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114 Cards in this Set
- Front
- Back
The respiratory center in the ____ and ____ integrates sensory info about level of O2 and CO2 in blood and determines signals to send to resp muscles.
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medulla oblongata and pons
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Respiratory center detects changes that activate central and peripheral _____, sending impulses to respiratory center and triggering incr or decr. in ____.
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chemoreceptors, breathing rate
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This center antagonizes effects of pneumotaxic center, and promotes inspiration by stimulation of neurons in medulla oblongata
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apneustic center
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This respiratory center is located dorsally in medulla and controls inspiration, neurons located near termination sites of afferent fibers of cranial nerves 9 and 10 --> causes inspiration when stimulated
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dorsal respiratory group
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This respiratory area is located in the pons and controls pattern and rate of breathing, communicates w apneustic center to TURN OFF INSPIRATION
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pneumotaxic area
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This respiratory area extends full length of ventral medulla and stimulates muscles of expiration (passive)
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ventral respiratory group
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These compose the respiratory rhythmicity center in the medulla
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ventral resp group and dorsal resp group
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The apneustic and pneumotaxic centers are located in the
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pons
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This respiratory center inhibits:
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pneumotaxic center
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These respiratory centers stimulate
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apneustic center, dorsal resp group, ventral resp group
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These sensors of the resp center are located anterolaterally in medulla and are extremely sensitive to H+ ions
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central
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H+ crosses blood-brain barrier (well/poorly) and CO2 therefore indirectly controls this region through formation of _____ and dissociation to ____.
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poorly, carbonic acid, H+
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CO2 + H20 --> H2CO3 -->
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H+ + HCO3-
hydrogen ion and carbonic acid |
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Central sensors in resp center respond to changes in _____ which is effective in regulating PaCO2.
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CSF H+
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Increases in PaCO2 elevate CSF H+ concentration which activates
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chemoreceptors.
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Over the course of ____, CSF HCO3- can compensate to match any change in arterial HCO3-.
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a few days
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Peripheral chemoreceptors are located in these 2 spots and are innervated by those 2 nerves
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carotid bodies (CN9)
aortic bodies (CN10) |
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Peripheral chemoreceptors are sensitive to changes in these 4 things:
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O2, CO2, pH, and arterial perfusion pressure
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Peripheral chemoreceptors stimulate inspiratory center when PaO2 decreases, most seen when MAP <
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70 mmHg
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The effect of peripheral chemoreceptors in response to hypoxia is eliminated by as little as ___ MAC.
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0.1 MAC
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Changes in peripheral chemoreceptor response to hypoxia may be dicey in patients with:
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COPD - dependent on hypoxic resp drive!
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These 2 receptors in lungs can influence respiration:
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stretch and irritant
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Three components of the respiratory process:
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ventillation, diffusion, perfusion
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ventillation
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mechanical movement of air flow to and from atmosphere and alveoli, involves work of breathing and requires nervous system control
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Surfactant is produced by ____ cells and reduces ____ of fluid lining alveolar sacs, decreasing tendency to ____.
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type II cells, surface tension, collapse
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This is the movement of gases down a pressure gradient from an area of high pressure to low pressure.
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diffusion
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CO2 diffuses ____ faster than O2.
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20x
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The normally thin alveolar membrane can thicken when pulmonary pathologies exist, such as
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pulmonary edema or ARDS
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4 Factors affect diffusion through alveolar-capillary membrane
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partial pressure and gradients, surface area, thickness, and length of exposure
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Atmospheric air is composed of these molecules
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N2, O2, CO2, H2O vapor
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Atmospheric air exerts this pressure at sea level:
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760 mmHg
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Repiratory process doesnt actively involve the use of
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N2 or H20 vapor
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Pressures exerted by O2 and CO2 in the alveoli and in end capillary vessels:
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O2 100mmHg
CO2 40mmHg |
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The purpose of denitrogenating prior to induction is:
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to replace N2 in lungs with O2
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What are the pressures of O2 and CO2 in mixed venous blood?
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O2 40 mmHg
CO2 45 mmHg |
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This law states that when a gas is exposed to liquid, some of it will dissolve into the liquid, determined by the partial pressure of that gas on the liquid and its solubility.
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Henry's Law
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This gas is highly soluble into blood:
This gas is highly insoluble in blood: |
CO2 dissolves
O2 insoluble |
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Pressure gradient
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difference between partial pressures, exists between atmosphere and alveoli and between alveoli and pulm capillaries
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The greater the pressure difference across a gradient...
