Magnesium Sulfate in Obstetrics

Educational Materials

1. Magnesiumsulfate (MgSO4) In Obstetrics
Associate Clinical Professor Dr. Aisha M. El-Bareg
MBBS, DGO, MCCG, PCTM, MMedSci (ART), ABOG, MD, PhD
Senior Consultant in (Obs & Gyn)/ Reproductive Medicine
Faculty of Medicine, Al-Amal Hospital, Misrata .LIBYA

2. Use in obstetrics
Seizer protection
Fetal neuroprotection
Tocolytics??????

3. Mechanism of action

4. Mechanism of action
❖Cerebral vasodilatation thus reducing ischemia due
to vasospasm.
❖Reduction in inflammatory cytokines and/or oxygen
free radicals.
❖It inhibits platelet activation.
❖Peripheral vasodilatation, thus decreases systemic
vascular resistance.
❖Dilates the orbital vessels, increases cardiac output,
renal blood flow and uteroplacental blood flow.

5. Contraindications
❖Impaired renal function.
❖Heart block, myocardial damage.
❖Myasthenia gravis.
❖Drug interaction: Nifedipine, anesthetic drugs.

6. Different Regimens of MgSO4
in Pre-eclampsia/Eclampsia
Combined IV /IM regimen
IV regimen

7. 50%
5 gm /10ml
10%
1 gm/10ml

8. 4g MgSO4 IV push over 20 min
Combined IM and IV regimen
•Loading dose: (total dose 9gm)
And
2.5g (5ml of 50%) MgSO4 IM into each buttock

9. 4g MgSO4 IV push over 20 min
Add 8ml 50% MgSO4 (4g) in 100ml 0.9% saline or
5% glucose administer IV over 20min.
OR, if you have syringe-driver pump
Add 8ml 50% MgSO4 (4g) to 12ml 0.9% saline or 5%
glucose and infuse IV over 20min at 60ml.h-1
2.5g (5ml of 50%) MgSO4 IM into each buttock

10. Combined IM and IV regimen
Maintenance dose:
❑2.5 g (5ml-50%) MgSO4 IM 4 hourly using
alternate buttocks.
❑Continue for 24 hours after last convulsion or
delivery.

11. For Recurrent Seizures
❖Administer a further 2g MgSO4 IV.
❖Draw 4ml (2g) of 50% MgSO4 into 10ml syringe
and add 6ml 0.9% saline or 5% glucose.
➢inject over 2min (5ml.min-1)
❖If convulsions still continue, consider diazepam
5mg or lorazepam 1mg (IV or IM).
❖Be aware of risk of respiratory depression.
Combined IM and IV regimen

12. Intravenous IV regimen
Loading Dose:
oFill a paediatric infusion burette set with 22 ml 5%
dextrose, Add 8 ml of 50 % MgSO4 (4g) .
oAdminister the 20ml solution at 60ml/hr.
oSo the total dose will run over 30 min.

13. Maintenance Dose:
➢Fill a paediatric infusion burette with 112ml 5%
glucose, add 8ml 50% MgSO4 (4g) making 120ml
solution
✓Administer at 30ml.h-1, the total will run over 4
hours (1g.h-1)
➢Repeat the same management every 4hr for at
least 24 hours after the last convulsion or delivery
Intravenous IV regimen

14. For Recurrent Seizures
❖Administer a second loading dose or increase
the infusion to 1.5 or 2g.h-1
Intravenous IV regimen

15. Each ampoule: 1gm/10ml/over 5min
4 ampoule is 4 gm/40ml/over 20 min
10%MgSO4
1 gm (10ml) over 5 min /hourly
Or
4gm (40ml) infusion pump at
10ml/hour/4hour

16. ❖Vasodilatation effect:
❖• Feeling of warmth
❖• Lethargy
❖• Facial flushing
❖• hypotension
Other side effects:
❑Nausea, Vomiting, sweating
❑Diminished reflexes
❑Confusion
❑Intense thirst

17. MgSO4 Toxicity
➢Loss of patellar reflexes.
➢Respiratory paralysis.
➢Heart block.
➢Collapse of circulatory system.
➢Death.

18. Monitoring of patients on MgOS4
narrow therapeutic index (4-7mEq/l)
3 R parameters
Respiratory rate should be 16 cycle per
min or more

19. Monitoring of patients on MgOS4
Renal output during
treatment should be at least 30
ml/hr, half the dose of the mag
should be given if less than 100
ml /4 hours.
Reflex of deep tendon
should be present prior to
initiating therapy.

