Chemical Pathology - Acid-Base Flashcards
What is seen on an ABG of a patient in respiratory failure
Type 1: Decreased O2, normal CO2
Type 2: Decreased O2, Increased CO2
What is seen on an ABG of a patient in metabolic acidosis?
pH: Decreased
pCO2: Decreased
HCO3: Decreased
What is seen on an ABG of a patient in metabolic alkalosis:
pH: Increased
pCO2: Increased
HCO3: Increased
What is seen on an ABG of a patient in respiratory acidosis:
pH: Decreased
pCO2: Increased
HCO3: Increased
What is seen on an ABG of a patient in respiratory alkalosis?
pH: Increased
pCO2: Decreased
HCO3: Decreased
What is compensation in terms of acid-base balance?
The return of the pH towards the normal at the expense of other values
What is a normal anion gap and the equation used to calculate it?
Normal range: 14-18
= Na + K - Cl - HCO3
What are some causes of metabolic acidosis in a patient with a high anion gap?
- Ketones
- Lactate (shock, ischaemia, sepsis)
- Alcohol
- Aspirin
- Metformin
- Ethylene glycol
- Uraemia
What are some causes of metabolic acidosis in a patient with a normal anion gap?
- Diarrhoea (Small bowel GI loss of HCO3)
- Acetazolamide
- High output stoma
- Pancreatic fistula
- Addison’s
- Renal tubular acidosis
- Ammonium chloride ingestion
What are some causes of metabolic alkalosis?
- Vomiting
- Loop diuretics
- Hypokalaemia
- Conn’s
- Antacid use
- Burns
What are some causes of respiratory acidosis?
Hypoventilation (T2RF):
- Acute/chronic lung disease (COPD)
- opioids
- sedatives
- neuromuscular weakness
Normal/high PaCO2 = worrying (ITU/vent support)
What are some causes of respiratory alkalosis?
Hyperventilation:
- Stroke
- SAH
- Meningitis
- Asthma
- Anxiety
- PE
- Pregnancy
- Altitude
- Salicylates
What is the anion gap?
- The difference between total concentration of principle cations and principle anions
- Concentration of unmeasured anions in the plasma
What is the predominant cause of an anion gap?
Albumin
What are some causes of an elevated anion gap in metabolic acidosis?
KULT
- K: Ketoacidosis (DKA, alcohol, starvation)
- U: Uraemia (renal failure)
- L: Lactic acidosis
- T: Toxins (ethylene glycol, methanol, paraldehyde, salicylate)