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the more rapid the flow of gases
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These increase pressure gradient:
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exercise, PP mech vent, intermittent PP breathing
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Causes of hypoxemia
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hypoventillation, low FiO2, V/Q mismatch, diffusion impairment, right to left shunt
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These causes of hypoxemia do not alter A-a gradient
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hypoventillation, low FiO2
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These causes of hypoxemia increase A-a gradient:
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VQ mismatch, diffusion impairment, right to left shunt
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The greater the available alveolar-capillary membrane surface area....
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the greater the amt of O2 and CO2 that can diffuse across it
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This pulm disorder destroys alveolar-capillary membrane and reduces surface area, impairing gas exchange
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emphysema
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These pulmonary disorders can reduce functioning surface area for gas exchange:
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severe pneumonia, lung tumors, pneumothorax, pneumonectomy
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The thinner the mebrane for gas exchange...
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the more rapid the rate of diffusion of gases
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Conditions that increase membrane thickness and decrease gas exchange:
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fluid in alveoli or interstitium or both (pulm edema, pneumonia)
inflammation/fibrosis of alveoli (ARDS, pneumoconiosis - dust in lungs from mines) |
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Diffusion of O2 requires about ___ seconds to reach equilibrium (balance between alveolar and capillary gas levels).
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0.25
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During high CO (exercise/stress) blood flows ____ through alveolar-capillary system, which can create hypoxia if pt has diffusion problems (pulm edema, pneumonia)
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faster
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O2 binds loosely and reversibly to hemoglobin to form ______ for transport to the tissues where it can be released.
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oxyhemoglobin
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SPO2
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percent of O2 bound to Hgb
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Oxyhemoglobin dissociation curve
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represents relationship of partial pressure of arterial PaO2 and hemoglobin saturation SaO2
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Left shift of curve indicates:
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increased affinity for O2 to Hgb -- less released into tissues
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Right shift of curve indicates:
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decreased affinity for O2 to Hgb -- more freely released into tissues
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A low PaO2 in the tissues stimulates
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O2 release from Hgb into tissues
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High PaO2 in pulm capillaries stimulates
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Hgb to bind more with O2 in lungs
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Perfusion
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pumping or flow of blood into tissues and organs
systemic and pulmonary |
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systemic perfusion
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from aorta through right atrium of heart
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Pulmonary perfusion
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from pulmonary artery through left atrium
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Pulmonary perfusion depends on these 3 factors
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CO, gravity, and pulm vascular resistance
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VQ ratio
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relationship expressed as ratio of alveolar ventilation to pulmonary capilary perfusion
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VQ ratio balance depends on:
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adequate diffusion of O2 and CO2 across alveolar-capillary membrane, and mvmt of O2 into and CO2 out of alveoli
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Ideal VQ ratio
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alveolar ventilation 4 L/min and capillary perfusion 5 L/min
4/5 = 0.8 |
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Partial pressure of O2 and CO2 varies throughout lungs because:
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ventilation is not distributed evenly because of gravity-dependent factors
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In spontaneous breathing, airflow naturally moves toward _____ and ____ during inspiration.
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diaphragm and peripheral lung
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Pulmonary capillary perfusion is _____ dependent, making perfusion greatest in the ______ areas of the lungs.
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gravity dependent, dependent areas
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Best VQ match is located at:
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base of lungs
greatest amt of gas exchange occurs here |
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______ has best ventilation and ______ has best perfusion.
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Apex, Base
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If ventilation is higher and perfusion is lower...
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high vq ratio
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If perfusion is higher and ventilation is lower...
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lower VQ ratio
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High VQ ratio means:
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normal to increased alveolar ventilation associated with decreased perfusion
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In high VQ ratio, the alveolar gas effect ...
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incr. cardiac output, decr. alveolar CO2, normally exists in upper lung fields
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High VQ ratio is abnormally present in these conditions
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decr. CO, PE, pneumothorax, destruction of pulm capillaries
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In high VQ ratio, the arterial blood gas effects...
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incr. PaO2, decr. Pa CO2, incr. pH
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The apex of lungs have _____ ventilation and ___ perfusion, causing an excess of ventilation to available perfusion.
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increased ventilation, reduced perfusion
HIGH VQ RATIO |
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Middle section of lungs has ____ ventilation and ____ perfusion, causing a _____ VQ ratio.
