Hypomagnesemic disorders

Two Cases of Liver Transplantation With a High Ionized Magnesium to Total Magnesium Ratio

Magnesium (Mg), an important cation, is involved in the activation of enzymes important for life support. The incidence of hypomagnesemia in critically ill patients admitted to the intensive care unit (ICU) is high and has been reported to be a factor in worsening prognosis. Ionized magnesium (iMg) is physiologically active, although total magnesium (tMg) is often used to evaluate the concentration of magnesium because of the limited availability of instruments that can measure iMg. However, the changes in tMg and iMg are not correlated in critically ill patients. We obtained considerable data on the simultaneous measurements of iMg and tMg in two patients with severe liver disease who underwent liver transplantation. In both patients, the iMg/tMg values were high, suggesting the influence of hypoalbuminemia associated with liver dysfunction. Mg correction using tMg as a guide may lead to overdose. Furthermore, when considering the data for each case, the correlation between iMg and tMg was very high, which suggested that the iMg/tMg ratio may be a value unique to each individual or disease. Investigating in a large-scale study the correlation between iMg levels and clinical symptoms and prognosis is necessary in the future.

Importance of micronutrients in bone health of monogastric animals and techniques to improve the bioavailability of micronutrient supplements - A review

Vitamins and minerals categorized as micronutrients are the essential components of animal feed for maintaining health and improving immunity. Micronutrients are important bioactive molecules and cofactors of enzymes as well. Besides being cofactors for enzymes, some vitamins such as the fat-soluble vitamins, vitamin A and D have been shown to exhibit hormone-like functions. Although they are required in small amount, they play an influential role in the proper functioning of a number of enzymes which are involved in many metabolic, biochemical and physiological processes that contribute to growth, production and health. Micronutrients can potentially have a positive impact on bone health, preventing bone loss and fractures, decreasing bone resorption and increasing bone formation. Thus, micronutrients must be provided to livestock in optimal concentrations and according to requirements that change during the rapid growth and development of the animal and the production cycle. The supply of nutrients to the animal body not only depends on the amount of the nutrient in a food, but also on its bioavailability. The bioavailability of these micronutrients is affected by several factors. Therefore, several technologies such as nanoparticle, encapsulation, and chelation have been developed to improve the bioavailability of micronutrients associated with bone health. The intention of this review is to provide an updated overview of the importance of micronutrients on bone health and methods applied to improve their bioavailability.

A systematic review of the interaction and effects generated by antimicrobial metallic substituents in bone tissue engineering

Changes brought about by metal ions and metal nanoparticles within bacterial cells and the damage caused to the cellular membrane upon contact with negatively charged surface components.

Guidelines for the Intravenous Management of Hypophosphatemia, Hypomagnesemia, Hypokalemia, and Hypocalcemia

Nutrition Support Consultant features issues pertinent to the clinical aspects of pharmacy nutritional support practice.

Total and ionized magnesium testing in the surgical intensive care unit - Opportunities for improved laboratory and pharmacy utilization

PURPOSE

Ionized fraction (iMg) is the physiologically active form of magnesium (Mg); total Mg may not accurately reflect iMg status. Erroneously "low" Mg levels may result in unnecessary repetitive testing.

MATERIALS AND METHODS

From 11/2015 to 01/2016, patients ordered for Mg from a pilot ICU also had iMg tested. Weighted kappa statistic was used to assess agreement between Mg categories (low, normal, high). Predictors of unnecessary repeated Mg testing and repletion using data were explored through logistic regression models using GEE techniques to account for repeated measurements in both bivariate and multivariable analyses.

RESULTS

There were 470Mg/iMg paired measurements from 173 patients. The weighted kappa statistic was 0.35 (95%CI 0.27-0.43) indicating poor agreement in assessment of magnesium status. Of the 34Mg samples reported as "low", only 6 (18%) were considered "low" using concurrent iMg testing. In the multivariable models, history of atrial fibrillation (aOR=1.61, 95%CI 1.16-2.21, p=0.004) and concomitant metoclopramide (aOR=1.71, 95%CI 1.03-2.81, p=0.036) were significant predictors of unnecessary repeat Mg testing.

CONCLUSIONS

In the surgical ICU, categorical agreement (low, normal, high) was poor between Mg and iMg. Over 80% of "low" total Mg values are erroneous and may result in unnecessary additional measurements and repletion.

Calcium - Magnesium imbalance implicated in benign prostatic hyperplasia and restoration by a phytotherapeutic drug - Croton membranaceus Müll.Arg

Background

Calcium (Ca)- magnesium (Mg) imbalance is implicated in prostate cancer. Ca/Mg ratio increases or decreases with proliferation or apoptosis, respectively. The study examined whether this Ca/Mg imbalance exists in BPH patients and the effect of a phytotherapeutic drug on the Ca/Mg ratio.

Methods

Thirty (30) BPH patients who used the ethanolic root extract of Croton membranaceus (60 mg/day) for 3 months were examined for serum Ca, Mg, phosphate, parathyroid hormone (PTH), vitamin D, prostate specific antigen (PSA) levels and renal function tests (RFT) before (BT) and after treatment (AT) alongside thirty (30) controls. Twenty (20) trace element including Mg and Ca were determined in the drug by neutron activation analysis (NAA).

