⚖️ Acid-Base
Acid-Base Balance Quick Reference
Quick-reference for identifying and interpreting acid-base disorders using ABG values and compensation patterns.
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Normal ABG Values
| Test / Parameter | Normal Range | Clinical Notes |
|---|---|---|
| pH | 7.35–7.45 | <7.35 = acidosis. >7.45 = alkalosis. |
| PaCO2 | 35–45 mmHg | Respiratory indicator. High = acidosis. Low = alkalosis. |
| HCO3 | 22–26 mEq/L | Metabolic indicator. High = alkalosis. Low = acidosis. |
| PaO2 | 80–100 mmHg | Oxygenation. <60 = respiratory failure. |
| Base Excess | -2 to +2 | Positive = metabolic alkalosis. Negative = metabolic acidosis. |
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Respiratory Disorders
| Test / Parameter | Normal Range | Clinical Notes |
|---|---|---|
| Respiratory Acidosis | pH ↓, PaCO2 ↑ | Hypoventilation (COPD, opioids, neuromuscular). Body retains CO2. |
| Respiratory Alkalosis | pH ↑, PaCO2 ↓ | Hyperventilation (anxiety, pain, sepsis, high altitude). Blows off CO2. |
| Compensation | Kidneys adjust HCO3 | Slow (hours-days). Acidosis: retain HCO3. Alkalosis: excrete HCO3. |
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Metabolic Disorders
| Test / Parameter | Normal Range | Clinical Notes |
|---|---|---|
| Metabolic Acidosis | pH ↓, HCO3 ↓ | DKA, lactic acidosis, renal failure, diarrhea. Anion gap helps identify cause. |
| Metabolic Alkalosis | pH ↑, HCO3 ↑ | Vomiting, NG suction, diuretics, antacid excess. Chloride-responsive vs. resistant. |
| Compensation | Lungs adjust PaCO2 | Fast (minutes). Acidosis: hyperventilate (Kussmaul). Alkalosis: hypoventilate. |
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Mixed Disorders
| Test / Parameter | Normal Range | Clinical Notes |
|---|---|---|
| Mixed Acidosis | pH very low, PaCO2↑ + HCO3↓ | COPD + DKA, cardiac arrest. Both respiratory and metabolic acidosis. |
| Mixed Alkalosis | pH very high, PaCO2↓ + HCO3↑ | Vomiting + anxiety hyperventilation. Both respiratory and metabolic alkalosis. |
| Partially Compensated | pH abnormal, both abnormal | One system trying to compensate for the other. pH still abnormal. |
| Fully Compensated | pH normal, both abnormal | Compensation has normalized pH. Both systems abnormal. |
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