2. Pre-eclampsia is a disorder of pregnancy, characterized
by hypertension (BP > 140/90 mmHg measured 2 times
with interval ≥ 4 hours) and proteinuria (urinary excretion
of ≥ 1+or more protein in dipstick) after the 20th weeks
of gestation in a previously normotensive and non-
proteinuric woman.
Pre-eclampsia when complicated with generalized tonic
clonic convulsion and/or coma is called Eclampsia.
3. Severe pre-eclampsia is defined by a systolic BP ≥ 160
mmHg or a diastolic BP ≥ 110 mmHg twice 4 hour
apart at bed rest with or without the following end-organ
findings: Proteinuria of ≥5 gm in a 24-hour urine
specimen (or 3+ on random urine dip on two occasions at
least 4 hours apart), Oliguria (<500 mL in 24
hours), Neurologic or visual disturbances (including
headache), Pulmonary edema, Elevation of
transaminases, Epigastric or right upper quadrant pain,
Thrombocytopenia, Fetal growth restriction or Eclampsia.
4. Magnesium sulfate is an anticonvulsant rather than
an anti-hypertensive. It prevents seizures in pre-
eclampsia and doesn’t treat hypertension. In
eclampsia, it is given as soon as the convulsion has
ended. It causes vasodilation, increases cerebral,
uterine and renal blood flow. It decreased cerebral
edema.
5. “x” % of Magnesium sulfate contains “x” gm in 100 ml
1 ampoule contains 50% of 2 ml Magnesium sulfate
1 ampoule contains 1 gm of Magnesium sulfate in 2 ml
4 ampoule provides 4 gm of Magnesium sulfate in 8 ml
To prepare 20% of 4 gm Magnesium sulfate, “y” ml of Normal
saline (NS) must be added:
◦ 20 gm/100 ml = 4 gm/(8 ml + “y” ml)
◦ 8 + “y” = 20
◦ “y” = 12
6. a. Loading dose:
Initially: 4 gm of 20% MgSO4 IV over not less than 3
minutes
Take one 20 ml syringe
Draw 4 ampoules of Magnesium sulfate
Add 12 ml Normal saline
7. Immediately followed by: 10 gm of 50% MgSO4 IM (5
gm in each buttock)
Take two 10 ml syringes
Draw 5 ampoules of MgSO4 in each syringe
Add 1 ml of 2% Lignocaine in each syringe
Give deep IM in each buttocks
8.
9. If convuslion persists after 30 minutes: 2 gm of 50%
MgSO4 IV bolus over 5 minutes
Take one 10 ml syringe
Draw 2 ampoules of Magnesium sulfate
To prepare 20% of 2 gm Magnesium sulfate, “y” ml
of Normal saline (NS) must be added:
◦ 20 gm/100 ml = 2 gm/(4 ml + “y” ml)
◦ 4 + “y” = 10
◦ “y” = 6
10. b. Maintenance dose:
5 gm of 50% MgSO4 IM 4 hourly in alternate buttocks
Take one 10 ml syringe
Draw 5 ampoules of MgSO4
Add 1 ml of 2% Lignocaine in each syringe
Give deep IM 4 hourly in alternate buttocks
Continue for 24 hours after the last convulsion or
delivery whichever is later.
11. Monitoring Hourly for Magnesium Sulfate toxicity:
Suspend or postpone use of Magnesium sulfate, if any of
the following is present:
Respiratory rate < 16/min (Respiratory depression)
Absent patellar reflex (Muscle paresis)
Urine output < 30 ml/hour in preceding 4 hours (Impaired
renal function)
Note: Loss of patellar reflex is the 1st sign of Magnesium
toxicity: The therapeutic level of serum magnesium is 4-7
mEq/l. Serum levels of Magnesium toxicity
13. a. If urine output < 30 ml/hour:
MgSO4 withheld
IV ringer lactate infusion 1 liter over 8 hours
Monitor for pulmonary edema
b. If respiratory arrest occurs:
Perform assisted ventilation
Antidote: Calcium gluconate 1 gm (10% of 10 ml) IV
slowly over 10 minutes
14. Contraindication of Magnesium Sulfate:
Myasthenia gravis
Impaired renal function
Note: Researches have found that the Zuspan regimen
is upto 8 times less effective than the Pritchard
regimen in preventing convulsions in severe pre-
eclampsia and eclampsia.