Oxygen Therapy Flashcards
What is ventilation?
Bringing in air from the environment to the lungs
What is diffusion?
Moving air from the alveoli to the capillaries
What are the factors that determine the amount of oxygen absorbed from the pulmonary system?
[Hb]
Blood volume
Circulation
What are the factors that determine the amount of oxygen delivered from the capillaries to the tissues?
Tissue oxygen use
What percent of oxygen is dissolved in plasma?
2-3%
What are the factors that shift the oxygen-Hb saturation curve to the left? (temp, 2,3, BPG, pH, and CO)
Decreased temp
Decreased 2,3 BPG
Decreased pH
Increased CO
What is the definition of hypoxia?
O2 delivery to the tissues is inadequate to meet metabolic needs
What is the definition of hypoxemia (arterial PO2 levels for adults and neonates)?
- Arterial PO2 less than 60 mmHg
- Less than 50 mmHg for neonates
What is Dysoxia?
Impaired ability for tissues to utilize oxygen
What are the three major causes of hypoxia?
- Hypoxemia
- Impaired blood flow
- Dysoxia
What are the two major causes of impaired alveolar-capillary diffusion?
- Inadequate time for PO2 to equilibrate
- Severe thickening of the membrane
What is a common cause of dysoxia?
CN poisoning
What is the normal V/Q ratio in the apices? Bases?
Apices = 3 Bases = less than 1
What is the V/Q ratio of dead spaces?
infinite
How does aging lower the V/Q ratio?
Lowers the elasticity of the alveoli
What is an anatomic shunt?
Right to left shunt that does not participate in gas exchange (bronchiolar capillaries)
Do anatomic shunts change with respiratory therapy?
No
What is the anatomic dead space?
Conducting airways
What are alveolar dead spaces? Do these respond to oxygen therapy?
Poorly perfused alveoli that do respond to oxygen therapy
What is the effect of hypoxemia on pulmonary artery pressures? What, then, is the effect of the heart?
- Increases
- Increased workload of the heart
How does hypoxemia result in impaired renal function?
Decreased blood flow
What is the effect of hypoxemia on the cerebral blood flow?
Vasodilation
What is the normal percent of oxygen in RA?
21%
What is the major, overall goal of oxygen therapy?
To maintain adequate tissue oxygenation
What are the physiologic effects of being exposed to 100% O2 for 0-12 hours?
- Tracheobronchitis
- Substernal chest pain
What are the physiologic effects of being exposed to 100% O2 for 12-24 hours?
Decreased vital capacity
What are the physiologic effects of being exposed to 100% O2 for 24-30 hours?
- Decreased lung compliance
- Increased P(A-a)O2
- Decreased exercise PO2