SACCM 15: Oxygen Therapy Flashcards
What is the difference between hypoxia and hypoxemia?
- hypoxia means decreased O2 supply to the tissues
- hypoxemia means decreased oxygenation of arterial blood
Explain how there can by hypoxemia without hypoxia and hypoxia without hypoxemia.
- 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
List 5 causes for hypoxemia
- Hypoventilation
- Ventilation/Perfusion mismatch
- decreased O2 content of inspired air (e.g., high altitude)
- Diffusion impairment
- intrapulmonary shunt
Whast are the 3 main causes for tissue hypoxia?
- Hypoxemia
- Perfusion impairment (i.e., circulatory shock)
- Anemia
If you use non-humidified air for oxygen supplementation what are the 4 complications this can lead to?
- Drying and irritation of the nasal mucosa
- Respiratory epithelial degeneration
- Impaired mucociliary clearance
- Increased risk of infection
How much FiO2 can be achieved with flow-by oxygen?
2-3 L/min will provide 25-40% FiO2
(if within 2 cm of nostrils and no panting)
How much FiO2 can be achieved with an oxygen mask?
with a tight fitting mask and high flow rate about 50-60%
What is the recommended flow-rate for nasal cannula oxygen administration and what FiO2 ratio can be achieved?
50-150 mL/kg/min
30-70% FiO2
What is the advantage of 2 nasal cannulas over just 1
- 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
Between which tracheal rings should you place the tracheostomy tube?
between 4th and 5th tracheal rings
What muscle must be bluntly dissected to place a tracheostomy tube?
sternohyoid muscle (between 3th and 5th tracheal ring
By how much will the hyperbaric oxygen chamber treatment increase the % of dissolved O2 in the blood?
from 10 to 20 %
Explain how oxygen supplementation may cause hypoventilation and which patient population is predisposed to this?
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
What are the 5 phases of oxygen toxicity?
- Initiation phase
- Inflammatory phase
- Destruction phase
- Proliferative phase
- Fibrosis phase
Which phase of oxygen toxicity has the highest mortality?
The destruction phase