Results

RFT, PTH and vitamin D for BT, AT and controls (C) were normal. Mean PSA was 1.0 ± 0.64 (C), 27.9 ± 19.0 (BT) and 16.2 ± 11.8 ng/mL (AT) (p = 0.002). Mg, Ca/Mg ratio BT, AT and control were significantly different (p = 0.0001, respectively). After treatment, Mg and Ca/Mg ratio were not different from controls. The prevalence of Ca/Mg imbalance was 80% (BT), 13.3% (AT) and 3.3% (control group).

Conclusion

Ca/Mg ratio imbalance is associated with BPH. This has previously not been demonstrated. The imbalance was significantly corrected after treatment with the phytotherapeutic drug.

Microelements for bone boost: the last but not the least

Osteoporosis is a major public health problem affects many millions of people around the world. It is a metabolic bone disease characterized by loss of bone mass and strength, resulting in increased risk of fractures. Several lifestyle factors are considered to be important determinants of it and nutrition can potentially have a positive impact on bone health, in the development and maintenance of bone mass and in the prevention of osteoporosis. There are potentially numerous nutrients and dietary components that can influence bone health, and these range from the macronutrients to micronutrients. In the last decade, epidemiological studies and clinical trials showed micronutrients can potentially have a positive impact on bone health, preventing bone loss and fractures, decreasing bone resorption and increasing bone formation. Consequently, optimizing micronutrients intake might represent an effective and low-cost preventive measure against osteoporosis.

Pharmacological interventions in traumatic brain injury: Can we rely on systematic reviews for evidence?

INTRODUCTION

Providing current, reliable and evidence based information for clinicians and researchers in a synthesised and summarised way can be challenging particularly in the area of traumatic brain injury where a vast number of reviews exists. These reviews vary in their methodological quality and are scattered across varying sources. In this paper, we present an overview of systematic reviews that evaluate the pharmacological interventions in traumatic brain injury (TBI). By doing this, we aim to evaluate the existing evidence for improved outcomes in TBI with pharmacological interventions, and to identify gaps in the literature to inform future research.

METHODS

We searched the Neurotrauma Evidence Map on systematic reviews relating to pharmacological interventions for managing TBI in acute phase. Two reviewers independently screened search results and appraised each systematic review using the validated AMSTAR tool and extracted data from the review.

RESULTS

A total of 288 systematic reviews relating to TBI were available on the Neurotrauma Evidence Map at the time of this study. We identified 19 systematic reviews on pharmacological management for acute TBI with publications dates ranging from 1998 to 2014. The studies were of varying methodological quality, with a mean AMSTAR score of 7.78 (range 2-11].

CONCLUSION

The evidence from high quality systematic reviews show that there is currently insufficient evidence for the use of magnesium, monoaminergic and dopamine agonists, progesterone, aminosteroids, excitatory amino acid inhibitors, haemostatic and antifibrinolytic drugs in TBI. Anti-convulsants are only effective in reducing early seizures with no significant difference between phenytoin and leviteracetam. There is no difference between propofol and midazolam for sedation in TBI patients and ketamine may not cause increased ICP. Overviews of systematic review provide informative and powerful summaries of evidence based research.

Enhanced analgesic effects of tramadol and common trace element coadministration in mice

Chronic pain is managed mostly by the daily administration of analgesics. Tramadol is one of the most commonly used drugs, marketed in combination with coanalgesics for enhanced effect. Trace elements are frequent ingredients in dietary supplements and may enhance tramadol's analgesic effect either through synergic mechanisms or through analgesic effects of their own. Swiss Weber male mice were divided into nine groups and were treated with a combination of the trace elements Mg, Mn, and Zn in three different doses and a fixed dose of tramadol. Two groups served as positive (tramadol alone) and negative (saline) controls. Nociceptive assessment by tail-flick (TF) and hot-plate (HP) tests was performed at baseline and at 15, 30, 45, and 60 min after intraperitoneal administration. Response latencies were recorded and compared with the aid of ANOVA testing. All three trace elements enhanced tramadol's analgesic effect, as assessed by TF and HP test latencies. Coadministration of these trace elements led to an increase of approximately 30% in the average pain inhibition compared with the tramadol-alone group. The most effective doses were 0.6 mg/kg b.w. for Zn, 75 mg/kg b.w. for Mg, and 7.2 mg/kg b.w. for Mn. Associating trace elements such as Zn, Mg, and Mn with the standard administration of tramadol increases the drug's analgesic effect, most likely a consequence of their synergic action. These findings impact current analgesic treatment because the addition of these trace elements may reduce the tramadol dose required to obtain analgesia.

Effect of continuous magnesium sulfate infusion on spinal block characteristics: A prospective study

Background:

Spinal anesthesia is an established mode of anesthesia for lower limb orthopedic surgeries. The limitations of the technique are short duration of action and limited post-operative analgesia. Concomitant use of intravenous infusion of magnesium sulfate may have an effect on the block characteristics and duration of action of intrathecal bupivacaine.

