Magnesium sulfate during pregnancy

1. Magnesium Sulfate
In
Pregnancy
Nurses' Manual 1

2. Introduction
Magnesium sulfate is the drug of choice for preventing and treating
convulsion in severe pre-eclampsia and eclampsia.
Nurses' Manual 2

3. Facts On Magnesium Sulfate
• AKA Epsom salt
• 1gm of salt= 98mg elements of magnesium
• Is an inorganic salt with formula MgSO4
• Is in the WHO model list of Essential Medicine
• Highly water soluble
• Solubility inhibited by lipids
Nurses' Manual 3

4. Physiological Roles
• Acts as mediator for Na⁺/K⁺-ATPase system.
• Helps in oxidative phosphorylation, glucose utilization and protein
synthesis
• Generation of cAMP via adenyl cyclase.
• Control release and action of parathyroid hormone thus regulates Ca2+
metabolism
• Synthesis of DNA,RNA and protein
Nurses' Manual 4

5. Cardiovascular Effects
• Direct depressant on myocardial and vascular smooth muscle.
• Reduce systolic BP but no changes in DBP.
• Inhibit release of catecholamines from adrenal medulla.
• Act as anti arrhythmic and slows HR.
• Reduce cardiac output and vascular tone causing hypotension
Nurses' Manual 5

6. Nervous System Effects
• Reduce release of Ach at Neuromuscular junction by antagonizing Ca2+
ions.
• Reduce excitability of nerves.
• Act as an anti convulsant by blocking Ca2+ channel.
Nurses' Manual 6

7. Routes
• Iv
• Im as anticonvulsants
• Orally -as laxative
Nurses' Manual 7

8. Uses In Gynae/Obs
• Severe pre-eclampsia
• Eclampsia
• Preterm labour (as tocolytic agent)
• Prevention of cerebral palsy in preterm babies (due to its
neuroprotective action)
Nurses' Manual 8

9. Other uses
• In hypomagnesia
• Treatment of severe asthma exacerbation
• Constipation
• Barium poisoning
Nurses' Manual 9

10. Mode Of Action
• Decrease acetylcholine(Ach) release from nerve endings and reduce
motor end plate sensitivity to Ach.
• Blocks calcium channel
• Cause vasodilation, increase cerebral, uterine and renal blood flow
Nurses' Manual 10

11. Pharmacology
For anticonvulsant action
• Onset: IV immediate/ IM 1 hour
• Protein bound 30%
• Excretion: via urine
Nurses' Manual 11

12. Advantages of MgSO4
• Relatively safe drug and DOC
• Can be given IV/IM
• In appropriate dose, it doesn’t affect fetus
• In appropriate dose, it doesn’t sedate patient
• Inexpensive and is on essential drug list
• It is metabolized by kidney, hence doesn’t cause hepatic problems
that are often associated with severe pre-eclampsia
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13. Disadvantages
• Respiratory depression
• Respiratory arrest
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14. Administration
• MgSO4 is the drug of choice in all circumstances – it should
always be available at both health centre and hospital levels
• Give diazepam 10 mg (2 ml) over 2 minutes if
• There is MgSO4 toxicity
• MgSO4 is not available
Nurses' Manual 14

15. In Health Centre
Loading dose:
• Wash hand properly and dry well
• Tell women that she may feel warmth while the medicine is given.
Nurses' Manual 15

16. Give 4 g of 20% MgSO4 solution
IV slowly over 5-15 min.
• Take one 20ml sterile syringe
• Draw 8ml(4g) of MgSO4 50% into
syringe.
• Add/dissolve with 12ml of sterile
water for injection to make a
solution of 20%.
• Observe for any complications
while giving.
Nurses' Manual 16

17. • Follow promptly with 10g of 50% mgso4
• Give 5 g in each buttock as deep IM with 1ml
of 2% lignocaine.
• Take two 10 ml syringe
• Draw 5g of MgSO4 (50%) i.e. 10ml in each
syringe with 1ml of 2% lignocaine.
• Inject 1st syringe by deep IM injection into 1
buttock(5g of mgso4) .
• Inject second syringe by deep IM into another
buttock(5g mgso4)
Nurses' Manual 17

