A 50-year-old man was brought to ER. Blood pressure is 90/50 mmHg, heart rate 120 beats/min, respiratory rate 35/min, and his temperature is 40C. He was found to have left foot cellulitis. ABG: PH 7.2 (7.35-7.45), PCO2 25 mmHg (35-45), HCO3 10 mEq/L (22-26), Na 148 mEq/L (135-145), K 2.5 mEq/L (3.5-5), Cl 103 (96- 106) mEq/L. What is the acid-base status?
سؤال مجاني 1 من 10 اليوم · اشترك وكمّل بدون حد
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الإجابة والشرح
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الإجابة: D. Metabolic acidosis with partial respiratory compensation
pH 7.2 with HCO3 10 → primary metabolic acidosis (AG = 148 − 113 = 35, likely lactic from septic shock). PCO2 25 is the respiratory response: Winter 1.5 × 10 + 8 = 23 ± 2, so it is appropriate, but the pH is still low → partially compensated metabolic acidosis. Low PCO2 here is compensation, not a primary respiratory alkalosis (C).
ليش كل خيار صح أو غلط
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A
ليش غلط
Alkalosis needs a high pH (> 7.45); this patient's pH is 7.2, which is acidosis.
✓ ABG & A-a gradient.pdf · p. 1 -
B
ليش غلط
Respiratory acidosis comes from hypoventilation with a high PCO2; this patient breathes at 35/min with a low PCO2 (25) and a low HCO3.
✓ ABG⭐️⭐️.pdf · p. 5 -
C
ليش غلط
With metabolic acidosis the PaCO2 should fall: this low PCO2 is the normal respiratory compensation, not a primary respiratory alkalosis (the pH is low).
✓ Step Up To Medicine 6th Edition 2024 (Acid-base imbalance).pdf · p. 6 -
D
ليش صح
Low pH with low HCO3 (10) is metabolic acidosis, and the low PCO2 (25) is its respiratory compensation; a similar lecture case (PCO2 18, HCO3 10) is labelled partially compensated metabolic acidosis.
✓ ABG⭐️⭐️.pdf · p. 5
- المصدر
- ABG⭐️⭐️.pdf · p. 5
Step Up To Medicine 6th Edition 2024 (Acid-base imbalance).pdf · p. 6 - المحاضرة
- Respiratory Failure & Acid–Base · Pulmonology · Module B
- ظهر في
- Respi bank