Disorders of acid-base balance Flashcards

1
Q

pH =

A

-log [H+]

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2
Q

Acidosis

A

disorder to make blood more acidic

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3
Q

Alkalosis

A

disorder to make blood more alkaline than normal

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4
Q

Acidemia

A

low blood pH

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5
Q

Alkalaemia

A

high blood pH

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6
Q

Standard bicarbonate

A

measures of metabolic component of any acid-base disturbance

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7
Q

Absolute bicarbonate is affected by

A

respiratory and metabolic components

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8
Q

Standard bicarbonate is standardised as …

A

pCO2 5.3kPa + temperature 37 degrees celcius

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9
Q

Base excess

A

quantity of acid required to return pH to normal under standard conditions

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10
Q

Standard base excess corrected to

A

Hb 50g/L

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11
Q

Base excess in acidosis?

A

negative

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12
Q

What do we measure: Arterial Blood Gases

A
pH
pO2
pCO2
Standard HCO3-
Standard base excess
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13
Q

2 major approaches to interpreting acid-base status

A

Henderson-Hasselbach Equation

Stewart’s theory

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14
Q

Henderson-Hasselbach equation

A
  • pH = pKa + log([A-]/[HA])
  • pH = pKa H2CO3 + log([HCO3-]/[H2CO3])
  • pH = 6.1 + log([HCO3-]/0.03 x pCO2)

ESSENTIALLY:
pH = pKa + log [conjugate base]/[acid]

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15
Q

Acidaemia: if pCO2 is increased …

A

respiratory acidosis

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16
Q

Acidaemia: if pCO2 is increased and [HCO3-] is high

A

respiratory acidosis with compensatory metabolic alkalosis

17
Q

Acidaemia: if HCO3- is low

A

metabolic acidosis

18
Q

Acidaemia: if HCO3- is low and pCO2 is low

A

metabolic acidosis with compensatory respiratory alkalosis

19
Q

Alkalaemia: if pCO2 is low

A

respiratory alkalosis

20
Q

Alkalaemia: if pCO2 is low and HCO3- is low

A

respiratory alkalosis with compensatory metabolic acidosis

21
Q

Alkalaemia: if HCO3- is high

A

metabolic alkalosis

22
Q

Alkalaemia: if HCO3- is high and pCO2 is high

A

metabolic alkalosis with compensatory respiratory acidosis

23
Q

Respiratory causes of acidosis

A

COPD
Asthma
Severe obesity
Hypoventilation

24
Q

Metabolic causes of acidosis

A

Hyperkalaemia
Hypoaldosteronism
Diabetic ketoacidosis
Renal failure

25
Respiratory causes of alkalosis
hyperventilation
26
Metabolic causes of alkalosis
diarrhoea | vomiting
27
Strong ion difference
SID = [strong cations] – [strong anions] cat + anion -
28
Anion gap
[Na+]+[K+] - [Cl-] - [HCO3-]
29
Normal anion gap
10-16
30
Wide anion gap
Lactic acidosis Ketoacidosis Ingestion of acid Renal failure
31
Narrow anion gap (e.g. high chloride)
Gastrointestinal HCO3- loss | Renal tubular acidosis
32
Compensatory mechanisms for metabolic acidosis
Hyperventilation to increase CO2 excretion
33
Compensatory mechanisms for metabolic alkalosis
Hypoventilation | Renal bicarbonate excretion
34
Compensatory mechanism of respiratory acidosis
``` increased renal H+ excretion Bicarbonate retention (but only if chronic) ```
35
Compensatory mechanism of respiratory alkalosis
Increased renal bicarbonate loss (if chronic