CLINICAL REFERENCE
NORMAL ABG RANGES (Arterial)
| Parameter | Range | Unit |
|---|---|---|
| pH | 7.35 – 7.45 | — |
| PaCO₂ | 35 – 45 | mmHg |
| HCO₃⁻ | 22 – 26 | mEq/L |
| PaO₂ | 80 – 100 | mmHg |
| SaO₂ | 95 – 100 | % |
| Base Excess | -2 to +2 | mEq/L |
| Anion Gap | 8 – 12 | mEq/L |
| Lactate | < 2.0 | mmol/L |
| A-a Gradient | 5 – 15 (age-dep.) | mmHg |
EXPECTED COMPENSATION (Winter's & Others)
Metabolic Acidosis: Expected PaCO₂ = (1.5 × HCO₃⁻) + 8 ± 2 (Winter's Formula)
Metabolic Alkalosis: Expected PaCO₂ = (0.7 × HCO₃⁻) + 21 ± 2
Acute Resp. Acidosis: HCO₃⁻ ↑ 1 per 10 ↑ PaCO₂
Chronic Resp. Acidosis: HCO₃⁻ ↑ 3.5 per 10 ↑ PaCO₂
Acute Resp. Alkalosis: HCO₃⁻ ↓ 2 per 10 ↓ PaCO₂
Chronic Resp. Alkalosis: HCO₃⁻ ↓ 5 per 10 ↓ PaCO₂
LACTATE CLINICAL INTERPRETATION
< 2.0 Normal
2.0 – 4.0 Hyperlactatemia — monitor, assess tissue perfusion
> 4.0 Severe — lactic acidosis, shock, tissue hypoxia likely
> 10.0 Critical — high mortality, emergent intervention needed
DELTA-DELTA (Δ/Δ) RATIO INTERPRETATION
< 1: Combined HAGMA + Non-AG Metabolic Acidosis (hyperchloremic)
1 – 2: Pure High Anion Gap Metabolic Acidosis
> 2: Combined HAGMA + Metabolic Alkalosis (pre-existing high HCO₃⁻)
HAGMA Causes (MUDPILES)
M — Methanol
U — Uremia
D — DKA / Diabetic Ketoacidosis
P — Propylene glycol / Paraldehyde
I — Isoniazid / Iron
L — Lactic Acidosis
E — Ethylene glycol
S — Salicylates
NAGMA Causes (HARDUPS)
H — Hyperalimentation (TPN)
A — Acetazolamide / Addison's
R — Renal Tubular Acidosis
D — Diarrhea
U — Ureteral diversions
P — Pancreatic fistula
S — Saline (0.9% NS excess)
For educational & clinical decision support only. Always correlate with clinical context.