Zuspan's Scheme Versus an Alternative Magnesium Sulfate Scheme: Randomized Clinical Trial of Magnesium Serum Concentrations

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Preparation, Characterisation and Thermal Properties of Hydrazinium Magnesium Sulfate

Hydrazinium magnesium sulfate, (N2H5)2Mg(SO4)2, has been prepared by dissolving magnesium powder in a solution of ammonium sulfate in hydrazine hydrate, by the reaction of ammonium magnesium sulfate with hydrazine hydrate, and by the cocrystallisation of dihydrazinium sulfate and magnesium sulfate. The product has been characterized by chemical analysis and infrared spectra. Thermal analysis of (N2H5)2Mg(SO4)2 by TG and DTA show exothermic decomposition at 302°C giving Mg(N2H4)SO4 as an intermediate and an endother-mic decomposition at 504°C producing MgSO4.

Intravenous magnesium for acute myocardial infarction

BACKGROUND: Mortality and morbidity from acute myocardial infarction (AMI) remain high. Intravenous magnesium started early after the onset of AMI is thought to be a promising adjuvant treatment. Conflicting results from earlier trials and meta-analyses warrant a systematic review of available evidence. OBJECTIVES: To examine the effect of intravenous magnesium versus placebo on early mortality and morbidity. SEARCH STRATEGY: We searched CENTRAL (The Cochrane Library Issue 3, 2006), MEDLINE (January 1966 to June 2006) and EMBASE (January 1980 to June 2006), and the Chinese Biomedical Disk (CBM disk) (January 1978 to June 2006). Some core Chinese medical journals relevant to the cardiovascular field were hand searched from their starting date to the first-half year of 2006. SELECTION CRITERIA: All randomized controlled trials that compared intravenous magnesium with placebo in the presence or absence of fibrinolytic therapy in addition to routine treatment were eligible if they reported mortality and morbidity within 35 days of AMI onset. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed the trial quality and extracted data using a standard form. Odds ratio (OR) were used to pool the effect if appropriate. Where heterogeneity of effects was found, clinical and methodological sources of this were explored. MAIN RESULTS: For early mortality where there was evidence of heterogeneity, a fixed-effect meta-analysis showed no difference between magnesium and placebo groups (OR 0.99, 95%CI 0.94 to 1.04), while a random-effects meta-analysis showed a significant reduction comparing magnesium with placebo (OR 0.66, 95% CI 0.53 to 0.82). Stratification by timing of treatment (< 6 hrs, 6+ hrs) reduced heterogeneity, and in both fixed-effect and random-effects models no significant effect of magnesium was found. In stratified analyses, early mortality was reduced for patients not treated with thrombolysis (OR=0.73, 95% CI 0.56 to 0.94 by random-effects model) and for those treated with less than 75 mmol of magnesium (OR=0.59, 95% CI 0.49 to 0.70) in the magnesium compared with placebo groups.Meta-analysis for the secondary outcomes where there was no evidence of heterogeneity showed reductions in the odds of ventricular fibrillation (OR=0.88, 95% CI 0.81 to 0.96), but increases in the odds of profound hypotension (OR=1.13, 95% CI 1.09 to 1.19) and bradycardia (OR=1.49, 95% CI 1.26 to 1.77) comparing magnesium with placebo. No difference was observed for heart block (OR=1.05, 95% CI 0.97-1.14). For those outcomes where there was evidence of heterogeneity, meta-analysis with both fixed-effect and random-effects models showed that magnesium could decrease ventricular tachycardia (OR=0.45, 95% CI 0.31 to 0.66 by fixed-effect model; OR=0.40, 95% CI 0.19 to 0.84 by random-effects model) and severe arrhythmia needing treatment or Lown 2-5 (OR=0.72, 95% CI 0.60 to 0.85 by fixed-effect model; OR=0.51, 95% CI 0.33 to 0.79 by random-effects model) compared with placebo. There was no difference on the effect of cardiogenic shock between the two groups. AUTHORS' CONCLUSIONS: Owing to the likelihood of publication bias and marked heterogeneity of treatment effects, it is essential that the findings are interpreted cautiously. From the evidence reviewed here, we consider that: (1) it is unlikely that magnesium is beneficial in reducing mortality both in patients treated early and in patients treated late, and in patients already receiving thrombolytic therapy; (2) it is unlikely that magnesium will reduce mortality when used at high dose (>=75 mmol); (3) magnesium treatment may reduce the incidence of ventricular fibrillation, ventricular tachycardia, severe arrhythmia needing treatment or Lown 2-5, but it may increase the incidence of profound hypotension, bradycardia and flushing; and (4) the areas of uncertainty regarding the effect of magnesium on mortality remain the effect of low dose treatment (< 75 mmol) and in patients not treate...

