Investigations

Question 1

RAGMA causes

Answer 1

1) Lactic Acid
a) Cyanid toxicity, arterial occlusion, hypovolaemia, profound anaemia
b1) liver failure, sepsis
b2) drugs - methanol, ethylene glycol, paraldehyde, paraquat, iron, isoniazid, metformin
b3) inborn errors of metabolism

2) Ketoacids
- diabetic ketoacidosis
- starvation
- alcoholic ketoacidosis

3) Salicylates

4) Uraemic renal failure

Question 2

NAGMA causes

Answer 2

1) HCO3- loss
- excessive diarrhoea
- renal tubular acidosis (distal more than proximal)
- fistulas (pancreaticoduodenal, uretoenteric)

2) Excessive 0.9% NaCl administration

3) Endocrinopathies
- mineralocorticoid or glucocorticoid deficiency
- Adrenal crisis

4) Drugs
- Carbonic anhydrase inhibitors (Acetazolamide)
- spironolactone

Question 3

Metabolic Alkalosis causes

Answer 3

1) HCI loss ie vomiting (loss of H+)

2) Drug induced - diuretics - frusemide, laxative abuse, milk-alkali syndrome (hyper Ca2+, metabolic alkalosis and kidney failure - excess calcium intake), NaHCO3 therapy

3) Endocrinopathies
- mineralocorticoid or glucocorticoid excess
- bartters syndrome

Question 4

Respiratory alkalosis causes

Answer 4

1) Central stimulation of respiratory drive
- head injury/ ICH
- anxiety or pain
- salicylate intoxication
- sympathomimetic intoxication (MDMA)

2) Profound hypoxia causing peripheral respiratory stimulation
- PE, pneumonia, APO, acute asthma , ARDS

Question 5

Respiratory acidosis

Answer 5

1) Acute on chronic exacerbation of COPD

2) Airway disorders
- acute asthma, airway obstruction

3) Depression of central respiratory drive
- drugs (opiates, sedative)
- ICH, CNS injury

4) Lung insults
- trauma- pneumothorax, contusion, haemothorax, flail segment
- lung membrane diseases (APO, LRTI, ARDS, aspiration)

5) Inadequate respiratory effort
- toxins: organophosphates, elapid envenomation
- myopathies, GBS

Question 6

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