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55 Cards in this Set
- Front
- Back
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Formula to determine blood CO2
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pH = 6.1 + log ([Bicarb]/[CO2]). A known value of bicarb is used and blood pH is measured. Solve for [CO2]
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What is polarography?
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technique to measure [oxygen] in fluid. uses rate of current flow (which is directly proportional to oxygen content)
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When is maximum expiratory flow greatest? empty lungs or filled lungs?
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filled lungs obviously
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Why does a maximum expiratory flow rate occur?
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There is a point when the force of exhalation causes bronchi to collapse, and increase in expiratory force causes a proportional collapse in the bronchi/alveoli. at this point, the more we push, the more constriction occurs so the rate stays the same
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As lung volume decreases, what happens to the maximum expiratory flow rate?
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decreases
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Why does lung volume decreasing cause a lower maximum expiratory flow rate?
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as lung volume decreases, there are less elastic forces keeping the bronchioles open. bronchiole collapse causes decreased flow rate
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In a patient with constricted lungs (fibrotic changes, tuberculosis), what do we expect to see regarding their maximum expiratory flow rate?
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lower than normal
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In a patient with constricted lungs (fibrotic changes, tuberculosis), what do we expect to see regarding their residual volume?
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lower than normal
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In a patient with constricted lungs (fibrotic changes, tuberculosis), what do we expect to see regarding their lung capacity?
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lower than normal
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Why is it more difficult for patients with airway obstruction (asthma, COPD) to exhale?
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extra positive pressure in the cavity (during exhalation) increases likelihood of bronchiole collapse
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Why do patients with airway obstructive disorders (asthma, COPD) have an increased total lung capacity?
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higher negative pleural pressure is needed to bring air in the lungs, causing the lungs to expand more than normal = higher lung capacity
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Patients with airway obstruction have difficulty exhaling. This is shown by a residual volume that is (higher/lower) than normal?
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higher than normal. more air stays in the lungs. can't get out due to bronchial collapse as the pleural pressure increases so greatly to force air out.
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A patient with a respiratory disorder has a total lung capacity greater than normal. What is the likely diagnosis? (asthma or tuberculosis). Why?
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asthma (airway obstruction causes a higher lung capacity as a greater negative pressure occurs to force air in. this causes lungs to hyper-expand)
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A patient with a respiratory disorder has a residual volume that is greater than normal. What is the likely diagnosis? (asthma or tuberculosis). Why?
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asthma. airway obstruction makes exhalation very difficult
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A patient with a respiratory disorder has a total lung capacity lower than normal. What is the likely diagnosis? (asthma or tuberculosis). Why?
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TB. fibrotic lung changes reduce the ability of lungs to expand. airway obstruction (asthma) causes higher negative pressure and more expansion of lungs
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What is the forced vital capacity (FVC).
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the max amount of air that can be exhaled
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Who would have a higher maximum expiratory flow rate? A patient with large lungs or small lungs?
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large lungs have more forces keeping them open, preventing bronchiole collapse
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What is the Forced expiratory volume at 1 second (FEV1)?
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The amount of air exhaled at 1 second
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What does the (FEV1)/(FVC) tell us?
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The % of air that was exhaled in 1 second. much lower in patients with airway obstruction
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In a patient with chronic asthma, what do we expect to see regarding their FEV1 compared to a normal person?
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decrease. asthmatics exhale much more slowly than normal
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What does the term pulmonary emphysema mean?
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extra air in the lungs
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How does smoking/chronic infection lead to emphysema?
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chronic infection = cilia paralysis = mucus build-up = obstruction of air flow = entrapped air
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4 major causes of problems with COPD
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airway resistance, less diffusing capacity (loss of alveolar surface area), shunts and dead space, pulmonary hypertension
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Why does pulmonary hypertension develop in patients with COPD?
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COPD = physiological shunts (no ventilation areas) = blood vessels constrict (pulmonary capillaries) = more resistance/ increase BP= right side heart failure
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What accumulates in the lungs during pneumonia?
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fluid and/or blood are in the alveoli
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Why do patients with atelectasis have a higher pulse ox than patients with pneumonia?
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The collapsed lung will collapse blood vessels with it, shunting more blood to the good lung.
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What is atelectasis?
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massive lung collapse
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2 major causes for atelectasis (not pneumothorax)
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airway obstruction and less surfactant
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How does airway obstruction lead to a collapsed lung?