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increased ventilation, increased perfusion,
LOW VQ RATIO |
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In Low VQ ratio, there will be ______ ventilation with ___ perfusion.
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decr. ventilation,
incr. perfusion |
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In Low VQ ratio, the alveolar gas effects are...
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decr. O2 in alveoli
incr. CO2 in alveoli occurs in lower lung fields |
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Low VQ ratio is abnormally present in these conditions:
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hypoventilation, obstructive lung disease, restrictive lung disease
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Low VQ Ratio has these ABG effects
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decr. PaO2,
incr. PaCO2, decr, pH |
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The west zone 1
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PA>Pa>Pv
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The west zone 2
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Pa>PA>Pv
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The west zone 3
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Pa>Pv>PA
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This is the percentage of CO that flows from R heart back into L heart without undergoing pulm gas exchange ( can be true or physiologic) or not achieving normal levels of PaO2 because of abnormal alveolar function
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Pulmonary shunt
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Shunts can be _____ in the alveolar level or ______ as in PFO or ventricular septal defect.
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respiratory, cardiac
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A-a gradient is useful for
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estimating degree of physiologic shunt and hypoxemia
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Normal shunt values
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A 104 mmHg
a 95 mmHg normal shunt is 5-10 mmHg |
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Increased A-a gradient is associated with:
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aging, shunting, VQ mismatch
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Total lung capacity
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volume in lungs at max inflation
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Residual volume
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volume of air remaining in lungs after max exhalation
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Expiratory reserve volume
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max volume of air that can be exhaled from end-expiratory position
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Inspiratory reserve volume
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max volume that can be inhaled from end-inspiratory level
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Inspiratory Capacity
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sum of inspiratory reserve volume and tidal volume
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Inspiratory vital capacity
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max volume of air inhaled from point of max expiration
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Vital capacity
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Total lung capacity - residual volume
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tidal volume
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volume of air moved into or out of lungs during quiet breathing
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functional residual capacity
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volume in lungs at end-expiratory position
residual volume + expiratory reserve volume |
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Functional reserve capacity is decreased by PANGOS
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pregnancy
ascites neonates general anesthesia obesity supine position |
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Closing volume
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volume needed in lungs at end expiration to keep alveoli open
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Closing capacity
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closing volume + residual volume
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Closing capacity is increased by CLASSO
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chronic bronchitis
liver failure age surgery smoking obesity |
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How does intra op supination affect ventilatory changes?
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cephalad shift of diaphragm, decreased FRC, VQ incr. in dependent portions of lungs
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How does anesthesia affect ventilatory changes? (there's a bunch)
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incr. RR, decr. TV, irregular breathing in lighter stages, airway resistance incr., change in thoracic muscle tone (to favor collapse), paralysis (favors collapse), positive pressure ventilation, excessive IVF (promotes shunting), absorption atelectasis with high inspired O2 conc., decr. removal of secretions and mucociliary flow, inhibition of hypoxic pulmonary vasoconstriction (HPV)
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How does positive pressure ventilation affect ventilatory changes during anesthesia?
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incr. VQ mismatch,
as ventilation incr. in nondependent areas and perfusion remains in dependent areas |
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What is HPV in anesthesia ventilation changes?
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Hypoxic pulmonary vasoconstriction
positive effect physiologic protective mechanism which prevents right to left shunting of blood |
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What is the Rate of PaCO2 rise during apnea, and when is it clinically significant?
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6 mmHg first minute,
3-4 mmHg each subsequent minute clincally significant during emergence, COPD, and brain death criteria(apneic test) |
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Hypoxia leads to anaerobic ventilation, with the buildup of hydrogen ion and lactate. This causes ____
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acidosis
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Early cardiovascular symptoms of hypoxia
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excitatory and vasoconstrictive
incr. HR, Stroke volume, contractility |
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Late cardiovascular symptoms of hypoxia:
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depressed and vasodilatory
decr. BP, HR --> shock --> fibrillation --> ASYSTOLE |
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Anesthesia may mask this physiologic response to hypoxia:
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sympathetic response
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Hypoxia symptoms mimic the symptoms of:
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hypercapnia
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This is a common cardiac sign of hypoxia:
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arrhythmias
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Neuromuscular blockers (NMBs) affect the cephalad movement of the diaphragm, leading to:
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alteration in VQ matching
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