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
how can we reduce the risk of ROP
maintain PO2 levels less than 80 mm Hg. Minimize other factors such as acidosis
how can O2 cause atelectasis
FiO2 levels above 0.50 cause atelectasis by washing nitrogen out of poorly ventilated units. The oxygen diffuses into the blood, and the alveoli collapse
how can we reduce the risk of absorption atelectasis
use the lowest FiO2 levels. Identify at risk patients. Use hyperinflation therapies to avoid or reverse the atelectasis
what is the fire triangle
oxygen, heat, fuel
what is the biggest hazard in the home setting
smoking
when should we attach a cannula to a bubble humidifier
when the flows are greater than 4 L/min (also infants and children)
what maximum flow does the text suggest for newborns
2 L/min
how does the patient breathing pattern affect the FiO2 delivered to the lungs when using a low flow device such as a cannula
a patient has a saturation of 94% on 2 L by cannula. he exercise and increases rate and depth, drawing in more room air while the O2 flows constantly at 2L. The additional airs drops the FiO2 in the trachea and the saturation
what is the primary disadvantage of the transtracheal catheter
requires surgical procedure; maintenance
what FiO2 range is usually delivered by low-flow devices
low 24% to 45%
because you cant tell exactly how much oxygen a patient is receiving at any given moment from a cannula or any low-flow device, how can you assess the effects of administering the drug
assess the patient response (clinical, SpO2)
in what setting are reservoir cannulas usually used
the home or ambulatory patients who need increased mobility
what is the primary difference between the partials rebreathing and non-rebreathing masks
valves; particularly between the bag and the mask
how can you tell if a non-breathing mask has an adequate flow rate
the bag does not fully deflate on inspiration
why does the AEM have larger opening on the side of the mask than the simple oxygen mask
allow excess flow and patient exhalation to escape
what effect does raising the delivered flow from the flowmeter have on the FiO2 delivered by an AEM?
little or no effect
how do you boost the total flow when using an AEM
increase the input flow
describe an easy way to tell if an air entrainment nebulizer is providing sufficient gas to meet the patients needs
observe the mist on the expiratory side when the patient inhales. calculate the flow delivered by the device. measure the patient minute ventilation, and multiply by 3. compare the two values
give on example of a specialized flow generator that produces an aerosol
a gas injection nebulizer
what effect does downstream resistance to flow have on FiO2 and total flow delivered by a typical AEM or nebulizer entrainment system
downstream resistance increases the FiO2 and decreased total flow delivered