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trapped air is absorbed into the blood and the alveoli collapse due to the negative pressure
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What happens in patients with fibrotic lung changes and trapped air in alveoli?
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the trapped air is absorbed into the blood and tries to collapse the alveoli, but they do not collapse and a very negative pressure builds. this forces fluid into the alveoli form the pulmonary capillaries
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Function of surfactant
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resist surface tension to prevent collapse of lungs
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How does an asthma attack happen as an allergic response?
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excess IgE is made towards the allergen. IgE binds mast cells, release histamine, SRS-A etc. localized inflammation/edema occurs to block the airways. bronchiolar spasms also occur
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Why does tuberculosis infection lead to fibrotic changes in the lungs?
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following bacterial infection, tissues "wall off" infection to prevent spread. walling off makes the infected area of tissue more fibrotic to prevent spread
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Why does tuberculosis lead to increased workload on respiratory muscles?
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fibrotic changes of the lung (due to walling off the infection) make the lung less pliable
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Why is cyanide poisoning fatal?
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inhibits cytochrome oxidase so oxidative phosphorylation cannot occur, regardless of oxygen content
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Would it be useful to give a patient with cyanide poisoning more oxygen?
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not really, the cyanide is preventing cytochrome oxidase from allowing oxygen to be used in cellular respiration. lack of oxygen isn't the problem
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Would you give a patient with the disease "beriberi" oxygen to help them?
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not that helpful. these patients have problems using the oxygen. they already have enough
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Is oxygen therapy useful in treating patients with atmospheric hypoxia?
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yes. they aren't getting enough oxygen out of the air so we should give it to them
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Is oxygen therapy useful in treating patients with hypoventilation hypoxia?
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yes. pure oxygen can help move more oxygen into the lungs
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Is oxygen therapy useful in treating patients with hypoxia due to impaired alveolar diffusion?
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yes. we can give pure oxygen and increase the gradient to very high levels in the alveoli to ensure diffusion across the respiratory membrane
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Is oxygen therapy useful in treating patients with anemic hypoxia?
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not really, they might already have normal oxygen, but cannot carry it/use it. but we might be able to give some as dissolved oxygen in plasma
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Even though they cannot bind oxygen (due to low Hb), why might we give oxygen therapy to severely anemic patients?
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some oxygen can be carried in dissolved state in plasma. can be the difference between life and death
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Cyanosis occurs when arterial blood contains more than how much deoxygenated blood?
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5% (5 grams/100mL)
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Why do anemic patients rarely become cyanotic?
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they don't have enough Hb to bind the 5% deoxygenated blood for cyanosis to occur
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Which is more likely to lead to cyanosis? anemia or polycythemia vera
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polycythemia vera, there are more RBCs so it is easier to obtain 5% deoxygenation of hemoglobin
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If hypoxia is occurring due to poor diffusion of oxygen across the respiratory membrane, would we expect to see hypercapnia as well?
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no, CO2 diffuses 20x better and wouldn't be as affected by these changes. CO2 can still get out of the blood
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In a patient with hypoxia due to hypoventilation, what would we expect their CO2 blood levels to be? high or low
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high, the CO2 is staying in the blood in stead of being exhaled
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In patients with circulatory deficiency, hypoxia and hypercapnia occur. Which condition is in a worse state?
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hypoxia. the hypercapnia is still not as bad this hypoxia because CO2 can be transported 3x better than oxygen. the hypercapnia is not as serious as the hypoxia here
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What is dyspnea?
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air hunger, causes disorientation and mental anguish
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What does a resuscitator do?
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forces air into the lungs and allows it passively leave
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How does a tank respirator work?
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has a leather diaphragm that creates negative and positive pressures
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While forcing air into the lungs, the resuscitator creates _______ pressure in the LUNGS. (positive or negative)
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positive. pressure in the lungs is increasing
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How does a tank respirator force air into the lungs during inhalation?
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creating a negative pressure outside the body (conversely, a resuscitator increases the pressure in the lungs)
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What happens to venous return while air is being forced into the lungs while a patient is in a resuscitator?
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venous return decreases since pressure is very high in the chest area. veins cannot push blood against this pressure
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What do we expect to see with regard to cardiac output while forcing air into a patient during resuscitation?
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decreased cardiac output. venous return decreases since pressure is very high in the chest area. veins cannot push blood against this pressure
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