Methods:

A total of 80 American Society of Anesthesiologists I and II patients, either sex, 20-60 years of age scheduled for elective orthopedic fixation of fracture of long bones of lower limbs under spinal anesthesia were included. Spinal anesthesia administered with 2.5 ml heavy bupivacaine mixed with 10 mcg fentanyl. The groups were then divided to receive an infusion of injection magnesium sulfate 50 mg/kg/h over 15 min followed by 15 mg/kg/h until the end of the surgery (Group M) and 15 ml of Normal Saline over 15 min followed by 100 ml/h until the end of surgery (Group S). Onset, duration of sensory and motor block and amount of post-operative analgesic were noted.

Results:

A total of 6 patients (Group M) and seven patients (Group S) had inadequate block and excluded from the study. Mean block height was T6. Time required to achieve block height was 8.82 min versus 7.42 min in Groups M and S respectively (P = 0.04). Mean duration of motor block was longer in group M (160.63 ± 17.76 min) compared with Group S (130.12 ± 20.70 min) (P = 0.000). Time for regression of sensory block to T12/L1was 206.88 ± 20.96 min (Group M) and 163.88 ± 15.46 min (Group S) (P = 0.000). Hemodynamic parameters were similar and statistically not significant. Need for first analgesic requirement was after 262.88 ± 21.11 min in group M and 193.25 ± 17.74 min in the group S (P = 0.000). Mean dosage of tramadol needed in first 24 h was less in group M (190 ± 30.38 mg vs. 265 ± 48.30 mg, P = 0.000).

Conclusion:

Use of intravenous magnesium with spinal anesthesia reduces post-operative pain and analgesic consumption.

Primary aldosteronism with concurrent primary hyperparathyroidism in a patient with arrhythmic disorders

A 25-year-old Caucasian woman was admitted to our department with severe hypokalemia that was associated with hypercalcemia. An endocrinological investigation showed the coexistence of primary hyperparathyroidism (PHPT) and primary aldosteronism (PA), arising from an adenoma of the left cortical adrenal gland. The patient underwent left laparoscopic adrenalectomy, but refused the surgical neck exploration that would be required for parathyroidectomy. The post-operative course was uneventful, and the patient realized a normalization of her potassium serum level and a reduction of her blood pressure values. We herein report the important issues regarding the management of a severe electrolyte imbalance, in view of the reciprocal interaction between aldosterone and parathyroid hormone, and their combined potential for causing cardiovascular damage.

Electrolyte disturbances associated with commonly prescribed medications in the intensive care unit

Electrolyte imbalances are common in critically ill patients. Although multiple disease states typically encountered in the intensive care unit may be responsible for the development of electrolyte disorders, medications may contribute to these disturbances as well. Medications can interfere with the absorption of electrolytes, alter hormonal responses affecting homeostasis, as well as directly impact organ function responsible for maintaining electrolyte balance. The focus on this review is to identify commonly prescribed medications in the intensive care unit and potential electrolyte disturbances that may occur as a result of their use. This review will also discuss the postulated mechanisms associated with these drug-induced disorders. The specific drug-induced electrolyte disorders discussed in this review involve abnormalities in sodium, potassium, calcium, phosphate, and magnesium. Clinicians encountering electrolyte disturbances should be vigilant in monitoring the patient's medications as a potential etiology. Insight into these drug-induced disorders should allow the clinician to provide optimal medical management for the critically ill patient, thus improving overall healthcare outcomes.

Drug-induced arrhythmias

The objective of this review is to characterize the mechanisms, risk factors, and offending pharmacotherapeutic agents that may cause drug-induced arrhythmias in critically ill patients. PubMed, other databases, and citation review were used to identify relevant published literature. The authors independently selected studies based on relevance to the topic. Numerous drugs have the potential to cause drug-induced arrhythmias. Drugs commonly administered to critically ill patients are capable of precipitating arrhythmias and include antiarrhythmics, antianginals, antiemetics, gastrointestinal stimulants, antibacterials, narcotics, antipsychotics, inotropes, digoxin, anesthetic agents, bronchodilators, and drugs that cause electrolyte imbalances and bradyarrhythmias. Drug-induced arrhythmias are insidious but prevalent. Critically ill patients frequently experience drug-induced arrhythmias; however, enhanced appreciation for this adverse event has the potential to improve prevention, treatment, patient safety, and outcomes in this patient population.

Plasma magnesium should be monitored perioperatively in patients undergoing colorectal resection

OBJECTIVE

Hypomagnesemia has been shown to have several clinically important sequelae. The aims of this study were: to assess the impact of bowel preparation, with sodium picosulphate (Picolax), on plasma electrolytes, with particular regard to plasma magnesium, in patients undergoing bowel preparation for colonoscopy and colorectal resection and to evaluate the influence of perioperative magnesium levels on postoperative cardiac dysrhythmias.

