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

Arterial Blood Gases and Control of Respiration Flashcards

(119 cards)

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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
Does emotional input affect breathing?
- yes
26
How is Yoga an example of voluntary control of breathing?
- yoga encourages slow deep breathes
27
How does pain affect breathing?
- pain can ⬆️ respiratory rate and depth - pain management encourages ⬇️ respiratory rate
28
How does emotion affect breathing?
- irregular breathing - poor ventilation
29
How does an increase in temperature affect breathing?
- ⬆️ temperature = ⬆️ respiratory rate - increased O2 demand (exercise) - we breath out hot air/moisture - enzymes may not be as effective
30
How does an decrease in temperature affect breathing?
- ⬇️ temperature = ⬇️ respiratory rate - cold air enters lungs - compliance is ⬇️ and elasticity ⬆️ - enzymes may not be as effective
31
In emotional input on breathing, is it the pons or the medulla oblongata that innervate first?
- pons stimulate medulla oblongata - both penumotaxic and apneustic centres are stimulated
32
What are mechanoreceptors?
- sensors in the body - able to detect changes in CO2, O2 and pH
33
Where are the central chemoreceptor located?
- ventrolateral surface of medulla oblongata - behind the dorsal respiratory group
34
What fluid does the central chemoreceptor monitor, and what changes does it generally monitor?
- senses changes in cerebrospinal fluid - generally changes in pH
35
What are the names of the 2 peripheral chemoreceptors
1 - aortic bodies 2 - carotid bodies
36
Where is the carotid body peripheral mechanoreceptors located?
- carotid sinus - where pulse is felt
37
Where is the aortic body peripheral mechanoreceptors located?
- aortic arch
38
What is the role of the carotid and aortic chemoreceptors?
- detect changes in PCO2 and PO2 - carotid also detects pH - initiate ⬆️ or ⬇️ respiratory rate
39
Do the carotid and aortic body chemoreceptors work in isolation?
- No - they are back up for each other
40
Are H+ and HCO3- able to cross the blood brain barrier?
- no
41
If PCO2 increases in the brain what does this do to the pH of the cerebrospinal fluid?
- ⬇️ pH
42
If there is an ⬆️ in PCO2 and a ⬇️ in pH in the cerebrospinal fluid, what is the bodies response?
- central chemoreceptors signal increased DRG activity - ⬆️ DRG activity = ⬆️ respiratory rate - DRG signals VRG = ⬆️ respiratory rate - aim is to ⬆️ O2 and ⬇️ CO2
43
When we exercise, what is the initial response to the respiratory system and where do the receptors in the active muscles signal?
- Skeletal muscles signal to pons and medulla oblongata - apneustic centre signals VRG and DRG to increase inspiration - ⬆️ respiratory rate allows ⬆️ ventilation
44
Following the initial ⬆️ in respiratory rate to increase ventilation as we exercise, what happens to breathing depth and frequency if exercise continues?
- skeletal muscles signal to pons and medulla oblongata - respiratory rate ⬇️, but still more than normal - ⬆️ ventilation = ⬆️ O2 inspire and ⬆️ CO2 expired (like hyperventialtion)
45
During exercise, is it more efficient to ⬆️ tidal volume or respiratory rate to ⬆️ ventialtion?
- ⬆️ tidal volume - provides increased time for gas exchange
46
What are irritant receptors in the lungs?
- 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)
47
What are some responses if the irritant receptors in the lungs are activated?
- hyperpnea (rapid and deep breathes) - coughing, sneezing and mucus production - vasoconstriction of bronchi
48
What are lung mechanoreceptors, also referred to as stretch receptors?
- 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
When lung mechanoreceptors are stimulated following excessive a stretching where in the brain do they signal?
- 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
What is the Hering-Breur reflex?
- a protective mechanism in lungs - activated when tidal volume \>3x rest - stops lungs over stretching
51
What are opioids?
- a substance prescribed to treat pain - also used in anesthesia
52
How do opioids affect the brainstem?
- reduce sensitivity to breathing stimulus - ⬇️ sensitivity of the pons - ⬇️ sensitivity of ventral and dorsal regulatory systems - ⬇️ sensitivity of the pre-Botzinger complex
