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Year 1 HLB Respiratory > Arterial Blood Gases and Control of Respiration > Flashcards

Arterial Blood Gases and Control of Respiration Flashcards

1
Q

Where is the medulla oblongata located in the brain?

A
  • brainstem
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2
Q

Where are the pons located in the brain?

A
  • above the medulla oblongata
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3
Q

What are the 3 main parts of the brainstem?

A
  • midbrain
  • pons
  • medulla oblongata
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4
Q

What is the order of the midbrain, pons and medulla oblongata from top to bottom?

A
  • midbrain - pons - medulla oblongata
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5
Q

Where is the dorsal respiratory group located?

A
  • dorsal = back
  • back of medulla oblongata
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6
Q

Where is the ventral respiratory group located?

A
  • ventral = front
  • front of medulla oblongata
  • below the pre-botzinger complex
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7
Q

What is the main role of the dorsal respiratory group of the medulla oblongata?

A
  • controls inspiration
  • receives receptor info due to close proximity to central chemoreceptors
  • transmits central chemoreceptors info to Ventral respiratory group
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8
Q

What is the main role of the ventral respiratory group of the medulla oblongata?

A
  • initiate inspiration and expiration
  • during exercise and active exhalation
  • controls diaphragm and external intercostals
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9
Q

What are the 2 main roles of the Pontine Respiratory Centres, which consists of the pneumotaxic and apneuistic centres?

A

1 - inhibit inspiration = pneumotaxic centre

2 - initiate inspiration = apneuistic centre

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10
Q

Where are the pneumotaxic and apneustic centres located in the brainstem?

A
  • pons
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11
Q

Out of the pneumotaxic and apneustic centres located in the pons, which is higher?

A
  • upper pons = pneumotaxic centre - lower pons = apneustic centre
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12
Q

What is the role of the pneumotaxic centre in the upper pons?

A
  • control pattern and rate of breathing
  • inhibit inspiration
  • linked to stretch receptors, important so lungs cannot over inflate
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13
Q

What is the role of the apneustic centre in the lower pons?

A
  • promote inspiration - controls intensity of breathing
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14
Q

Where does the apneustic centre in the lower pons signal in the medulla oblongata?

A
  • dorsal respiratory group to intitate inspiration
  • ventral respiratory group to initiate inspiration and expiration
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15
Q

What part of the brain stem is the equivalent of the pace maker in the heart for breathing?

A
  • pre-Botzinger complex
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16
Q

Where is the pre-Botzinger complex located?

A
  • in the brainstem - part of the ventral respiratory group
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17
Q

What are interneurons?

A
  • neurons able to communicate between the CNS and sensory/somatic motor neurons
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18
Q

What is the pre-Botzinger complex?

A
  • cluster of interneurons
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19
Q

Which part of the pons would activate the respiratory system if someone were to begin hyperventilating, with the aim of slowing down breathing?

A
  • hyperventilating = fast breathing - pneumotaxic centre inhibits breathing - allows expiration
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20
Q

What is involuntary respiration?

A
  • breathing subconsciously - when we are asleep
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21
Q

If we need to increase or decrease CO2 or O2 the dorsal respiratory group will innervate which muscles of the thoracic cavity?

A
  • diaphragm - external intercostal muscles - mainly during rest
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22
Q

If we need to increase or decrease CO2 or O2 during exercise the ventral respiratory group will innervate which muscles of the thoracic cavity?

A
  • internal intercostal muscles - activated during active exhalation - exercise for example
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23
Q

If CO2 increases what happens to pH in the blood?

A
  • blood ph will ⬇️
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24
Q

How does breathing change in an attempt to reduce CO2?

A
  • apneustic centre signals DRG to increase inspiration
  • central chemoreceptors signal increased activity from DRG
  • ⬆️ respiratory rate
  • ⬆️ breather depth
  • removes more CO2
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25
Q

Does emotional input affect breathing?

A
  • yes
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26
Q

How is Yoga an example of voluntary control of breathing?

A
  • yoga encourages slow deep breathes
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27
Q

How does pain affect breathing?

