There are no prospective studies on the optimum therapy for patients in myxedema coma; therefore, treatment recommendations are not uniform. However, initial therapy is directed toward stabilization. Patients may require endotracheal intubation and mechanical ventilation for airway protection and correction of hypoventilation, hypercapnia, and hypoxia. Indications for airway intervention are the same as for other conditions (see Chap 15, "Tracheal Intubation and
Mechanical Ventilation"). Correction of hypothermia is directed toward decreasing further heat loss. Cautious use of gentle passive external rewarming should be initiated but care should be taken to avoid hypotension from reversal of a patient's hypothermic vasoconstriction.
Specific therapy includes intravenous levothyroxine, which is recommended by most authors.11 An initial intravenous bolus of levothyroxine (iT§ble..20.Z.:.§) is administered, followed by a reduced daily dose until the patient can take oral medication. This has the advantage of repleting the T 4 pool and allowing the hormone to enter tissues slowly. Other authors suggest that there may be decreased T4 to T3 conversion and subsequently recommend T3 as the initial replacement hormone.
TABLE 207-6 Treatment of Myxedema Coma
Routine administration of glucocorticoid is recommended to avoid the potential of precipitating adrenal crisis in patients with unrecognized adrenal insufficiency or hypothyroidism secondary to hypopituitarism. If possible, a baseline cortisol level should be drawn prior to initiating therapy. Correction of hyponatremia is by means of fluid restriction. Severe hyponatremia has been successfully treated with hypertonic saline administration (see Chap. 23, "Fluids and Electrolyte Problems").
A search for a precipitating etiology must be initiated and aggressively treated. Infection is a common precipitant of myxedema coma. If possible, appropriate cultures should be obtained prior to initiating empiric antibiotic therapy.
All patients with a suspected diagnosis of myxedema coma should be admitted to an appropriately monitored inpatient bed for further evaluation and treatment. CHAPTER REFERENCES
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