Neuroprotective dose and safety profile of magnesium sulphate therapy in term neonates with perinatal asphyxia

Abstract

Introduction: Perinatal asphyxia has become a major public health problem accounting for 9% of total under-5 mortality. It can lead to serious neuro-motor sequelae in survivors. Newer neuroprotective strategies for management of perinatal asphyxia have gained momentum in recent era.

Background: To determine the effective dosage regimen and safety profile of intravenous magnesium sulphate as a neuroprotective agent for perinatal asphyxia in term neonates.

Materials and methods: 60 term asphyxiated neonates admitted in NICU of a tertiary care teaching hospital were evaluated. Babies were treated as per the standard treatment protocol for perinatal asphyxia. The infants received 250 mg/kg per dose intravenous magnesium over 1 hour within 6 hrs of birth, with 2 additional doses repeated at intervals of 24 hours. The heart rate, respiratory rate, blood pressure and oxygen saturation were monitored continuously. A baseline serum magnesium level was measured soon after delivery and two more serum magnesium levels at 24 hr and at 48 hr was measured.

Results: The pre intervention baseline serum magnesium level was 1.52 (±0.302) meq/L. The serum magnesium level increased from the baseline level of 1.52 (±0.302) meq/L to 2.63 (±0.558) meq/L at 24 hour and 2.72 (±0.495) meq/L at 48 hour. The neuroprotective range of serum magnesium is 2.4 – 5 Meq/L. This dosage regimen will ensure plasma concentration of magnesium in the neuroprotective range for 48 hours. All physiologic variables remained unchanged including heart rate, respiratory rate, blood pressure and oxygen saturation during intervention.

Conclusion: Intravenous infusion of 3 doses of magnesium 250 mg/kg/dose in first 48 hrs after birth will ensure serum magnesium level in the neuroprotective range. This therapeutic dosage regimen has been found to have the best margin of safety profile in term asphyxiated infants.