A
  • pain can ⬆️ respiratory rate and depth - pain management encourages ⬇️ respiratory rate
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28
Q

How does emotion affect breathing?

A
  • irregular breathing - poor ventilation
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29
Q

How does an increase in temperature affect breathing?

A
  • ⬆️ temperature = ⬆️ respiratory rate
  • increased O2 demand (exercise)
  • we breath out hot air/moisture
  • enzymes may not be as effective
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30
Q

How does an decrease in temperature affect breathing?

A
  • ⬇️ temperature = ⬇️ respiratory rate
  • cold air enters lungs
  • compliance is ⬇️ and elasticity ⬆️
  • enzymes may not be as effective
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31
Q

In emotional input on breathing, is it the pons or the medulla oblongata that innervate first?

A
  • pons stimulate medulla oblongata
  • both penumotaxic and apneustic centres are stimulated
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32
Q

What are mechanoreceptors?

A
  • sensors in the body - able to detect changes in CO2, O2 and pH
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33
Q

Where are the central chemoreceptor located?

A
  • ventrolateral surface of medulla oblongata
  • behind the dorsal respiratory group
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34
Q

What fluid does the central chemoreceptor monitor, and what changes does it generally monitor?

A
  • senses changes in cerebrospinal fluid - generally changes in pH
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35
Q

What are the names of the 2 peripheral chemoreceptors

A

1 - aortic bodies

2 - carotid bodies

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36
Q

Where is the carotid body peripheral mechanoreceptors located?

A
  • carotid sinus - where pulse is felt
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37
Q

Where is the aortic body peripheral mechanoreceptors located?

A
  • aortic arch
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38
Q

What is the role of the carotid and aortic chemoreceptors?

A
  • detect changes in PCO2 and PO2
  • carotid also detects pH
  • initiate ⬆️ or ⬇️ respiratory rate
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39
Q

Do the carotid and aortic body chemoreceptors work in isolation?

A
  • No - they are back up for each other
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40
Q

Are H+ and HCO3- able to cross the blood brain barrier?

A
  • no
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41
Q

If PCO2 increases in the brain what does this do to the pH of the cerebrospinal fluid?

A
  • ⬇️ pH
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42
Q

If there is an ⬆️ in PCO2 and a ⬇️ in pH in the cerebrospinal fluid, what is the bodies response?

A
  • central chemoreceptors signal increased DRG activity
  • ⬆️ DRG activity = ⬆️ respiratory rate
  • DRG signals VRG = ⬆️ respiratory rate
  • aim is to ⬆️ O2 and ⬇️ CO2
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43
Q

When we exercise, what is the initial response to the respiratory system and where do the receptors in the active muscles signal?

A
  • Skeletal muscles signal to pons and medulla oblongata
  • apneustic centre signals VRG and DRG to increase inspiration
  • ⬆️ respiratory rate allows ⬆️ ventilation
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44
Q

Following the initial ⬆️ in respiratory rate to increase ventilation as we exercise, what happens to breathing depth and frequency if exercise continues?

A
  • skeletal muscles signal to pons and medulla oblongata
  • respiratory rate ⬇️, but still more than normal
  • ⬆️ ventilation = ⬆️ O2 inspire and ⬆️ CO2 expired (like hyperventialtion)
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45
Q

During exercise, is it more efficient to ⬆️ tidal volume or respiratory rate to ⬆️ ventialtion?

A
  • ⬆️ tidal volume
  • provides increased time for gas exchange
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46
Q

What are irritant receptors in the lungs?

A
  • receptors located between epithelial cell
  • cold air, dust or dangerous gases can trigger these
  • trigger a cough to remove irritants
  • initiate hyperresponsiveness (type I hypersensitivity)
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47
Q

What are some responses if the irritant receptors in the lungs are activated?

A
  • hyperpnea (rapid and deep breathes)
  • coughing, sneezing and mucus production
  • vasoconstriction of bronchi
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48
Q

What are lung mechanoreceptors, also referred to as stretch receptors?

