Final Exam Suite

Cram Sheet

Here is one page with the things you need most. Lab patterns, ABG rules, the look-alike pairs, and the findings that mean act now. It uses the same content as the drills.

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ABG interpretation

pHCO₂HCO₃Interpretation
↓↑nRespiratory acidosis, uncompensated (acute)
↓↑↑Respiratory acidosis, partially compensated
n <7.40↑↑Respiratory acidosis, fully compensated (long-standing, as in COPD)
↑↓nRespiratory alkalosis (anxiety, pain, fever, early PE)
↓n↓Metabolic acidosis (DKA, shock, renal failure, diarrhea)
↓↓↓Metabolic acidosis, compensating (Kussmaul)
↑n↑Metabolic alkalosis (vomiting, NG suction, diuretics)
ROME — Respiratory Opposite, Metabolic Equal.
The problem is the CO₂ when it moved opposite the pH, and the HCO₃ when it moved the same way as the pH. That is ROME. The other value is the compensation.
Normals pH 7.35–7.45 · CO₂ 35–45 · HCO₃ 22–26 · PaO₂ 80–100 · SaO₂ >95%
Lungs compensate in minutes. Kidneys take hours to days. So full compensation means the problem is long-standing.
Vomiting loses acid → alkalosis. Diarrhea loses bicarbonate → acidosis.
Hypoxemia means low O₂ in the blood. Hypoxia means low O₂ at the tissue. Anemia and CO poisoning cause hypoxia even when the PaO₂ is normal.

Lab signatures

Look-alikes and the one clue that tells them apart

Act now

Cross-system chains

Numbers worth knowing

Anemia MCV <80 microcytic · 80–100 normocytic · >100 macrocytic
Nephrotic proteinuria >3.5 g/day
BUN:Cr >20:1 = prerenal
GFR normal ~90–125 mL/min; stage 5 CKD <15
Oliguria <400 mL/day
Ejection fraction reduced <40% = systolic failure
SA node 60–100 · AV node 40–60 · Purkinje 20–40
Chronic bronchitis productive cough ≥3 months × 2 years
Torsion salvage window ~6 hours
Morning stiffness RA >1 hour · OA <30 min
Melanoma ABCDE diameter >6 mm
Burn shock first 24–48 h fluid; after that, infection
Scar strength never gets past about 80% of the original
Hirschsprung no meconium in 48 h

Pathophysiology · Final Exam (Weeks 8–14) · Dr. Akash Garg