20.02 Magnesium Sulfate in Pregnancy

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  1. Used as an anticonvulsant in the pregnant patient
    1. Decreases risk of preeclampsia from turning into eclampsia
  2. Has been used as a tocolytic, but research shows there are other more effective options
  3. May suppress uterine contractions in the laboring patient

Nursing Points


  1. If given in an actively seizing patient, it is an emergency.  
    1. IV bolus given
    2. IM injections
    3. Then continuous IV infusion.
  2. Given in a preeclamptic patient to prevent seizure
    1. May be continued up to 24 hours postpartum


  1. Closely monitor mag levels
    1. Normal serum mag level is 1.5-2.5 mEq/L
    2. Target therapeutic range for this indication is 2.5-7.5 mEq/L
    3. Mag over 12 mEq/L can be fatal
  2. Closely monitor vitals per protocol/order set
    1. Hypotension
  3. Closely monitor deep tendon reflexes, respiratory function, heart monitor
    1. Patellar reflex = legs hanging over bed, use reflex hammer to hit the quadricep tendon, do it on both legs and rate.  Suppressed reflex can be a sign of impending respiratory arrest!
      1. 0 – no response
      2. 1 –  sluggish
      3. 2 – normal
      4. 3 – more brisk, slightly hyperactive
      5. 4 – brisk, hyperactive
    2. Call if RR is less than 12/min
    3. Check RR + reflex before IV doses.  Reflex MUST be present and RR greater than 16 before each IV dose (unless hospital policy reflects otherwise).
  4. Watch renal function on BMP or CMP and urinary output (med eliminated by kidneys

Therapeutic Management

  1. Titrating magnesium based on assessment findings
  2. Calcium gluconate easily accessible
    1. Antidote for Magsulfate

Nursing Concepts

  1. Pharmacology
  2. Lab values
  3. Safety

Patient Education

  1. Side effects
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