A
  • receptors in lungs that respond to excessive stretching
  • protective mechanism to stop over stretching
  • when stretched to capacity they send a signal to pneumotaxic centre
49
Q

When lung mechanoreceptors are stimulated following excessive a stretching where in the brain do they signal?

A
  • signal sent via the vagus nerve to penumotaxic centre (PC)
  • PC signals dorsal respiratory group (DRG)
  • DRG switches off inspiration drive
  • ⬆️ respiratory rate and decrease inspiration
50
Q

What is the Hering-Breur reflex?

A
  • a protective mechanism in lungs
  • activated when tidal volume >3x rest
  • stops lungs over stretching
51
Q

What are opioids?

A
  • a substance prescribed to treat pain - also used in anesthesia
52
Q

How do opioids affect the brainstem?

A
  • reduce sensitivity to breathing stimulus - ⬇️ sensitivity of the pons - ⬇️ sensitivity of ventral and dorsal regulatory systems - ⬇️ sensitivity of the pre-Botzinger complex
53
Q

How do opioids affect the peripheral mechanoreceptors??

A
  • ⬇️ sensitivity to CO2 in aortic and carotid bodies
  • increased risk of acidosis and alkalosis
54
Q

What do opioids do to ventilation?

A
  • inhibit pons (pneumotaxic and apneuistic centres) which ultimatley inhibits DRG (inspiration) and VRG (inspiration and expiration)
  • inability to monitor breathing depth and frequency due to pre botzinger complex
  • ⬇️ respiratory rate
  • ⬇️ tidal volume
  • ⬇️ ventilation
55
Q

What do opioids to to irritant receptors in the lungs?

A
  • inhibit the cough response
  • increased risk of chocking
  • increased risk of irritants damaging respiratory tissue
56
Q

What can Naloxone be used to treat that is addicitve?

A
  • use of opioids
57
Q

What is respiratory depression?

A
  • depression of all respiratory functions
  • caused by opioids use
58
Q

What is the Arterial Blood Gas (ABG) testing?

A
  • blood sample taken from artery to measure:
  • ventilation
  • gas exchange
  • acid base shift (BEcef)
59
Q

What is the acid base shift (BEcef)?

A
  • movement in pH out of the optimal range - normal pH range 7.35 to 7.45
60
Q

Does the acid base shift (BEcef) link more with respiratory or metabolic buffering?

A
  • metabolic buffering - includes haemoglobin, phosphates and proteins - HCO3- is most important
61
Q

What information does the Arterial Blood Gas (ABG) provide?

A
  • PaO2
  • PaCO2
  • pH
  • HCO3-
  • acid base shift (BEcef)
  • SaO2
62
Q

What will an increase in CO2 and H+ do to pH?

63
Q

What is normal arterial partial pressure (Pa) for O2 and CO2?

A
  • PaO2 = >10.5 - 13.3kPA or >79 - 100mmHg
  • CaO2 = >4.5 - 6.0kPA or 33.8 - 45mmHg
64
Q

What is respiratory failure?

A
  • low gas exchange
  • means low O2 and could be high CO2
65
Q

What PaO2 identifies respiratory failure?

A
  • <8.0kPA or 60mmHg
66
Q

Can Arterial Blood Gas testing diagnose respiratory disease?

67
Q

What is hypoxaemia?

A
  • ⬇️ partial pressure of O2 in the blood
68
Q

What is hypoxia?

A
  • ⬇️ tissue oxygenation
69
Q

What is ventilation (V) / perfusion (Q) mismatch, also referred to as V-Q)?

A
  • imbalance between O2 taken into respiratory tract (ventilation) and O2 that is perfused from alveolar to capillaries
70
Q

What generally happens to O2 levels when ventilation (V) / perfusion (Q) mismatch, also referred to as V-Q) is present?

A
  • O2 levels ⬇️
71
Q

Can ventilation (V) / perfusion (Q) mismatch, also referred to as V-Q) occur due to a pulmonary embolism?

A
  • yes
  • embolism = blood clot
  • blood clot blocks pulmonary blood flow
  • ⬇️ blood flow = ⬇️ blood perfusion
72
Q

Can ventilation (V) / perfusion (Q) mismatch, also referred to as V-Q) occur due to a emphysema?

