Comparison of the Efficacy of Oral versus Intravascular Magnesium in the Prevention of Hypomagnesemia and Arrhythmia after CABG

Abstract

ObjectiveCardiac arrhythmias are a common challenge following open-heart surgeries. Hypomagnesemia is believed to be correlated with this condition. Prophylactic intravenous magnesium supplementation has been practiced for a long time in patients undergoing CABG. This study was designed in an attempt to compare the efficacy of oral versus intravenous routes in the prevention of hypomagnesemia and arrhythmia.MethodsIn this interventional clinical study, 82 patients were randomly assigned to 2 groups. All patients were evaluated for baseline serum magnesium level and arrhythmias. One group received 1,600 mg of oral magnesium hydroxide through nasogastric (NG) tube prior to surgery, while the other group received 2 g of magnesium sulfate during the induction of anesthesia. The serum magnesium level was monitored for 48 hours after the operation. The difference in preoperative hypomagnesemia was non-significant (Sig: 0.576).ResultsDuring the operation, the serum magnesium level peaked around 4 mg/dL, and no hypomagnesemia was detected in any patient. Although the curve of oral group declined parallel and below that of intravenous (IV) group, no significant differences were detected during postoperative monitoring. In addition, a prevalence of arrhythmia of 13.9% and 6.5% was noticed in IV and oral groups, respectively (OR: 0.428).ConclusionProviding 1,600 mg of oral magnesium supplement to patients is as effective as 2,000 mg of magnesium sulfate IV in preventing hypomagnesemia and arrhythmia after CABG. Thus, the authors introduce this treatment regimen as a promising and cost-effective method.

Preoperative Investigation of Malnutrition in Elective Surgery Cases and Relationship with Serum Magnesium Level

“…Magnesium deficiency was detected in 7-11% of hospitalized patients, and it was observed that 40% had accompanying hypokalemia, hypophosphothemia, hyponatremia and hypocalcemia (10). Therefore, it may be important to detect hypomagnesemia in the perioperative period in patients with malnutrition, which may lead to significant consequences in anesthesia management (10)(11)(12). Known causes of hypomagnesemia in surgical patients; decreased dietary intake, poor gastrointestinal absorption, increased loss of the gastrointestinal tract, alcoholism, diabetes mellitus and increased renal loss (12).…”

“…Therefore, it may be important to detect hypomagnesemia in the perioperative period in patients with malnutrition, which may lead to significant consequences in anesthesia management (10)(11)(12). Known causes of hypomagnesemia in surgical patients; decreased dietary intake, poor gastrointestinal absorption, increased loss of the gastrointestinal tract, alcoholism, diabetes mellitus and increased renal loss (12). In addition, it is important to detect it in the perioperative period due to its interaction with agents such as anesthetic agents, diuretics, thiazides, and valproic acid (10).…”

Ionized or Total Magnesium levels, what should we measure in critical ill patients?

“…Some studies evaluated the achievement of stable magnesium levels after bolus intravenous administration, how it is usually used, or followed by continuous infusion that is demonstrated the same effective levels [ 45 ]. The oral route has been suggested in prophylactic therapy to prevent postoperative arrhythmias [ 46 ], but these investigations have aimed at measurement on total magnesium and not ionized bioactive free form [ 47 ].…”

Ionized or Total Magnesium Levels, What Should We Measure?

“…Some studies evaluated the achievement of stable magnesium levels after bolus intravenous administration, how it is usually used, or followed by continuous infusion that is demonstrated the same effective levels [45]. The oral route has been suggested in prophylactic therapy to prevent postoperative arrhythmias [46], but these investigations have aimed at measurement on total magnesium and not ionized bioactive free form [47]. dosages from 50 to 100 mg/kg without reported complications [54], others consider it possibly dangerous and thinking there is not currently licensed for intrathecal administration [55].…”