A 76-year-old male patient with 70 pack years of smoking and known to have osteoarthritis on chronic pain killers, presenting with bronchitis. Arterial blood gas and serum electrolytes are shown: pH 7.1 Serum Sodium 140 mmol/L PaCO2 50 mmHg Potassium 5 mmol/L PaO2 51 mmHg Chloride 102 mmol/L Bicarbonate 15 mmol/L What is the interpretation of the ABG?
سؤال مجاني 3 من 10 اليوم · اشترك وكمّل بدون حد
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الإجابة: C. Acute respiratory acidosis + Anion gap acidosis
AG = 140 − (102 + 15) = 23 (high) → anion-gap metabolic acidosis. Winter: expected PaCO2 = 1.5 × 15 + 8 = 30.5 ± 2, but actual is 50 → an added respiratory acidosis (heavy smoker with bronchitis; HCO3 is low, so the CO2 rise is acute). Options A/B ignore the CO2 retention, and E is wrong because PaCO2 is high, not low.
ليش كل خيار صح أو غلط
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A
ليش غلط
A simple metabolic acidosis needs PaCO2 within the Winter range (1.5 × 15 + 8 = 30.5 ± 2); his PaCO2 of 50 is far above it, so a respiratory acidosis is also present.
✓ Step Up To Medicine 6th Edition 2024 (Acid-base imbalance).pdf · p. 6 -
B
ليش غلط
The anion gap is 140 − (102 + 15) = 23, above the normal 5 to 15, so this is an anion-gap, not a normal-gap, acidosis.
✓ Step Up To Medicine 6th Edition 2024 (Acid-base imbalance).pdf · p. 2 -
C
ليش صح
The gap is high (23), and PaCO2 50 is higher than the Winter-predicted 30.5, which means metabolic acidosis with an added respiratory acidosis (underbreathing).
✓ Step Up To Medicine 6th Edition 2024 (Acid-base imbalance).pdf · p. 6 -
D
ليش غلط
The anion gap is 140 − (102 + 15) = 23, above the normal 5 to 15, so the metabolic component is not a normal-gap acidosis.
✓ Step Up To Medicine 6th Edition 2024 (Acid-base imbalance).pdf · p. 2 -
E
ليش غلط
Respiratory alkalosis would need an actual PaCO2 lower than the Winter-predicted value; his PaCO2 of 50 is higher.
✓ Step Up To Medicine 6th Edition 2024 (Acid-base imbalance).pdf · p. 6
- المصدر
- Step Up To Medicine 6th Edition 2024 (Acid-base imbalance).pdf · p. 6
Step Up To Medicine 6th Edition 2024 (Acid-base imbalance).pdf · p. 2 - المحاضرة
- Respiratory Failure & Acid–Base · Pulmonology · Module B
- ظهر في
- Respi bank