A
  • yes
  • emphysema = damage to alveolar = ⬇️ alveolar surface area
  • ⬇️ surface area = ⬇️ perfusion
73
Q

What is type 1 respiratory failure?

A
  • lungs unable to maintain normal O2 levels
  • Pa02 = <8kPa or 100mmHg
  • lung tissue may be damaged
  • ⬇️ perfusion and oxygenation of the blood
74
Q

In type 1 respiratory failure what is the only measure that is abnormal on arterial blood gas?

A
  • PaO2 - < 8kPA or 60mmHg
75
Q

What is type 2 respiratory failure?

A
  • PaCO2 >6kPa or 50mmHg
  • PaO2 <8kPA or 100mmHg
  • ⬇️ alveolar ventilation
  • CO2 cannot be removed and
  • can cause hypercapneia and hypoxaemia
76
Q

In type 2 respiratory failure what measures are abnormal on arterial blood gas?

A
  • ⬇️ PaCO2 >6.5kPA or 48.7mmHg - ⬇️ PaO2 < 8kPA or 60mmHg - ⬇️ pH due to CO2 build up
77
Q

In type 2 respiratory failure, will patients oxygen saturation be low?

A
  • yes - ⬇️ perfusion = ⬇️ O2 saturation
78
Q

In acute type 2 respiratory failure, how long can it take to develop normally?

A
  • minutes to hours
79
Q

In acute type 2 respiratory failure, is the renal system able to compensate for build up in CO2 by retaining HCO3-?

A
  • no - renal system takes days to change pH effectively - ⬇️ in pH
80
Q

In chronic type 2 respiratory failure, how long can it take to develop normally?

A
  • days to weeks
81
Q

In chronic type 2 respiratory failure, is the renal system able to compensate for build up in CO2 by retaining HCO3-?

A
  • renal system excretes H2CO3 (carbonic acid) - renal system retains HCO3- - small change in pH, but likely to still be low
82
Q

Can chronic diseases be made worse by chronic type 2 respiratory failure?

83
Q

What is normal PaO2?

A
  • normal PaO2 = 10.5 - 13.3kPA or 80 - 100mmHg
84
Q

What are some examples of type 1 respiratory failure?

A
  • pneumonia, asthma, COPD, fibrosis
  • pulmonary disease (embolism or hypertension)
  • reduced perfusion and ⬇️ O2
85
Q

What is a common treatment for type 1 respiratory failure?

A
  • first option = nasal cannula
  • second option = optiflow (similar to nasal cannula)
  • third option = O2 face max
  • accounts for lung failing to perfuse
86
Q

What are a few diseases that cause type 2 respiratory failure?

A
  • asthma - COPD
87
Q

When examining arterial blood gas (ABG), generally what is the firs step?

A
  • examine pH - normal pH = 7.35-7.45
88
Q

Once you have checked the pH, what is the second step of analysing the arterial blood gas (ABG) data?

A
  • determine if abnormal pH is respiratory or metabolic - look at PaO2 and PaCO2 - look at HCO3-
89
Q

What is the normal HCO3- level in the blood?

90
Q

What is the Henderson-Hasslebalch equation?

A
  • CO2 + H2O = H2CO3 = HCO3- and H+
  • ⬆️ CO2 = ⬆️ H2CO3 - ⬆️ H2CO3 = ⬆️ BHCO3- and H+
91
Q

What does an increase in H+ do to blood pH?

92
Q

If H+ ⬆️ and pH subsequently ⬇️, what does this to to ventialtion?

A
  • central and peripheral chemoreceptors detect ⬇️ pH
  • apneustic centre signals ventral and dorsal respiratory groups
  • respiratory rate increases
  • CO2 is expired
93
Q

What is generally step 3 when analysing arterial blood gas (ABG)?

A
  • investigate the anion gap
94
Q

What are anions and cations?

A
  • anions have negative charge = HCO3-, Cl- - cations have positive charge = K+, NA+
95
Q

Are all cations and anions counted in the body?

