Impact of different syringe pumps on red cells during paediatric simulated transfusion

Background: Critically ill patients frequently need blood transfusions. For safety, blood must be delivered via syringe infusion pumps, yet this can cause red cell damage and increase the rate of haemolysis. Aims and objectives: To evaluate biochemical and haemolytic markers of red blood cells transfused in three different, common type of syringe infusion pumps with two different infusion rates (10 and 100 ml/h). Methods: A lab-based study using aliquots of 16 red blood cells bags was undertaken. Haemolysis markers (total haemoglobin(g/dl), haematocrit(%), free haemoglobin(g/dl), potassium(mmol/L), lactate dehydrogenase(U/L), osmolality(mOsm/kg), pH, degree of haemolysis(%)) were measured before and after red blood cells infusion and exposure. Three different syringe infusion pumps brands (A, B and C) were compared with two different infusion rates (10 and 100 ml/h). Results: The total haemoglobin fell significantly in all red blood cells units during manipulation (Pre-infusion: 26.44±5.74; Post-exposure: 22.62±4.00; p=0.026). The degree of haemolysis significantly increased by 40% after manipulation of the red blood cells. Syringe infusion pump A caused a threefold increase in potassium levels (3.78±6.10) when compared to B (-0.14±1.46) and C (1.63± 1.98) (p=0.015). This pump also produced the worst changes, with an increase in free haemoglobin (0.05±0.05; p=0.038) and more haemolysis (0.08±0.07; p=0.033). There were significant differences and an increase in the degree of haemolysis (p=0.004) in the infusion rate of 100 mL/h. Conclusions: Syringe infusion pumps may cause significant red blood cell damage during infusion, with increases in free haemoglobin, potassium and the degree of haemolysis. Some pumps types, with a cassette mechanism, caused more damage. Relevance to clinical practice: In many ICUs, bedside nurses are able to consider infusion pump choice and understanding the impact of different pump types on RBC during a transfusion provides the nurses with more information to enhance decision-making and improve the quality of the transfusion

Solution density influence on syringe infusion pumps performance: An experimental study

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Quasimolecular JtetJ_{\rm tet}=3/2 moments in the cluster Mott insulator GaTa4_4Se8_8

Quasimolecular orbitals in cluster Mott insulators provide a route to tailor exchange interactions, which may yield novel quantum phases of matter. We demonstrate the cluster Mott character of the lacunar spinel GaTa$_4$Se$_8$ using resonant inelastic x-ray scattering (RIXS) at the Ta $L_3$ edge. Electrons are fully delocalized over Ta$_4$ tetrahedra, forming quasimolecular $J_{\rm tet}$=3/2 moments. The modulation of the RIXS intensity as function of the transferred momentum q allows us to determine the cluster wavefunction, which depends on competing intracluster hopping terms that mix states with different character. This mixed wavefunction is decisive for the macroscopic properties since it affects intercluster hopping and exchange interactions and furthermore renormalizes the effective spin-orbit coupling constant. The versatile wavefunction, tunable via intracluster hopping, opens a new perspective on the large family of lacunar spinels and cluster Mott insulators in general.Comment: 7 pages, 4 figures, plus supplementary informatio

Variability in the establishment of an external reference point for central venous pressure measurement in children