53
How do opioids affect the peripheral mechanoreceptors??
- ⬇️ sensitivity to CO2 in aortic and carotid bodies - increased risk of acidosis and alkalosis
54
What do opioids do to ventilation?
- 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
What do opioids to to irritant receptors in the lungs?
- inhibit the cough response - increased risk of chocking - increased risk of irritants damaging respiratory tissue
56
What can Naloxone be used to treat that is addicitve?
- use of opioids
57
What is respiratory depression?
- depression of all respiratory functions - caused by opioids use
58
What is the Arterial Blood Gas (ABG) testing?
- blood sample taken from artery to measure: - ventilation - gas exchange - acid base shift (BEcef)
59
What is the acid base shift (BEcef)?
- movement in pH out of the optimal range - normal pH range 7.35 to 7.45
60
Does the acid base shift (BEcef) link more with respiratory or metabolic buffering?
- metabolic buffering - includes haemoglobin, phosphates and proteins - HCO3- is most important
61
What information does the Arterial Blood Gas (ABG) provide?
- PaO2 - PaCO2 - pH - HCO3- - acid base shift (BEcef) - SaO2
62
What will an increase in CO2 and H+ do to pH?
- ⬇️ pH
63
What is normal arterial partial pressure (Pa) for O2 and CO2?
- PaO2 = \>10.5 - 13.3kPA or \>79 - 100mmHg - CaO2 = \>4.5 - 6.0kPA or 33.8 - 45mmHg
64
What is respiratory failure?
- low gas exchange - means low O2 and could be high CO2
65
What PaO2 identifies respiratory failure?
- \<8.0kPA or 60mmHg
66
Can Arterial Blood Gas testing diagnose respiratory disease?
- yes
67
What is hypoxaemia?
- ⬇️ partial pressure of O2 in the blood
68
What is hypoxia?
- ⬇️ tissue oxygenation
69
What is ventilation (V) / perfusion (Q) mismatch, also referred to as V-Q)?
- imbalance between O2 taken into respiratory tract (ventilation) and O2 that is perfused from alveolar to capillaries
70
What generally happens to O2 levels when ventilation (V) / perfusion (Q) mismatch, also referred to as V-Q) is present?
- O2 levels ⬇️
71
Can ventilation (V) / perfusion (Q) mismatch, also referred to as V-Q) occur due to a pulmonary embolism?
- yes - embolism = blood clot - blood clot blocks pulmonary blood flow - ⬇️ blood flow = ⬇️ blood perfusion
72
Can ventilation (V) / perfusion (Q) mismatch, also referred to as V-Q) occur due to a emphysema?
- yes - emphysema = damage to alveolar = ⬇️ alveolar surface area - ⬇️ surface area = ⬇️ perfusion
73
What is type 1 respiratory failure?
- lungs unable to maintain normal O2 levels - Pa02 = \<8kPa or 100mmHg - lung tissue may be damaged - ⬇️ perfusion and oxygenation of the blood
74
In type 1 respiratory failure what is the only measure that is abnormal on arterial blood gas?
- PaO2 - \< 8kPA or 60mmHg
75
What is type 2 respiratory failure?
- PaCO2 \>6kPa or 50mmHg - PaO2 \<8kPA or 100mmHg - ⬇️ alveolar ventilation - CO2 cannot be removed and - can cause hypercapneia and hypoxaemia
76
In type 2 respiratory failure what measures are abnormal on arterial blood gas?
- ⬇️ PaCO2 \>6.5kPA or 48.7mmHg - ⬇️ PaO2 \< 8kPA or 60mmHg - ⬇️ pH due to CO2 build up
77
In type 2 respiratory failure, will patients oxygen saturation be low?
- yes - ⬇️ perfusion = ⬇️ O2 saturation
78
In acute type 2 respiratory failure, how long can it take to develop normally?
- minutes to hours
79
In acute type 2 respiratory failure, is the renal system able to compensate for build up in CO2 by retaining HCO3-?
- no - renal system takes days to change pH effectively - ⬇️ in pH
80
In chronic type 2 respiratory failure, how long can it take to develop normally?
- days to weeks
81
In chronic type 2 respiratory failure, is the renal system able to compensate for build up in CO2 by retaining HCO3-?
- renal system excretes H2CO3 (carbonic acid) - renal system retains HCO3- - small change in pH, but likely to still be low
82
Can chronic diseases be made worse by chronic type 2 respiratory failure?
- yes
83
What is normal PaO2?
- normal PaO2 = 10.5 - 13.3kPA or 80 - 100mmHg
84
What are some examples of type 1 respiratory failure?
- pneumonia, asthma, COPD, fibrosis - pulmonary disease (embolism or hypertension) - reduced perfusion and ⬇️ O2
85
What is a common treatment for type 1 respiratory failure?
