Lecture 5: Control of Respiration Flashcards

1
Q

why would you take arterial blood gas rather than vein

A

to assess:

  • acid base balance
  • ventilatory status
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2
Q

what are the important buffers in the blood

A
  • bicarbonate
  • circulatory proteins with histodine residues, eg albumim
  • phosphates
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3
Q

how can we measure the levels of fixed acids

A

the anion gap:

difference between uncounted anions and uncounted cations

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4
Q

what are the main causes of non-anion gap metabolic acidosis

A

loss of bicarbonate through:

  • renal tubular acidosis
  • gastrointestinal losses
  • acetozolamide
  • excess chloride administration
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5
Q

what is the range of acidaemia

A

<7.38

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6
Q

what is the range of alkalaemia

A

> 7.44

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7
Q

what are causes of metabolic alkalosis

A
  • vomiting as it removes H+

- increased aldosterone

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8
Q

what are causes of respiratory acidosis

A
  • increased dead space eg emphysema
  • muscle weakness
  • depression of respiratory centre
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9
Q

what are causes of respiratory alkalosis

A

hyperventilation due to pain or anxiety or pregnancy

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10
Q

where’s the respiratory centre in the brain

A

pons and medulla in the hindbrain

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11
Q

what are the groups of the medulla and what do they do

A
  • dorsal respiratory: trigger inspiratory impulses

- ventral respiratory: triggers inspiratory and expiratory impulses during exercise

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12
Q

what are the inspiratory muscles

A
  • diaphragms
  • external intercostal muscles
  • sternocleidomastoid
  • scalene muscles
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13
Q

what are the muscles of exhalation

A
  • abdominal wall

- internal intercostal muscles

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14
Q

what are the mechano and irritant receptors in the lung

A
  • C-fibre nociceptors
  • mechanically sensitive receptors
  • lung stretch receptors
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15
Q

where are central chemosensors and what do they detect

A
  • hindbrain
  • detect H+ conc. in CSF
  • very sensitive
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16
Q

what are the bodies of peripheral chemosensors

A
  • carotid body outside bifurcation of carotid arteries

- aortic body within aortic arch

17
Q

what do the carotid body detect

A
  • pH
  • PaCO2
  • PaO2
18
Q

what do the aortic body detect

A
  • paO2

- PaCO2

19
Q

causes of respiratory depression

A
  • opioids / narcotics
  • alcohol
  • anaesthesia
  • cerebral diseases eg cerebral vascular accident
20
Q

what ABG results do you get from respiratory depression

A
  • hypoxaemic hypoxia
  • hypercarbia
  • acute respiratory acidosis