Continuous Magnesium Infusion Research Articles

Anaesthetic management of children with a single ventricle with pulmonary atresia coming for emergency burr hole tapping

Background and Aims:Post-operative atrial fibrillation (POAF) occurs in 30–50% of patients after coronary artery bypass surgery (CABG). Serum hypomagnesemia is common after cardiac surgeries. The primary objective was to evaluate whether magnesium infusion could reduce the incidence of POAF after off-pump CABG.Methods:This prospective, single-centre, randomised controlled study was conducted among 100 patients who underwent off-pump CABG. The participants were classified into two groups: group (M), study group, started on magnesium infusion for 3 days after an initial bolus dose as the patient is received in the intensive care unit (ICU), and group (C), control group, managed with usual care. The target in group M was to attain a serum magnesium level of 1.5 to 2 mmol/L. The incidence of POAF was observed in both the groups. A p value < 0.05 was taken as statistically significant.Results:The incidence of POAF was significantly higher in the control group (20%) when compared to the study group (2%) (p = 0.008). There were no significant changes in the secondary objectives (vasoactive inotropic scores, length of ICU stay, additional pharmacotherapy, and cardioversion needed) between both the groups.Conclusion:The study established that continuous magnesium infusion was effective in preventing POAF in patients undergoing off-pump CABGs.

Abstract No. : ABS2957: Efficacy of continuous magnesium infusion in prevention of post- operative atrial Fibrillation in patients undergoing off-Pump Coronary Artery Bypass Graft Surgery

Background & Aims:Postoperative atrial fibrillation (POAF) occurs in 30-50% of patients after coronary artery bypass surgery (CABG). Serum hypomagnesemia is common after cardiac surgeries.The primary objective was to evaluate whether magnesium infusion could reduce the incidence of postoperative atrial fibrillation (POAF) after off pump CABG.Methods:This prospective, singe centre, randomised controlled study was conducted among 100 patients who underwent off-pumpCABG. The participants were classified into two groups: Group (M); study group in which magnesium infusion was started for three days after an initial bolus dose when the patient was received in intensive care unit (ICU) and Group (C); control group was managed with usual care. The target in Group M was to attain a serum magnesium level of 1.5 to 2 mmol/L. Theincidence of POAF was observed in both the groups. A p value < 0.05 was taken as statistically significant.Results:The incidence of POAF was significantly higher in control group (20%) when compared to the study group (2%)(p=0.008). There were no significant changes in vasoactive inotropic scores, length of ICU stay, additional pharmacotherapy and cardioversion needed between both the groups.Conclusion:The study established that continuous magnesium infusion was effective in preventing POAF in patients undergoing off-pump CABGs.

A pilot study of the pharmacokinetics of continuous magnesium infusion in critically ill patients

Objective: The pharmacokinetics and haemodynamic effect of continuous magnesium infusion in non-cardiac intensive care unit (ICU) patients are poorly understood. We aimed to measure serum and urine magnesium levels during bolus and continuous infusion in critically ill adults, compare serum levels with those of a control population, and assess its haemodynamic effect. Design: Pharmacokinetic study Setting: A single tertiary adult ICU. Participants: Mechanically ventilated adults requiring vasopressor support. Intervention: A 10 mmol bolus of magnesium sulfate followed by 1.5-3 mmol/h infusion for 24 hours. Main outcome measures: The primary outcome was the change in total serum magnesium concentration. The main secondary outcome was mean arterial pressure (MAP)- adjusted vasopressor dose. Results: We matched 31 treated patients with 93 controls. Serum total magnesium concentration increased from a median 0.94 mmol/L (interquartile range [IQR], 0.83-1.10 mmol/L) to 1.38 mmol/L (IQR, 1.25-1.69 mmol/L; P < 0.001) and stabilised between a median 1.64 mmol/L (IQR, 1.38-1.88 mmol/L) at 7 hours and 1.77 mmol/L (IQR, 1.53-1.85 mmol/L) at 25 hours. This was significantly greater than in the control group (P < 0.001). The MAP-adjusted vasopressor dose decreased during magnesium infusion (P < 0.001). Conclusion: In critically ill patients, a magnesium sulfate bolus followed by continuous infusion achieved moderately elevated levels of total serum magnesium with a decrease in MAP-adjusted vasopressor dose. Trial registration number: ACTRN12619000925145.