The influence of sulfuric environments on concretes elaborated with sulfate resistant cements and mineral admixtures. Part 2: Concrete exposed to Magnesium Sulfate (MgSO4) = Estudio de la influencia de los medios con presencia de sulfatos en hormigones con cementos sulforresistentes y adiciones minerales. Parte 2.Hormigones expuestos a sulfato magnésico (MgSO4)

The present work studies the resistant of the concrete against magnesium sulfate (MgSO4) and compare the results with values obtained previously of the same concretes exposed to sodium sulfate (Na2SO4). Thus, it is possible analyze the influence of the cation type. To that end, four different concrete mixes were made with sulfur resistant cement and mineral admixtures (silica fume, fly ash and blast furnace slag). The concretes were submerged for different period in magnesium sulfate (MgSO4). After that, different tests were carried out to define mechanical and microstructural properties. The results obtained were compared with reference values of concretes cured in calcium hydroxide [Ca(OH)2]. According to the results, the concrete with blast furnace slag presented the best behavior front MgSO4, meanwhile the concretes with silica fume and fly ash were the most susceptible. The resistance of the concrete with blast furnace slag could be attributed to the characteristics of the hydrated silicates formed during the hydration time, which include aluminum in the chemical chain that hinder its chemical decomposition during the attack of magnesium. The magnesium sulfate solution was most aggressive than sodium sulfate solution. El presente trabajo estudia la resistencia de hormigones al ataque de sulfatos provenientes de sulfato magnésico (MgSO4) y compara estos valores con resultados previos de los mismos hormigones atacados con sulfato sódico (Na2SO4). De esta manera se estudia la interacción del catión que acompaña al ion sulfato durante su afectación a la matriz cementicia. Para lo anterior, se diseñaron cuatro dosificaciones empleando cementos sulforresistentes y adiciones minerales (humo de sílice, ceniza volante y escoria de alto horno). Los hormigones se sumergieron, por distintos periodos de tiempo, en disolución de sulfato magnésico (MgSO4) de concentración 1M, para después realizarles ensayos mecánicos y a nivel microestructural. Los valores obtenidos se compararon con los obtenidos en el hormigón de referencia curado en hidróxido cálcico. El hormigón con escoria de alto horno presentó el mejor comportamiento frente a MgSO4, siendo las mezclas de humo de sílice y ceniza volante las más susceptibles. La resistencia del hormigón con escoria se atribuye a las características de los silicatos hidratados formados durante la hidratación, los cuales incorporan aluminio en las cadenas impidiendo su descomposición ante un ataque por magnesio. El medio con sulfato magnésico mostro una mayor agresividad que el medio con sulfato sódico.

Magnesium sulfate chemistry and technology : a literature search /

The literature relative to the chemistry and technology of magnesium sulfate is presented. The literature titles and chemical abstracts numbers are given, together with a subject index.

Cautionary tales in the interpretation of systematic reviews of therapy trials

This is the second in a series of articles emphasizing the cautions in the interpretation of health-care studies. Systematic reviews are presented as comprehensive, unbiased summaries of evidence and are often referred to by clinicians, guideline developers and health policy-makers. Their strengths and limitations, and how their results can be subject to bias and misinterpretation, are discussed.