20. Monitoring of patients on MgOS4
Don’t forget fetal heart rate monitoring

21. MgSO4 Toxicity Antidote
❑Calcium gluconate: 1g (10ml of 10% IV
over 10 minutes. Repeat doses may be
necessary).
❑Calcium chloride can also be used
500 mg of 10% calcium chloride IV given
over 5-10 minutes.

23. The convulsions were controlled in
women. Recurrence of convulsions occurred in
25
MgSO
Conclusions:
safe and effective in controlling convulsions.
❑loadingdoseof4gmof50%IVMgSO4dilutedin20ccof
5%ofdextroseover10-15minutes,simultaneously4gm
ofMgSO4.Intramuscularly,2gmoneachbuttock..Ifthe
convulsionsarenotcontrolledevenafter30minutesof
givingsingledoseMgSO4,thenitisswitchedoverto
otherregimeslikelowdosemagnesiumsulphateand
Phenytoinregime.

24. ❑Theconvulsionswerecontrolledin75%of
women.Recurrenceofconvulsionsoccurredin
25%ofwomenafterreceivingthesingledose
MgSO4regime.
❑Conclusions:HencethesingledoseMgSO4is
safeandeffectiveincontrollingconvulsions.

25. Methods:Aprospectiverandomizedcontrolledstudyof
magnesiumsulphatetherapyinwomenwithseverepreeclampsia
wasconductedwith50patientseachincontrolandstudygroup.
Thecontrolgroupreceived24hoursofpostpartummagnesium
sulphatetherapyandthestudygroupreceivedfor4hoursorone
intramusculardoseinpostpartumperiod.
Conclusions:Inpatientswithseverepreeclampsiashorterduration(4
hoursoronedose)ofpostpartummagnesiumsulphatetherapy,isas
effectiveasthestandard24hoursofpostpartumtherapy.

27. Conclusion: Magnesium sulfate combined with Nifedipine in
the treatment of PIHS has a significant effect, which can
effectively control edema, blood pressure, proteinuria and
protect kidney. It is worth clinical promotion.

29. MgSO4
and
fetal neuroprotection

30. Despiteimprovementsinperinatalcare,pretermbirthstill
occursregularlyandtheassociatedbraininjuryand
adverseneurologicaloutcomesremainapersistent
challenge.AntenatalMgSO4administrationisan
interventionwithdemonstratedneuroprotectiveeffectsfor
pretermbirthsbefore32weeksofgestation.Owingtoits
biologicalproperties,includingitsactionasanN-methyl-d-
aspartatereceptorblockeranditsanti-inflammatory
effects,magnesiumsulphateisagoodcandidatefor
neuroprotection.

31. Inhypoxiamodels,includinghypoxia-ischemia,
inflammation,andexcitotoxicityinvariousspecies
(mice,rats,pigs),magnesium sulfate
preconditioningdecreasedtheinducedlesions’
sizesandinflammatorycytokinelevels,prevented
celldeath,andimprovedlong-termbehavior.In
humans,someobservationalstudieshave
demonstratedreducedrisksofcerebralpalsyafter
antenatalmagnesiumsulfatetherapy.

32. Conclusions:
MgSO4isasafeandeffectivemoleculethatplaysakeyrole
inprotectingtheimmaturebrain.Itisacost-effective,
feasible,efficient,andsafeinterventionthatcontributesto
theimprovementofneurologicaloutcomes.WhileMgSO4
hasnotbeenfoundtosignificantlyimprovecognitionand
behavioroutcomesatschoolage,itpreventscerebral
palsyat2years.Itsuseisnowrecommendedbyseveral
pediatricandobstetricalsocieties,aswellastheWorld
HealthOrganization(strongrecommendationbasedon
moderate-qualityevidence)forwomenatriskofimminent
pretermbirthbefore32WG.

33. Conclusions—Antenatal magnesium sulfate exposure is
independently associated with a decreased risk of MRI-
detected cerebellar hemorrhage in premature newborns,
which could explain some of the reported neuroprotective
effects of magnesium sulfate.

34. Conclusions
Antenatal magnesium sulphate given prior to preterm birth
for fetal neuroprotection prevents CP and reduces the
combined risk of fetal/infant death or CP. Benefit is seen
regardless of the reason for preterm birth, with similar
effects across a range of preterm gestational ages and
different treatment regimens. Widespread adoption
worldwide of this relatively inexpensive, easy-to-administer
treatment would lead to important global health benefits for
infants born preterm.

35. Low doses:
4 g loading dose ±1 g/h maintenance dose for 12 h,
16 g maximum total dose).
High doses:
6 g loading dose + 2 g/h maintenance dose during
24 h, maximum total dose received: 54 g).
.