Acid-Base (Moore) Flashcards

1
Q

What way does the oxygen dissociation curve shift when alkalotic?

A

LEFT (oxygen has a higher affinity for hemoglobin)

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2
Q

Since the oxygen dissociation curve shifts left in an alkalotic patient, what does this mean for their saturation?

A

They might have good pO2 and O2 saturation, but they are pallid or cyanotic

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3
Q

What does a right shift of the oxygen dissociation curve imply?

A
  • Decreased affinity of O2 with hemoglobin
  • Decrease O2 carried from lungs
  • O2 given up more readily to the tissues
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4
Q

What are causes of right shift of oxygen dissociation curve?

A
  1. Acidosis (decreased pH)
  2. Elevated temperature
  3. Hypercarbia (elevated CO2)
  4. Increased DPG
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5
Q

What does a left shift of the oxygen dissociation curve imply?

A
  • Increased affinity of O2 with hemoglobin
  • Increased O2 carried from lungs
  • O2 given up less readily in the tissues
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6
Q

What are the causes of a left shift of the oxygen dissociation curve?

A
  1. Alkalosis (increased pH)
  2. Hypothermia
  3. Hypocarbia (decreased CO2)
  4. Decreased DPG
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7
Q

What are the 3 ways CO2 is transported and what are the % of each?

A
  1. 7% in plasma
  2. 23% carried in globin portion of hemoglobin
  3. 70% as bicarbonate in the plasma
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8
Q

What does carbonic anydrase do?

A

It can either combine CO2 and water to make carbonic acid or take carbonic acid and make CO2 and H20

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9
Q

What kind of acid is carbonic acid?

A

WEAK

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10
Q

How does the body prevent acidosis?

A

It takes a H ion from carbonic acid and buffers it with hemoglobin leaving bicarbonate ions

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11
Q

Where does bicarb move and in exchange for what?

A

Bicarb will move out of RBCs into plasma and Cl ion will move into the cell

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12
Q

In the lungs, what direction does the mass action equation move and what is the result of this ?

A

To the left to make CO2 to exhale

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13
Q

What is an acid and what is acidosis?

A
  • pH under 7
  • Gives up H ions
  • pH under 7.35
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14
Q

What is a base and what is alkalosis?

A
  • pH over 7
  • Accepts H ions
  • pH over 7.45
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15
Q

What is normal plasma pH?

A

Between 7.35 and 7.45

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16
Q

Cellular metabolism produces H ions from what?

A

Glucose, fatty acids, AA

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17
Q

How is acid/base balance maintained?

A

By controlling H ion concentration (body is very sensitive to small changes in H concentration)

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18
Q

What 3 systems are in place to maintain acid base balance?

A
  1. Buffering
  2. Respiratory
  3. Renal
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19
Q

What are buffers?

A

Chemicals that act quickly to temporary changes in H concentraion– Minimize changes in overall pH by accepting H ions when pH falls (acidosis) or by donating H ions when pH rises (alkalosis)

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20
Q

Is H removed from body?

A

NOPE…just removed from solution

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21
Q

What are the 3 buffering systems in the body?

A
  1. Carbonic acid-bicarbonate system
  2. Phosphate system
  3. Protein system (hemoglobin and plasma proteins)
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22
Q

What is the ratio of bicarb to carbonic acid needed to maintain a normal pH?

A

20:1

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23
Q

What are the functions of the buffering system?

A
  1. Provide important and immediate responses to potential changes in pH
  2. Prevent changes in pH until excess H ions can be excreted or bicarb levels can be resorted
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24
Q

What happens if the 20:1 ratio of bicarbonate to carbonic acid can’t be maintained?

A

A change in pH will occur

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25
Q

Why is the respiratory system so important in the control of acid-base balance?

A

It can respond quickly (short term control of pH)

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26
Q

What happens when CO2 is dissolved in H20?

A

Bicarbonate is formed

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27
Q

By increasing the rate or depth of breathing and increasing the amount of CO2, the level of bicarb in the body…?

A

Will decrease…less CO2 means less bicarbonate

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28
Q

What effect does the renal system have on acid-base balance?

A

Long term control…regulates the secretion of bicarbonate ions and excreting acids via renal tubule cells

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29
Q

What are the 3 ways the renal tubule alters pH?

A
  1. Secretes H ions into the filtrate, clearing the blood of excess acids and making the urine more acidic
  2. Reabsorb bicarb ions
  3. Produce new bicarb ions to augment the buffering of H ions in the blood
30
Q

Respiratory acid base imbalances?

A

Lungs and CO2

31
Q

Metabolic acid base imbalances?

