رجل عمره ٦٣ سنة عنده مرض كلى مزمن متقدم ولم يبدأ الغسيل، يشتكي غثياناً وفقدان شهية وحكة شديدة، وصار نعساناً. التنفس عميق وسريع ٢٨، والضغط ١٦٨/٩٦. غاز الدم: pH ٧٫٢١، HCO3 ١٢، PaCO2 ٢٨. اليوريا مرتفعة جداً. ما التفسير الأدق للتنفس؟

A 63-year-old man with advanced CKD not yet on dialysis has nausea, anorexia, severe itching and drowsiness. Breathing is deep and rapid at 28; BP 168/96. ABG: pH 7.21, HCO3 12, PaCO2 28. Urea is very high. What best explains his breathing?

1. An acute asthma attack from fluid in the lungs
2. Respiratory acidosis from weak breathing muscles
3. Respiratory compensation for metabolic acidosis from kidney failure
4. Primary respiratory alkalosis from anxiety about his illness

Answer: C) Respiratory compensation for metabolic acidosis from kidney failure. Failing kidneys cannot excrete acid or retain bicarbonate, causing metabolic acidosis; the lungs compensate with deep rapid (Kussmaul) breathing. With uraemic symptoms, these are indications to start dialysis.