Myxedema

WHEN DOROTHY SMITH, 68, ARRIVES IN THE EMERGENCY department, she's unconscious and her face is puffy and masklike. Her skin is slightly yellow, and her abdomen is distended. The paramedics have started an intravenous (I.V.) rapid infusion of 0.9% sodium chloride solution. They've also placed her on 10 liters of oxygen via non-rebreather mask and attached her to a cardiac monitor, which shows sinus bradycardia. Having checked her blood glucose, they report mild hypoglycemia.

What's the sittion?

Mrs. Smith is unresponsive to verbal or painful stimuli. Her vital signs are: BP, 90/50; heart rate, 52; respirations, 12; and temperature, 96.7o F (35.9o C). Her skin is cool, and you notice generalized nonpitting edema, scant body hair, and a thyroidectomy scar.

You attach Mrs. Smith to a cardiac monitor and a pulse oximeter; her Spo2 is 89%. Auscultation reveals decreased breath sounds and hypoactive bowel sounds.

Mr. Smith says that he found his wife unconscious when he came home from work. He also informs you that Mrs. Smith has high BP and under vent a thyroidectomy a year ago. She's taking 100 mcg of oral levothyroxine (Synthroid) daily for thyroid hormone replacement, but her prescription recently ran out and she hasn't refilled it, her husband says. For several months, she's complained of increasing weakness, fatigue, and weight gain. She's had a cold with a productive cough for 2 weeks.

What's your assessment?

Based on Mrs. Smith's history and her hypoactive state, you suspect myxedema coma, a state of profound hypothyroidism precipitated by a stressor-in this case, an upper respiratory infection. Hypothyroidism causes progressive slowing of all body functions.

What must you do immediately?

Your first priority is to maintain a patent airway and correct Mrs. Smith's hypoventilation. Prepare her for immediate intubation and mechanical ventilation. After intubation, auscultate for equal breath sounds and tape the tube securely.

Arrange for a portable chest X-ray and an electrocardiogram. Insert a urinary catheter and nasogastric tube.

Start a second I.V. line and obtain a blood sample for lab work, including thyroid hormone levels. Also obtain urine and sputum samples for lab work.

Administer the first dose of a broadspectrum antibiotic, as ordered, to cover any underlying infection.

Because Mrs. Smith is exhibiting signs of clinical shock, you'll use the second I.V. line to begin a rapid infusion of isotonic fluid and vasopressors, as ordered. Apply blankets to help rewarm her.

Myxedema coma is treated based on clinical presentation and medical history. Keep Mrs. Smith on the cardiac monitor and administer an infusion of 300 to 500 mcg of I.V levothyroxine over 2 minutes. The onset of action for intravenous levothyroxine is 6 hours and the drug is fully effective in 24 hours. t bdd be dm bXn The lab results reveal an abnormally high level of thyroidstimulating hormone and an abnormally low thyroxine level, confirming the diagnosis of hypothyroidism and subsequent myxedema coma. Mrs. Smith also has mild hyponatremia and hypoglycemia, so administer I.V. fluids containing dextrose and sodium.

Seven hours after the thyroid hormone infusion began, Mrs. Smith is responding to verbal stimuli, her vital signs are within normal limits, her Spo2 is 97%, and she's extubated.

Prepare Mrs. Smith for transfer to the intensive care unit, where she'll receive 50 to 100 mcg of levothyroxine daily. Before discharge, she'll be taught about the importance of taking thyroid replacement therapy for the rest of her life and taught to recognize signs and symptoms of hypothyroidism. Advise her to wear a medical-alert bracelet.

BY JUDY YOUNG, RN, CCRN, BSN

Emergency Department St. Mary Medical Center Langhorne, Pa.

Copyright Springhouse Corporation Jan 1999
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