Critical care clinics
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Critical care clinics · Jan 2001
ReviewManagement of hypothyroidism and hyperthyroidism in the intensive care unit.
Thyroid storm and myxedema coma are uncommon problems in the ICU, but both usually present with typical findings, and when recognized early, are treatable. Thus, rapid recognition with early institution of therapy may be life saving. It is always important to search diligently to determine the underlying cause of the decompensation and to treat that aggressively.
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Adequate magnesium stores are vitally important for life. Critically ill patients will almost always have diminished levels of circulating magnesium, and this predisposes them to a variety of adverse effects, some life threatening. The causes of hypomagnesemia are many and varied, but in the critically ill, losses from the kidneys, often secondary to medications and from the gastrointestinal (GI) tract, predominate. ⋯ Magnesium is clearly useful for certain types of ventricular tachycardia, and probably assists in the treatment of several types of supraventricular tachycardia. Its role in acute myocardial ischemia is less certain, although there is no benefit once reperfusion therapy has already been carried out. Finally, the role of magnesium in the treatment of acute cerebral insults is an exciting area of active investigation with initial studies suggesting much promise.
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Adrenal insufficiency is a common and underdiagnosed disorder that develops in critically ill patients. Most forms are acquired and will resolve with treatment of the underlying disease. Hypotension that is refractory to fluids and requires vasopressors is the most common presentation of adrenal insufficiency in the ICU. ⋯ Diagnosis usually can be made on the basis of a stress cortisol level. Occasionally, when the level of stress is uncertain, the low-dose corticotropin stimulation test will be required for definitive diagnosis. A therapeutic trial with hydrocortisone should be started in patients with suspected adrenal insufficiency pending results of diagnostic testing.
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Stress hyperglycemia is common and likely to be associated with at least some of the same complications as hyperglycemia in true diabetes mellitus, such as poor wound healing and a higher infection rate. The predominant cause is the intense counterregulatory hormone and cytokine responses of critical illness, often compounded by excessive dextrose administration, usually as TPN. Although randomized data suggesting benefit of controlling hyperglycemia in hospitalized patients are paltry, prospective controlled trials are feasible and should be initiated. In the interim, the practice at the authors' institution is to use insulin to lower plasma glucose concentrations to a safe range of 150 mg/dL to 200 mg/dL in all patients.
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The hormonal alterations observed during critical illness are extremely diverse, being both adaptive and maladaptive. Central and peripheral mechanisms are at play depending on the duration and severity of the insult. ⋯ Whether the physiology of the wound can be manipulated to heighten organism resistance to stress either emergently or electively is theoretically appealing and supported by animal models. Currently, however, it remains a subject of ongoing controversy and research.