Continuous Magnesium Infusion to Prevent Atrial Fibrillation After Cardiac Surgery: A Sequential Matched Case-Controlled Pilot Study

The authors aimed to test whether a bolus of magnesium followed by continuous intravenous infusion might prevent the development of atrial fibrillation (AF) after cardiac surgery. Sequential, matched, case-controlled pilot study. Tertiary university hospital. Matched cohort of 99 patients before and intervention cohort of 99 consecutive patients after the introduction of a continuous magnesium infusion protocol. The magnesium infusion protocol consisted of a 10 mmol loading dose of magnesium sulphate followed by a continuous infusion of 3 mmol/h over a maximum duration of 96 hours or until intensive care unit discharge. The study groups were balanced except for a lower cardiac index in the intervention cohort. The mean duration of magnesium infusion was 27.93 hours (95% confidence interval [CI]: 24.10-31.76 hours). The intervention group had greater serum peak magnesium levels: 1.72 mmol/L ± 0.34 on day 1, 1.32 ± 0.36 on day 2 versus 1.01 ± 1.14 and 0.97 ± 0.13, respectively, in the control group (p < 0.01). Atrial fibrillation occurred in 25 patients (25.3%) in the intervention group and 40 patients (40.4%) in the control group (odds ratio 0.49, 95% CI, 0.27-0.92; p = 0.023). On a multivariate Cox proportional hazards model, the hazard ratio for the development of AF was significantly less in the intervention group (hazard ratio 0.45, 95% CI, 0.26-0.77; p = 0.004). The magnesium delivery strategy was associated with a decreased incidence of postoperative AF in cardiac surgery patients. These findings provide a rationale and preliminary data for the design of future randomized controlled trials.

Magnesium Sulfate Treatment During Total Knee Arthroplasty Decreases Postoperative Urinary Retention: A Retrospective Propensity Score-Matched Analysis.

Postoperative urinary retention (POUR) is a common complication after total knee arthroplasty. Currently, there are no clinical data regarding the effects of magnesium sulfate on POUR. Here, we investigated the effects of intraoperative magnesium sulfate infusion in patients with POUR following total knee arthroplasty. We reviewed the medical records of patients who underwent elective unilateral total knee arthroplasty under spinal anesthesia between June 2016 and May 2018. The patients were grouped based on whether they were treated with magnesium (magnesium group) or not (control group). We investigated the incidence of POUR and the postoperative analgesic requirement. Totally, 483 patients were included in the analysis. After propensity score matching with the control group, the magnesium group showed a lower incidence of POUR (odds ratio, 0.49; 95% CI, 0.29–0.83; p = 0.011) and lesser opioid consumption (p = 0.049) than the control group. Multivariate logistic regression analysis revealed that intraoperative continuous infusion of magnesium (p = 0.008) and age (p = 0.001) were significantly related to the incidence of POUR. This retrospective observational study demonstrated that administration of magnesium sulfate was associated with a lower incidence of POUR following total knee arthroplasty.

Magnesium and Ketamine Reduce Early Morphine Consumption After Open Bariatric Surgery: a Prospective Randomized Double-Blind Study.

Optimal pain management in bariatric patients is crucial for early recovery. This study aims to evaluate the effects of magnesium and ketamine combination on morphine consumption after open bariatric surgery (primary outcome), as well as on postoperative pain scores and occurrence of side effects. A total of 60 patients undergoing elective open gastric bypass were randomized into 3 groups. All patients received the same general anaesthesia protocol. The magnesium and ketamine group (Mg + K) received an IV bolus of magnesium 50mg/kg and ketamine 0.2mg/kg followed by continuous infusion of magnesium (8mg/kg/h) and ketamine (0.15mg/kg/h) until extubation. The ketamine group (K) received the same bolus and infusion of ketamine, together with a bolus and continuous infusion of normal saline. The placebo group (P) received normal saline. All patients received 48h of paracetamol 1g IV q6h and morphine sulphate 0.1mg/kg subcutaneous q6h PRN. Morphine consumption, VAS pain scores and occurrence of side effects were recorded for 48h postoperatively. Patients in group (Mg + K) (2.4 ± 2.62mg) and in group (K) (2.8 ± 2.66mg) had significantly lower morphine consumption in the PACU compared with the patients in group (P) (4.85 ± 4.51mg) (p = 0.045). Patients in group (Mg + K) consumed significantly less morphine the first 24 postoperative hours, with a relative reduction of 87% and 21% compared with group (K) and group (P) respectively (p = 0.028). However, this difference was not observed at 48h. No significant difference was shown between the three groups in terms of nausea and vomiting, time to extubation or excessive sedation. The association of magnesium and ketamine bolus followed by infusion in open bariatric surgery appears to be safe and decreases morphine requirements in the first 24h compared with both ketamine alone and placebo.