METHOD

Sixty-one patients receiving sodium picosulphate (Picolax) bowel preparation were studied in two groups: Colonoscopy (31 patients) and Colorectal resection (30 patients). Plasma sodium, potassium, magnesium, calcium, urea, creatinine and blood haematocrit were measured in all patients prior to commencement of bowel preparation, at the time of colonoscopy or colorectal resection and 24 h postoperatively (surgery group only). Mean electrolyte and haematocrit levels were then compared. Postoperative cardiac dysrhythmias were recorded and analysed.

RESULTS

No significant changes following bowel preparation were observed in plasma sodium, potassium, calcium or creatinine. Plasma urea fell following bowel preparation (colonoscopy P < 0.001, resection P = 0.004) and rose following resection (P = 0.002). Magnesium levels increased following bowel preparation in both groups (colonoscopy P < 0.001, resection P = 0.007) and fell following resection (P < 0.001). Thirty-four per cent (21/60 patients) were hypermagnesemic following bowel preparation and 20% (6/30 patients) became hypomagnesemic following surgery. Postoperative cardiac dysrhythmias were associated with lower magnesium levels at induction and postoperatively (P = 0.022 and P = 0.033).

CONCLUSION

Bowel preparation with Picolax does not appear to cause significant electrolyte disturbance, except in elevating plasma magnesium. Postcolorectal resection plasma magnesium dropped significantly suggesting perioperative monitoring and replacement should be routine following colorectal surgery.

Calcium regulating hormones and serum calcium and magnesium concentrations in septic and critically ill foals and their association with survival

BACKGROUND

Disorders of calcium regulation are frequently found in humans with critical illness, yet limited information exists in foals with similar conditions including septicemia. The purpose of this study was to determine whether disorders of calcium exist in septic foals, and to determine any association with survival.

HYPOTHESIS

Blood concentrations of ionized calcium (Ca(2+)) and magnesium (Mg(2+)) will be lower in septic foals with concomitant increases in parathyroid hormone (PTH), calcitonin (CT), and parathyroid-related peptide (PTHrP) compared with healthy foals. The magnitude of these differences will be negatively associated with survival.

ANIMALS

Eighty-two septic, 40 sick nonseptic, and 24 healthy foals of <or=7 days were included.

METHODS

Prospective, observational study. Blood was collected at initial examination for analysis. Foals with positive blood culture or sepsis score >or=14 were considered septic. Foals with disease other than sepsis and healthy foals were used as controls. Hormone concentrations were measured with validated immunoassays.

RESULTS

Septic foals had decreased Ca(2+) (5.6 versus 6.1 mg/dL, P < .01) and increased serum PTH (16.2 versus 3.2 pmol/L, P < .05), and phosphorus concentrations (7.1 versus 6.3 mg/dL, P < .01). No differences in serum Mg(2+), PTHrP, and CT concentrations were found. Nonsurviving septic foals (n = 42/82) had higher PTH concentrations (41.1 versus 10.7 pmol/L, P < .01) than survivors (n = 40/82).

CONCLUSIONS AND CLINICAL IMPORTANCE

Septic foals were more likely to have disorders of calcium regulation compared with healthy foals, where hyperparathyroidemia was associated with nonsurvival.

Magnesium for acute traumatic brain injury

BACKGROUND

Acute traumatic brain injury is a leading cause of death and disability in young adults. Numerous pharmacological and non-pharmacological tools have been investigated and considered as potential mechanisms for improving neurological outcome. Magnesium has been considered as one of these potential therapeutic tools because of its activity on NMDA-receptors, calcium channels and neuron membranes. Animal studies have indicated a beneficial effect of magnesium on outcome after brain injury, but its efficacy in humans is unknown.

OBJECTIVES

To quantify the effect of magnesium administration on mortality and morbidity in patients with acute traumatic brain injury.

SEARCH STRATEGY

We searched the Cochrane Injuries Group's specialised register, Cochrane Central Register of Controlled Trials, CENTRAL (The Cochrane Library issue 2, 2008), MEDLINE (and PubMed to 28 May, 2008: last 60 days), EMBASE, National Research Register, Current Controlled Trials, SIGLE, LILACS, and Zetoc. Searches were initially conducted in July 2005. The latest search was conducted in May 2008.

SELECTION CRITERIA

We included all randomized controlled trials comparing any magnesium salt with no magnesium or with placebo, in patients following acute traumatic brain injury.

DATA COLLECTION AND ANALYSIS

Two authors independently screened search results and assessed the full texts of potentially relevant studies for inclusion. Data were extracted and methodological quality was examined.

MAIN RESULTS

Four studies met the inclusion criteria; one of which is an ongoing study. Data from three studies were included in the analysis. Data on mortality were only available in one study; RR 1.48 [1.00, 2.19], Test for overall effect: Z = 1.96 (P = 0.05). Glasgow Outcome Score at six months was described in the three studies. The Mean Difference = 0.02 (95% CI -0.38 to 0.041), Test for overall effect: Z = 0.08 (P = 0.94).

AUTHORS' CONCLUSIONS

There is currently no evidence to support the use of magnesium salts in patients with acute traumatic brain injury.

Pharmacology of traumatic brain injury: where is the "golden bullet"?

