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Acid-Base Imbalances: Quick Revision Notes
The 15-Minute "Cram Session" Cheat Sheet
1. The Absolute Essentials (Memorize These!)
Value Normal Range Quick Meaning
pH 7.35 – 7.45 < 7.35 = Acidosis / > 7.45 = Alkalosis
PaCO2 35 – 45 mmHg Respiratory (Lungs). High = Acid / Low = Alk
HCO3 22 – 26 mEq/L Metabolic (Kidneys). High = Alk / Low = Acid
PaO2 80 – 100 mmHg Oxygenation (Not Acid-Base)
Base Excess -2 to +2 +2 = More Base (Alk) / -2 = More Acid
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2. The ROME Mnemonic (Interpretation Hack)
• Respiratory = Opposite
opH up (Alk) / PaCO2 down → Respiratory Alkalosis
o pH down (Acid) / PaCO2 up → Respiratory Acidosis
• Metabolic = Equal
o pH up (Alk) / HCO3 up → Metabolic Alkalosis
o pH down (Acid) / HCO3 down → Metabolic Acidosis
3. Compensation Status (Is the body fixing it?)
1. Uncompensated: pH bad / One value abnormal / One value normal.
2. Partially Compensated: pH bad / Both values abnormal.
3. Fully Compensated: pH normal / Both values abnormal. (Look at pH: 7.36 = primary
Acidosis; 7.44 = primary Alkalosis).
4. The Big Four: At-a-Glance Chart
Acid-Base Imbalances: Quick Revision Notes
The 15-Minute "Cram Session" Cheat Sheet
1. The Absolute Essentials (Memorize These!)
Value Normal Range Quick Meaning
pH 7.35 – 7.45 < 7.35 = Acidosis / > 7.45 = Alkalosis
PaCO2 35 – 45 mmHg Respiratory (Lungs). High = Acid / Low = Alk
HCO3 22 – 26 mEq/L Metabolic (Kidneys). High = Alk / Low = Acid
PaO2 80 – 100 mmHg Oxygenation (Not Acid-Base)
Base Excess -2 to +2 +2 = More Base (Alk) / -2 = More Acid
, 2|Page
2. The ROME Mnemonic (Interpretation Hack)
• Respiratory = Opposite
opH up (Alk) / PaCO2 down → Respiratory Alkalosis
o pH down (Acid) / PaCO2 up → Respiratory Acidosis
• Metabolic = Equal
o pH up (Alk) / HCO3 up → Metabolic Alkalosis
o pH down (Acid) / HCO3 down → Metabolic Acidosis
3. Compensation Status (Is the body fixing it?)
1. Uncompensated: pH bad / One value abnormal / One value normal.
2. Partially Compensated: pH bad / Both values abnormal.
3. Fully Compensated: pH normal / Both values abnormal. (Look at pH: 7.36 = primary
Acidosis; 7.44 = primary Alkalosis).
4. The Big Four: At-a-Glance Chart
