Can one really measure magnesium deficiency using the short-term magnesium loading test?

OBJECTIVE: To compare a 1-h-version of a magnesium-loading-test (MLT) designed for outpatients in healthy controls with the 8-h standard; to establish the test in patients after renal transplantation prone to develop magnesium (Mg) deficiency; to correlate femur Mg-concentration and percentage retention of the given load. DESIGN: Comparison of mean values from healthy controls with respective from the literature; a prospective, randomized, controlled 4-month study; an intra-individual correlation of Mg-serum values and loading-test data with femur-Mg concentrations. SETTING: One centre study in a medical university; outpatients from the transplant unit; inpatients from the orthopedic unit. SUBJECTS: Twenty-four healthy controls aged 36.7 +/- 7.4 years; 34 patients after renal transplantation (46.5 +/- 14.3 years); 41 patients with hip replacement therapy (63.9 +/- 18.6 years). INTERVENTION: Baseline Mg values were measured by atomic absorption spectroscopy (AAS) in serum and urine. An intravenous Mg load with 0.1 mmol Mg-aspartate hydrochloride per kilogram bodyweight was given during 1 h. In 24 h-urine, the amount of excreted Mg was measured by AAS and the percentage retention of the given load calculated according to the formula: 1 - [Mg 24 h-urine/Mg test dose] x 100. Femur Mg was measured by AAS in a peace of the femur neck. Patients after renal transplantation were randomized after the first Mg load to either obtain daily 5 mmol Mg-aspartate hydrochloride per kilogram bodyweight, or placebo. Four months later a second loading-procedure was performed. MAIN OUTCOME MEASURE: Serum Mg, percentage retention of the given Mg load (%Ret) and femur Mg concentration. RESULTS: Mean serum Mg values were within the normal range. In controls, %Ret was -18 +/- 21 and not different from the literature. In the first MLT after renal transplantation, %Ret was 47 +/- 43. In patients under Mg medication it decreased significantly to 16 +/- 26, but was 58 +/- 27 in the placebo group. Femur Mg concentration was 62.6 +/- 20.9 mmol kg-1 dry substance and the corresponding %Ret was 14 +/- 28 with r = - 0.7093. CONCLUSION: The short-term version of the MLT is as good as the standard and was easily applied in outpatients. The indication from the good correlation between bone-Mg and %Ret and a marked decrease in %Ret in patients after Mg medication was that one can really measure magnesium deficiency.     

Does lipid emulsion reduce amphotericin B nephrotoxicity? A systematic review and meta-analysis

This meta-analysis of 13 studies revealed that amphotericin B delivered as a locally prepared lipid emulsion or in liposomes reduced nephrotoxicity to a similar degree, by 18.4% (relative risk [RR], 0.40 [99% confidence interval, .25-.64]; n?=?459) and 18.1% (RR, 0.48 [99% CI, .36-.64]); n?=?1233), respectively.     

Can we reduce hypoglycaemia with insulin detemir?

Tight glycaemic control is essential for reducing the risk of long-term diabetic complications in people with type I or II diabetes. Intensive blood-glucose control attempts to normalise both pre- and postprandial glycaemia, while avoiding severe hypoglycaemia. A basal insulin, providing a low level of insulin to cover postprandial and overnight fasting periods, is central to intensive blood-glucose control. However, hypoglycaemia, particularly nocturnal hypoglycaemia, is a major treatment-related complication of therapy with most basal insulins currently available for use in clinical practice. This is a result of pronounced peaks in absorption, which lead to inappropriate hyperinsulinaemia following evening administration, and especially poorly reproducible pharmacokinetic profiles when injected subcutaneously. Indeed, for many patients and health-care providers, concern around hypoglycaemia forms a critical barrier to the attainment of tight glycaemic control. Insulin detemir is a novel long-acting analogue of human insulin designed to overcome these practical limitations. Clinical evidence from comparative studies with NPH insulin shows that insulin detemir provides a consistent and clinically relevant reduction in hypoglycaemic risk, especially for nocturnal events, at equivalent or better levels of glycaemic control.     

Can decreasing smoking prevalence reduce leukemia mortality?

Previous studies have demonstrated a modest association between smoking and leukemia particularly for myeloid disorders. Our objective was to examine whether changing trends in cigarette smoking prevalence nationally and within selected states parallel similar trends in mortality from leukemia. Trends in national smoking rates were correlated with trends in leukemia mortality rates obtained from the Centers for Disease Control and Prevention and the Surveillance Epidemiology and End Results registry, respectively. State-specific correlations were assessed from 1984 to 2004 using smoking prevalence data from the Behavioral Risk Factor Surveillance System and leukemia mortality data from National Vital Statistics System. Correlations were computed using the Spearman rank correlation coefficient. Leukemia mortality decreased overall in the United States in parallel with decreased smoking. Analyzed on a state-specific basis, leukemia mortality decreased in states where smoking rates declined markedly but remained unchanged where smoking prevalences were relatively stable. The findings suggest that declining rates of leukemia mortality are associated with changing patterns of smoking behavior.     

Is magnesium sulfate friend or foe of off-pump coronary artery bypass surgery?

Magnesium sulfate is often used empirically in cardiac surgical settings. Magnesium sulfate may cause platelet dysfunction leading to bleeding complication. This editorial commentary discusses the published study of intra-operative use of magnesium sulfate during off-pump coronary artery bypass grafting published in this issue of Indian Heart Journal.     

Can microvolt T-wave alternans testing reduce unnecessary defibrillator implantation?

