UMEM Educational Pearls

Title: Neonatal hypermagnesemia and respiratory depression

Keywords: magnesium toxicity, neonatal hypotonia, neonate, intubation, neonatal resuscitation (PubMed Search)

Posted: 4/8/2011 by Adam Friedlander, MD
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So the magnesium didn't work, and the baby is on the way! You're prepared with everything you need for the delivery from bulb suction to a tripod for Dad's camera... But what is going to special about this baby?

Babies born to mothers who received magnesium therapy for any reason are at risk for hypotonia and severe respiratory depression.

DO provide respiratory support as needed, as respiratory depression is the only dangerous side effect of hypermagnesemia in the neonate (be prepared to provide supplemental oxygen, positive pressure ventilation (PPV), and possibly intubation)
DO recognize that generalized hypotonia may be a clue as to how significantly affected the neonate may be, however, don't let the hypotonia itself scare you - it will go away, and is not dangerous in and of itself
DO follow neonatal resus guidelines (PPV for HR<100, CPR for HR<60), but remember that supportive measures will resolve all problems related to hypermagnesemia in the neonate...if there are other issues, don't blame the mag
DO NOT give calcium as, in contrast to their mothers, these patients are not hypocalcemic (and the hypermagnesemia will spontaneously resolve in 48 hours)
DO remember that these infants frequently require a brief NICU stay until they no longer require respiratory support

References

NRP Guidelines 2005
McGuinness GA, Weinstein MM, Cruikshank DP, Pitkin RM. Effects of magnesium sulfate treatment on perinatal calcium metabolism. II. Neonatal responses. ObstetGynecol. 1980 Nov;56(5):595-600

Special thanks to Dr. Mimi Lu for the reference above