Kettering-PFT's (copy)
Terms
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- What are spirometers
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-Positive displacement-flow
-Measures volumes and flow - What do pneumotachs measure
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-Flow
-Not accurate at high or low flows - What are the types of pneumotachs?
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-Wright
-Fleisch(pressure differential) Can be used to continuously measure minute ventilation - Body Box
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-Based on Boyle's Law
- Temp remains constant
- Measures airway resistance and compliance
-FRC or TGC (thoracic gas volume) - How is volume calibration, leak tests and flow calibration done
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-Volume calibration and leak tests are done by using a large volume syrings (super syringe at 3 L)
- Flow is done with rotometer - What measures restrictive lung diseases?
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-Vital Capacity (SVC, VC)
-VT, IRV, ERV, IC, VC
- Vital capacity is the best measurement (IRV+VT+ERV)
-Volumes - What measures obstructive lung disease?
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-FVC The volume that can be expired forcefully. Provides flow rates
-FEV1 (should be able to blow out 75% - What measurement is the best indicator of obstructive lung disease
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-FEV1/FVC
-If FEV1 is decreased but FEV1/FVC is normal, restrictive only - FEF 200-1200
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-Large airway obstruction
-Typical value: 8L/sec (480L/min - FEF 25-75
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-Small airway obstruction
-Typical value 6L/sec - PEFR
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-Effort dependent
- Typical value 10L/sec - FVC
- This is not a flow, it is a volume. SHould be equal to SVC. If FVC smaller than SVC, air trapping. If cannot be completed in 3 seconds, obstructive
- MVV
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-The patient is told to breathe inand out as fast as possible until told to stop (12-15 seconds)
-Measures muscular mechanics
-Decreased=obstructive, increase RAW, muscle weakness, dec. conpliance, poor patient effort - Pre and Post bronchodilator PFT testing
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-measures reversibility of obstruction
-Increase of 15% is significan
- Stop bronchodilator therapy 8 hours prior to testing - He dilution
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-closed meethod
-determines FRC - N2 washout
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-Open method, FRC is washed out
-Calculates FRC - What do flow volume loops evaluate
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-restrictive=skinny and tall
-Obstructive=short and wide
-Best evaluates a patient with partial vocal cord paralysis (large airway obstruction) - In gas distribution, what does phase oneand two indicate
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Phase one=deadspace
Phase two is combination of deadspace and alveolar gases - In gas distribution, what does phase three and four indicate
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-Phase 3=evenness of gas distribution (flat mid portion)
- Phase 4=a sudden rise in N2% and is called closing volume - What is a normal DLCO and when does it decrease?
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Normal=25 mL CO/min/mmHg STPD
- Decrease occurse in PEASE, pulm fibrosis, sarcoidosis, ARDS, edema, emphysema - What is a bronchial provocation test?
- It is performed by administering a provocotave agent (meth, histamine, fold air, irritant, exercise) to a patient to see if there is airway hyperactivity.
- When is the bronchial provocation test positive
- When there is a 20% decrease in FEV1
- What is the dosage of methacholine required for a positive test called?
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-Provocative dose or PD20%
- Can be given via a nebulizer or dosimeter - How long should patients not take the following drugs prior to bronchial provocation test? Beta 2 drugs, methyl, comolyn sodium, antihistamines
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-Beta 2 drugs 8 hours
-methylxanthines - 12 hours
-cromolyn sodium - 24 hours
- antihistamines - 48 hours - In bronchial provocation testing, what can asthma be described as
- -a paradoxical finding of decreased compliance, couples with decreased maximum lung elastic recoil
- What are predicted values based on for PFT's?
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age
height
gender - How do you interpret PFT's
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80-100% of predicted=normal
60-79 = mild disorder
40-59 = moderate disorder
<40% = severe disorder - What test should be used with PFT tests
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-The best test should be determined and used for recording
- best test=highest FVC/FEV1