Acid Base Flashcards

1
Q

What is normal blood pH range?

A

7.35 - 7.45

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2
Q

What impact does COPD have on acid base?

A

Leads to chronic respiratory acidosis due to the build up of CO2

These people can be in two categories:

pink puffers = very breathless as they are sensitive to this CO2

blue bloaters = no longer breathless, CO2 levels become the driver to breathe so caution when ventilating

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3
Q

What does aspirin do to acid base?

A

Mixed metabolic acidosis + respiratory alkalosis

Very low Co2 and low bicarb

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4
Q

What causes the resp alkalosis in the mixed acidosis + alkalosis in aspirin overdose?

A

Due to hyperventilation as aspirin is a salicylate which stimulates resp centres

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5
Q

What is metabolic alkalosis?

A

High pH = Low H+ ions

Normal CO2 but
High HCO3-

Hypokalaemia

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6
Q

What causes metabolic alkalosis?

A

H+ loss through vomiting/pyloric stenosis

Hypokalaemia (vomiting, diarrhoea, diuretics, conns)

ingestion of bicarb = antacids

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7
Q

How to compensate for metabolic alkalosis?

A

Reduced ventilation = hypoventilation

to increase the pCO2

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8
Q

What results will be expected in compensated metabolic alkalosis?

A

Normal pH

High CO2

High bicarb

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9
Q

What is metabolic acidosis?

A

Low pH

with normal pCO2 but

LOW HCO3-

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10
Q

What are the causes of metabolic acidosis?

A

Increased production of H+ = DKA, Lactic acidosis (sepsis, metformin overdose)

Decreased excretion - renal tubular acidosis

Bicarbonate loss - intestinal fistula, diarrhoea, laxative abuse

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11
Q

How to compensate for metabolic acidosis?

A

Laboured breathing = hyperventilation to reduce CO2 levels atleast

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12
Q

What does compensated metabolic acidosis look like?

A

Normal pH

Low pCO2

Low bicarb

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13
Q

What is respiratory alkalosis?

A

High pH

Low pCO2 driving the alkalosis

Normal Bicarb

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14
Q

Causes of respiratory alkalosis?

A

Hyperventilation e.g. anxiety, hypoglycaemia, salicylates

Assisted ventilation

Urea cycle disorders

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15
Q

What does metformin overdose do to acid base?

A

Causes lactic acidosis which results in metabolic acidosis

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16
Q

Why does alkalosis sometimes cause tetany?

A

Alkalosis decreases free ionised calcium which can cause symptoms of tetany and carpopedal spasm (hypocalcaemia)

17
Q

How does your body compensate for respiratory alkalosis?

A

Kidneys retain H+ and decrease production of Bicarb

18
Q

What does compensated respiratory alkalosis look like?

A

Normal pH

Low CO2

low Bicarb

19
Q

Both respiratory alkalosis and metabolic acidosis when compensated for look like:

Low bicarb, low CO2
- How to differentiate?

A

If the pCO₂ was initially low, it’s respiratory alkalosis.

If the HCO₃⁻ was initially low, it’s metabolic acidosis.

20
Q

What is Respiratory acidosis?

A

Low pH

Driven by HIGH pCO2

Normal bircab

21
Q

What causes respiratory acidosis?

A

Hypoventilation = asthma attach, anaesthesia, opiate overdose, raised ICP

Lung problems e.g. COPD, emphysema, pneumonia, PE, ARDS

22
Q

How to compensate for respiratory acidosis?

A

Renal retention of bicarbonate ions

23
Q

What does compensated respiratory acidosis look like?

A

Normal pH

High CO2
High bicarb

24
Q

Both metabolic alkalosis and respiratory acidosis when compensated for present with

Normal pH, high CO2, high Bicarb

how to know what acid base imbalance occured?

A

If the HCO₃⁻ was initially high, it’s metabolic alkalosis.

If the pCO₂ was initially high, it’s respiratory acidosis.

25
Q

What does opiate overdose to do acid base?

A

Respiratory acidosis = via hypoventilation