Traumatic brain injury (TBI) represents a major health care problem and a significant socioeconomic challenge worldwide. In the United States alone, approximately 1.5 million patients are affected each year, and the mortality of severe TBI remains as high as 35%-40%. These statistics underline the urgent need for efficient treatment modalities to improve posttraumatic morbidity and mortality. Despite advances in basic and clinical research as well as improved neurological intensive care in recent years, no specific pharmacological therapy for TBI is available that would improve the outcome of these patients. Understanding of the cellular and molecular mechanisms underlying the pathophysiological events after TBI has resulted in the identification of new potential therapeutic targets. Nevertheless, the extrapolation from basic research data to clinical application in TBI patients has invariably failed, and results from prospective clinical trials are disappointing. We review the published prospective clinical trials on pharmacological treatment modalities for TBI patients and outline future promising therapeutic avenues in the field.

Dietary magnesium deficiency induces heart rhythm changes, impairs glucose tolerance, and decreases serum cholesterol in post menopausal women

OBJECTIVE

To determine whether or not dietary magnesium restriction to about 33% of the Recommended Dietary Allowance (RDA) causes changes in glucose, cholesterol and electrolyte metabolism that could lead to pathologic consequences.

DESIGN

The length of the experiment was 136 days. Subjects were fed a basal Western-type diet that provided 4.16 mmol (101 mg) magnesium per 8.4 MJ (2000 kcal) for 78 days then replenished with magnesium by supplementing the diet with 200 mg magnesium as the gluconate per day for 58 days. If a subject exhibited adverse heart rhythm changes before 78 days of depletion were completed, she entered the repletion period early.

SETTING

The metabolic research unit of the Grand Forks Human Nutrition Research Center.

SUBJECTS

A total of 14 post menopausal women were recruited by advertisement throughout the United States. Thirteen women (ages 47 to 75 years) completed the study.

RESULTS

During magnesium depletion, heart rhythm changes appeared in 5 women and resulted in 4 prematurely entering the magnesium repletion period (42 to 64 days of depletion instead of 78). Three women exhibited atrial fibrillation and flutter that responded quickly to magnesium supplementation. Magnesium deprivation resulted in a non-positive magnesium balance that became highly positive with magnesium repletion. Magnesium deprivation decreased red blood cell membrane magnesium, serum total cholesterol and erythrocyte superoxide dismutase concentrations, increased the urinary excretion of sodium and potassium, and increased serum glucose concentration.

CONCLUSIONS

Magnesium balance may be a suitable indicator of magnesium depletion under experimental conditions. Magnesium deficiency resulting from feeding a diet that would not be considered having an atypical menu induces heart arrhythmias, impairs glucose homeostasis, and alters cholesterol and oxidative metabolism in post menopausal women. A dietary intake of about 4.12 mmol (100 mg) Mg/8.4 MJ is inadequate for healthy adults and may result in compromised cardiovascular health and glycemic control in post menopausal women.

Magnesium for acute traumatic brain injury

BACKGROUND

Acute traumatic brain injury is a leading cause of death and disability in young adults. Magnesium had been considered as a potential therapeutic tool because of its activity on NMDA-receptors, calcium channels and neuron membranes. Animals studies have indicated a beneficial effect of magnesium on outcome after brain injury, but its efficacy in humans is unknown.

OBJECTIVES

To quantify the effect of magnesium administration on mortality and morbidity in patients with acute traumatic brain injury.

SEARCH STRATEGY

We searched the Cochrane Injuries Group's specialised register, Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, National Research Register, Current Controlled Trials, SIGLE, LILACS, Zetoc. The searches were conducted in July 2005.

SELECTION CRITERIA

We included all randomized controlled trials comparing any magnesium salt with no magnesium or with placebo, in patients following acute traumatic brain injury.

DATA COLLECTION AND ANALYSIS

Two authors independently screened search results and assessed the full texts of potentially relevant studies for inclusion. Data were extracted and methodological quality was examined.

MAIN RESULTS

Three studies met the inclusion criteria, one of which is an ongoing study. Two studies were included in the analysis. No data on mortality were available. For Glasgow Outcome Score at six months the pooled WMD = 0.55 (95% CI -0.15 to 1.26), P = 0.12.

AUTHORS' CONCLUSIONS

There is currently no evidence to support the use of magnesium salts in patients with acute traumatic brain injury.

Freqüência relativa de hipomagnesemia em pacientes com limitação crônica do fluxo aéreo atendidos em ambulatório de referência do norte do Paraná

OBJETIVO: Determinar a freqüência relativa de hipomagnesemia em pacientes com limitação crônica do fluxo aéreo atendidos num ambulatório de referência do norte do Paraná, nos anos de 2000 a 2001, e verificar se há relação entre esse distúrbio e hipoxemia, outros distúrbios eletrolíticos e com a gravidade da doença. MÉTODOS: Estudo descritivo sobre a freqüência relativa de hipomagnesemia em 72 pacientes com limitação crônica do fluxo aéreo. Os pacientes realizaram dosagens séricas de magnésio e outros eletrólitos, além de realizarem o estadiamento de sua doença de base. RESULTADOS: A prevalência encontrada de hipomagnesemia foi de 27,8%. A idade média foi de 65 ± 9,9 anos, com predominância de homens. O volume expiratório forçado no primeiro segundo médio foi de 1,13 ± 0,52 L. A maioria dos pacientes encontrava-se em estádios avançados da doença (68,1%). Não houve associação do magnésio sérico baixo com outros distúrbios eletrolíticos, hipoxemia ou estádios de gravidade. CONCLUSÃO: A alta freqüência de pacientes em estádios avançados deve-se, provavelmente, ao fato de o ambulatório ser um centro de referência da região. Novos estudos devem ser realizados para determinar prováveis causas dessa alta prevalência de hipomagnesemia.

