SODIUM CHLORIDE 20%

SODIUM CHLORIDE 20%
(sod'i-um)
Sodium Chloride 20%
Classifications: abortifacient;
Therapeutic: abortifacient

Pregnancy Category: X

Availability

20% solution

Action

Hypertonic saline instillation into the amniotic sac induces abortion and fetal death. Mechanism is unclear, but abortifacient activity may be a response to prostaglandins released by hypertonic NaCl-damaged cells.

Therapeutic Effect

Uterine contractions induced by the saline solution are sufficient to cause evacuation of fetus and placenta; however, in 25–40% of the patients, abortion may be incomplete.

Uses

To induce abortion late in the second trimester of pregnancy. Oxytocin may be used as an adjunct (concurrent) uterine stimulant.

Contraindications

Pregnancy (category X) of less than 15 wk or more than 24 wk; prior uterine surgery (including cervix), pelvic adhesions; sickle cell disease, diabetes mellitus; increased intraamniotic pressure (as in contracting or hypertonic uterus); poor health, blood disorders, coagulation factor deficiencies.

Cautious Use

Malignant hypertension, cardiovascular and kidney disease, thrombocytopenia, fibrinolytic defects.

Route & Dosage

Abortion Induction
Adult: Instillation Intraamniotic with 20% solution in volumes equal to amount of amniotic fluid removed (max: 200–250 mL) administered slowly over 20–30 min; repeat in 48 h if uterine contractility, cervical effacement, or cervical dilation is inadequate or if labor has not begun

Administration

Instillation
  • Prepare skin as for surgery prior to procedure. Withdraw about 1 mL of amniotic fluid by transabdominal tap to confirm location of needle (amniotic fluid has pH 7.4 and ability to fern). If blood is present or if no amniotic fluid is withdrawn, needle is repositioned. Some clinicians then remove all amniotic fluid (30–250 mL); others wait until NaCl instillation.
  • Instill NaCl through 3-way stopcock with needle and polyethylene catheter inserted into amniotic cavity.
  • Administer IV infusion of dilute solution of oxytocin within 1–2 h after hypertonic solution instillation and after uterine response to the solution has ceased at rate, 20–100 mU/min. Oxytocin action as an adjunctive uterine stimulant shortens the abortifacient-abortion interval.
  • Be prepared to treat extraamniotic injection: Stop procedure promptly. Start IV infusion of D5W; additional support for hypernatremic shock.

Adverse Effects (≥1%)

Hematologic: (Within 12–24 h of instillation) Coagulation changes; increased plasma volume, fibrin levels, thrombin, prothrombin, and partial thromboplastin times; mild self-limiting form of disseminated intravascular coagulation. Metabolic: Ascites, hypervolemia, circulation failure, uterine necrosis, severe electrolyte disturbances. Urogenital: Cervical lacerations and perforation, uterine rupture, retained placenta, hemorrhagic fever, infection, sepsis. Respiratory: Pulmonary embolism. Body as a Whole: Fever, flushing, cortical necrosis of kidneys.

Interactions

Drug: Indomethacin may delay onset time of abortion; terbutaline, ritodrine inhibit uterine activity induced by hypertonic NaCl.

Pharmacokinetics

Absorption: Some drug diffuses into maternal blood. Onset: Within 51 h. Distribution: Sodium concentration in amniotic fluid must be at least 2.2 mEq/mL to induce abortion; most of drug concentrates in decidua and fetal part of placenta.

Nursing Implications

Assessment & Drug Effects

  • Observe patient for at least 30 min after instillation procedure. Be available for complaints and to check vital signs: temperature, pulse rate, BP.
  • Note: Intraamniotic instillation is a painless procedure. No anesthetic or sedative is needed or given so that patient is able to report early signs of extraamniotic injection including mental confusion, hypotension, severe headache, vague distress, extreme nervousness, pain, sensation of heat, thirst, fingertip numbness, dry mouth, salty taste, tinnitus.
  • Suspect accidental intraperitoneal, intravascular, or myometrial injection if patient begins vomiting. Cardiovascular collapse, seizures, and maternal death may follow.

Patient & Family Education

  • Drink at least 2 L water on day of procedure to promote NaCl excretion.
  • Return promptly to treatment center with onset of labor, signs of rupture of fetal membrane, vaginal bleeding, fever, or any other untoward symptom.
  • Return to physician for evaluation and treatment if labor has not begun within 48 h of hypertonic saline instillation.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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