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Magnesium flux during and after open heart operations in children
C M Satur1, S R Stubington, A Jennings
1Department of Cardiothoracic Surgery, Killingbeck Hospital, Leeds, United Kingdom.
Insights
Hypomagnesemia, or low magnesium, is common in children post-heart surgery, with significant depletion occurring in muscle tissue. Cardiac arrhythmias were not statistically linked to these magnesium levels.
Area of Science:
- Pediatric Cardiology
- Cardiovascular Surgery
- Clinical Biochemistry
Background:
- Hypomagnesemia is linked to cardiac arrhythmias and neurological issues.
- Children undergoing intensive care after open-heart surgery may experience magnesium depletion.
Purpose of the Study:
- To assess magnesium deficiency incidence in pediatric intensive care patients post-open-heart surgery.
- To correlate intraoperative metabolic changes with magnesium levels and clinical outcomes.
Main Methods:
- Prospective study in 41 pediatric intensive care patients post-open-heart surgery.
- Plasma magnesium levels measured immediately post-operation and the following morning.
- Perioperative changes in extracellular and tissue magnesium, potassium, and calcium analyzed in 21 children.
Main Results:
- Plasma magnesium significantly decreased post-operation and on the following morning.
- 34.2% of patients had plasma magnesium < 0.7 mmol/L; 17.1% had < 0.6 mmol/L.
- Hemodilution reduced magnesium levels (0.81 to 0.61 mmol/L); skeletal muscle magnesium depleted (6.75 to 5.65 mumol/g).
- Elevated plasma potassium (3.7 to 4.15 mmol/L) and ionized calcium (1.17 to 1.49 mmol/L) observed.
- No statistical relationship found between cardiac arrhythmias and hypomagnesemia.
Conclusions:
- Magnesium deficiency is prevalent in children after open-heart surgery.
- Intraoperative hemodilution contributes to magnesium depletion.
- Skeletal muscle magnesium stores are significantly depleted post-surgery.
- Further research is needed to understand the clinical implications of these findings.
Abstract:
Hypomagnesemia and depletion of the body's magnesium stores is known to be associated with an increased incidence of both cardiac arrhythmias and neurological irritability. In a two-part prospective study we have evaluated whether magnesium deficiency is a significant occurrence in children treated in the intensive care unit after open heart operations, and subsequently have sought to identify how intraoperative metabolic changes were related to the resultant findings. In 41 children studied after operation the plasma magnesium concentration showed a significant decrease from 0.92 mmol/L (10th to 90th centile, 0.71 to 1.15 mmol/L) immediately after operation to 0.77 mmol/L (0.65 to 0.91 mmol/L) on the following morning. The subsequent change in grouped values was not significant but 14 (34.2%) and 7 (17.1%) possessed values of less than 0.7 mmol/L and 0.6 mmol/L, respectively. The occurrence of cardiac arrhythmias was not statistically related to the occurrence of hypomagnesemia. In 21 children perioperative changes in extracellular and tissue magnesium, potassium, and calcium content were measured. It was found that hemodilution with a prime low in magnesium caused a reduction from a median of 0.81 mmol/L to 0.61 mmol/L (p < 0.01). Plasma potassium level, however, was elevated from 3.7 mmol/L to 4.15 mmol/L (p < 0.05) and the ionized calcium content from 1.17 mmol/L (1.07 to 1.25 mmol/L) to 1.49 mmol/L (1.25 to 2.56 mmol/L) (p = 0.0009). The myocardial content of magnesium did not change significantly but skeletal muscle content was depleted from 6.75 mumol/g (2.85 to 8.35 mumol/g) to 5.65 mumol/g (2.45 to 7.2 mumol/g) (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)