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68 Cards in this Set
- Front
- Back
What is the O% in air?
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21%
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What is the CO2% in air?
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0.03%
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What is the N% in air?
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78%
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How much compressed air does an E tank hold?
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1900psi(g)
14.3psi(a) |
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A full E cyclinder will evolve ____L of gaseous O2 at atm.
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660L
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If a tank pressure is 950 psig, the tank is ___% full. How many L will be left?
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50% (950/1900)
330L |
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How much will 1L of compressed O2 yield of gaseous O2?
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150L
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How much will 1L of liquid O2 yield of gaseous O2?
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850L
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The concentration of O2 in alveoli AKA the driving end of O2 pp gradient is the ________ pp between _______ & ___________________________.
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Alveolar (PAO2)
Alveolus & Pulm Cap blood (O2 diffuses down gradient into serum) |
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How does O2 bind when it is in serum and it enters the RBC? Wht does it bind to? Based on what? (Hope this last question makes sense to ya'll!)
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REVERSIBLY
Hgb OxyHgb dissociation curve |
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What causes the rapid O2 exchange that evens out Hgb saturation in RBC's?
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arterial pp (PaO2)
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O2 DISSOCIATES from Hgb (per OxyHgb dis curve) down pp gradient into ??? (3)
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Capillary wall
Cell Mitochondria |
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What is the final step in the oxygen cascade? Where does it happen and at what torr?
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O2 combines with free H+; H2O made!
MITOCHONDRIA LEVEL @ 0.5 torr |
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What does VO2 mean?
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Oxygen consumption by the tissues.
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What is the final electron acceptor?
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Oxygen!
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Where is CO2 produced?
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Mitochondral Cytosol
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***___ production is tightly coupled to ___ consumption***
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CO2
O2 |
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What is the normal A-aDO2 gradient?
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10 torr (Room Air)
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What an FiO2 of 100%, what is the A-aDO2 gradient? What is it due to?
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30-50 torr
Anatomic shunt |
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What is the normal anatomic shunt? Via what veins?
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2-5%
Bronchial, pleural, and thebesian veins |
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What is the A-aDO2 equation?
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A-aDO2 = PAO2 - PaO2
Solve for PAO2 = (PB - PH2O)FiO2 - PaCO2/0.8 |
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What is the Resp Exchange ratio?
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Fraction of oxygen consumption(VO2) used for:
Oxidative phosphorylation & Associated CO2 production |
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What is the equation for the resp exchange ratio? What does it equal?
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VCO2 / VO2
=0.8 |
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The resp exchange ratio compensates for ______ CO2 transferred into the alveolus than _____ removed from.
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LESS CO2 transferred than O2 removed
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Since the A-aDO2 changes with varying conc of FiO2, what is used instead D/T its staying relatively constant regardless of FiO2? What is the normal value?
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a-ADO2
Nl > 0.75 |
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O2 is carried in combination with _____ AND dissolved in __________
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Hgb
Plasma |
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O2 transport is a fxn of: (3)
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CO
Hgb Hgb affinity for O2 |
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1 gm of Hgb carries ________ mL O2
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1.34
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O2 is not dissolved nor yielding a pp when its?
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Bound to Hgb
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What does the OxyHgb curve show?
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Varying O2 tensions in correlation with O2 saturation.
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During a L shift, what does Hgb do to O2?
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HOLDS onto it!
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When can blood exchange large amounts of O2 with small changes in O2 tension?
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B/t 20-80 torr
This maintains the driving pressure b/t bld & tissues |
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What is the definition for P50?
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O2 tension at which 50% of Hgb is saturated
(37 C, 40 torr, pH 7.4) |
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What does oxygen content involve?
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O2 dissolved & bound to Hgb
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What is the value to O2 in plasma?
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0.003mL O2/dl plasma/torr
1dL = 100mL |
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What is the nl O2 content in arterial blood(CaO2)?
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20gm %
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What is the nl O2 content in venous blood (CvO2)?
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15 gm %
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What is the OXYGEN CONTENT equation?