Magnesium supplementation: Pharmacokinetics in cardiac surgery patients with normal renal function

BackgroundIntravenous magnesium is routinely administered in intensive care units (ICU) to treat arrhythmias after cardiothoracic surgery. There are no data on the pharmacokinetics of continuous magnesium infusion therapy. ObjectiveTo investigate the pharmacokinetics of continuous magnesium infusion, focusing on serum and urinary magnesium concentration, volume of distribution and half-life. MethodsWe administered a 10 mmol bolus of magnesium-sulfate followed by a continuous infusion of 3 mmol/h for 12 h in twenty cardiac surgery patients. We obtained blood and urine samples prior to magnesium administration and after one, six, and 12 h. ResultsMedian magnesium levels increased from 1.09 (IQR 1.00–1.23) mmol/L to 1.59 (1.45–1.76) mmol/L after 60 min (p < .001), followed by 1.53 (1.48–1.71) and 1.59 (1.48–1.76) mmol/L after 6 and 12 h. Urinary magnesium concentration increased from 9.2 (5.0–13.9) mmol/L to 17 (13.6–21.6) mmol/L after 60 min (p < .001). Cumulative urinary magnesium excretion was 28 mmol (60.9% of the dose given). The volume of distribution was 0.25 (0.22–0.30) L/kg. There were no episodes of severe hypermagnesemia (≥3 mmol/L). ConclusionCombined bolus and continuous magnesium infusion therapy leads to a significant and stable increase in magnesium serum concentration despite increased renal excretion and redistribution.

The Effect of Systemic Magnesium on Postsurgical Pain in Children Undergoing Tonsillectomies: A Double-Blinded, Randomized, Placebo-Controlled Trial.

Tonsillectomy is a frequently performed surgical procedure in children; however, few multimodal analgesic strategies have been shown to improve postsurgical pain in this patient population. Systemic magnesium infusions have been shown to reliably improve postoperative pain in adults, but their effects in pediatric surgical patients remain to be determined. In the current investigation, our main objective was to evaluate the use of systemic magnesium to improve postoperative pain in pediatric patients undergoing tonsillectomy. We hypothesized that children who received systemic magnesium infusions would have less post-tonsillectomy pain than the children who received saline infusions. The study was a prospective, randomized, double-blinded, clinical trial. Subjects were randomly assigned using a computer-generated table of random numbers to 1 of the 2 intervention groups: systemic magnesium infusion (initial loading dose 30 mg/kg given over 15 minutes followed by a continuous magnesium infusion 10 mg/kg/h) and the same volume of saline. The primary outcome was pain scores in the postanesthesia care unit (PACU) measured by FLACC (Face, Legs, Activity, Cry, Consolability) pain scores. Pain reduction was measured by the decrement in the area under the pain scale versus 90-minute postoperative time curve using the trapezoidal method. Secondary outcomes included opioid consumption in the PACU, emergence delirium scores (measured by the pediatric anesthesia emergence delirium scale), and parent satisfaction. Sixty subjects were randomly assigned and 60 completed the study. The area under pain scores (up to 90 minutes) was not different between the study groups, median (interquartile range [IQR]) of 30 (0-120) score × min and 45 (0-135) score × min for the magnesium and control groups, respectively (P = 0.74). Similarly, there was no clinically significant difference in the morphine consumption in the PACU between the magnesium group, median (IQR) of 2.0 (0-4.44) mg IV morphine, compared with the control, median (IQR) of 2.5 (0-4.99) mg IV morphine (P = 0.25). The serum level of magnesium was significantly lower in the control group than in the treatment group at the end of the surgery (P < 0.001). Despite a large number of studies demonstrating the efficacy of systemic magnesium for preventing postsurgical pain in adults, we could not find evidence for a significant clinical benefit of systemic magnesium infusion in children undergoing tonsillectomies. Our findings reiterate the importance of validating multimodal analgesic strategies in children that have been demonstrated to be effective in the adult population.