Maximum acceptable infusion rate of citrate: relationship between blood ionized calcium levels and cardiovascular effects in anesthetized rats

BACKGROUND & AIMS

Citrate is a useful chemical as a stabilizer for infusion solutions. However, cardiovascular depression associated with ionized hypocalcemia has been observed during massive transfusion of citrated blood products. The goal of the present study was to determine the maximum acceptable infusion rate of citrate and safe blood ionized calcium (Ca(2+)) levels.

METHODS

Citrate was administered intravenously to anesthetized rats at infusion rates between 0.5 and 2.0 mmol/kg/h for 4 h. Changes in heart rate (HR), arterial blood pressure, and the concentrations of plasma citrate and blood Ca(2+) were measured.

RESULTS

Infusion of citrate caused decreases in arterial blood pressure and HR, but no severe cardiovascular depression was observed at infusion rates up to 1.0 mmol/kg/h. Plasma citrate levels reached a steady state within 1 h after the start of infusion at up to 1.0 mmol/kg/h. The concentrations of plasma citrate and blood Ca(2+) were 1.35 and 0.89 mmol/l, respectively, 4h after the start of infusion at 1.0 mmol/kg/h.

CONCLUSIONS

The maximum acceptable infusion rate of citrate was 1.0 mmol/kg/h in anesthetized rats, and no severe cardiovascular effects were observed when the blood Ca(2+) level was 0.89 mmol/l or above.

A randomized clinical trial of magnesium sulphate as a vehicle for nebulized salbutamol in the treatment of moderate to severe asthma attacks

Although it is well known that intravenous administration of MgSO4 as an adjunct to conventional therapy is effective in treating asthma attacks, the effect of nebulized MgSO4 as a vehicle for salbutamol has been less evaluated. The aim of this study was to compare the effects of nebulized salbutamol administrated through either MgSO4 or isotonic saline solution on the 'peak expiratory flow rate' (PEFR), other respiratory and clinical parameters, and hospitalization rate of patients suffering from moderate to severe asthma attacks. Twenty-six patients with asthma attack were enrolled in the study in a randomized single blind fashion. After obtaining initial peak expiratory flow measurements (PEFR) and clinical evaluation, all patients received 1mg/kg corticosteroids and oxygen therapy and then either isotonic MgSO4 (2.5 ml, 6.3%)+salbutamol (2.5 ml) or saline (2.5 ml)+salbutamol (2.5 ml) through a jet nebulizer (group 1 (n=14) vs group 2 (n=12), respectively). The nebulizations were repeated every 20 min for the first hour and every hour for the rest of 4 h. The PEFR measurements and clinical assessment were performed after nebulization at 20th, 60th, 120th, 180th and 240th minutes. Patients were discharged when PEFR reached the target level of 70% of predicted. The baseline PEFRs and clinical parameters were similar between groups 1 and 2 (50.2+/-18.5 vs 44.1+/-13.9, respectively, p>0.05). The mean% increase in PEFR at different measurement levels was similar between the groups. When the treatment response was evaluated within the groups, group 2 showed statistically significant increase in PEFR (% of predicted) 1h earlier than group 1 (60th vs 120th minute, p=0.003 vs p=0.007). The mean duration of achieving target-PEFRs was 105.7+/-72.1 min for group 1 and 118.3+/-96.7 min for group 2 (p>0.05). This study suggested that the additional usage of MgSO4 to nebulized salbutamol has no beneficial effect on the treatment of asthma attacks.

Total and ionized serum magnesium in critically ill patients

OBJECTIVE

To assess the alterations in total serum magnesium (tsMg) and ionized serum magnesium (Mg(2+)) and their association with prognosis in critically ill patients.

DESIGN AND SETTING

Prospective, cohort study in the intensive care unit (ICU) of a university teaching hospital.

PATIENTS

Adult patients admitted to the ICU without previous factors influencing magnesium homeostasis were included during a 6-month period.

MEASUREMENTS AND RESULTS

One hundred forty four patients were included. Mean age was 60.6+/-15.4 years; mean APACHE II score was 12.6+/-6.9. Blood samples were collected in the first 24 h after ICU admission and again on the second, third, and last days of stay in the ICU. At ICU admission 52.5% had total hypomagnesemia and 13.5% total hypermagnesemia; with respect to the Mg(2+) 9.7% showed ionized hypomagnesemia and 23.6% ionized hypermagnesemia. Patients who developed ionized hypermagnesemia had higher mortality than patients without ionized hypermagnesemia development (P=0.04). A moderate correlation between tsMg and Mg(2+) concentrations was found; however, a number of patients with total hypomagnesemia (69-85% during the study) had ionized normomagnesemia. The measure of agreement between tsMg and Mg(2+) levels was poor.