A
  • no - more non counted anions than cations - this is why we study the anion gap
96
Q

What is the anion gap?

A
  • difference between cations and anions
  • specifically the anions that are not included in the formula
97
Q

What is the anion gap formula?

A
  • (K+ add Na+) - (HCO3- subtract Cl-) (generally K+ not included)
  • Na+ - HCO3- add Cl- = 137 - (104+24) - 9mEq/L
  • 9mEq/L is the anion gap (normal = 3-11mEq/L
  • the anion gap is all the unmeasured anions in plasma
98
Q

What is the normal range for the anion gap?

A
  • 3-11 mEq/L
  • blood must be neutral
  • measuring anion gap tells us what is causing metabolic acidosis
99
Q

Why should the anion gap be 0?

A
  • because all anions have a charge
  • BUT blood is neutral, so cations and anions must balance
100
Q

What are the 2 types of anion gap?

A

1 - high anion gap

= high = levels of unmeasured anions (hyperalbuminaemia)

2 - normal anion gap

= normal = diarrhoea (HCO3- is lost, but Cl- is retained so gap is normal)

101
Q

Why do we need to measure the anion gap, and identify if gap is normal or high?

A
  • helps identify cause of metabolic acidosis
  • if normal = could be loss of HCO3- or Cl- the normal anions
  • if high = unmeasured anions are high (hyperalbuminaemia)
102
Q

What are some common causes of a high anion gap?

A
  • hyperalbuminaemia (high albumin)
  • hyperphosphataemia (high phosphate)
  • can cause alkalosis
103
Q

What happens to anions when there is a normal anion gap present?

A
  • ⬇️ in HCO3-
  • ⬆️ Cl- retained in kidneys to balance anion gap formula
104
Q

What are some common causes of a normal anion gap?

A
  • diarrhoea
  • renal tubular acidosis
105
Q

What is the key for normal and high anion gap when trying to diagnose a patient?

A
  • ⬆️ anion gap = ⬆️ organic acids
  • normal anion gap = ⬇️ HCO3-
106
Q

What is generally used as step 5 when interpreting arterial blood gas (ABG)?

A
  • determine compensatory mechanisms
107
Q

How is respiratory compensatory determined?

A
  • ⬇️ pH = ⬆️ ventialtion = ⬇️ CO2
  • ⬇️ CO2 = ⬇️ H2CO3 = ⬆️ pH
108
Q

How fast can respiratory compensation occur?

A
  • within the first hour
109
Q

How is metabolic compensatory determined?

A
  • use pH
  • HCO3- levels
  • anion gap
110
Q

When would metabolic compensatory be initiated?

A
  • respiratory acidosis - kidneys retain HCO3- and excrete H+ - pH ⬆️
111
Q

What are some common causes of respiratory acidosis?

A
  • asthma - respiratory depression (opioids) - COPD
112
Q

What are some common causes of metabolic acidosis, which is essentially a reduction in the HCO3-?

A
  • Sepsis (tissue hypoxia)
  • Lactic acidosis (build up of acids)
  • Ketoacidosis (keto acids build up)
  • Severe diarrhea (anions lost in stool)
  • Renal tubular acidosis
113
Q

What are some common causes of respiratory alkalinosis?

A
  • severe vomiting
  • cushings disease
  • diuretics
114
Q

What are some common causes of metabolic alkalinosis?

A
  • altitude sickness
  • hyperventilation
  • hepatic failure
  • anxiety CNS trauma/disease
115
Q

What is narcosis?

A
  • excessive CO2 and nitrogen (N)
116
Q

What does narcosis generally cause?

A
  • hypercapnia (⬆️ CO2)
117
Q

What does a pulmonary embolism do to oxygenation and CO2 levels?

A
  • hypercapnia (⬆️ CO2) - hypoxaemia (⬇️ O2 partial pressure in blood)
118
Q

What is central sleep apnea?

A
  • respiratory drive is insufficient - unable to subconsciously breathe
119
Q

What does central sleep apnea do to CO2 levels?

A
  • hypercapnia (⬆️ CO2)

Year 1 HLB Respiratory (25 decks)

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