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CaO2 = (Hgb x 1.34 x SaO2) -Oxygen attached to Hgb + (PaO2 x 0.003) - Oxygen dissolved in plasma
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What is the equation for O2 transport?
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TO2 = CaO2 x CO
(TO2 may exceed DO2) ex: AV fistula |
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What is the equation for O2 delivery?
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DO2 = CO x CaO2
ex: Taken up by tissues |
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What is the equation for O2 consumption?
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VO2 = CO x C(a-v)O2
Assuming no shunt NL = 250 ml/min (~3mg/kg/min) |
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Nl venous O2 = ?
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40 torr
70% saturation O2 content = 15 gm % |
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Anesthesia affects oxygenation by ?
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~10-15% CO shunt
Atelectasis VQ mismatch worse when low TV. |
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During GA, what is the lowest acceptable FiO2?
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30%
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If 1L NC is 24% FiO2, what is 4L NC?
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36%
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What are the advantages of O2 use in Anesthesia?
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Dec inc of post-op infxn
Dec PONV Improved oxygenation of marg perf tissues Red risk of liability in hypoxia-related injuries |
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What does the HBO do?
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Inc HP, O2 tension, N gradient & O2 supply, tissue oxygenation, slows clostridea growth D/T PO2 > 250 torr
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HBO uses?
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Decompression sickness
Crush injuries, skin grafts Chr. Osteomyelitis Is bacteriostatic CO poisoning, cyanide tox, acute severe anemia |
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HBO Toxicity D/T
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Superoxides
Singlet O2 Hydroxyl radical Hydrogen peroxide |
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Key point for CO poisoning
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CO reversibly binds to Hgb 200x > O2
CARBOXYHGB interferes w/ BINDING & DISSOCIATION of O2 & Hgb |
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How is CO poisoning dx'd?
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Co-oximeter (Diff. carboxy & oxy Hgb)
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S/sxs of CO poisoning?
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HA,NV, NO cyanosis, PaO2 NORMAL on ABG, pulse ox FALSELY HIGH
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CarboxyHgb cause what kind of shift on the dissociationn curve?
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LEFT
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What is the early warning of hypoxemia?
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O2 sat < 90%
PaO2 of 60 torr or less. |
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What is the ETCO2 in vol %? torr?
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4-6 vol %
35-45 torr |
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At rest, how much CO2 do we produce?
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2/5mL CO2/kg/min
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What is hypoxia?
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Red of oxygen supply to a tissue
RESULT: CYANOSIS Cessation of oxid. phosphorylation @ mito level = LACTATE/PYRUVATE RATIOS RISE ATP/ADP RATIOS FALL! |
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Hypoxia causes what kind of damage?
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IRREVERSIBLE damage
Occurs w/i 4-5 minutes |
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What is a major effect of hypoxia?
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INTRACELLULAR ACIDOSIS
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What is hypoxemia? What is it D/T?
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Deficient oxygenation of the blood.
PaO2 <60 torr, PvO2 < 30 torr Dec PAO2 or true pulm shunt |
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When venous blood from bronchial, thebesian, and the L heart enter the LA & LV, it is called what?
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Anatomic shunt
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R heart blood enters the L heart WITHOUT exchanging alveolar gas D/T?
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True (Absolute) Shunt
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What does NOT improve a true shunt? What causes it?
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Increasing the FiO2
Atelectasis, Pulm edema, Bilat pneumonia |
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What are the compensating factors in a true shunt?
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Inc CO
Dec O2 utilizaton which causes: Inc A-aDO2 systemic shunt Pulm distribution perf changes DECREASE shunt |
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What is the most common cause of hypoxemia?
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Relative shunt (VQ mismatch)
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What is the nl V/Q?
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>0.75
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What helps differentiate b/w VQ mm & true shunt?
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O2
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What is the Intrapulm Shunt Fraction?
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Qs/Qt =
A-aDO2 (0.003) / (CaO2 - CvO2) + (A-aDO2)(0.003) CaO2 - CvO2 = 5 0.003 = Sol coefficient O2 in plasma |