CONCLUSIONS

Magnesium alterations are frequently found in critically ill patients. The usually determined tsMg levels are not a reflection of Mg(2+) levels. Development of ionized hypermagnesemia is associated with prognosis.

Electrocardiographic manifestations: electrolyte abnormalities

Because myocyte depolarization and repolarization depend on intra- and extracellular shifts in ion gradients, abnormal serum electrolyte levels can have profound effects on cardiac conduction and the electrocardiogram (EKG). Changes in extracellular potassium, calcium, and magnesium levels can change myocyte membrane potential gradients and alter the cardiac action potential. These changes can result in incidental findings on the 12-lead EKG or precipitate potentially life-threatening dysrhythmias. We will review the major electrocardiographic findings associated with abnormalities of the major cationic contributors to cardiac conduction-potassium, calcium and magnesium.

Possible central nervous system infection by SARS coronavirus

On day 22 of illness, generalized tonic-clonic convulsion developed in a 32-year-old woman with severe acute respiratory syndrome (SARS). Cerebrospinal fluid tested positive for SARS coronavirus (SARS-CoV) by reverse transcriptase–polymerase chain reaction. SARS-CoV may have caused an infection in the central nervous system in this patient.

Obstetrical Accidents Involving Intravenous Magnesium Sulfate

Magnesium sulfate is commonly used in obstetrical practice both as seizure prophylaxis in women with preeclampsia, as well as to inhibit preterm labor contractions. However, despite (and perhaps because of) years of use and provider familiarity, the administration of magnesium sulfate occasionally results in accidental overdose and patient harm. Fortunately, in most instances when potentially fatal amounts of magnesium sulfate are given, the error is recognized before permanent adverse outcomes occur. Nevertheless, a significant and sometimes unappreciated risk of harm to mothers and babies continues to exist. Intravenous magnesium sulfate treatment has become routine practice in obstetrics, but this does not lessen the vigilance required for safe care for mothers and babies. Implementation of the recommendations provided in this article will promote patient safety and decrease the likelihood of an accidental overdose, as well as increase the chances of identifying an error before a significant adverse outcome occurs.

Dietary magnesium intake in a national sample of US adults

Despite the role of magnesium in maintaining health, much of the U.S. population has historically not consumed adequate amounts of magnesium. Furthermore, significant racial or ethnic disparities in magnesium intake exist. Our objective was to provide more recent data about magnesium intake in the U.S. population. We analyzed the 24-h dietary recall data from 4257 participants aged >or=20 y from the National Health and Nutrition Examination Survey 1999-2000. The median intake of magnesium was 326 mg/d (mean 352 mg/d) among Caucasian men, 237 mg/d (mean 278 mg/d) among African American men, 297 mg/d (330 mg/d) among Mexican American men, 237 mg/d (mean 256 mg/d) among Caucasian women, 177 mg/d (mean 202 mg/d) among African American women, and 221 mg/d (mean 242 mg/d) among Mexican American women. Among men and women, Caucasians had significantly higher mean intakes of dietary magnesium than African Americans but not Mexican Americans. Magnesium intake decreased with increasing age (P for linear trend = 0.035 for Caucasians; P for linear trend <0.001 for African Americans and Mexican Americans). Men had higher intakes of magnesium than women for each of the three race or ethnic groups (P < 0.001 in each group). Caucasian men, African American men and Caucasian women who used vitamin, mineral or dietary supplements consumed significantly more magnesium in their diets than did those who did not. Substantial numbers of U.S. adults fail to consume adequate magnesium in their diets. Furthermore, racial or ethnic differences in magnesium persist and may contribute to some health disparities.

Magnesium deficiency induces apoptosis in primary cultures of rat hepatocytes

The effects of extracellular magnesium (Mg) concentration on the rate of apoptosis in rat hepatocytes in primary culture were examined. After overnight attachment, incubations were conducted for up to 72 h in serum-free media containing low (0-0.4 mmol/L), physiological (0.8 mmol/L) or high (2 and 5.6 mmol/L) Mg concentrations. At 72 h, we observed numerous rounded hepatocytes on top of a shrunken cell monolayer at extracellular Mg concentrations < 0.8 mmol/L. These morphological features were associated with Mg-dependent differences in the total protein levels. The various Mg concentrations did not affect DNA synthesis; however, at a concentration < 0.8 mmol/L, the susceptibility of cultured rat hepatocytes to oxidative stress was increased as shown by the reduced glutathione concentration (10.6 +/- 2.8 vs. 37.3 +/- 4.1 nmol/mg protein with 0 and 0.8 mmol/L, respectively; P < 0.05) and increased lipid peroxidation (0.36 +/- 0.03 vs. 0.21 +/- 0.01 nmol malondialdehyde/mg protein with 0 and 0.8 mmol/L, respectively; P < 0.05). Fluorescence microscopy after Hoechst dye staining revealed numerous apoptotic figures in Mg-free monolayers compared with 0.8 and 5.6 mmol/L Mg conditions. These observations were confirmed quantitatively by flow-cytometric analysis after propidium iodide staining. The proportion of subdiploid cells decreased with increasing Mg concentration; for example, it was greater at 72 h in Mg-free cultures (76%) than in cultures containing 0.8 mmol/L or 5.6 mmol/L Mg (28%; P < 0.05). Caspase-3 was highly activated in Mg-free cultures after 48 h of treatment compared with 0.8 and 5.6 mmol/L conditions (P < 0.05). Overall, these results show that extracellular Mg deficiency has a negative effect on the survival of cultured rat hepatocytes by inducing apoptosis; however, supplementation of extracellular Mg did not reduce the spontaneous apoptosis that occurred over time in rat hepatocyte cultures.

