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CMECNE

Eclampsia and Role of Magnesium Sulfate

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Learning Objectives and CME/Disclosure Information

This activity is intended for healthcare providers delivering care to women and their families.

After completing this activity, the participant should be better able to:

1. Restate the measures to prevent magnesium toxicity
2. Discuss measures to treat eclampsia

Estimated time to complete activity: 0.25 hours

Faculty:

Susan J. Gross, MD, FRCSC, FACOG, FACMG
President and CEO, The ObG Project

Disclosure of Conflicts of Interest

Postgraduate Institute for Medicine (PIM) requires instructors, planners, managers and other individuals who are in a position to control the content of this activity to disclose any real or apparent conflict of interest (COI) they may have as related to the content of this activity. All identified COI are thoroughly vetted and resolved according to PIM policy. PIM is committed to providing its learners with high quality CME activities and related materials that promote improvements or quality in healthcare and not a specific proprietary business interest of a commercial interest.

Faculty: Susan J. Gross, MD, receives consulting fees from Cradle Genomics, and has financial interest in The ObG Project, Inc.

Planners and Managers: The PIM planners and managers, Trace Hutchison, PharmD, Samantha Mattiucci, PharmD, CHCP, Judi Smelker-Mitchek, MBA, MSN, RN, and Jan Schultz, MSN, RN, CHCP have nothing to disclose.

Method of Participation and Request for Credit

Fees for participating and receiving CME credit for this activity are as posted on The ObG Project website. During the period from Dec 31 2017 through Dec 31 2021, participants must read the learning objectives and faculty disclosures and study the educational activity.

If you wish to receive acknowledgment for completing this activity, please complete the post-test and evaluation. Upon registering and successfully completing the post-test with a score of 100% and the activity evaluation, your certificate will be made available immediately.

For Pharmacists: Upon successfully completing the post-test with a score of 100% and the activity evaluation form, transcript information will be sent to the NABP CPE Monitor Service within 4 weeks.

Joint Accreditation Statement

In support of improving patient care, this activity has been planned and implemented by the Postgraduate Institute for Medicine and The ObG Project. Postgraduate Institute for Medicine is jointly accredited by the Accreditation Council for Continuing Medical Education (ACCME), the Accreditation Council for Pharmacy Education (ACPE), and the American Nurses Credentialing Center (ANCC), to provide continuing education for the healthcare team.

Physician Continuing Medical Education

Postgraduate Institute for Medicine designates this enduring material for a maximum of 0.25 AMA PRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Continuing Nursing Education

The maximum number of hours awarded for this Continuing Nursing Education activity is 0.2 contact hours.

Designated for 0.1 contact hours of pharmacotherapy credit for Advance Practice Registered Nurses.

Read Disclaimer & Fine Print

SUMMARY:  

Eclampsia is a severe, life-threatening manifestation of preeclampsia.  While long-term neurologic damage is rare, there is risk of maternal hypoxia and death. Most women will experience signs such as headaches or visual changes prior to a seizure.

Eclampsia

  • Defined as convulsions during pregnancy and/or postpartum
    • Tonic-clonic, focal, or multifocal
    • New onset
    • Unexplained by other neurologic pathology
  • Consider other underlying cerebral conditions when
    • Seizures occur 2 to 3 days postpartum
    • Patient on magnesium sulfate

Note: Not all women will demonstrate classic features of preeclampsia (hypertension, proteinuria)

Magnesium Sulfate – Seizure Prophylaxis  

  • Magnesium sulfate is the treatment of choice for seizure prophylaxis (ACOG recommended dosing) 
    • Loading dose of 4–6 g of magnesium sulfate administered per infusion pump over 20–30 minutes (i.e., slowly) followed by a maintenance dose of 1-2 g per hour as a continuous intravenous infusion  
    • Continue 24 hours postpartum
  • Recurrent seizures
    • Additional dose of 2-4 g can be infused over 5 minutes
  • Refractory seizures
    • Sodium amobarbital: 250 mg IV in 3 minutes
    • Thiopental or phenytoin: 1,250 mg IV at a rate of 50 mg/minute
    • Patient should be managed in ICU
    • Consider neuroimaging
  • IM option
    • 10 g initially as a loading dose (5 g IM in each buttock) followed by 5 g every 4 hours
    • Use if IV access limited
    • Mix with 1 mL xylocaine 2% to alleviate pain