18. • Place needle and syringe in puncture proof container
• Remove gloves and discard properly
• Wash hand thoroughly with soap and water
• If convulsant reoccur after 15minutes, give 2g of mgso4(4ml) IV over
five minutes.
• Rationale:
Pre-eclampsia can quickly develop into eclampsia
Shaking during transport is a convulsion stimulus
Nurses' Manual 18

19. In Hospitals
• Loading dose-same as above
• Maintenance dose:
5 g of Mgso4 with 1ml of 2%
lidocaine in the same syringe by deep
IM every 4 hrs. in alternate buttock
If no signs of toxicity, give next IM dose
after 4 hours.
Nurses' Manual 19

20. • Maintaining IV dose:
Continue treatment for 24 hours after childbirth or the
last convulsion, whichever occur last.
Nurses' Manual 20

21. TIPS
20% MgSO4 Solution
Recommended for IV injection
50% MgSO4 Solution
Recommended for IM injection
21Nurses' Manual

22. Monitoring Signs Of Toxicity
• Count Respiration rate for 1 minute every hour, should be ≥ 16
• Check Patellar reflex q. 4 hours, should be present
• Measure Urine output, should be ≥30ml/hr.
• Measure BP
• Measure serum magnesium level (1.7 to 2.2 mg/dL)
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23. MgSO4 toxicity
Nurses' Manual 23
BURP
BP
Urine output
Respiration rate
Patellar reflex absent

24. NOTE
Repeat dose of MgSO4 should be withheld or delayed if Signs of
toxicity are seen.
Nurses' Manual 24

25. Antidote
• Keep antidote ready.
• In case of respiratory arrest:
Assist ventilation(bag & mask ,anesthesia ,
intubation)
Give Calcium Gluconate 1g(10ml of 10%
solution) IV slowly over 3 minutes, until
respiration begins to counteract effects of
MgSO4
Nurses' Manual 25

26. Side Effects
It is relatively safe drug
• Diminished knee jerk
• Respiratory failure
• Flushing
• Sweating
• Hypotension
• GI disturbances
• Hypothermia
• Circulatory collapse, cardiac and CNS depression
Nurses' Manual 26

27. Contraindications of MgSO4
• Renal function impairment
• Heart block, myocardial damage
• Myasthenia gravis
• Drug interaction: with Nifedipine
Nurses' Manual 27

28. Nursing Consideration
• Assess vital signs with in 15min after IV dose
• Monitor serum magnesium level if used during labor, contractions and
intensity
• Assess urine output and notify physician if ≤30ml/hour
• Examine patellar reflex.
• Use seizure precautions
Nurses' Manual 28

29. Attention !!!
• Administration can be very painful, so administer it deep IM in
gluteal region using 3-inch-long 20G needle
• 1ml of 2% xylocaine is added to reduce pain
• Each injection should be preceded by aspiration to ensure tip is not in
blood vessel.
• Massaging buttocks after injection will help disperse magnesium in
tissue.
Nurses' Manual 29

30. 1. Is Magnesium sulphate dangerous?
• After administration, about 30% of plasma magnesium is protein
bound.
• Magnesium is almost exclusively excreted in the urine, with 90% of the
dose excreted during the first 24 hours after an intravenous infusion of
MgSO4. Hence the need to monitor urine output in patients receiving
the drug.
30Nurses' Manual

31. 2. Is Magnesium sulphate dangerous in
pregnancy ?
• MgSO4 toxicity is rare when it is carefully administered and
monitored.
• Studies show that the benefits of MgSO4 may outweigh the risks to
her and to her baby.
The answer to this question is NO!
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32. Why is Eclampsia still a major cause of
maternal deaths in Nepal?
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33. Nurses' Manual 33