when it comes to diffusion across alveolar capillary membrane and tissue, O2 and CO2 move in the same direction along their gradients. T or F, F. when it comes to diffusion across alveolar capillary membrane and tissue, O2 and CO2 move in opposite directions along their gradients, , They both do but more so the destruction of alveolar tissues and associated capillaries, The sum of all pressures in the lung, at any point must equal ___mmHg , The sum of all pressures in the lung, at any point must equal 760mmHg, what is the PIO2 of RA at dry? what about fully saturated?, , Why is alveolar oxygen pressure (PAO₂) about 100 mmHg instead of 150 mmHg(humidified)?, , The diffusion gradient is much lower for O2 than CO2. T or F, F. it is higher, At rest, pulmonary capillary blood removes approx ___cc/min of O2 from the alveoli and replaces it with ___cc/min of CO2, At rest, pulmonary capillary blood removes approx 250cc/min of O2 from the alveoli and replaces it with 200cc/min of CO2, What is the Respiratory exchange ratio number? how did you get that?, if you do 200/250=0.8, , 100%, The alveolar gas equation is a formula used to approximate the..., , Once the PAO2 is calculated this value can be used to determine how well the lungs are transferring oxygen from alveoli into the blood. T or F, T, Alveolar air equation cannot be used to identify the cause of a low PaO2 (hypoxemia) T or F, F it can identify the cause, Why does alveolar gas volume shrink slightly during gas exchange?, , Why does alveolar pressure remain 760 mmHg even though alveolar gas volume shrinks?, , Why does nitrogen concentration increase in the alveoli during gas exchange?, , What is the alveolar air equation?, , PaCO2 is substituted for PACO2 because these 2 values are generally equal in absence of high alveolar dead space. T or F, T, if FiO2 > 0.6, then acceptable to use: ___, , P(A-a)O2 is an index used to quantitate..., , Ideally the P(A-a)O2 would be zero but on average the normal difference is 10-15mmHg. T or F, T, Physiological shunt is the only cause of hypoxemia therefore calculation of P(A-a)O2 is one method of determining the cause of hypoxemia in a patient. T or F, F, as an example say a patient's PaO2↓, PaCO2↑, P(A-a)O2 on RA is normal & at 100% fiO2 is normal. What is the abnormality in this case?as an example say a patient's PaO2↓, PaCO2↑, P(A-a)O2 on RA is normal & 100% fiO2 is normal. What is the abnormality in this case?, Hypoventilation, as an example say a patient's PaO2↓, PaCO2(normal or ↓), P(A-a)O2 on RA↑ & at 100% fiO2↑. What is the abnormality in this case?, Absolute shunt, as an example say a patient's PaO2↓, PaCO2(normal or ↓ or ↑), P(A-a)O2 on RA↑ & at 100% fiO2 is normal. What is the abnormality in this case?, Relative shunt, as an example say a patient's PaO2(normal at rest), PaCO2(normal or ↓), P(A-a)O2 on RA is normal at rest & at 100% fiO2 is normal. What is the abnormality in this case?, Diffusion defect, what is the cause of hypoxemia in this case? calculate P(A-a)O2 for more info, remember to know normals for PaO2, PaCO2, pH, , What treatment should be initiated?, O2 therapy via HFNC, In the previous flashcard, try oxygen therapy via HFNC at FiO2=0.35, the new PaO2 is 198mmHg. Has the shunt responded to O2 therapy?, you should get a PaO2=207.55mmHg and a P(A-a)O2=9.55mmHg. Which means it has responded well to O2 therapy, What is fick's law? what is fick's law of diffusion formula?, , in regards to fick's law of diffusion formula which variables increase the diffusion rate and which decrease the diffusion rate?, , Alveolar capillary membrane is a ________, Alveolar capillary membrane is a liquid barrier, Factors which affect the rate of diffusion in a liquid environment will not determine the rate of diffusion of O2 and CO2 across the alveolar capillary membrane. T or F, F. , What are the two factors which determine rate of diffusion of gas molecules in a liquid environment are..., , Individually, Graham's Law and Henry's Law show how each factor influences the rate of diffusion of CO2 and O2 across the alveolar capillary membrane. T or F, T, quick comparisons between Fick's, Graham's and Hentry's law, , in Graham's Law the lighter gas = slower diffusion rate. T or F, F. Lighter gas = faster diffusion rate, according to Graham's Law which gas diffuses faster, O2 or CO2? by how much?, O2 diffuses 1.17 faster than CO2 because O2 is the lighter gas, According to Henry's Law the amount of gas dissolving in a liquid is directly proportional to the gas partial pressure. T or F, T, According to Henry's Law which gas is more soluble, O2 or CO2?, at body temp, CO2 is 24 times more soluble than O2, Combining Graham's and Henry's Laws, which gas diffuses faster O2 or CO2? by how much?, , define capillary transit time, how much time is it?, Capillary transit time is the amount of time blood spends traveling through the pulmonary capillaries around an alveolus. Normally it is 0.75 seconds at rest, What is alveolar-capillary equilibrium?, Alveolar-capillary equilibrium occurs when the partial pressure of a gas in capillary blood becomes equal to the partial pressure of that gas in the alveoli., For oxygen how long does it take to reach alveolar-capillary equilibrium in normal conditions?, within the first 0.25 seconds of capillary transit, What does it mean when a gas is diffusion limited?, when the rate of transfer is limited by how fast the gas can cross the AC membrane. Struggles to reach equilibrium when the AC membrane is thick , What does it mean when a gas is perfusion limited?, when the rate of transfer depends on how much blood flows past the alveoli. Gas reaches equilibrium occurs quickly but the only way to move more gas is to bring more blood, Is O2 transfer diffusion limited or perfusion limited?, both, Is CO transfer diffusion limited or perfusion limited?, only diffusion limited, Is NO2 transfer diffusion limited or perfusion limited?, only perfusion limited, why don't we use O2 to determine the extent to which the AC membrane impedes the diffusion rate? which type of gas should be used then? perfusion limited/diffusion limited? , , what would the equilibrium line look like for CO?, , What gas do we use to check pulmonary blood flow limitations? is it perfusion/diffusion limited? , therefore N2O is perfussion limited only and can be used to measure pulmonary blood flow, to measure pulmonary blood flow limitation, increased blood flow removes the N2O saturated blood from the capillary sooner allowing more N2O to cross the AC membrane. T or F, T, what would the equilibrium line look like for N2O?, , In what way would changes in pulmonary blood flow interfere with the measurement of diffusion capacity of the lung for oxygen (as opposed to carbon monoxide)?, CO is only diffusion limited while O2 is diffusion limited & perfusion limited. So using Oxygen to measure to see if AC membrane is the problem is not accurate because O2 also reflect blood flow thereby skewing the results , What is the main reason CO2 diffuses across the capillary membrane so much more rapidly than O2?, because CO2 is so much more soluble than O2 (Henry's law), What is the diffusion path length?, , what are some abnormal examples that can increase the diffusion path?, , What is the diffusion surface area?, , what might decrease the diffusion surface area?, , , , what is a DLCO test?, , what is normal DLCO values? what is normal DLO2 values?, , What are all the factors affecting DLCO?, , What are some conditions that decrease diffusion capacity which affect DLCO test?, , why do we clinically use DLCO?, , , the DLCO test. Because using the blood-gas analysis that measures arterial blood reveals the problem only during exercise not at rest whereas using DLCO test reveals the problem even without exercise, , C, , B, , C, , B, , C, , A.

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