High Anion Gap Metabolic Acidosis

C Carbon Monoxide, Cyanide
A Alcohol, Alcoholic Ketoacidosis
T Toluene
M Metformin, Methanol
U Uraemia
D Diabetic Ketoacidosis
P Paraldehyde, Phenformin, Paracetamol, Propylene glycol
I Iron, Isoniazid
L Lactic acidosis (any cause)
E Ethylene glycol
S Salicylates

Causes of Lactic Acidosis

Type A: Imbalanced oxygen supply and demand Type B: Metabolic derangements
  • Carbon monoxide
  • Shock
  • Severe anaemia
  • Severe hypoxia
  • Excessive oxygen demand:
  • Fever, seizure, exercise, shivering
  • β2-agonists
  • Cancer
  • Cyanide
  • Ethanol
  • Hepatic failure
  • Ketoacidosis
  • Metformin / Phenformin
  • Sepsis
  • Thiamine deficiency
  • Inborn errors of metabolism

Non-anion Gap Metabolic Acidosis

U Ureteroenterostomy
S Small bowel fistula
E Extra chloride, Normal saline hydration
D Diarrhoea
C Carbonic anhydrase inhibitors (acetozolamide, topiramate…)
A Adrenal insufficiency
R Renal tubular acidosis
P Pancreatic fistula

Causes of a low anion gap

Increased cations Calcium, magnesium, lithium, multiple myeloma
Decreased anions Dilution, hypoalbuminaemia
Artefactual Bromism, Iodism, Propylene glycol, Triglycerides

Metabolic Alkalosis

C Contraction (volume contraction)
L Liquorice, Diuretics (Lasix™)
E Endocrine (Bartter’s, Cushing’s, Conn’s)
V Vomiting, NG suction (Chloride loss)
E Excess alkali (Antacids, Dialysis, Milk-Alkali Syndrome)
R Refeeding alkalosis
R Renal bicarbonate retention (Hypochloraemia, Hypokalaemia, Chronic hypercapnia)

Respiratory acidosis

Acute Chronic
  • Airway obstruction
  • Aspiration
  • Bronchospasm
  • CNS depression
  • Muscle weakness
  • Pulmonary disease
  • Chronic lung disease
  • Neuromuscular disorders
  • Obesity

Respiratory alkalosis

C CNS disease (Raised ICP)
H Hypoxia (Altitude, anaemia, VQ mismatch)
A Anxiety
M Mechanical hyperventilation
P Progesterone, pregnancy
S Sepsis, Salicylates, Other Toxins (nicotine, xanthines)
Blood Gas Mnemonics
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