Central Queensland University: Magnesium Sulphate and Preeclampsia

This report delves into the use of magnesium sulphate in the pre-hospital management of preeclampsia and eclampsia, focusing on the Queensland Health guidelines. It defines preeclampsia, outlines the pharmacological actions of magnesium sulphate, and details administration routes, dosages (IM and IV), and current guidelines. The report discusses treatment criteria, including dissemination and excretion, and emphasizes the importance of monitoring for toxicity, including signs, symptoms, and antidotes. It further explores the effects of magnesium sulphate on the nervous and cardio-respiratory systems, the fetus, and contractions, while also addressing interactions with other drugs like nifedipine. The report highlights the objectives of preeclampsia management, the protocols for eclampsia, and the implications of introducing new pharmacology into paramedic practice. References and assignment briefs are included to provide a comprehensive overview of the topic.

MAGNESIUM SULPHATE AND THE MANAGEMENT OF
PREECLAMPSIA/ECLAMPSIA IN THE PREHOSPITAL SETTING
Definition
Preeclampsia is a hypertensive disorder that occurs in pregnant women between 20 weeks of gestation and thirty days postpartum. The diagnosis is determined by a
systolic blood pressure above 140mmHg and a diastolic pressure above 90mmHG (Gordon et al., 2014).Pharmacological Actions of Magnesium Sulphate
Administration
Most preferred routes are an intramuscular injection(IM) and intravenous infusion (IV).
Start dose- 4g in 20% of Normal saline solution followed by 5g in 50% solution intramuscular
injection on each buttock.
In IM injection, a maintenance dose of 5g in 50% solution is usually prescribed four hourly.
For IV injection, after a loading dose of 4g, a maintenance dose of 1g is administered hourly after
the last episode of seizure(Duhig and Shennan, 2015).
The dose can be altered 2-4g depending on the mother’s weight or status change of the condition
Dissemination and plasma amounts
A loading dose of 4g immediately rises in plasma levels for about 3.0mmol/l and then reduces to
up to 1.5mmol/l in an hour (Peres et al., 2018)
A dosage of 1g/h reaches 1.7mmol/l after a day, at 2g/h go up to 2.2mmol/l in six hours.
Excretion
Half of the magnesium sulfate is excreted in four hours after administration.
Magnesium sulfate Considered as among the first cleaning drug
Take caution in cardiac and respiratory failure(Duhig et al., 2018).
Toxicity
Toxicity is experienced when plasma levels are over 5mmol/l
Signs and symptoms of toxicity include respiratory distress, nausea, tendon flexes, malaise, and
blurred vision.
If the plasma levels of magnesium sulfate exceed up to 6.3 -7.1, there is possible muscle paralysis
and cardiac arrest.
A dose of 1g magnesium gluconate is used to correct toxicity(Jana et al., 2018).
Effect on the nervous system
Can work at the peripheral neuromuscular junction with less significant effects or at central
nervous system blocking the neural junctions(Duhig and Shennan, 2015)
In preeclampsia, Magnesium sulfate acts directly on CNS causing the release of excitatory
transmitter(acetylcholine) leading to reductions of convulsions(Duhig and Shennan, 2015).
Effect on the cardio-respiratory system
Leads to a drop in blood pressure which may lead to hypotension in high dosages
Due to its fast clearing, the above effect is rare to manifest clinically(Peres et al., 2018).
Weakens the heart and lower heart rate since it has inotropic effects.
Respiratory rates gradually drop with the use of magnesium sulfate(Peres et al., 2018)
Effect on fetus
Really crosses the placenta creating an equilibrium
Long periods of administration can raise the levels of magnesium in amniotic fluid.
After birth, magnesium in breast milk gradually drops in 24 hours (Duhig and Shennan, 2015
No risk is usually associated as healthy babies can easily create magnesium
Effects on Contractions
Magnesium sulfate neither long labor or increase risks for undergoing a cesarean section. (Peres et
al., 2018)
Interaction with other drugs(nifedipine)
Nifedipine is normally used along magnesium sulfate to control hypertension.
Major side effects of their interaction are hypotension thus increasing magnesium sulfate toxicity
Current guideline and comparison to contemporary evidence
The basic objective in preeclampsia is to control blood pressure and prevent the
development of eclampsia (Queensland Ambulance Service, 2019).
If eclampsia occurs, the goals change to seizures management and hypoxia
prevention in both mother and child (Queensland Ambulance Service, 2019).
Treatment Criteria
Infuse IV fluids and magnesium sulfate in
patients with eclampsia (Queensland
Ambulance Service, 2019).
Magnesium sulfate is the first line of
treatment where there are high risks for
eclampsia followed by midazolam as a
second-line treatment.
With the presence of symptoms, take the
patient to the hospital as soon as possible
Make a proper diagnosis of eclampsia as
some conditions like epilepsy may present
with similar symptoms (Queensland
Ambulance Service, 2019).
A 20mmol dose should be infused in a
30ml syringe to attain the required
concentration and then administered over
20 minutes
Only a loading dose should be given, then
the patient should be taken to the hospital
for maintenance doses and further review.
Implications of introducing
new pharmacology into
paramedic practice
Always check the blood pressure
before treatment, treat only when
it above 140/90 mmHg
It is important to initiate
midazolam in refractive
seizure thus care should be
taken during the assessment
Consider drug interaction and
adverse effects while using
other blood pressure drugs
Drugs interaction may be
References
DUHIG, K., VANDERMOLEN, B. &
SHENNAN, A. 2018. Recent advances
in the diagnosis and management of
pre-eclampsia. F1000Res, 7, 242.
DUHIG, K. E. & SHENNAN, A. H. 2015.
Recent advances in the diagnosis
and management of pre-eclampsia.
F1000Prime Rep, 7, 24.
GORDON, R., MAGEE, L. A., PAYNE, B.,
FIROZ, T., SAWCHUCK, D., TU, D.,
VIDLER, M., DE SILVA, D. & VON
DADELSZEN, P. 2014. Magnesium
sulphate for the management of
preeclampsia and eclampsia in low
and middle income countries: a
systematic review of tested dosing
regimens. J Obstet Gynaecol Can, 36,
154-163.
JANA, N., BARIK, S. & ARORA, N.
2018. Re: Clinical practice patterns
on the use of magnesium sulphate
for treatment of pre-eclampsia and
eclampsia: a multi-country survey:
Magnesium sulphate regimens for
eclampsia: should we adopt same
'gold standard' for all women? BJOG,
125, 909.
PERES, G. M., MARIANA, M. &
CAIRRAO, E. 2018. Pre-Eclampsia and
Signs and Symptoms
Headache
Visual problems
Vomiting or nausea
High blood pressure, acute
pulmonary edema
Jaundice