Continuous infusion of magnesium–lidocaine mixture for prevention of ventricular arrhythmias during on-pump coronary artery bypass grafting surgery

BackgroundDuring on-pump coronary artery bypass grafting (CABG) surgery, the incidence of reperfusion ventricular fibrillation (VF) is high and post-bypass ventricular arrhythmias are common. Both reperfusion VF and ventricular arrhythmias can cause additional myocardial injury to the already ischemic myocardium. This trial aimed to test the assumption that continuous combined magnesium and lidocaine infusion would be efficient and long lasting for the prevention of post-myocardial vascularization ventricular arrhythmias including VF.MethodsEighty ASA III patients, who were candidates for CABG surgery, were randomly assigned into two groups: Group I (control group, n = 40) and Group II (Group ML, n = 40). After endotracheal intubation, patients of control group were infused with plain normal saline in a volume equivalent to study drugs’ mixture volume. Patients of Group ML were infused with magnesium–lidocaine mixture to achieve a bolus of magnesium sulfate 2 g and lidocaine 100 mg followed by continuous infusion of Mg sulfate 500 mg/h and lidocaine 1 mg/min. The initial cardiac rhythm after aortic cross clamp (ACC) release and the occurrence of post-CPB significant ventricular arrhythmias were recorded.ResultsThe incidences of reperfusion VF and post-CPB ventricular arrhythmias in Group ML were significantly lower than that in control group (22.5% vs. 72.5%) (P < 0.001) and (7.5% vs. 25%) (P < 0.05), respectively. However, in Group ML, this beneficial effect was associated with higher incidence of sinus bradycardia (72.5% vs. 17.5%) and hence pacing needs (22.5% vs. 0.0%) when compared with control group.ConclusionOur study concluded that, during on-pump CABG surgery, the combined administration of magnesium and lidocaine as a bolus dose starting after intubation followed by continuous infusion reduced the incidence of reperfusion VF by 62% and post-CPB ventricular arrhythmias by 70% on expense of increased the incidence of sinus bradycardia and pacing.

A rare cause of status epilepticus

Dear Editor, Status epilepticus (SE) has a long list of potential causes. In about 15% of cases, no cause is identified [1]. We report on a patient who presented with convulsive SE due to concomitant reversible cerebral vasoconstriction syndrome (RCVS) and posterior reversible encephalopathy syndrome (PRES) in the early postpartal period. A 44-year-old nulliparous pregnant woman was admitted for labor induction at gestational week 41. Intravaginal prostaglandin gel was applied but emergency caesarean section was then performed because of recurrent fetal bradycardia. Her initial blood pressure was 110/70 mmHg. Spinal anesthesia was associated with maternal hypotension and bradycardia, which responded to ephedrine 60 mg and atropine 0.75 mg boluses followed by intravenous administration of 500 mL of crystalloids. Her blood pressure then reached up to 162/82 mmHg. She also received oxytocin 10 IU intravenously during caesarean section followed by a continuous infusion of 10 IU over the next 6 h. During the cesarean section, she experienced a thunderclap headache. Immediately after delivery, her blood pressure increased to 160/85 mmHg requiring nicardipine infusion. She experienced a first tonic–clonic seizure less than 3 h after the caesarean section, when her blood pressure was 110/60 mmHg. A second seizure occurred rapidly and stopped only after an intravenous bolus of 2 mg of midazolam and 2 g of magnesium over 30 min. A continuous 2 g/day magnesium infusion was started. A third seizure during transportation to the radiology suite required an additional intravenous bolus of 1 mg of midazolam. Figure 1a, d shows results of the first cerebral magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA). She was transferred to the ICU with a diagnosis of SE related to both RCVS and PRES. On ICU admission, blurred vision was the only abnormal clinical finding. Blood pressure was 120/62 mmHg. Routine electroencephalogram was normal. On day 2, her hemodynamic status was stable, her vision was normal, and her seizures were controlled. The continuous magnesium infusion was stopped. Intravenous administration of nimodipine (2 mg/h) was started to treat

Anesthesia Literature Review

Anesthesia Literature Review

Retrospective analysis of parenteral magnesium sulfate administration in decreased incidence of clinical and neuroradiological cerebral vasospasm: a single center experience

Objective: Experimental work suggests a neuroprotective role for magnesium sulfate in aneurysmal subarachnoid hemorrhage. We retrospectively review the incidence of clinically relevant vasospasm in patients treated or not with continuous magnesium infusion after onset of subarachnoid hemorrhage.Methods: All patient records in Albany Medical Center with the diagnosis of SAH between January 1999 and June 2004 were reviewed. Patients who presented to the emergency department within 72 hours of onset were entered in the study. Patients were defined as in clinical vasospasm if there was an acute neurological change in association with abnormal trancranial Doppler (TCD), CT angiogram (CTA) or digital subtraction angiography (DSA).Results: A total of 85 patients were selected. Magnesium sulfate was infused in 43 patients. When compared with patients who did not receive MgSO4, there was a statistically significant lower incidence of clinical and radiological vasospasm in those who had the continuous infusion of magnesium sulfate (p<0.01). There was no statistically significant difference between patients who were coiled or clipped.Conclusion: Continuous magnesium sulfate infusion for the management of clinically significant cerebral vasospasm is safe and reduces the incidence of clinically significant cerebral vasospasm. Large, multicenter, controlled studies should be performed in order to determine the true effectiveness of the treatment in a controlled setting.

