Continuous renal replacement therapy in COVID-19-associated AKI: adding heparin to citrate to extend filter life-a retrospective cohort study.

BACKGROUND: Coronavirus disease 2019 (COVID-19) may predispose patients to thrombotic events. The best anticoagulation strategy for continuous renal replacement therapy (CRRT) in such patients is still under debate. The purpose of this study was to evaluate the impact that different anticoagulation protocols have on filter clotting risk. METHODS: This was a retrospective observational study comparing two different anticoagulation strategies (citrate only and citrate plus intravenous infusion of unfractionated heparin) in patients with acute kidney injury (AKI), associated or not with COVID-19 (COV + AKI and COV - AKI, respectively), who were submitted to CRRT. Filter clotting risks were compared among groups. RESULTS: Between January 2019 and July 2020, 238 patients were evaluated: 188 in the COV + AKI group and 50 in the COV - AKI group. Filter clotting during the first filter use occurred in 111 patients (46.6%). Heparin use conferred protection against filter clotting (HR = 0.37, 95% CI 0.25-0.55), resulting in longer filter survival. Bleeding events and the need for blood transfusion were similar between the citrate only and citrate plus unfractionated heparin strategies. In-hospital mortality was higher among the COV + AKI patients than among the COV - AKI patients, although it was similar between the COV + AKI patients who received heparin and those who did not. Filter clotting was more common in patients with D-dimer levels above the median (5990 ng/ml). In the multivariate analysis, heparin was associated with a lower risk of filter clotting (HR = 0.28, 95% CI 0.18-0.43), whereas an elevated D-dimer level and high hemoglobin were found to be risk factors for circuit clotting. A diagnosis of COVID-19 was marginally associated with an increased risk of circuit clotting (HR = 2.15, 95% CI 0.99-4.68). CONCLUSIONS: In COV + AKI patients, adding systemic heparin to standard regional citrate anticoagulation may prolong CRRT filter patency by reducing clotting risk with a low risk of complications.

Measurement of TFF3 mRNA in aspirates from thyroid nodules using mesh filtration: the first clinical trial in 130 cases.

Measurement of gene expression levels in thyroid tumor cells in aspirates was difficult because it is interfered with peripheral blood cells or infiltrating lymphocytes. In this study, we established a novel method to separate thyroid tumor cells from blood cells efficiently with mesh filtration. The expression level of trefoil factor 3 (TFF3) mRNA was estimated using LGALS3 mRNA as an internal control (T/G ratio) in 148 preoperative thyroid aspirates. Intra-assay coefficients of variation (CV) of T/G ratio for high, moderate, and low samples were 6.5%, 2.5%, and 9.7%, respectively, and inter-assay CV for high, moderate, and low samples were 27.7%, 21.9%, and 38.2%, respectively. Nondiagnostic samples in terms of T/G ratio and cytology were 12.2% and 16.9%, respectively. We observed no interference with the data by contaminating blood cells. Among these patients, 12 patients received more than two repeated aspirations. We did not observe a marked day-to-day variation except in two cases. All 13 preoperative aspirates diagnosed as malignant by cytology showed an extremely low T/G ratio, whereas 93 aspirates diagnosed as benign by cytology showed extremely varied T/G ratios and 21.5% of them showed a T/G ratio below the cut-off value. Eleven cases underwent surgery. All nodules showing a low T/G ratio were diagnosed as papillary carcinoma by pathological diagnosis. However, one nodule diagnosed as follicular adenoma after surgery showed a high T/G ratio. Our present method may be a promising preoperative test for measuring mRNAs in thyroid aspirates.

A national survey of prevention of infection in obstetric central neuraxial blockade in the UK.

We conducted a postal survey of all consultant-led UK obstetric anaesthetic units in August 2009, to assess the standard of aseptic technique used for neuraxial blocks. One hundred and sixty-four units responded giving a response rate of 76%; 93% of units (149/160) follow recommended precautions and attach a bacterial micropore filter to the epidural catheter. Epidural top-ups are provided by 72% (116/162) of units, with about two thirds using premixed solutions (of local anaesthetic with opioid) in a variety of ways: 51% (57/111) via a continuous infusion pump; 47% (52/111) by a prefilled syringe; and 23% (25/111) by multiple use of a premixed bag of solution. For spinals, 91% of units (149/164) add diamorphine: of these 85% (126/149) draw the diamorphine from non-sterile-wrapped ampoules. If required to draw opioid from a non-sterile-wrapped ampoule, 86% (119/138) of units use a micropore filter and 21% (29/138) wipe the ampoule neck with an alcohol swab. Although sepsis secondary to neuraxial block in obstetric practice is uncommon (declared by 8.5% of units over an unspecified period of time), there is scope for further improvement.

