Term
| What does the difference btwn PaO2 and PvO2 tell you? |
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Definition
| PaO2- PvO2=how much oxygen is being taken up by the tissues |
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Term
| What 2 Thing prevent Alveolar Collaspse? |
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Definition
| 1) Surfactant 2) Mechanical Interdependence |
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Term
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Definition
| Slope of P-V Curve; typical 0.2 L/cm H2O |
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Term
| What is the difference in Compliance btwn Obstructive (Emphysema) & Restrictive ( FID) Lung Dz? |
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Definition
Emphysema: hyperinflation, dec. recoil pressure, inc. Compliance
Fibrosing Interstitial diseases: restricted volume, inc. recoil pressure, dec. compliance |
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Term
| Causes of Decreased Compliance |
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Definition
P-V curve shifted downward
and to right, slope ␣ – Many causes: - Diffuse interstitial (infiltrative) lung diseases (DILD):
IPF, sarcoidosis, pneumoconioses, etc. - Alveolar consolidation: pneumonia, edema, etc. - Removal of lung tissue (surgery) - Extrapulm. restriction: pleural effusion, ascites, etc. |
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Term
| Causes of Increased Compliance? |
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Definition
P-V curve shifted upward and to left, slope ␣ – only 1 major cause: emphysema
- Note: loss of elastic recoil also occurs in long-standing or severe asthma – curve shifts upward, but slope (CL) remains within normal limits. |
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Term
| What is EFL & when is it usually seen? |
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Definition
-Accounts for reproductivity of FEVC
-Normal Persons: EFL may occur during strenuous exercise (high flow rates)
-Obstructive Airways Dieseases: depending on disease severity, EFL occurs during moderate exertion or even during tidal breathing at rest.
-->Leads to dynamiic hyperinflation
-->Major contributor to dyspnea & disability in OAD
-Inspiratory flow limitation doesn't occur in the tracheobronchial tree |
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Term
| Steps in O2 transport to tissues? |
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Definition
In the Lungs:
--> O2 from alveolar gas into blood, the OO2 of pulmonary capillary blood becomes 100mmHg
-->very high affinity of hemoglobin for O2 at a PO2 of 100mmHg Facilitates the diffusion-maintaining the partial pressure gradient
In Peripheral Tissues:
-->O2 diffuses from arterial blood to the cells
-->lower affinity of hemoglobin for O2 in steep portion of curve facilitates unloading of O2 to the tissues |
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Term
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Definition
␣␣Pa0 =95-100mmHg(sealevel,decrease w/ age)
␣␣ PaC0 = 38-42 mmHg
␣␣ PA0 = 110 mmHg
␣␣ PvO = 40 mmHg
␣␣ Sa0 = 96-100% (sea level, decreases with age) Sa0 = 96-100% (sea level, decreases with age)
2
␣␣ Sp0 = 96-100% (sea level, decreases with age)
␣␣ Ca0 = 20 ml/100ml blood (assumes Hgb = 15 gm) |
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Term
| 4 Mechanisms of Abnormal Gas Exchange |
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Definition
1) Ventilation-Perfusion (V/Q) Mismatch
-->Mild= Dec. PaO2
-->Severe = Dec. PaO2 & INC. PaCO2 (inc. in PaCO2 b/c areas are not ventilating-ILD)
2)Right- Left Shunt
-->giving O2 will not help
--> PaO2/FIO2 < 200= Shunt (> 20 % inc. of CO2)
3) Diffusion Impairment
-->Emphysema
-->helped by giving O2
4) Hypoventilation
--A) Global Hypo--mechanical, normal AaD
--B) Net Hypo--lung prob, inc or widen AaD |
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Term
| Applications of PaO2/FIO2 |
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Definition
Hypoxia Ratio--> ratio can be used as an index of O2 transfer regardless of FiO2
-Normal= 470
- Acute Lung Injury= 200-300
-ARDS= < 200 |
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Term
| Clinical Utility of diffusing capacity |
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Definition
Normal Value= 30 ml/min/mmHg
-used to test for EMPHYSEMA (reduced bc destruc. of alveolar-capillary membranes & pulmonary capillaries) |
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Term
| What is Respiratory Failure? |
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Definition
***Lung fails to maintain adequate ABG- PaO2 < 60mmHg or PaCO2 > 50 mmHg)
Two types:
-Type I (Hypoxemic)-dec. PaO2; PaCO@ is normal or low
-Type II (Alveolar Hypovent) Dec. PaO2 & Inc PaCO2 |
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Term
| What ratio do you look at to distinguish between Obstructive and Restrictive Lung Disease? |
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Definition
FEV1/FVC ration
-low=Obstructive LD
-normal/inc=Restrictive LD
-measured through Spirometry |
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Term
| What test is used to diagnose Asthma or AHR? |
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Definition
Asthma or Airway Hyperresponsivness is measured thourgh METHACHOLINE
-in asthmatics, doses below the cutoff cause an abnormally large decline in FEV1 |
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Term
| When do you test muscle function for Inspiratory or Expiratory Muscles? |
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Definition
Muscle Strength:
-Inspiratory Muscles->measured at RV or FRC (min volume)
-Expiratory Muscles-->measured at TLC (max. volume) |
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Term
| What causes a dec. in FEV1/FVC w/ a disproportionate dec. in FVC? |
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Definition
| Mixed obstructive-restrictive Diseases |
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Term
| What is the difference between Diffusion Capacity and Diffusion Limitation? |
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Definition
Diffusion Capacity-->is dec when there is a loss of alveolar membrane
Diffusion Limitation--> is present when a gas fails to equilibrate btwn airspaces & alveolar capillaries |
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Term
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Definition
| Low PvO2 in ill patients is bad b/c it means that the tissues are extracting more O2 b/c of demand, however the lungs are unable to ventilate adequate to saturated the blood w/ O2, leading to more hypoxemia |
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Term
| What is the Normal throat Flora of the |
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Definition
Throat Flora:
aerobic, facultative, aerotolerant species
– mostly Gram + and - cocci or coccobacilli (viridans Strep., Neisseria/Moraxella), Gram + bacilli (diphtheroids)
– variably some yeast, Staph., enterics, Haemophilus (incl. rough H. influenzae), rough S. pneumoniae
– transiently, GAS, encapsulated H. influenzae, S. pneumoniae, N. meningitidis |
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Term
| Where are Staphy aureus and epidermis found? |
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Definition
| Staph aureus (30 %) & Staphy epidermis (80 %) most commonly found in anterior nares |
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Term
| How can you tell a pt has apiration pneumonia/ lung abscess and what is the common pathogen? |
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Definition
Aspiration pneumonia / lung abscess
– Generally mixed anaerobic infection (cf. trench mouth)
– acute or subacute – dark, foul-smelling
sputum |
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Term
| What would you suspect if a patient has recurrent infections w/ Staph. aureus & Pseudomonas aeruginosa |
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Definition
Recurrent infections with Staph. aureus and Pseudomonas aeruginosa (and more common respiratory pathogens, too)
-->think inherited defects in mucociliary clearance
(in.e CF or Primary Ciliary Dyskinesia) |
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Term
| What is the typical case of CF |
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Definition
| Infant who has homozygous defect of CFTR␣F508 |
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Term
| What pathogens cause pneumonia in CF pts? |
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Definition
• Persistentcolonization – H. influenzae, S. aureus, P. aeruginosa, Burkholderia
cepacia; also Aspergillus spp. • Exaggeratedinflammatoryresponse
– From induction of Pseudomonas alginate synthesis? |
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