Chapter 42 Worksheet Flashcards
what is acute hypoxemia?
hypoxemia is a decreased level of oxygen in the blood. “acute” means sudden
What are the threshold criteria for defining hypoxemia in adults according to the AARC clinical?
PaO2 < 60 mm Hg
SaO2 <90%
Describe the two compensatory mechanism for the cardiopulmonary system when faced with hypoxemia
Lungs: increased ventilation: faster rate and increased depth
Heart: Increased cardiac output: faster heart rate, increased stroke volume equals increased CO2
in what acute cardiac condition is oxygen therapy especially important?
Myocardial infarction, because when the heart is stressed or damaged, it is especially important to reduce workload
What effects does hypoxemia have on the pulmonary blood vessels? What are long term consequences of this effect?
alveolar hypoxemia causes vasoconstriction of pulmonary vessels. if prolonged, this results in pulmonary hypertension, increased work of the right heart, and eventually cor pulmonale or right heart failure
List 3 basic ways to determine if a patient needs O2?
- laboratory evidence
- patient’s specific condition or problem
- bedside assessment
List 6 common acute clinical situations where hypoxemia is so common that oxygen therapy is usually provided
- carbon monoxide poisoning
- cyanide poisoning
- shock
- trauma
- acute myocardial infarction
- post-op patients
oxygen toxicity can affect what two organ systems?
- lungs
2. central nervous system
the harm caused by oxygen is influenced by what two factors?
- PO2
2. exposure time
describe the effect on lung tissue by breathing excessive O2
tracheobronchitis and substernal chest pain develop during the first 12 hours. Next, vital capacity and lung compliance being to decrease (12 to 30 hours) A state similar to bronchopneumonia develop. The alveoli and capillaries are damaged, resulting in interstitial edema. Type 1 cells are destroyed. In the end stages, hyaline membranes form, the pulmonary fibrosis and hypertension develop
what is meant by “viscous circle” in reference to oxygen toxicity?
high FiO2 caused O2 toxicity, which causes shunting, which results in lower PaO2 levels, which require high FiO2 levels for treatment
although every patient is unique, what general rule of thumb can be applied to prevent oxygen toxicity
limit exposure to 100% oxygen to less than 24 hours whenever possible. High FiO2 levels are acceptable if the concentration can be lowered to 70% within 2 days, and 50% within 5 days
what specific type of COPD patient is likely to experience depression of ventilatory drive while breathing oxygen
a small percentage of severe COPD patients with carbon dioxide retention tend to ventilate less when exposed to moderate to high levels of oxygen
when should oxygen be withheld from a hypoxic COPD patient to avoid depressing ventilation
never
during what time period after birth is a preemie likely to develop ROP
premature infants and neonates up to 1 month
