15: Oxygen Therapy Flashcards

1
Q

What is the difference between hypoxia and hypoxemia?

A
  • hypoxia means decreased O2 supply to the tissues
  • hypoxemia means decreased oxygenation of arterial blood
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2
Q

Explain how there can by hypoxemia without hypoxia and hypoxia without hypoxemia.

A
  • Oxygen delivery relies on CO and CaO2 → if CaO2 is lower (hypoxemia) increased CO may compensate for this to a degree
  • If perfusion is compromised (e.g, shock, anemia, etc.) there may be tissue hypoxia without hypoxemia
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3
Q

List 5 causes for hypoxemia

A
  • Hypoventilation
  • Ventilation/Perfusion mismatch
  • decreased O2 content of inspired air (e.g., high altitude)
  • Diffusion impairment
  • intrapulmonary shunt
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4
Q

Whast are the 3 main causes for tissue hypoxia?

A
  • Hypoxemia
  • Perfusion impairment (i.e., circulatory shock)
  • Anemia
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5
Q

If you use non-humidified air for oxygen supplementation what are the 4 complications this can lead to?

A
  • Drying and irritation of the nasal mucosa
  • Respiratory epithelial degeneration
  • Impaired mucociliary clearance
  • Increased risk of infection
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6
Q

How much FiO2 can be achieved with flow-by oxygen?

A

2-3 L/min will provide 25-40% FiO2

(if within 2 cm of nostrils and no panting)

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7
Q

How much FiO2 can be achieved with an oxygen mask?

A

with a tight fitting mask and high flow rate about 50-60%

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8
Q

What is the recommended flow-rate for nasal cannula oxygen administration and what FiO2 ratio can be achieved?

A

50-150 mL/kg/min

30-70% FiO2

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9
Q

What is the advantage of 2 nasal cannulas over just 1

A
  • higher flow rates can be administered without causing as much discomfort as letting it flow through just one cannula
  • can therefore administer higher flow rates
  • same flow rate, however, will not achieve higher FiO2
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10
Q

Between which tracheal rings should you place the tracheostomy tube?

A

between 4th and 5th tracheal rings

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11
Q

What muscle must be bluntly dissected to place a tracheostomy tube?

A

sternohyoid muscle (between 3th and 5th tracheal ring

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12
Q

By how much will the hyperbaric oxygen chamber treatment increase the % of dissolved O2 in the blood?

A

from 10 to 20 %

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13
Q

Explain how oxygen supplementation may cause hypoventilation and which patient population is predisposed to this?

A

in a normal animal hypercapnia is the main drive for respiration

in animals with disease (e.g., chronic pulmonary disease, BAS) causing chronic hypercapnia the CO2 devels do not drive respiration and hypoxemia is the main drive

When giving these animals supplemental oxygen they may lose their drive to ventilate leading to hypoventilation and respiratory failure

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14
Q

What are the 5 phases of oxygen toxicity?

A
  1. Initiation phase
  2. Inflammatory phase
  3. Destruction phase
  4. Proliferative phase
  5. Fibrosis phase
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15
Q

Which phase of oxygen toxicity has the highest mortality?

A

The destruction phase

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16
Q

Explain the pathophysiology of oxygen toxicity

A

Oxygen is directly toxic to the pulmonary epithelium

Oxygen ⇒ O2-derived free radical species ⇒ cellular antioxidant stores become depleted ⇒ epithelial cell damage ⇒ recuitment of inflammatory cells and release of inflammatory mediators ⇒ increased endothelial permeability and edema formation

⇒ severe tissue destruction

⇒ increased accumulation of type II pneumocytes and monocytes

⇒ collagen deposition and interstitial fibrosis

17
Q

What is recommended to avoid oxygen toxicity

A

Do not administer and FiO2 > 50% for longer than 24-72 hours