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SOURCE

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Source: Devlin JW, Matzke GR. Acid–base disorders. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 10th ed. New York, NY: McGraw-Hill; 2017. http://accesspharmacy.mhmedical.com/content.aspx?bookid=1861&sectionid=146062232. Accessed March 3, 2017.

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DEFINITION

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  • Acid–base disorder characterized by increased pH with an increased serum bicarbonate (HCO3) concentration.

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ETIOLOGY

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  • Clinical situations resulting in loss of H+ or gain of HCO3 and impairment of renal HCO3 excretion (Table 1)

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Table Graphic Jump Location
TABLE 1.Causes of Metabolic Alkalosis Differentiated on the Basis of Their Responsiveness to Sodium Chloride
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PATHOPHYSIOLOGY

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  • Initiated by increased pH and HCO3 that can result from:

    • Loss of H+ via gastrointestinal (GI) tract (eg, nasogastric suctioning, vomiting) or kidneys (eg, diuretics, Cushing syndrome)

    • Gain of bicarbonate (eg, administration of bicarbonate, acetate, lactate, or citrate)

  • Maintained by abnormal renal function that prevents kidneys from excreting excess bicarbonate.

  • Primary compensation: respiratory response to metabolic alkalosis is increased in PaCO2 by hypoventilation.

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RISK FACTORS

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  • Hospitalized patients with acid–base disturbances due to many factors, including (but not limited to):

    • Vomiting.

    • Nasogastric suctioning.

    • Secretory diarrhea.

    • Use of diuretics.

    • Administration of bicarbonate or infusion of organic anions metabolized to bicarbonate.

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CLINICAL PRESENTATION

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SIGNS AND SYMPTOMS
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  • Mild to moderate alkalosis: symptoms may be related to underlying disorder.

    • Muscle weakness with hypokalemia.

    • Postural dizziness with volume depletion.

  • Severe alkalemia (pH >7.60) can be associated with cardiac arrhythmias and neuromuscular irritability.

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DIAGNOSIS

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MEANS OF CONFIRMATION AND DIAGNOSIS
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  • Blood gases, serum electrolytes, medical history, and clinical condition are the primary tools for determining the cause of acid–base disorders and for designing therapy.

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LABORATORY TESTS
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  • Arterial blood gases (ABG) measured to determine oxygenation and acid–base status.

  • Metabolic panel.

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DESIRED OUTCOMES

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