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41 Cards in this Set
- Front
- Back
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alveoli try to maintain PA O2 and CO2
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100 mm Hg and 40 mmHg
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Conducting airways
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trachea, bronchi, bronchioles, terminal bronchioles
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velocity in conducting airways
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decreases as aggregate surface area increases
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Respiratory zone
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respiratory bronchioles, alveolar ducts, alveolar sacs
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total lung capac
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total air in lung @ maximum inspiration; IRV + TV + ERV + RV
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tidal volume
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volume typically inspired or expired
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inspiratory reserve volume
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extra able to breathe in on top of tidal volume.
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expiratory reserve vol
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extra able to breathe out after tidal expiration
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residual volume
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vol remaining after max expiration
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FRC
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volume remaining after tidal expiration. ERV + RV; indicates degree of lung inflation in absence of muscular force (end of quiet expiration). determined by inward elastic recoil of lung and outward elastic recoil of chest
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inspiratory capacity
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max you can breathe in. TV + IRV
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vital capacity
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max that can be expired after max inspiration. IRV + TV + ERV
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FEV-1
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forced expiratory volume in one second; useful in diagnosing obstructive disease when expressed over forced vital capacity. About 80% of FVC in healthy people. <70% signals obstructive disease
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obstructive lung diseases
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chronic bronchitis, asthma, emphysema, CF. Increased resistance to airflow. Takes longer to exhale air.
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volumes seen in obstructive lung diseases
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normal FVC, increased FRC and RV. TLC may increase due to remodeling of chest wall.
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FVC and FEV1 in obstructive disease
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FVC normal, FEV1 smaller, FEV1/FVC <70%
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restrictive lung diseases
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obesity, fibrosis. lung expansion constrained
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lung volumes in restrictive lung diseases
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compresses lung volumes and capacities. patients increase frequency of breaths to offset reductions in volume.
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FVC, FEV1 in restrictive disease
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FVC smaller, FEV1 smaller, FEV1/FVC fairly (maybe even high?)
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obesity
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Normal TLC, decreased FRC (more chest elastance pushes more air out), decreased FRC but normal RV (aka decreased ERV)
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fibrosis
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proliferation of fibroblasts, deposition of CT increases elastic recoil and stiffens lungs. Less CPL, tough to inflate. Decreased TLC, FRC, RV
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obstructive emphysema
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Increased TLC, FRC, FV
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Obstructive bronchitis
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TLC constant, increased FRC, RV
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Neuromuscular disease
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decreased TLC, FRC constant, increased RV
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Helium Dilution
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inhale known concentration of Helium, hold breath for 10 sec; measure He concentration after expiration. Calculate FRC. **Underestimates air volume if pt has obstructive lung disease
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normal ABG values
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pH 7.4; pCO2 40; pO2 100; O2 sat 98-100
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Minute Ventilation
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total volume of air entering / exiting lungs per minute
= TV x frequency of breaths |
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alveolar ventilation
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total volume that enters alveoli per minute and is available for gas exch. Reduced b/c some air stays in anatomical dead space (TV - Volume of dead space) x frequency
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Alveolar Dead Space
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ventilation exceeds capacity of capillary flow to exchange gases
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physiologic dead space
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anatomical dead space + alveolar dead space
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alveolar gas equation
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PAO2 (alveolar) = 147 - PaCO2/ RQ (arterial; RQ .8-1.0)
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normal V:Q ratio
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close to 1.0
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VQ mismatch and airway obstruction
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VQ from 1.0 to 0. 0 = complete shunt. perfusion but no ventilation
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VQ mismatch and pulmonary vascular disease
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VQ from 1.0 to infinity; ventilation but no perfusion
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shunt
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ultimate VQ mismatch; give O2 and pt doesn't improve.
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hypoventilation
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not moving air in/out; sleeping, sedatives
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low inspired PO2
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high altitude, airplane
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Alveolar - arterial difference
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normal is 10; 17-22 in elderly
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hypoxemia w/ elevated (A-a) gradient is due to
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VQ mismatch or shunt
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hypoxemia w/ elevated PCO2 and normal (A-a) is normally due to
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hypoventilation
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hypoxemia w/ elevated PCO2 AND elevated (A-a gradient) is due to
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severe VQ mismatch, shunt
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