Note: Magnesium sulfate should not be considered an antihypertensive agent

Magnesium Sulfate – When to Use

  • Severe features of preeclampsia 
    • Administer to all women 
  • No severe features of preeclampsia and systolic BP > 140 and < 160 mm Hg or diastolic BP > 90 and < 110 mm Hg 
    • There is no consensus on this matter as prophylaxis will reduce eclampsia but 1 in 100 to 129 women need to be treated and side effects (although not life threatening) will increase
    • ACOG states that the decision to use magnesium sulfate when severe features are not present should be the decision of the “physician or institution, considering patient values or preferences, and the unique risk-benefit trade-off of each strategy” 

Delivery and Postpartum 

  • Vaginal delivery
    • Continue infusion 24 hours postpartum
  • Cesarean
    • Begin infusion (if not yet running) before surgery and continue 24 hours postpartum
    • Discontinuing prior to operative vaginal birth or cesarean section to avoid uterine atony or anesthetic drug interactions is not recommended

 Prevention of Magnesium Sulfate toxicity 

  • Place Foley to monitor renal function (hourly output)  
  • Confirm normal serum creatinine  
  • Serial evaluation of patellar deep tendon reflexes 
  • Monitor respiratory rate  
  • Serum magnesium levels not routinely required
    • Monitor serum magnesium levels in setting of renal dysfunction and/or absence of patellar reflexes 
    • Maintain serum concentrations 5 to 9 mg/dL (4–7 mEq/L) range  
  • Predictive symptoms of magnesium sulfate toxicity  
    • Loss of deep tendon reflexes >9 mg/dL (greater than 7 mEq/L)  
    • Respiratory depression >12 mg/dL (greater than 10 mEq/L) 
    • Cardiac arrest >30 mg/dL (greater than 25 mEq/L) 

Pending toxicity 

  • Notify appropriate health care provider  
  • Discontinue magnesium infusion  
  • Administer supplemental oxygen  
  • Obtain a serum magnesium level  
  • Reverse magnesium 
    • 10 mL of 10% calcium gluconate IV (1 g total) and over 3 min (i.e., slowly) to avoid hypotension and/or bradycardia 
    • Calcium effect (competitively inhibits magnesium at neuromuscular junction) can wear off if magnesium level stays high 
    • Furosemide may help increase urinary excretion
  • Respiratory arrest: Intubation and assisted ventilation as indicated

Other Prophylactic Agents

  • Magnesium sulfate is superior to diazepam, phenytoin and lytic cocktail (chlorpromazine, promethazine, pethidine) in reducing significantly the risk of seizure recurrence  
    • Cochrane Review 2010: Magnesium sulfate reduced eclampsia compared to phenytoin (relative risk 0.08, 95% CI 0.01 to 0.60)   
  • Morbidity related to pneumonia, mechanical ventilation and admission to an intensive care unit are significantly reduced with the use of magnesium sulfate compared with phenytoin  
  • Magnesium sulfate does not cause maternal or newborn CNS depression 
    • Diazepam or lorazepam does stop or shorten seizures, but risk of maternal apnea and/or cardiac arrest
  • Diazepam and phenytoin may be considered if
    • Patient on these medications to treat epilepsy
    • Magnesium sulfate is contraindicated
      • Myasthenia gravis | Hypocalcemia | Moderate-to-severe renal failure | Cardiac ischemia | Heart block | Myocarditis

Learn More – Primary Sources:

National Partnership for Maternal Safety: Consensus Bundle on Severe Hypertension During Pregnancy and the Postpartum Period 

ACOG Practice Bulletin 222: Gestational Hypertension and Preeclampsia

ACOG Committee Opinion 767: Emergent Therapy for Acute-Onset, Severe Hypertension During Pregnancy and the Postpartum Period

Management of pre-eclampsia: issues for anaesthetists 

Acute pulmonary oedema in pregnant women 

Cochrane Review: Magnesium sulphate and other anticonvulsants for women with pre-eclampsia 

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Related ObG Topics:

Diagnosing Preeclampsia – Key Definitions and ACOG Guidelines
ACOG Guidance: Emergency Treatment for Severe Hypertension in Pregnancy

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Disclosure of Unlabeled Use

This educational activity may contain discussion of published and/or investigational uses of agents that are not indicated by the FDA. The planners of this activity do not recommend the use of any agent outside of the labeled indications.

The opinions expressed in the educational activity are those of the faculty and do not necessarily represent the views of the planners. Please refer to the official prescribing information for each product for discussion of approved indications, contraindications, and warnings.

Disclaimer

Participants have an implied responsibility to use the newly acquired information to enhance patient outcomes and their own professional development. The information
presented in this activity is not meant to serve as a guideline for patient management. Any procedures, medications, or other courses of diagnosis or treatment discussed or suggested in this activity should not be used by clinicians without evaluation of their patient’s conditions and possible contraindications and/or dangers in use, review of any applicable manufacturer’s product information, and comparison with recommendations of other authorities.

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