OBJECTIVE: To investigate the variability in the establishment of the midaxillary line as external reference point (ERP), by different healthcare workers, for the measurement of central venous pressure in children. METHODS: Descriptive and correlational study carried out in a pediatric intensive care unit of a teaching hospital. During the establishment of the midaxillary line as ERP for central venous pressure measurement, five assessments of the same patient made by healthcare workers and one assessment made by a trained evaluator were compared. A total of 120 assessments were made by 44 healthcare workers, 17 (38.6%) by nursing assistants and nursing technicians, 16 (36.3%) by nurses and 11 (25.1%) by physicians, in addition to 24 assessments made by the trained evaluator. The data were analyzed using the chi-square test, ANOVA, Kruskal-Wallis test and t test. Significance level was set at 5%. RESULTS: There was statistically significant difference between the assessments made by healthcare workers and by the evaluator (p < 0.001). The comparison of the variability in the measurements made by healthcare workers revealed that 56 (46.7%) measurements were lower than those obtained by the evaluator (range from -0.5 to -9), 44 (36.7%) were higher (range from 0.5 to 4) and 20 (16.7%) were concordant (zero variability). Professional category did not influence the concordance between the ERPs (p = 0.899), or the variability observed (p = 0.778). However, the measurements made by professionals with greater experience in intensive care tended to differ more sharply from those made by the evaluators. CONCLUSION: The indications of the midaxillary line as ERP presented variations when measured by the healthcare team and by the trained evaluator. Variability was not influenced by professional category, and the more experienced the healthcare worker, the greater the probability for underestimation of the ERP. According to the results of this study, such situations may compromise both the efficacy of this procedure and patient safety.OBJETIVO: Verificar variabilidade na determinação da linha axilar média como ponto externo de referência (PER), por diferentes profissionais de saú de, para a aferição de pressão venosa central em crianças. MÉTODOS: Estudo descritivo e de correlação realizado em uma unidade de cuidados intensivos pediátricos de um hospital universitário. Durante a determinação da linha axilar média como PER para a aferição da pressão venosa central, cinco avaliações realizadas no mesmo paciente por profissionais de saúde e uma realizada por um avaliador treinado foram comparadas. O resultado foi um total de 120 indicações de 44 profissionais de saúde, 17 (38,6%) auxiliares e técnicos de enfermagem, 16 (36,3%) enfermeiros e 11 (25,1%) médicos, além de 24 identificações realizadas por avaliador treinado. Os dados foram analisados utilizando os testes do qui-quadrado, ANOVA, Kruskall-Wallis e teste t, fixando o nível de significância em 5%. RESULTADOS: Houve diferença significante entre as identificações realizadas pelos profissionais de saúde e pelo avaliador (p < 0,001). Comparando a variabilidade das medidas realizadas pelos profissionais, 56 (46,7%) foram menores do que a identificação do avaliador (variação de -0,5 até -9), 44 (36,7%) foram maiores (variação de 0,5 até 4) e 20 (16,7%) foram coincidentes (variação nula). Não se identificou influência da categoria profissional sobre a concordância entre os PER indicados (p = 0,899), tampouco na variabilidade observada (p = 0,778). Observou-se, contudo, que profissionais com maior tempo de experiência em unidades de cuidados intensivos demonstraram uma tendência a maior variabilidade com as medidas dos avaliadores. CONCLUSÃO: Verificou-se variabilidade nas indicações da linha axilar média como PER entre os profissionais e o avaliador treinado. A variabilidade não foi influenciada pela categoria profissional e quanto maior o tempo de experiência do profissional, maior a tendência em subestimar o ponto de referência. Os resultados deste estudo indicaram situações que poderiam comprometer a eficácia do procedimento e a segurança do paciente.Universidade Federal de São Paulo (UNIFESP)Universidade Federal de São Paulo (UNIFESP) Departamento de EnfermagemUNIFESP Departamento de EnfermagemUNIFESP Departamento de PediatriaUNIFESP, Depto. de EnfermagemUNIFESP, Depto. de EnfermagemUNIFESP, Depto. de PediatriaSciEL

Quasimolecular electronic structure of the spin-liquid candidate Ba3InIr2O9

The mixed-valent iridate Ba3InIr2O9 has been discussed as a promising candidate for quantum spin-liquid behavior. The compound exhibits Ir4.5+ ions in face-sharing IrO6 octahedra forming Ir2O9 dimers with three t2g holes per dimer. Our results establish Ba3InIr2O9 as a cluster Mott insulator. Strong intradimer hopping delocalizes the three t2g holes in quasimolecular dimer states while interdimer charge fluctuations are suppressed by Coulomb repulsion. The magnetism of Ba3InIr2O9 emerges from spin-orbit entangled quasimolecular moments with yet unexplored interactions, opening up a new route to unconventional magnetic properties of 5d compounds. Using single-crystal x-ray diffraction we find the monoclinic space group C2/c already at room temperature. Dielectric spectroscopy shows insulating behavior. Resonant inelastic x-ray scattering reveals a rich excitation spectrum below 1.5 eV with a sinusoidal dynamical structure factor that unambiguously demonstrates the quasimolecular character of the electronic states. Below 0.3 eV, we observe a series of excitations. According to exact diagonalization calculations, such low-energy excitations reflect the proximity of Ba3InIr2O9 to a hopping-induced phase transition based on the condensation of a quasimolecular spin-orbit exciton. The dimer ground state roughly hosts two holes in a bonding j=12 orbital and the third hole in a bonding j=32 orbital