Acid Base Disturbances Flashcards
What happens to give rise to a respiratory acidosis?
Rise in CO2 levels due to alveolar hypoventilation
What can happen in respiratory acidosis?
Renal compensation - leading to compensated respiratory acidosis
Causes of respiratory acidosis
COPD
Decompensation in other resp conditions e.g. life threatening asthma / pulmonary oedema
Sedative drugs; benzodiazepines, opiates
What happens in respiratory alkalosis?
Hyperventilation resulting in a loss of carbon dioxide, resulting in an increasing pH
Causes of respiratory alkalosis
Psychogenic; anxiety leading to hyperventilation
Hypoxia causing a subsequent hyperventilation; PE, high altitude
Early salicylate poisonings
CNS stimulation; stroke, SAH, encephalitis
Pregnancy
What is the most common surgical acid base disorder?
Metabolic acidosis
What happens to result in metabolic acidosis?
Reduced bicarbonate levels
Two possible mechanisms for metabolic acidosis
- Gain of a strong acid e.g. DKA
- Loss of a base (e.g. from bowel in diarrhoea)
What is metabolic acidosis classified according to and how do you work this out?
Anion gap
(Na+ + K+) - (Cl- + HCO3-)
What would be a clue in the question that you should work out the anion gap?
If the chloride value is given
What is a normal anion gap also known as?
Hyperchloremic metabolic acidosis
Causes of normal anion gap metabolic acidosis
GI bicarbonate loss
Renal tubular acidosis
Drugs e.g. acetazolamide
Ammonium chloride injection
Addisons disease
Causes of raised anion gap metabolic acidosis
Lactate; shock, hypoxia
Ketones; DKA, alcohol
Urate; renal failure
Acid poisoning; salicylates, methanol
Two types of metabolic acidosis caused by high lactate levels
Type A
Type B
Type A lactate causing metabolic acidosis is due to….
Perfusion disorders e.g. shock, hypoxia, burns
