT. METHODS: For 100 consecutive patients with PCI, mean lumen diameter (LD) and lumen area (LA) were measured at the proximal and distal reference sites before and after coronary stent implantation with OCT. RESULTS: Mean LD and LA of the distal reference site were significantly increased after PCI with stent implantation (2.57 ± 0.6 to 2.62 ± 0.64 mm, p < 0.01 and 5.20 ± 2.66 to 5.41 ± 2.54 mm2, p < 0.01, respectively). By contrast, these indices at the proximal reference site were significantly decreased. ROC curve analysis selected MLA of 1.50 mm2 as the best cutoff value for changes in mean LD. Distal mean LD was markedly increased after PCI in lesions with MLA < 1.50 mm (2.28 ± 0.48 to 2.40 ± 0.17 mm, P < 0.001), but did not change in lesions with MLA > 1.50 mm2. Tissue characteristics were not correlated with changes in reference lumen size. CONCLUSIONS: When we select the stent size during OCT-guided PCI, we need to pay attention to the decrease in the luminal measurement of the reference sites, especially in lesions with tight stenosis.