The therapeutic use of magnesium in anesthesiology, intensive care and emergency medicine: a review

PURPOSE

To review current knowledge concerning the use of magnesium in anesthesiology, intensive care and emergency medicine.

METHODS

References were obtained from Medline(R) (1995 to 2002). All categories of articles (clinical trials, reviews, or meta-analyses) on this topic were selected. The key words used were magnesium, anesthesia, analgesia, emergency medicine, intensive care, surgery, physiology, pharmacology, eclampsia, pheochromocytoma, asthma, and acute myocardial infarction.

PRINCIPLE FINDINGS

Hypomagnesemia is frequent postoperatively and in the intensive care and needs to be detected and corrected to prevent increased morbidity and mortality. Magnesium reduces catecholamine release and thus allows better control of adrenergic response during intubation or pheochromocytoma surgery. It also decreases the frequency of postoperative rhythm disorders in cardiac surgery as well as convulsive seizures in preeclampsia and their recurrence in eclampsia. The use of adjuvant magnesium during perioperative analgesia may be beneficial for its antagonist effects on N-methyl-D-aspartate receptors. The precise role of magnesium in the treatment of asthmatic attacks and myocardial infarction in emergency conditions needs to be determined.

CONCLUSIONS

Magnesium has many known indications in anesthesiology and intensive care, and others have been suggested by recent publications. Because of its interactions with drugs used in anesthesia, anesthesiologists and intensive care specialists need to have a clear understanding of the role of this important cation.

Vasodilator Agents Protect against Indinavir Nephrotoxicity

Indinavir (IDV) is a protease inhibitor widely used in AIDS treatment. A sustained elevation of creatinine was identified in IDV-treated patients. We have previously demonstrated that IDV causes renal vasoconstriction in rats. The objective of this study was to investigate the mechanism of IDV-induced vasoconstriction and the effect that the vasodilator agents L-arginine (LA), nifedipine (NF), as well as magnesium supplementation (Mg), have on IDV-induced nephrotoxicity. Male Wistar rats were kept on fast overnight and given free access to water. IDV (80 mg/kg BW) and NF (3 mg/kg BW) were given by gavage for 15 days. LA (1.5%) and MgCl2.6H2O (1%) were added to drinking water. Six groups were studied: Control ( n=6): normal rats treated with vehicle, a 0.05 M citric acid solution; IDV ( n=7): IDV-treated rats; IDV+LA ( n=6): IDV- and LA-treated rats; IDV+NF ( n=7): IDV- and NF-treated rats; IDV+Mg ( n=7): IDV- and MgCl2-treated rats; IDV+Mg+L-NAME ( n=9): IDV- and MgCl2-treated rats, supplemented with L-NAME (2.5 mg/l in drinking water). Clearance studies and evaluations of urinary nitrite (NO2) excretion were performed on day 16. No changes in blood pressure were observed. NO2 excretion decreased in IDV-treated rats. LA and NF protected against IDV effects, improving GFR (IDV+LA, 1.95 ±0.10; IDV+NF, 1.94 ±0.07 vs IDV, 1.15 ±0.07 ml/min, P<0.001) and RBF (IDV+LA, 7.83 ±0.09; IDV+NF, 7.63 ±0.14 vs IDV, 6.17 ±0.25 ml/min, P<0.001). These results suggest that IDV-induced vasoconstriction is mediated by NO and Ca2+ channels. Magnesium also ameliorated GFR and RBF in IDV-treated rats (GFR IDV+Mg, 1.77 ±0.08 ml/min, P<0.001; RBF IDV+Mg, 7.35 ±0.158 ml/min, P<0.001). Magnesium protection is not NO-mediated since it was not blocked by L-NAME. In conclusion, LA, NF and Mg protect against IDV-induced nephrotoxicity in rats. This study may have potential clinical implications for prevention of IDV-induced nephrotoxicity.

Primary hyperparathyroidism, hypercalcemic crisis and subsequent seizures occurring during pregnancy: a case report

A first-trimester primigravid patient presented with hyperemesis and malaise. Work-up was consistent with primary hyperparathryoidism. During acute treatment, she developed generalized motor seizures considered to be secondary to hypercalcemia. Evaluation and treatment of women with primary hyperparathyroidism and hypercalcemia are reviewed, and the pathogenesis of seizures associated with hypercalcemia is discussed.