Blood Gas Flashcards

1
Q

What is the pH range in the human body?

A

7.35-7.45

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2
Q

What is Ka

A

The dissociation constant

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3
Q

Define pKa

A

The negative log of the dissociation constant

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4
Q

When is the body in acid-base balance?

A

PH = pKa

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5
Q

What does a buffer consist of?

A

A weak acid and a salt of its conjugate base

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6
Q

What is the function of a buffer?

A

To allow a solution to resist changed in pH upon adding acid or base

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7
Q

What is the most important buffering system in the body?

A

H2CO3 (bicarbonate)

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8
Q

What organ in the body changes HCO3 concentration?

A

Kidneys

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9
Q

What organs regulate the acid base balance (transport of CO2)?

A

Lungs and Kidneys

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10
Q

_____ is the end product of most aerobic metabolic processes.

A

CO2

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11
Q

Dissociation of __a__ causes the development of a concentration gradient due to the increase in __b__ concentration within the RBC.

A

A) H2CO3
B) HCO 3-

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12
Q

How do the kidneys regulate pH?

A
  • excreting acid (primarily in the ammonium ion)
  • reclaiming HCO3- from glomerular filtrate
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13
Q

The dissolved carbon dioxide (dCO2) that is expelled by the lungs is known as the ___

A

Respiratory component

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14
Q

How the kidneys control the bicarbonate concentration by reabsorption or excretion is known as the ___

A

Metabolic component

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15
Q

Acidemia/Acidosis

A

When the blood pH is less than the reference range

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16
Q

Causes of acidosis include

A

1) primary metabolic imbalance: the amount of acid exceeds the capacity of the buffer systems and there is a decrease in bicarbonate

2) primary respiratory imbalance

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17
Q

How does the body compensate for metabolic acidosis?

A

Hyperventilation

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18
Q

Alkalemia/alkalosis

A

When blood pH is greater than the reference range

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19
Q

Cause of primary respiratory alkalosis

A

Increased rate of alveolar ventilation which causes an excessive elimination of CO2 by the lungs

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20
Q

How do the kidneys compensate for primary respiratory alkalosis?

A

By excreting HCO3- in the urine and reclaiming H+ to the blood through decreased activity of Na+ and H+ exchange

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21
Q

-osis

A

Refers to a process in the body

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22
Q

-emia

A

Refers to the corresponding state in blood

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23
Q

Acidemia

A

Will result if the hydrogen ion concentration increased through pCO2 concentration or decreases in the bicarbonate concentration

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24
Q

Alkalemia

A

Will result if the H+ concentration decreases, either from decreased PCO2 or increased concentration of bicarbonate

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25
Q

Primary Respiratory Acidosis or Alkalosis

A

A disorder caused by respiratory dysfunction — a change in the pCO2

26
Q

Metabolic acidosis or alkalosis

A

A disorder resulting from a change in the bicarbonate level — a consequence of renal or metabolic dysfunction

27
Q

Compensation

A

The response to maintain acid-base homeostasis and is accomplished by the organ not associated with the primary process

28
Q

Fully compensated

A

Implies that the pH has retuned to the normal range and ratio has returned to 20:1 (normal)

29
Q

Partially compensated

A

Implies that the pH is approaching normal

30
Q

Uncompensated

A

Implied that the pH is abnormal and the body has not started compensating for the acid-base imbalance

31
Q

Carbonic acid is a ___ acid

A

weak

32
Q

What does the HH equation do?

A

It expresses the acid base relationship in a mathematical equation

33
Q

What is CO2 in the acid base balance of lungs and kidney?

A

End product of metabolic processes

34
Q

What is the relationship between the bicarbonate and hgb buffering systems?

A

CO2 has an acid/base effect despite not being one

35
Q

What is the most acidic pH your urine can be?

A

pH = 4.6

36
Q

What happens to HCO3 re absorption when there is increased plasma pH

A

There is decreased Na-H exchange and HCO3 re absorption is decreased

37
Q

What happens to HCO3 re absorption when there is decreased plasma pH

A

There is increased Na-H exchange and HCO3 reabsorption is increased

38
Q

What is in equilibrium in the bicarbonate buffering system?

A

The dissolved CO2 (dCO2) is in equilibrium with CO2 gas in the lungs, which can be expelled.​

39
Q

What is the respiratory component of the bicarbonate system?

A

The dissolved carbon dioxide (dCO2) that is expelled by the lungs​

40
Q

What is the metabolic component of the bicarbonate system?

A

How the kidneys control the bicarbonate concentration by reabsorption or excretion​

41
Q

What is acidosis?

A

When blood pH is less than 7.35

42
Q

How is metabolic acidosis compensated for?

A

Increased rate or depth of breathing (hyperventilation)

43
Q

What is alkalosis?

A

When blood pH is greater than 7.45

44
Q

How does the body compensate for metabolic alkalosis?

A

The kidneys compensate by excreting HCO3− in the urine and reclaiming H+ to the blood through decreased activity of the Na+-H+ exchange.​

45
Q

What is respiratory acidosis?

A

Decreased alveolar ventilation causes a decreased elimination of Co2

46
Q

What is respiratory alkalosis?

A

Caused by an increased rate of alveolar ventilation which is causing an excessive elimination fo Co2 by the lungs

47
Q

What are the characteristics of acid base disorders?

A
48
Q

What is the percentage of oxygen and nitrogen in blood gas exchange?

A

20% O2

78% Nitrogen

49
Q

What factors influence the amount of O2 that moves into the alveoli?

A

Destruction of the alveoli

Pulmonary edema

Airway blockage

50
Q

What factors infleunce the amount of O2 delivered to the tissues

A

Inadequate blood supplt

Diffusion of CO2 and O2

Intrapulmonary shunting

Anemia

51
Q

What are the four forms in which Hgb exists?

A

Oxyhemoglobin (O2Hb)

Deoxyhemoglobin (HHb)

Carboxyhemoglobin (COHb)

Methemoglobin (MetHb)

52
Q

What is Oxyhemoglobin (O2Hb)

A

hgb with ferrous iron in the heme group that is reversibly bound to O2

53
Q

What is Deoxyhemoglobin (HHb)

A

Reduced hgb-hgb without O2

54
Q

What is
Carboxyhemoglobin (COHb)

A

hgb bound to CO

55
Q

What is Methemoglobin (MetHb)

A

Hgb unable to bind to O2 because Iron is in an oxidized state

56
Q

What are the four parameters commonly used to assess a patient’s oxygen status

A

1) O2 saturation

2) fraction % of oxyhemoglobin which is the ratio of oxyhgb to toal hgb

3) Trens in O2 sat asses by transcutaneous and pulse ox

4) amount of O2 dissolved in plasma

57
Q

T/F:

Hgb acts as both an acid base buffer and an O2 buffer

A

TRUE

58
Q

What do blood gas analyzers use to measure pO2, pCO2, and pH?

A

Electrodes and glass membranes as sensing devices

59
Q

What is a calulated parameter for blood gas analyzers?

A

HCO3 using HH equation

Positive = base excess, indicates a excess of bicarbonate, positive alkalosis​

Negative = base deficit = deficit of bicarbonate = Metabolic acidosis

60
Q

What levels are surrogate liquid control levels at for QC?

A

usually 3 levels, low, normal, high—significantly different matrix than fresh whole blood.