396715498-New-Microsoft-Word-Document-2.ppt

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1. The role of Magnesiu
m Sulphate
in
Obstetrics
By Sneha Sehrawat
M.
Ṣc Nursing I
st
Year

2. Introduction
•Magnesium is an essential constituent of many
enzyme systems particularly those involved in
energy generation, the largest store are in the
skeleton.
•Magnesium salts are not well absorbed from the
GIT which explains its use as an osmotic
laxative.
•Magnesium is mainly excreted by the kidneys,
and is therefore retained in renal failure causing
muscle weakness and arrhythmias.

3. •Magnesium sulphate is use as
- a tocolytic agent as in Preterm
labour and Premature rupture of
membranes.
- as an anticonvulsant in Severe Pre-
eclampsia and Eclampsia

4. Tocolysis
•The exact mechanism of action of
magnesium sulphate is not known but it
appears to inhibit calcium uptake into
smooth muscle cells, reducing uterine
contractility.
•Apparently less effective than ritodrine,
salbutamol or terbutaline but better
tolerated than beta-mimetics and as a
result, has become the first-line agent.

5. •Side effects of beta- mimetic adreneric
agents which limits there use include:-
-pulmonary oedema
-ARDS
-elevated systolic and reduced
diastolic blood pressure
-both maternal and fetal tachycardia
-Hyperglycaemia
-Hypokalemia
-Cardiac arrhythmias

6. •Dosage
-IV magnesium sulphate 4g start. To be
given slowly to prevent flushing or
vomiting.
-Then continuous infusion should be
started at 2g per hour using 5% dextrose.
-The infusion can be titrated up by
increments of 0.5g per hour to a maximum
of 4.0g per hour until adequate tocolysis is
achieved.
-Reduce the rate of infusion if magnesium
toxicity is observed.

7. Anti-convulsant effect
•Magnesium sulphate is a safe and effective
agent to prevent and treat convulsions in Severe
pre-eclampsia/Eclampsia.
•Can be given by the IM or IV route.
•The mechanism of action is twofold:-
-It interferes with transmission at
neuromuscular junction.
-Also has central nervous system effect
.The hypotensive effect is transient and related to
bolus administration and rapid infussion. A
continuous infusion will not maintain
hypotension’.

8. Magnesium sulphate regimens for
women with pre-eclampsia and eclampsia
•Zuspan regimen
-Intravenous
-Start with a loading dose of 4g
•Sibai regimen
-Intravenous
-Start with a loading dose of 6g
•Pritchard regimen
-Intramuscular/Intravenous
-Start with a loading dose of 14g
in which 4g given as intravenous
and 10g given as intramuscular

10. Intravenous(iv)
magnesium sulphate regimen cont
•Sibai regimen
•Loading dose
-6g iv over 20 mins
•Maintenance therapy
- 2-3g per hour

14. Monitoring during magnesium
sulphate therapy contd
•Loss of patellar reflexes is the first sign of
magnesium sulphate toxicity.
•Respiratory paralysis is the next. (<12/min)
•Renal failure. (<30mls/hr)
•If a seizure occurs within 20minutes after the
loading dose, convulsion is usually short, no
treatment.
•If the seizure occurs more than 20minutes after
the loading dose, an additional 2-4g is given.

15. Magnesium sulphate blood levels
Blood levelSymptoms and signs
4-8mg/dlTherapeutic
9-12mg/dlNausea, vomiting, flushing,
double vision, slurred speech,
weakness, loss of patellar reflexes,
somnolence, feeling of warmth
15-17mg/dlMuscular paralysis and respiratory
arrest
30-35mg/dlCardiac arrest

17. •Anticonvulsant therapy for eclampsia
Magnesium sulphate is inexpensive and
its administration and monitoring are
relatively straightforward without a need
for expensive equipment. Intramuscular
administration can be used when staff with
experience in intravenous administration
and monitoring is not available.

18. Conclusion
•Magnesium sulfate more than halves the
risk of eclampsia, and probably reduces
the risk of maternal death. A quarter of
women have side-effects, notably flushing.
The lack of clarity on what constitutes
severe pre-eclampsia may render this
intervention difficult to implement. Women
at low risk of pre-eclampsia may not be
suitable candidates for treatment with
magnesium sulfate.