Acid–Base/ABG Interpretation - NCLEX Rn

1. Identify the disorder: pH $7.50$, $PaCO_2$ $40$ mm Hg, $HCO_3^-$ $30$ mEq/L.

   Uncompensated metabolic alkalosis. High pH with normal PaCO2 and high HCO3- signifies excess base without ventilatory compensation.

2. What is the normal arterial $PaO_2$ range used for ABG interpretation?

   $80$ to $100$ mm Hg. This oxygen partial pressure ensures adequate oxygenation of hemoglobin in arterial blood for tissue delivery.

3. What term describes pH above $7.45$ on an ABG?

   Alkalemia. High pH indicates reduced hydrogen ions, resulting in alkaline blood that may affect neurological function.

4. What is the priority clinical response for metabolic alkalosis caused by prolonged vomiting or NG suction?

   Replace volume and chloride (isotonic saline; consider KCl). Fluid and electrolyte replacement corrects hypovolemia and chloride loss to normalize HCO3- levels.

5. What is the normal arterial blood pH range used for ABG interpretation?

   $7.35$ to $7.45$. This range maintains homeostasis by balancing hydrogen ion concentration in arterial blood for optimal cellular function.

6. Identify the disorder: pH $7.30$, $PaCO_2$ $40$ mm Hg, $HCO_3^-$ $18$ mEq/L.

   Uncompensated metabolic acidosis. Low pH with normal PaCO2 and low HCO3- reflects reduced buffering without respiratory adjustment.

7. What is the normal serum $HCO_3^-$ range used for ABG interpretation?

   $22$ to $26$ mEq/L. This bicarbonate level supports the body's buffering capacity against acid-base imbalances in metabolic processes.

8. What is the normal arterial oxygen saturation ($SaO_2$) range used for ABG interpretation?

   $95$% to $100$%. This saturation level indicates efficient oxygen binding to hemoglobin under normal physiological conditions.

9. Identify the disorder: pH $7.47$, $PaCO_2$ $48$ mm Hg, $HCO_3^-$ $34$ mEq/L.

   Partially compensated metabolic alkalosis. pH stays high with partial PaCO2 elevation not fully correcting high HCO3-.

10. Which change in ventilation decreases $PaCO_2$: increased or decreased alveolar ventilation?

    Increased alveolar ventilation decreases $PaCO_2$. Hyperventilation expels more CO2, reducing its partial pressure in arterial blood.

11. Identify the disorder: pH $7.30$, $PaCO_2$ $52$ mm Hg, $HCO_3^-$ $24$ mEq/L.

    Uncompensated respiratory acidosis. Low pH with elevated PaCO2 and normal HCO3- shows no renal compensation yet.

12. What is the normal arterial $PaCO_2$ range used for ABG interpretation?

    $35$ to $45$ mm Hg. This range reflects normal carbon dioxide partial pressure, indicating effective respiratory elimination of CO2.

13. Identify the disorder: pH $7.44$, $PaCO_2$ $30$ mm Hg, $HCO_3^-$ $20$ mEq/L.

    Fully compensated respiratory alkalosis. Normal pH results from reduced HCO3- balancing low PaCO2 in compensated states.

14. Which variable is the primary indicator of a metabolic acid–base disorder: $PaCO_2$ or $HCO_3^-$?

    $HCO_3^-$. Altered HCO3- levels disrupt buffering, causing pH changes in metabolic conditions.

15. What is the fastest body system to compensate for acid–base disturbances?

    Respiratory system (minutes). Lungs adjust CO2 levels rapidly via changes in ventilation to restore pH balance.

16. Which variable is the primary indicator of a respiratory acid–base disorder: $PaCO_2$ or $HCO_3^-$?

    $PaCO_2$. Elevated PaCO2 increases carbonic acid, lowering pH in respiratory disorders.

17. What term describes pH below $7.35$ on an ABG?

    Acidemia. Low pH signifies excess hydrogen ions, leading to acidic blood conditions requiring intervention.

18. Identify the disorder: pH $7.33$, $PaCO_2$ $50$ mm Hg, $HCO_3^-$ $30$ mEq/L.

    Partially compensated respiratory acidosis. pH remains low as HCO3- increase is insufficient to fully offset elevated PaCO2.

19. Identify the disorder: pH $7.36$, $PaCO_2$ $55$ mm Hg, $HCO_3^-$ $30$ mEq/L.

    Fully compensated respiratory acidosis. Normal pH achieved through elevated HCO3- counteracting high PaCO2 in chronic conditions.

20. What is the primary organ system responsible for metabolic compensation in acid–base disorders?

    Kidneys (hours to days). Renal system regulates bicarbonate reabsorption and hydrogen excretion over time to correct imbalances.

21. What is the priority clinical response for metabolic acidosis from diabetic ketoacidosis (DKA)?

    IV fluids and insulin; correct potassium as indicated. These interventions address hyperglycemia and ketosis, restoring metabolic balance in DKA.

22. What is the priority nursing action for acute respiratory acidosis due to hypoventilation?

    Improve ventilation (airway support, increase RR/TV). Enhancing gas exchange reverses CO2 retention to normalize pH in hypoventilating patients.

23. What is the normal base excess (base deficit) range used for ABG interpretation?

    $-2$ to $+2$ mEq/L. This value quantifies the metabolic component of acid-base balance, with zero indicating no excess or deficit.

24. Identify the disorder: pH $7.50$, $PaCO_2$ $30$ mm Hg, $HCO_3^-$ $24$ mEq/L.

    Uncompensated respiratory alkalosis. High pH with low PaCO2 and normal HCO3- indicates acute hyperventilation without compensation.

25. What is the priority nursing action for acute respiratory alkalosis caused by anxiety-driven hyperventilation?

    Reduce hyperventilation (coach slow breathing, treat anxiety). Calming techniques restore normal ventilation patterns to raise PaCO2 and correct alkalosis.

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