Effects of magnesium sulphate on the pharmacodynamics of rocuronium in patients aged 60 years and older: A randomised trial

BACKGROUND There is little information on the interaction between magnesium sulphate (MgSO4) and rocuronium in elderly patients. With a growing number of older patients who need surgical procedures, it is increasingly important to study this age group. OBJECTIVE To evaluate the effects of MgSO4 administration on the pharmacodynamics of rocuronium in patients aged 60 years or older. DESIGN A randomised controlled trial. SETTING A tertiary care hospital. PATIENTS Sixty-four patients, aged 60 years or older, American Society of Anesthesiologists (ASA) physical status classes I to III, scheduled for elective oncological head and neck surgery. Exclusion criteria were severe renal insufficiency (calculated creatinine clearance <30 ml min-1), preoperatorive serum magnesium concentration of more than 1.25 mmol l1 and patients receiving drugs known to affect neuromuscular function. INTERVENTIONS Patients were randomly allocated to one of two groups: in the magnesium group, patients received MgSO4 30mgkg1 intravenously, for 10 min, and then a continuous intravenous infusion at a rate of 1 g h-1. The control group received the same volume of physiological saline. Neuromuscular function was evaluated continuously in both groups. MAIN OUTCOME MEASURES Total recovery time was the primary outcome. Onset time, clinical duration, recovery index and recovery time were considered as secondary endpoints. Values are given as mean [SD]. RESULTS Total recovery time from neuromuscular block (NMB) was 113 [36] min in the magnesium group and 101 [39] min in the control group. Clinical duration was 69 [23] min in the magnesium group and 59 [28] min in the control group. Recovery index was 19 [36] min in the magnesium group and 17 [6] min in the control group. Recovery timewas 44 [22] min in the magnesium group and 42 [18] min in the control group. There were no statistically significant differences between the groups in any of the recovery indices. In the magnesium group, the mean onset time was 144 [58] s, significantly shorter than the onset time in the group that received physiological saline, which was 187 [90] s (P-0.03). Group variances were compared using an F test: onset time varied significantly less in the magnesium group (P-0.02). CONCLUSION In oncology patients of 60 or more years of age, preadministration of MgSO4, with the doses used in this study, significantly reduced the onset time of NMB induced by rocuronium. © 2013 European Society of Anaesthesiology.

Performance of magnesia cements in porous blocks in acid and magnesium environments

The performance of porous blocks containing three different reactive magnesia-based cements - namely magnesia alone, magnesium oxide: Portland cement (PC) in 1:1 ratio, cured in ambient conditions, and magnesia alone, cured at elevated carbon dioxide conditions, in hydrochloric acid and magnesium sulfate solution - was investigated. Different aggressive chemical solution conditions were used, to which the samples were exposed for up to 12 months and then tested for strength and microstructure. The performance was also compared with that of standard PC-based blocks. The results showed the significant resistance to chemical attack offered by magnesia, both alone and with PC blend in the porous blocks when cured under ambient carbon dioxide conditions, and confirmed the much poorer performance of blocks made from PC alone. The blocks of solely magnesia cured in elevated carbon dioxide conditions, at 20% concentration, showed slightly lower resistance to acid attack than PC; however, the resistance to sulfate attack was much higher. © 2012 Thomas Telford Ltd.

