Asthma and COPD Q 10

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An unconscious client is admitted to an emergency room. Arterial blood gas measurements reveal a pH of 7.30, a low bicarbonate level, a normal carbon dioxide level, and a normal oxygen level. An elevated potassium level is also present. These results indicate the presence of:

  

     A. Metabolic acidosis

     B. Respiratory acidosis

     C. Combined respiratory and metabolic acidosis

     D. Over compensated respiratory acidosis

    

    

Correct Answer: A. Metabolic acidosis

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In an acidotic condition, the pH would be low, indicating the acidosis. In addition, a low bicarbonate level along with the pH would indicate a metabolic state. Metabolic acidosis is characterized by an increase in the hydrogen ion concentration in the systemic circulation resulting in a serum HCO3 less than 24 mEq/L. Metabolic acidosis is not a benign condition and signifies an underlying disorder that needs to be corrected to minimize morbidity and mortality.

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Option B: Respiratory acidosis typically occurs due to failure of ventilation and accumulation of carbon dioxide. The primary disturbance is an elevated arterial partial pressure of carbon dioxide (pCO2) and a decreased ratio of arterial bicarbonate to arterial pCO2, which results in a decrease in the pH of the blood.

Option C: An arterial blood gas (ABG) and serum bicarbonate level is necessary to evaluate patients with suspected respiratory acidosis. Other tests can be conducted to evaluate the underlying causes. In respiratory acidosis, the ABG will show an elevated PCO2 (>45 mmHg), elevated HCO3- (>30 mmHg), and decreased pH (<7.35).

Option D: To compensate for the disturbance in the balance between carbon dioxide and bicarbonate (HCO3-), the kidneys begin to excrete more acid in the forms of hydrogen and ammonium and reabsorb more base in the form of bicarbonate. This compensation helps to normalize the pH.

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