A

Kidneys and Bicarb

32
Q

What are mixed imalances

A

DANGEROUS

33
Q

What other factor can be looked at along with bicarb?

A

Base excess (matches bicarb levels)

34
Q

PCO2 increased?

A

Respiratory acidsosis (decreased CO2 elimination)

35
Q

PCO2 decreased?

A

Respiratory alkalosis (increased CO2 elimination)

36
Q

Bicarb/BE increased?

A

Metabolic alkalosis (acid lost or bicarb gained)

37
Q

Bicarb/BE decrease?

A

Metabolic acidosis (acid added or bicarb used up or lost)

38
Q

Normal pH?

A

7.35-7.45

39
Q

Normal pO2?

A

80-100mmHg

40
Q

Normal pCO2?

A

35-45mmHg

41
Q

Normal bicarb?

A

22-25mmol/L

42
Q

Normal BE?

A

-2 (+/-2)

43
Q

Normal SaO2?

A

97%

44
Q

Respiratory acidosis?

A
  • pH low
  • pCO2 elevated
  • pO2 decreased
45
Q

Probable causes of respiratory acidosis?

A

Respiratory failure, COPD

46
Q

Treatment for respiratory acidosis?

A

Assisted ventilations….if already on a ventilator increase the minute volume or tidal volume to decrease pCO2

47
Q

Metabolic acidosis?

A
  • pH low
  • HCO3 low
  • BE low
48
Q

Probable causes metabolic acidosis?

A

DKA, renal failure, sepsis

49
Q

Treatment for metabolic acidosis?

A

Underlying problem

50
Q

Respiratory alkalosis?

A
  • pH elevated

- pCO2 low

51
Q

Probable causes of respiratory alkalosis?

A

Ventilator, hysterical hyperventilation

52
Q

Treatment for respiratory alkalosis?

A

Decrease minute volume or tidal volume so pCO2 can rise

53
Q

Metabolic alklalosis?

A
  • pH low
  • HCO3 elevated
  • BE elevated
54
Q

Probable cause of metabolic alkalosis?

A

Hyperemesis

55
Q

Why is blood gas analysis not always straight forward?

A

If pH is too high or too low, cellular function ceases

56
Q

Can you have a widely abnormal gas with relatively normal pH?

A

Yes… the body has natural mechanisms for keeping pH in normal limits

57
Q

What happens to compensate a respiratory acidosis (increased pCO2)?

A

The metabolic component (bicarb) will increase… the increasing alkalinity will bring the pH back to normal

58
Q

What happens to compensate a metabolic acidosis (decreased bicarb)?

A

The respiratory component (CO2) will decrease by hyperventilation to blow off CO2 and compensate to bring pH back towards normal

59
Q

What is full compensation?

A

Brings pH back to normal limit

60
Q

What is partial compensation?

A

Some compensation, but not enough to alter the pH

61
Q

What could be the problem in a respiratory acidosis with metabolic compentation and what is the treatment?

A

COPD… treat the underlying respiratory condition

62
Q

Causes of respiratory acidosis?

A

Inadequate ventilation and retention of CO2

  1. COPD
  2. PE
  3. Hypoventilation
  4. Over sedation
63
Q

How does the body compensate for respiratory acidosis?

A

Bicarb is reabsorbed by the kidneys to augment the buffering system of H ions in the blood

64
Q

What are the causes of metabolic acidosis?

A

Excess acid production or loss of bicarb

  1. DKA
  2. Renal failure
  3. Sepsis
  4. Cardiac arrest
65
Q

What is the compensation of metabolic acidosis?

A

Hyperventilation to increase rate and depth

66
Q

What are the causes of respiratory alkalosis?

A

Any condition leading to hyperventilation causing excretion of too much CO2

  1. Hysterical hyperventilation
  2. Over mechanical ventilation
67
Q

What is the compensation of respiratory alkalosis?

A
  1. Rebreathing of CO2

2. Decrease ventilation tidal volume and rate

68
Q

What are the causes of metabolic alkalosis?

A

Any condition leading to an increase in bicarb or loss of acid

  1. Vomiting
  2. Diuretic
  3. Antacid overdose
69
Q

What is the compensation of metabolic alkalosis?

A

Rate and depth of respiration are decreased in order to retain CO2

70
Q

What is overcompensation?

A

When the pH becomes overcorrected by a compensation

71
Q

What 2 situations can you see overcompensation in?

A
  1. When a patient has metabolic acidosis and respiratory acidosis
  2. When a patient has metabolic alkalosis and respiratory alkalosis
72
Q

What do you treat in the overcompensation?

A

The primary problem… the overcomepnsation issue will then correct itself