Prophylactic magnesium to decrease the arrhythmogenic potential of class III antiarrhythmic agents in a rabbit model.

We assessed the prophylactic effect of intravenous magnesium sulfate on the occurrence of torsades de pointes and early after-depolarizations, and on the QT interval (QTc) in an established rabbit model. Ten rabbits were given intravenous methoxamine to slow their heart rates. After 12 minutes five animals received a 60-mg/kg bolus and continuous infusion of magnesium 0.6 mg/kg/minute, and five received equivolume normal saline concurrently with the class III antiarrhythmic agent clofilium 5 mg/kg over 30 minutes. Electrocardiogram lead II and the monophasic action potential were recorded continuously throughout the experiment. The magnesium group experienced significantly less torsades de pointes and early after-depolarizations than the normal saline group (1/5 and 5/5 both parameters, respectively, p=0.048). There were no differences between groups in QT or QTc interval at baseline or at maximum QT or QTc prolongation. Magnesium decreases the occurrence of torsades de pointes without affecting the QT or QTc interval but does decrease the occurrence of early after-depolarizations. These findings must be validated in human studies.

The Effect of Continuous Magnesium Infusion on Infarct Size and Oedema in Acute Stroke in Mice

The Effect of Continuous Magnesium Infusion on Infarct Size and Oedema in Acute Stroke in Mice

Modification by ketamine on the neuromuscular actions of magnesium, vecuronium, pancuronium and alpha-bungarotoxin in the primate.

The neuromuscular effects of ketamine, at cumulative doses of 2.5 and 10 mg.kg-1 iv, were studied by electromyographically quantifying the thumb response evoked by ulnar nerve stimulation in 25 monkeys anaesthetized with pentobarbital-N2O-O2. Ketamine alone at these doses had no neuromuscular effects. When the EMG response was maintained at 50% of control by a continuous infusion of magnesium, vecuronium, or pancuronium, ketamine depressed the responses by an additional 13 +/- 3%, 34 +/- 7% and 32.5 +/- 3.3% (mean +/- SEM), respectively, at the highest dose, P less than 0.05. In contrast, ketamine had no effect on the neuromuscular block produced by incremental doses of alpha-bungarotoxin. These results indicate that ketamine does not act on the postjunctional acetylcholine receptor. It plays a secondary role in neuromuscular block, possibly by prejunctional or postjunctional effects independent of receptor occupation.

The Effect of Tetraethylammoninum (TEA) and Temperature on the Neuromuscular Block Produced by Magnesium

Summary. An investigation of the effect of temperature on the neuromuscular block caused by magnesium in the isolated phrenic nerve diaphragm preparation from the rat has been carried out. The effect of tetraethylammonium (TEA) on the neuromuscular depression produced by magnesium has been investigated in the rat diaphragm preparation as well as in nerve muscle preparations in situ in rabbits and cats. A concentration of 6 mM magnesium in the bath just produced complete neuromuscular block of the responses to single nerve shocks at 37°C. At 22° C 10 mM magnesium was needed. In the presence of a neuromuscular block due to magnesium at 37° C, lowering the temperature to 22° C restored transmission. TEA in a concentration of 1 mM in the bath partly restored neuromuscular transmission depressed by magnesium. The β‐hydroxy‐derivative of TEA and choline only increased the magnesium block. In the rabbit and cat TEA in a dose of 4 to 7 mg per kg body weight injected intravenously restored neuromuscular transmission strongly depressed by continuous infusion of magnesium. In spite of continuous magnesium infusion, the restoration of muscle contractions obtained with the single dose of TEA was far more sustained than the blood pressure fall caused by TEA. The sensitivity of the motor end plate to externally applied acetylcholine was not increased after TEA had restored transmission in the magnesium‐blocked rat diaphragm. The end plate potential obtained under a magnesium block was increased in amplitude without significant change in time course, when TEA was added. It is concluded that TEA like calcium antagonizes the neuromuscular block caused by magnesium by effecting an increased output of acetylcholine from the presynaptic nerve terminals.