Microbial retention characteristics of sterilizing-grade membrane filters with alginate substituted for oil-based products.

For oil-based products, FDA recommends substitution of the oil with a compound which has similar viscosity and physical characteristics. In this study, a substitute for oil-based products was screened by measuring the viscosity and filterability, and examined for the presence of cell clumps in the various test fluids using an optical microscopy. The viscosity of the test fluids measured in the range of about 60-75 cP. Brevundimonas diminuta (formerly Pseudomonas diminuta), a standard challenge test organism for validation of 0.2 micron rated membrane filters, formed clumps in oils (corn, olive, sesame, and soybean) and polyethylene glycol (PEG, Molecular Weight (MW) = 400 and 1,000). During the viability test, cells suspended in 80% glycerol showed a ten-fold mortality rate after an exposure for 6 hours, but there was no significant change in viability in alginate (low, medium, and high viscosity) for 24 hours. These results suggested that alginate is better suited as a substitute for oil-based products than 80% glycerol. Since high viscosity fluids take longer to filter, the glycerol mortality rate would influence the challenge test negatively. A scaled-down filtration system has been developed for the described trials, and the bacterial challenge and bubble point tests have been performed in 1.6% alginate (66.7 cP), which was the choice of carrier fluid.

Monitoring method for surface contamination caused by selected antineoplastic agents.

A method of evaluating surface contamination caused by selected antineoplastic agents was studied. The antineoplastic agents tested were cyclophosphamide, ifosfamide, doxorubicin hydrochloride, fluorouracil, and paclitaxel. Each agent was reconstituted and prepared as a stock solution. A 0.1-mL portion of each solution was spread evenly over a 600-cm2 area of a stainless steel surface, a resin countertop surface, and a vinyl flooring surface. After drying, the surfaces were wiped with each of two types of commercially available wiping materials (What-man no. 42 filters and Kimberly-Clark Kimwipes). A blend of methanol, acetonitrile, and buffered water was used both as the wetting agent for wiping the surfaces and as a desorbing solution. The desorbate was analyzed for drug concentration by reverse-phase high-performance liquid chromatography (HPLC). Mean +/- S.D. percent total recovery ranged from 72.4% +/- 17.6% to 95.3% +/- 2.9% for the vinyl surface wiped with filters, 91.5% +/- 5.4% to 104.7% +/- 0.8% for the resin surface wiped with filters, 73.9% +/- 2.3% to 95.3% +/- 1.7% for the stainless steel surface wiped with filters, and 18.2% +/- 1.4% to 372.8% +/- 8.0% for the stainless steel surface wiped with Kimwipes. Results were best for ifosfamide and cyclophosphamide. Kimwipes were deemed ineffective for this monitoring method because an ingredient interfered with the quantitative analytical tests. A wipe-sampling, desorption, and HPLC method for monitoring surface contamination by selected antineoplastic agents was sufficiently accurate and sensitive to evaluate surfaces typically found in both the pharmacy and drug administration areas of oncology treatment facilities.

Membrane filtration for virus removal.

Incorporation of adequate clearance methodologies for viral safety assurance constitutes an integral part of the manufacturing process for plasma-derived biologicals. Filtration, being non-invasive, non-destructive and a <> mechanism for virus removal is often the method of choice. This paper discusses the virus filter performance characteristics and other process-related issues specifically applying to the Pall Ultipor VF filters (Grade DV50 and Grade DV20), which are operated in the direct flow filtration (DFF) mode and the Pall Filtron Omega VR filters (the Omega 300 K and Omega 100 K), which are operated in the tangential flow filtration (TFF) mode.

Extent and practicalities of filter use in anaesthetic breathing circuits and attitudes towards their use: a postal survey of UK hospitals.

A postal survey of 120 UK hospitals was conducted to assess the current use of filters in anaesthetic breathing systems and consultant anaesthetists' opinion of their value; 76% of the questionnaires were returned complete. The survey showed that 77.2% of anaesthetic departments use a new filter for every case, a variety of different filter types being used. A connector distal to the filter was used in 78.3% of patients, providing a possible route for cross infection. Anaesthetists rated the prevention of bacterial infection and gross contamination as being higher priorities than the prevention of viral infection. Of those surveyed, 66.3% believed filters were worthwhile whereas only 35.9% thought they were cost effective. Only 34.8% of anaesthetists believed that the supposed extra efficiency of pleated hydrophobic membrane filters over electrostatic filters merited their extra cost.