The Multicenter Automatic Defibrillator Implantation Trial II (MADIT II) and the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) have established that patients with a reduced ejection fraction gain an overall mortality benefit from prophylactic implantable cardioverter-defibrillator therapy. Only a small proportion of the patients in these studies, however, have received life-saving therapy from the defibrillator. Because defibrillator therapy is invasive and expensive, patients with a low ejection fraction would benefit from effective risk stratification so that defibrillator therapy was used only in those at significant risk. In this review, we analyze prospective clinical trials that have evaluated microvolt T-wave alternans (MTWA) testing as a predictor of ventricular tachyarrhythmic events in populations of patients similar to those studied in MADIT II or SCD-HeFT; that is, patients with a reduced ejection fraction who were not selected on the basis of a history of ventricular tachyarrhythmias. In these studies, the average annual rate of fatal and nonfatal ventricular tachyarrhythmic events among the patients who tested negative for MTWA was around 1%. This rate is so low that it is unlikely that such patients would benefit from implantable cardioverter-defibrillator therapy. The mortality, moreover, was lower among MTWA-negative patients who did not receive implantable defibrillators than that observed in the MADIT II and SCD-HeFT patients who received implantable cardioverter-defibrillators. In response, patients with a low ejection fraction who are being considered for implantable cardioverter-defibrillator therapy should undergo MTWA testing as part of their evaluation.     

Can haloperidol prophylaxis reduce the incidence of delirium in critically ill patients in intensive care units? A systematic review and meta-analysis

IntroductionThe purpose of this study was to evaluate the efficacy and safety of haloperidol in the prevention of delirium in intensive care unit (ICU) patients.MethodsWe systematically searched PubMed, Embase, and the Cochrane Library for eligible randomized controlled trials up to July 2019. No publication type or language restrictions were applied.ResultsCompared to the placebo, haloperidol did not significantly reduce the incidence of delirium in all ICU patients (relative risk (RR), 0.83; 95% confidence interval (CI), 0.62–1.10, p = 0.20). However, haloperidol prophylaxis could reduce the incidence of delirium exclusively in postoperative patients admitted to an ICU (RR, 0.63; 95% CI, 0.47–0.86, p = 0.004). We observed no significant differences between the haloperidol and placebo groups in terms of length of ICU stay, all-cause mortality, and adverse events.ConclusionsThe use of prophylactic haloperidol might reduce the incidence of delirium in postoperative patients admitted to an ICU, but not in all ICU patients.     

Does preoperative pharmacologic prophylaxis reduce the rate of venous thromboembolism in pancreatectomy patients?

BackgroundWhether the risk of venous thromboembolism (VTE) may be reduced by preoperative administration of prophylactic heparin is unknown. We hypothesized that timing of heparin administration does not significantly alter the incidence of VTE in pancreatic surgery.MethodsAn analysis was conducted using data from Massachusetts General Hospital's National Surgical Quality Improvement Program from 2012 to 2017. All patients admitted for elective pancreatic resection were included. The primary outcome was development of VTE. Multivariable regression was performed, adjusting for patient demographics and various clinical factors.ResultsIn total, 1448 patients were analyzed, of whom 1062 received preoperative heparin (73.3%). Overall, 36 (2.5%) patients developed VTE. On unadjusted analysis, there was no statistically significant difference between patients who received preoperative heparin compared with those who did not (2.6% vs. 1.3%, respectively; p = 0.079). On adjusted analysis, there was an association with increased VTE rates among patients who received preoperative heparin (OR 2.93, 95% CI 1.10–7.81; p = 0.031).ConclusionThere was an association between preoperative heparin administration and increased incidence of VTE on adjusted analysis, possibly reflecting appropriate surgical judgment in patient selection for prophylaxis. These data question the inclusion of preoperative VTE pharmacologic prophylaxis as a reliable quality indicator.     

Can change in high-density lipoprotein cholesterol levels reduce cardiovascular risk?

Background

The cardiovascular risk reduction observed in many trials of lipid-lowering agents is greater than expected on the basis of observed low-density lipoprotein cholesterol (LDL-C) level reductions. Our objective was to explore the degree to which high-density lipoprotein cholesterol (HDL-C) level changes explain cardiovascular risk reduction.

Methods

A systematic review identified trials of lipid-lowering agents reporting changes in HDL-C and LDL-C levels and the incidence of coronary heart disease (CHD). The observed relative risk reduction (RRR) in CHD morbidity and mortality rates was calculated. The expected RRR, given the treatment effect on total cholesterol level, was calculated for each trial with logistic regression coefficients from observational studies. The difference between observed and expected RRR was plotted against the change in HDL-C level, and a least-squares regression line was calculated.

Results

Fifty-one trials were identified. Nineteen statin trials addressed the association of HDL-C with CHD. Limited numbers of trials of other therapies precluded additional analyses. Among statin trials, therapy reduced total cholesterol levels as much as 32% and LDL-C levels as much as 45%. HDL-C level increases were <10%. Treatment effect on HDL-C levels was not a significant linear predictor of the difference in observed and expected CHD mortality rates, although we observed a trend in this direction (P = .08). Similarly, HDL-C effect was not a significant linear predictor of the difference between observed and expected RRRs for CHD morbidity (P = .20).

Conclusions

Although a linear trend toward greater risk reduction was observed with greater effects on HDL-C, differences were not statistically significant. The narrow range of HDL-C level increases in the statin trials likely reduced our ability to detect a beneficial HDL-C effect, if present.