EFEIFOS DO SULFATE DE MAGNESIO NA HEMODINAMICA CARDIOVASCULAR DE CAES ANESTESIADOS COM PENTOBARBITAL SODICO

Background and Objectives - A controversy exists in the literature regarding the effects of the acute administration of magnesium on the cardiovascular system of animals and humans. The purpose of this study was to evaluate the effects of hypermagnesemia on the cardiovascular hemodynamics of dogs. Methods - Sixteen mongrel dogs were anesthetized with pentobarbitone 30 mg.kg-1 and submitted to volume expansion with Ringer's solution (0.4 ml.kg-1.min-1 and mechanical ventilation with room air. In this model, the hemodynamic repercussions of the following drugs and doses were studied. pentobarbitone 5 mg.kg-1 Group 1, control - and the association of pentobarbitone and magnesium sulphate (MS), at the dose of 140 mg.kg-1 injected in 15 minutes, followed by an infusion of 80 mg.kg-1.h-1 - Group 2. The parameters studied were: heart rate, blood pressure, inferior vena cava pressure, cardiac index, systolic index and peripheral resistance index, evaluated at 5 different moments: 15(M1), 30(M2), 60(M3) and 75(M4) minutes after the first suppplementary dose of pentobarbitone and 15 minutes (M5) after the second supplementary dose. In Group 2, the moments M3, M4, M5 corresponded to 15, 30 and 60 minutes after the priming dose of magnesium sulphate. Results - Group 1 animals exhibited tachycardia since the beginning of the experiment. There was a decrease in the cardiac index, in the systolic index and an increase in the inferior vena cava pressure. Group 2 animals also exhibited tachycardia, but heart rate decreased after MS infusion. The blood pressure and the peripheral resistance index decreased. The systolic index increased and the cardiac index decreased only at the end of the experiment. Conclusions: The antiadrenergic effects of MS could have been responsible for the decrease in heart rate. The vasodilating effects of the magnesium induced the decrease in the peripheral resistance index. The systolic index increased, showing that myocardial depression did not occur.

EFEITOS DO SULFATE DE MAGNESIO NA HEMODINAMICA E FUNCAO RENAL DE CAES ANESTESIADOS CORN PENTOBARBITAL SODICO

Background and objectives - The use of magnesium sulphate for the prevention of seizures in pre-eclampsia may induce hypermagnesemia. Clinical and experimental studies are not in agreement about the effects of magnesium on the renal hemodynamics and function. We therefore studied the effects of hypermagnesemia on the renal hemodynamics and function of dogs anesthetized with pentobarbitone. Methods - Sixteen mongrel dogs were anesthetized with pentobarbitone 30 mg.kg-1 and submitted to extracellular ) and mechanical ventilation with room air. The dogs were volume expansion with Ringer's solution (0.4 ml.kg.min allocated into two groups of 8 animals, for the study of renal hemodynamics and function following the administration of 5 mg.kg-1 of pentobarbitone (Group 1 - control or of pentobarbitone associated with magnesium sulphate in the dose (Group 2). The parameters studied were: PAH of 140 mg.kg, administered in 15 minutes, followed by 80 mg.kg-1.h-1 clearance, creatinine clearance, osmolar clearance, free water clearance, renal blood flow, renal vascular resistance, filtration fraction, urinary volume, plasmatic and urinary osmolarity, urinary and fractionary excretion of sodium and potassium, measured at five moments: 15 (M1), 30 (M2), 60 (M3) and 75 (M4) minutes after the first supplementary dose of pentobarbitone and 15 minutes (M5) after the second supplementary dose in Group 1. In Group 2, the moments M3, M4, M5 were 15, 30 and 60 minutes after the priming dose of magnesium sulphate and during the maintenance dose. Results - In Group I no significant changes were observed in renal hemodynamic parameters and creatinine clearance. The extracellular volume expansion increased urinary volume and decreased urinary osmolarity as a consequence of sodium, potassium and free water clearance. The fractionary excretion of sodium was maintained. The plasmatic osmolarity increased. In Group 2, renal hemodynamic parameters and creatinine clearance were also maintained. There was an increase in renal sodium clearance, as detected by the increase in the fractionary excretion of sodium. Conclusions - Magnesium sulphate did not produce significant changes in renal hemodynamics and facilitated the renal excretion of sodium in dogs anesthetized with pentobarbitone.

