Critical Procedure - Eclamptic seizures and prophylaxis

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For all procedures, ask yourself, 'does this need to be done 'now vs later'? And should this be done by 'me vs someone else?' Very often the answers will be 'now' and 'me' - so read on!

Eclamptic seizures


Description

Management and prevention of eclamptic seizures in severe pre-eclampsia and eclampsia.

Indications

Eclamptic seizures and seizure prophylaxis in severe pre-eclampsia and eclampsia. <

Contraindications

Relative - renal failure (reduce dose or magnesium).

Equipment

Magnesium Sulphate IV
IV Pump

Procedure

Magnesium Sulphate Protocol

Give a loading dose followed by a continuous infusion for 24 hours or until 24 hours after delivery – whichever is the later.
Loading dose:
MgSO4 4g IV diluted to 30mls over 20-30 minutes via a pump.
Dilute in dextrose-saline, 5% dextrose or N. Saline

Maintenance dose:
MgSO4 1g/hr IV infusion.
20 g (40 ml) MgSO4 diluted to 1000 mls. Infuse at 1 g/hr (50 ml/hr) using a pump.
Dilute in dextrose-saline, 5% dextrose or N. Saline

Clinical monitoring.
Close monitoring with clinical assessment of the patient is essential. Re-evaluate the decision to continue the infusion, continuously.

Monitor the following:
  • continuous pulse oximetry
  • hourly urine output
  • hourly respiratory rate
  • deep tendon reflexes q4h
  • level of consciousness q4h

Only continue the infusion if, after each 4 hour period:
  • the biceps reflex is present
  • the respiratory rate is > 12/min.
  • the urine output is greater than 100 ml in the previous 4 hours

Side effects of MgSO4
  • motor paralysis
  • absent tendon reflexes
  • respiratory depression
  • cardiac arrhythmia
  • hypotension secondary to reductions in systemic vascular resistance
  • facial flushing
  • visual disturbances
  • flushing/necrosis at injection site
  • chest pain
  • nasal stuffiness

These can all occur, but will be minimised if MgSO4 is administered slowly and the patient is observed as above.

Antidote
Calcium gluconate 10%
Dose: 1G IV slowly over 7 minutes

Potential pitfall

Delay in starting Magnesium Sulphate in the woman with severe pre-eclampsia.
Inadequate monitoring of conscious level, respiratory rate, tendon reflexes and urine output.

"Plan B"

Discuss with a specialist unit.

BC Women’s Maternal-Fetal Medicine Team 604 875 2161
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Last modified: Thursday, 13 August 2020, 9:15 AM