- first option = nasal cannula - second option = optiflow (similar to nasal cannula) - third option = O2 face max - accounts for lung failing to perfuse
86
What are a few diseases that cause type 2 respiratory failure?
- asthma - COPD
87
When examining arterial blood gas (ABG), generally what is the firs step?
- examine pH - normal pH = 7.35-7.45
88
Once you have checked the pH, what is the second step of analysing the arterial blood gas (ABG) data?
- determine if abnormal pH is respiratory or metabolic - look at PaO2 and PaCO2 - look at HCO3-
89
What is the normal HCO3- level in the blood?
- 24mmol/L
90
What is the Henderson-Hasslebalch equation?
- CO2 + H2O = H2CO3 = HCO3- and H+ - ⬆️ CO2 = ⬆️ H2CO3 - ⬆️ H2CO3 = ⬆️ BHCO3- and H+
91
What does an increase in H+ do to blood pH?
- ⬇️ pH
92
If H+ ⬆️ and pH subsequently ⬇️, what does this to to ventialtion?
- central and peripheral chemoreceptors detect ⬇️ pH - apneustic centre signals ventral and dorsal respiratory groups - respiratory rate increases - CO2 is expired
93
What is generally step 3 when analysing arterial blood gas (ABG)?
- investigate the anion gap
94
What are anions and cations?
- anions have negative charge = HCO3-, Cl- - cations have positive charge = K+, NA+
95
Are all cations and anions counted in the body?
- no - more non counted anions than cations - this is why we study the anion gap
96
What is the anion gap?
- difference between cations and anions - specifically the anions that are not included in the formula
97
What is the anion gap formula?
- (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
What is the normal range for the anion gap?
- 3-11 mEq/L - blood must be neutral - measuring anion gap tells us what is causing metabolic acidosis
99
Why should the anion gap be 0?
- because all anions have a charge - BUT blood is neutral, so cations and anions must balance
100
What are the 2 types of anion gap?
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
Why do we need to measure the anion gap, and identify if gap is normal or high?
- 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
What are some common causes of a high anion gap?
- hyperalbuminaemia (high albumin) - hyperphosphataemia (high phosphate) - can cause alkalosis
103
What happens to anions when there is a normal anion gap present?
- ⬇️ in HCO3- - ⬆️ Cl- retained in kidneys to balance anion gap formula
104
What are some common causes of a normal anion gap?
- diarrhoea - renal tubular acidosis
105
What is the key for normal and high anion gap when trying to diagnose a patient?
- ⬆️ anion gap = ⬆️ organic acids - normal anion gap = ⬇️ HCO3-
106
What is generally used as step 5 when interpreting arterial blood gas (ABG)?
- determine compensatory mechanisms
107
How is respiratory compensatory determined?
- ⬇️ pH = ⬆️ ventialtion = ⬇️ CO2 - ⬇️ CO2 = ⬇️ H2CO3 = ⬆️ pH
108
How fast can respiratory compensation occur?
- within the first hour
109
How is metabolic compensatory determined?
- use pH - HCO3- levels - anion gap
110
When would metabolic compensatory be initiated?
- respiratory acidosis - kidneys retain HCO3- and excrete H+ - pH ⬆️
111
What are some common causes of respiratory acidosis?
- asthma - respiratory depression (opioids) - COPD
112
What are some common causes of metabolic acidosis, which is essentially a reduction in the HCO3-?
- Sepsis (tissue hypoxia) - Lactic acidosis (build up of acids) - Ketoacidosis (keto acids build up) - Severe diarrhea (anions lost in stool) - Renal tubular acidosis
113
What are some common causes of respiratory alkalinosis?
- severe vomiting - cushings disease - diuretics
114
What are some common causes of metabolic alkalinosis?
- altitude sickness - hyperventilation - hepatic failure - anxiety CNS trauma/disease
115
What is narcosis?
- excessive CO2 and nitrogen (N)
116
What does narcosis generally cause?
- hypercapnia (⬆️ CO2)
117
What does a pulmonary embolism do to oxygenation and CO2 levels?
- hypercapnia (⬆️ CO2) - hypoxaemia (⬇️ O2 partial pressure in blood)
118
What is central sleep apnea?
- respiratory drive is insufficient - unable to subconsciously breathe
119
What does central sleep apnea do to CO2 levels?
- hypercapnia (⬆️ CO2)

Year 1 HLB Respiratory (25 decks)

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