Concentração sérica de sulfato de magnésio em gestantes com pré-eclâmpsia, submetidas aos esquemas de Zuspan e de Sibai

Pós-graduação em Ginecologia, Obstetrícia e Mastologia - FMB

The effect of acute magnesium loading on the maximal exercise performance of stable chronic obstructive pulmonary disease patients

OBJECTIVE: The potential influence of magnesium on exercise performance is a subject of increasing interest. Magnesium has been shown to have bronchodilatatory properties in asthma and chronic obstructive pulmonary disease patients. The aim of this study was to investigate the effects of acute magnesium IV loading on the aerobic exercise performance of stable chronic obstructive pulmonary disease patients. METHODS: Twenty male chronic obstructive pulmonary disease patients (66.2 +/- 8.3 years old, FEV1: 49.3 +/- 19.8%) received an IV infusion of 2 g of either magnesium sulfate or saline on two randomly assigned occasions approximately two days apart. Spirometry was performed both before and 45 minutes after the infusions. A symptom-limited incremental maximal cardiopulmonary test was performed on a cycle ergometer at approximately 100 minutes after the end of the infusion. ClinicalTrials.gov: NCT00500864 RESULTS: Magnesium infusion was associated with significant reductions in the functional residual capacity (-0.41 l) and residual volume (-0.47 l), the mean arterial blood pressure (-5.6 mmHg) and the cardiac double product (734.8 mmHg.bpm) at rest. Magnesium treatment led to significant increases in the maximal load reached (+8 w) and the respiratory exchange ratio (0.06) at peak exercise. The subgroup of patients who showed increases in the work load equal to or greater than 5 w also exhibited significantly greater improvements in inspiratory capacity (0.29 l). CONCLUSIONS: The acute IV loading of magnesium promotes a reduction in static lung hyperinflation and improves the exercise performance in stable chronic obstructive pulmonary disease patients. Improvements in respiratory mechanics appear to be responsible for the latter finding.

Influence of the magnesium aspartate hydrochloride administration to the maternal circuit on the aspartate concentration of the fetal circuit under in vitro perfusion of human placenta

OBJECTIVES: Magnesium aspartate hydrochloride (Magnesiocard, Mg-Asp-HCl) is proposed as a substitute of magnesium sulfate for the treatment of preeclampsia and premature labor. After an i.v. administration of a dose equivalent to that used in the treatment of preeclampsia to nonpregnant volunteers, a 10-fold increase of aspartic acid (Asp) over the physiological level was observed. Animal experiments have demonstrated that highly increased fetal levels of acidic amino acids such as Asp could be associated with neurotoxic damage in the fetal brain. The influence of such an elevation of Asp concentration in the maternal circuit on the fetal level, using the in vitro perfusion model of human placenta, was investigated. STUDY DESIGN: After a control phase (2h), a therapeutic dose of Mg combined with Asp (Magnesiocard, Mg-Asp-HCl) was applied to the maternal circuit approaching 10 times the physiological level of Asp. The administration was performed in two different phases simulating either a peak of maximum concentration (bolus application, 2h) or a steady state level (initially added, 4h). RESULTS: In four experiments, during experimental phases (6h) a slow increase in concentration in the fetal circuit was seen for Mg, AIB (alpha-aminoisobutyric acid, artificial amino acid) and creatinine confirming previous observations. In contrast, no net transfer of Asp across the placenta was seen. A continuous decrease in the concentration of Asp on both maternal and fetal side suggests active uptake and metabolization by the placenta. Viability control parameters remained stable indicating the absence of an effect on placental metabolism, permeability and morphology. CONCLUSION: Elevation of Asp concentration up to 10 times the physiological level by the administration of Mg-Asp-HCl to the maternal circuit under in vitro perfusion conditions of human placenta has no influence on the fetal level of Asp suggesting no transfer of Asp from the maternal to fetal compartment. Therefore, the administration of Mg-Asp-HCl to preeclamptic patients would be beneficial for the patients without any impact on placental or fetal physiology.

Sulfate Resistance of Alkali Activated Pozzolans

The consequence of sulfate attack on geopolymer concrete, made from an alkali activated natural pozzolan (AANP) has been studied in this paper. Changes in the compressive strength, expansion and capillary water absorption of specimens have been investigated combined with phases determination by means of X-ray diffraction. At the end of present investigation which was to evaluate the performance of natural alumina silica based geopolymer concrete in sodium and magnesium sulfate solution, the loss of compressive strength and percentage of expansion of AANP concrete was recorded up to 19.4% and 0.074, respectively.