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Sim Corner
Magnesium Sulfate Toxicity
Presented by Carrie Johnson, MD
February 22, 2017
Case Summary:
31 y/o G1 P0 @37 weeks gestation who presented with complaints of severe headache and visual changes. Shortly after arrival in triage, the patient has a witnessed seizure. Per usual hospital protocol, 4gm IV magnesium sulfate loading dose followed by 2gm/hour IV maintenance dose are administered. Within the first hour after admission, the patient has another seizure and receives an additional 2gm IV bolus of magnesium sulfate.
Length: 10-15 minutes
Target group: Obstetricians, Midwives, Nurses
Possible Team Members for Scenario:
- Obstetrician
- Midwife or Obstetrician #2
- Anesthesia
- Primary RN
- Secondary RN
- Patient
- Family Member
General Learning Objectives:
- Communicate effectively with patient/family.
- Communicate effectively with team using crisis resource management skills.
Scenario Specific Goals:
- Identify & Declare Emergency
- Respiratory Distress
- Magnesium Toxicity
- Obtain staff and tools to optimize outcome.
- Implement TeamSTEPPS principles, focusing on leadership, SBAR, situation monitoring and shared mental model. TeamSTEPPSportal.org
- Inform Patient and family of treatment plan and likely outcome
Patient Case Summary:
Mrs. Maggie Magenta is a 31 y/o G1 admitted with the diagnosis of eclampsia. After 24 hours of labor she delivered vaginally without complications.
Additional Information:
- Past Medical/Surgical History: Negative
- Past Ob History: s/p SVD one hour ago
- Prenatal Care: uncomplicated
- Allergies: NKDA
- Medications:
- Magnesium Sulfate IV @ 2gm/hour
- Oxytocin IV 20mu/500 cc @ 80 cc/hour
- Labetalol for BP control
- Vital Signs
- afebrile, RR <10/minute, BP 100/50, pulse 60
Set Up
- Patient holding newborn in labor bed with IV in place, magnesium sulfate infusion and postpartum oxytocin running. Family member is at bedside.
Equipment:
- High or low fidelity mannequin
- Non-Rebreather O2 Mask
- Crash cart
- “Simulated” Medications, (Magnesium Sulfate, Calcium Gluconate)
- Stethoscope, reflex hammer
- Vital sign monitors,
Sequence of Events:
1. Family calls out that patient is having trouble breathing. (Patient and family member are in the room)
2. RN # 1
- Responds to family’s call for help
- Assesses patient
- Calls for help while remaining with patient
3. OB #1
- Receives SBAR
- Recognizes and announces emergency
- Requests additional staff
- Activates “OB Rapid Response” team
4. RN # 2 Arrives with OB #2
- Receive SBAR
- Prepare for CPR
- Bring crash cart in room
- Ensure magnesium sulfate is turned off
- Prepare/administer antidote, may need to repeat
5. Anesthesia
- Receive SBAR
- Assesses patient
- Initiate/Assist with CPR if necessary
Debrief:
- Review sequence of events.
- Review learning objectives.
- Review communication and teamwork skills.
- How did you feel? What went well?
- What would you change or do differently?
- What is your take home message?
Teaching Points:
Magnesium Toxicity Review:
Magnesium sulfate is considered a high alert medication, requiring pharmacy premixing and independent verification of the dose and rate prior to initiation. Most institutions have a nursing policy on administration to cover the specifics. But in general:
- Ensure compatibility with other IV fluids and medications.
- Administer as a premixed IV piggy back.
During administration the patient’s vital signs, DTRs and urine output should be monitored on a routine schedule. (This will vary by institution). Signs of magnesium sulfate toxicity: * Absent DTRs * RR < 12 * SOB * Respiratory Arrest * Chest Pain * Coma * Significant drop in BP *Urine Output < 30cc/hour * Signs of Fetal Distress
Magnesium Levels
|
mEq/L
|
mmol/L
|
Therapeutic Range
|
5-7
|
2.5-3.5
|
Loss of Deep Tendon Reflexes
|
10
|
> 5
|
Respiratory Failure
|
12-15
|
> 7.5
|
Cardiac Failure
|
25
|
> 12
|
Calcium gluconate is the antidote for magnesium sulfate toxicity. The standard is to administer 1 ampule IV over 10 minutes. A repeat dose may be given if needed.
1 ampule of Calcium Gluconate =
- 10mL of 10% solution
- 1 gram of Calcium
Patient needs to be on continuous ECG during administration.
Carrie Lynn Johnson, MD is an OBGYN Hospitalist who currently practices in Cleveland, OH area.
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