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36 Cards in this Set
- Front
- Back
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why do we perform PFTs?
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to determine if issues are obstructive or restrictive
gas exchange meds working? / necessary? trend progress pre op screening |
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What are the 3 testing components?
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volumes / capacities
mechanics diffusion capacity (DLCO) |
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absolute contraindications for PFT testing?
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MI within 1 month
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relative contraindications for PFT testing:
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cannot follow instructions
bladder issues pain - gut / mouth |
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Which volumes / capacities can be measured directly?
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Vt
VC IC FVC - 20 - 30% effort dependent IRV ERV |
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Which volumes / capacities must be measured IN-directly?
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residual volume - RV
TLC - total lung capacity FRC |
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The FEV1 / FVC ratio indicates what kind of problem under what percentage point?
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obstructive
<70% |
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What test indicates what's going on in small airways?
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FEF25-75%
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DLCO
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0.3% CO inhaled for 10 seconds
normal reading is 25-30 ml/min/mm Hg |
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MEP
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Maximal Expiratory Pressure
Exhale against meter for 3 seconds Report best positive reading of 3 efforts Reflects ability to cough / clear secretions Normal 90-100 cm H2O / Minimum 40 cm H2O |
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Disease Severity (***NBRC****)
All Values Except FEV1/FVC ratio |
>120% of predicted volumes - Hyperinflation
80% - 120% of predicted - normal range ******************* 60% - 79% of predicted - Mild disorder 40% to 59% of predicted - moderate disorder <40% of predicted - severe disorder |
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FEV1/FVC Ratio
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Helps separate normal vs. obstructive vs. restrictive
Use to rule out obstructive < 70% Fev1/FVC = obstructive problem |
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indications of obstructive disorder
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VC decrease - reflects decreased flow rate
air trapping / hyperinflation = increased volumes FRC increased RV increased TLC increased |
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indications of restrictive disorder
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decreased volumes
VC & FVC decreased FRC decreased RV decreased TLC decreased ERV decreased IRV decreased |
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Pre/Post Bronchodilator
Reversible airways FVC &/or FEV1 post test increase |
> 12% & 200 ml
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Inspiratory Reserve Volume
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IRV
Maximum amount of air that can be inhaled after a normal inspiration practice it: Inhale your normal Vt. Now take a breath all the way in - that was your IRV |
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Expiratory Reserve Volume
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ERV
Volume of air exhaled after a normal expiration practice it: Exhale your normal Vt. Now push out all the air you can - that was your ERV |
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Residual Volume
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RV
Volume of air left in the lungs after a maximal expiration. Cannot be measured directly Practice it: Exhale all your air. There is some air that still remains in the lung. That is the RV - You cannot exhale it. |
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Inspiratory Capacity
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Vt + IRV
Maximum amount of air that can be inhaled after a normal expiration Practice it: Exhale your normal Vt. Now inhale as much air as possible - you just inhaled your IC When teaching patients to use an incentive Spirometer they use this breathing pattern |
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Vital Capacity
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Vt + IRV + ERV
Amount of air that can be exhaled following a maximum inspiration Practice it: Breath in as deeply as possible, now exhale all your air - that is your VC |
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FVC
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Forced Vital Capacity
*** Most commonly performed maneuver Used to measure FEVs & flows ***** The amount of air which can be forcibly exhaled from the lungs after taking the deepest breath possible. Patient coaching is important! 1st 20-30% effort dependent Next 70-80% effort independent Practice it: Take a deep breath all the way in, then blast out all your air as hard & fast as possible...Keep blowing hard until all the air is out of your lungs. |
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TLC
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Total Lung Capacity
RV + VC or FRC + IC Amount of air in the lungs at the end of a maximal inhalation |
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Functional Residual Capacity
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ERV + RV
Amount of air left in the lung after a normal exhalation Practice it: Exhale your normal Tidal Volume. The amount of air now left in your lungs is the FRC |
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Peak Flow
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During full PFT - measured in liters per second
With peak flow meter Measured in liters per minute Fast assessment Asthma monitoring Normal value 400 to 600 L/min |
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Forced Vital Capacity
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FVC *** most common test *** Used to measure FEVs & flows
Patient coaching is important! 1st 20-30% effort dependent Next 70-80% effort independent Practice it: Take a deep breath all the way in, then blast out all your air as hard & fast as possible...Keep blowing hard until all the air is out of your lungs. |
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Forced Expiratory Volume
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During FVC maneuver
Volume of air exhaled in a specific time measured in liters FEV1 - 1st second of FVC FEV1/FVC ratio compares FEV1 to FVC At least 70% of FVC should exhale in the 1st second FEV1/FVC ratio < 70% = increased airway resistance = obstructive problem |
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Forced Expiratory Flow 25% - 75%
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FEF 25% - 75%
Average flow rate (L/sec.) during middle half of FVC Assess small airways |
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FEV1
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the maximal amount of air you can forcefully exhale in one second.
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FEF200-1200
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Forced Expiratory Flow 200-1200
Average flow rate between 200 ml & 1200 ml of FVC Reflects large airways |
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DLCO
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Diffusing capacity of lung:
single breath method Pt inhales gas mixture: 0.3% CO, 10% helium, + medical air Holds it 10 sec; then full exhale CO diffuses across a-c membrane Affinity for HB: 250-300 x O2 Exhalation analyzed for CO not returned Normal = 25-30 mL/min/mm Hg (**** NBRC normals*****) decreases with obstructive & restrictive dis |
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Maximum Voluntary Ventilation
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MVV
Largest volume of air that can be voluntarily breathed in & out in 1 min Tested for 10, 12 or 15 seconds Reflects ventilatory reserve |
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Bronchial Challenge
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Airway reactivity to methacholine
Physician present Bronchodilators & resuscitation equipment available Procedure: FEV1 tested Sequential methacholine aerosols given If FEV1 decreases by 20% or more from baseline, test terminated Object: find methacholine dosage decrease FEV1 by 20% Methacholine stimulates the parasympathetic system in the lungs. Causes bronchoconstriction. |
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What does the FVL look like on an airway obstruction?
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box-like shape
*********** NBRC*********** |
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Negative Inspiratory Force
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Maximum negative pressure generated during inhalation
Reflects diaphragm, inhalation muscle strength, ventilatory drive Usage: Wean from ventilators, Monitor neuromuscular disease (Guillone Berea / Myo gravis) Normal reading - 60 cm H2O to -100 cm H2O (average normal readings **************) Can protect airway, deep breathe, cough effectively Reading: - 20 cm H2O absolute minimum (********************) |
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Indications for spirometry
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Detect the presence or absence of lung dysfunction suggested by history or physical signs and symptoms or the presence of other abnormal diagnostic tests. (chest xray, ABG)
Quantify the severity of known lung disease Assess the change in lung function over time or aftger administration of or change in therapy Assess the potential effects or response to environmental or occupational exposure Assess the risk for surgical procedures known to affect lung function Assess impairment or disability (e.g. for rehabiliation, legal reason, military) |
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contraindications for spirometry
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Hemoptysis of unknown origin
Pneumothorax unstable cardiovascular status or recent myocardial infarction or pulmonary embolus Thoracic, abdominal, or cerebral aneurysms Recent eye surgery presence of an acute disease process that might interfere with test performance |
