Acid-base Abnormality

Question 1

Respiratory Acidosis

Answer 1

• hypoventilation that rapidly increases arterial pCO2
• Low pH, high CO2, normal/high HCO3

Question 2

Causes of Respiratory Acidosis

Answer 2

1. decreased respiratory drive (opioids, benzos, lesions (stroke))
2. NMJ disorders (MS, MND, myasthenia gravis)
3. decreased alveolar gas exchange (COPD, pneumonia, pulm oedema)
4. Airway obstruction (chronic sleep apnoea, foreign body)

Question 3

Respiratory Alkalosis

Answer 3

• hyperventilation that rapidly decreases arterial pCO2
• high pH, low CO2, normal/low HCO3

Question 4

Causes of Respiratory Alkalosis

Answer 4

1. CNS stimulation (hyperventilation, cerebrovascular accident)
2. Hypoxia (high altitude, severe anaemia)
3. Pulmonary disease (asthma, PE, pneumothorax, interstitial lung disease)
4. Drugs stimulating resp. drive (salicylates, aminophyllines, progesterone)

Question 5

Pnuemonic:

Causes of Respiratory Acidosis

Answer 5

AS A COW
- airway obstruction (foreign body)
- sedative use (benzodiazepines)
- acute lung disease (pneumonia, pulmonary oedema)
- chronic lung disease (COPD)
- opiods
- weakened respiratory muscles (MS, MND, myasthenia gravis)

Question 6

Pneumonic:

Causes of Respiratory Alkalosis

Answer 6

PAST PH
- panic attacks (hyperventilation)
- asthma
- salicylates
- tumours
- pulmonary embolism, pneumothorax
- hypoxia (high altitudes, severe anaemia)

Question 7

Metabolic Acidosis

Answer 7

• Increase in total body acid (H+) & decrease in arterial HCO3
• low pH, normal/low CO2, low HCO3

Question 8

Causes of high anion gap metabolic acidosis

Answer 8

1. increased endogenous acid production (ketoacidosis, lactic acidosis)
2. increased exogenous acid intake (methanol, ethylene glycol)
3. reduced acid excretion (chronic renal failure)

all about increasing acid, increases anion gap

Question 9

Causes of normal anion gap metabolic acidosis

Answer 9

1. loss of bicarbonate (diarrhoea, carbonic anhydrase inhibitors)
2. diluted blood bicarbonate (saline infusion)
3. impaired renal acid excretion (renal tubular acidosis)

Question 10

Pneumonic:

Causes of high anion gap metabolic acidosis

Answer 10

MUDPILES
- methanol
- uremia
- diabetic ketoacidosis
- propylene glycol (food additive)
- iron tablets and isoiazid
- lactic acidosis
- ethylene glycol (antifreeze)
- salicytates (asprin)

Question 11

Pneumonic:

Causes of normal anion gap metabolic acidosis

Answer 11

HARDASS
- hyperalimentation (total parenteral nutrition)
- addison disease
- renal tubular acidosis
- diarrohea
- acetazolamide (carbonic anhydrase inhibitor)
- spironolactone (aldosterone antagonist)
- saline infusion

Question 12

Metabolic Alkalosis

Answer 12

• Increased HCO3 (bicarbonate) levels in the blood
• pH high, CO2 normal/high, HCO3 high

Question 13

Causes of metabolic alkalosis

Answer 13

1. loss of H+ ions (vomiting, antacids, diuretics)
2. intracellular H+ shift (hypokalaemia, hyperaldosteronism)

Question 14

Pneumonic:

Causes of metabolic alkalosis

Answer 14

LAVA
- loop diruetics
- antacid use
- vomiting
- aldosterone increase