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30 Cards in this Set
- Front
- Back
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Specialized PFT's
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Maximal Voluntary Vent. (MVV)
Single-Breath Carbon Monoxide Mathacholine Challenge Testing Closing Volume Exercise Testing |
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Indication for MVV
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MVV reflects overall status of lung-thorax to provide peak ventilation available to meet physiologic demands
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Technique for MVV
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Pt breathes rapidly and deeply as possible for 12-15 secs
Total volume exhaled is recorded Multiplied x 5 or 4 for a total volume moved by lungs in 1 min |
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Predicted Normal MVV for young healthy adults
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170 L/M
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How can validity of MVV be est?
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Multiplying FEV1 x 35
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Why isn't MVV a very useful test?
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Results vary widely
Very effort dependent |
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Indication for Carbon Monoxide Diffusing Capacity
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To elvaluate the ability of a gas to dffuse across the A-C membrane of the lungs
-Idiopathic Pulm. Fbrosis -Emphysema -Primary Pulm. Hypertension -Evaluation of Lungs 2ndary to systemic disease |
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Factors affecting diffusing capacity
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Diffusion coefficient of the gas used in testing
Surface area of the A-C membrane Thickness of the A-C membrane Blood vol and flow n the Pulm. Cap. network Distribution of the insp gas Hematocrit |
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Sngle Breath Carbon Monoxide Diffusing Capacity Tech.
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CO has greater affinity to bind to Hb (210x)
Pt maximally inspires gas mixture 10 sec breath hold Pt exhales and concentrations of He and CO are analyzed -He reflects dilution -Initial PCCO calculated before dffusion |
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Gas Mixture for DLCOsb
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.3-,4% CO
10% He Air |
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Nomal Resting DLCOsb for an avg young man
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25 mL/min/mm Hg CO
women's is slightly lower (smaller lungs) |
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DLCO increases with
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Exercise (2-3X)
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DLCO decreases with
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Restrictive Lung disease (pulm fibrosis)
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Methacholine Challenge Testing AKA
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Bronchial Provocation Testing
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MCT Description
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Assessing airway responsiveness in which the pt inhales an aerosol of one or more concentrations of methacholine to induce bronchospasm
Spirometry s performed pre and post to quantitate response |
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MCT Positive result
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A decrease in FEV1 value of 20% from baseline
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MCT that causes a decrease from baseline is called...
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Provocative Concentration
or Provacative Dose |
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Indications for MCT
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Diagnosis of airway hyperactvity (asthma)
Occupational Asthma Severity of Hyperresponsiveness The risk of developing asthma Response to therapeutic interventions -increase in FEV1 by 12% or greater -increase in FVC 200 mL or greater |
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Testing Conditions for MCT
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Pt must be asymptomatic at baseline
Bronchodialators and anti-histamines must be withheld from the pt before test Inhaled corticosteroids should not be withheld Emergency equipment should be readily available |
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MCT Technique
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Baseline FEV1 are measured
First dose adminitered is 0.025 mg/mL Dosing schedules are used each time doubling dose up to a max of 25 mg/mL Test s concluded once a PD20% is reached (document dosage) |
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MCT Results in the healthy
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-Do NOT show a decrease of 20% in FEV1 during testing
-PD20% is greater than the max dosage used in testing |
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MCT Results in pt with Hyperreactve airways
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Positive Test
PD20% is achieved with 8 mg/mL or less |
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Closing Vol
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A special form of nitrogen washout used for early diagnosis of obstruction in the small airways (COPD)
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Closing Vol Technique
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Pt inhales a single breath - 100% FIO
Slowly exhales completely while N2 concentrations are monitored and plotted against exhaled vol. Four phases are clearly seen |
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Four Phases of Closing Vol
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I: Anatomic dead space contain mostly 100% O2
II: Mixture of deadspace & alv gas III: Alv Plateau (Alv gas) IV; Airway closure in bases and emptying of apices |
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Normal results for CV in healthy results
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10% of VC
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CV in a 60 Year Old
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40%
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Increase in CV is in indicator of ...
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Small airway obstruction
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Indications for Exercise Testing
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To determine whether exercise limitations is caused by Pulm. or Cardio insufficiency
To evaluate work capacity and to provide direction To demonstrate oxygen desaturation and determine supplemental O2 therapy via 6 mn walk test |
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Types of Exercise Testng
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Stress Electrocardiography
Vent. Capaciity Blood Gas Defects Exercise Challenge Anaerobic Threshold Max. Oxygen Uptake 6 Min Walk Test (6MWT) |
