What is the term used to describe the volume of gas that can be exhaled maximally after full inspiration?
Vital capacity (VC)
What volume is obtained by subtracting the VC from the TLC?
Residual Volume (RV)
Which of the following tests would you recommend to quantify the disease severity of a pt w/ Asthma?
Which of the following vital capacity measurements indicates inadequate ventilatory reserve?
What percentage of the FVC is normally exhaled in the first second?
What spirometry parameter would you recommend to assist a pt w/ asthma in monitoring their day-to-day status and need for treatment?
PEF (peak expiratory flow)
Which parameter is represented as the maximal positive deflection on the Y-axis of a standard inspiratory-expiratory flow-volume curve?
PEF (peak expiratory flow)
Spirometry results for a pt indicate a FVC of 3.5 L and an EFV1 of 2.5 L. What is this pt/s estimated MVV?
(FEV1 x 35)
In addition to calibration w/ a 3 L syringe, which of the following methods should be used to validate spirometer performance &accuracy of software computations?
Testing w/ biologic controls
A valid FVC maneuver requires that the subject exhale for at least:
When performing bedside spirometry, you observe an S-shaped plotted FVC-vs-Time curve. Which of the following is the likely problem w/ this maneuver?
Failure to achieve a rapid start to exhalation
The upper & lower limits of normal spirometry data are calculated as being how many standard deviations (SD) from the mean?
Bedside spirometry results for a patient indicate a FVC lower than the LLN, and both the FEV1 and FEV1% higher than the LLN. Which of the following are possible interpretations?
- The pt has a restrictive impairment
- The pt isn't providing maximal effort
Which of the following pre- and post bronchodilator spirometry results is most indicative of a reversible obstructive disorder?
FEV1 increases by 15%
Based on their basic spirometry results, which patient would you recommend for a static lung volume determination (FRC/TLC measurement)
A pt with
- FVC < LLN
- FEV1% > LLN
Which tests would you recommend to measure the extent of gas trapping in a patient with emphysema?
Body plethysmography (box) measurement of TGV
Which of the following are consistent w/ obstructive lung disease?
- increased lung volumes
- decreased flows
Which of the following tests would you recommend to help differentiate between interstitial & chest wall/neuromuscular causes of a restrictive ventilatory impairment?
Single-breath diffusing capacity of the lung
Which of the following would invalidate the results of a single-breath DLCO maneuver?
Patient performing a Valsalva maneuver during breath hold
Evaluate the patients lab results:
- FVC < LLN
- FEV1% >LLN
- TLC < LLN
- IC < LLN
- DLCO >LLN
Static lunch compliance is computed using which formula?
lung vol/Transpulmonary pressure gradient
Which pt would you recommend for methacholine brochoprovocation testing?
- A pt who experiences unexplained wheezing at his job site
- a pt with a history of nighttime SOB and coughing
After progressive step-up to 16 mg/mL methacholine, a pt exhibits a 15% decrease in FEV1 compared to the baseline. How would you interpret these results?
Normal airway responsiveness
Which of the following would invalidate the results of an expired nitric oxide maneuver?
Performance after spiromerty
An adult pt w/ recurrent episodes of SOB, wheezing, and coughing has an expired nitric oxide level of 15 ppb. Which of the following diagnosis is least likely
Which of the following pts' 6-min walk test results indicate an abnormally low functional capacity?
Male patient, 6MWD 400 meters
Which of the following are indications for cardiopulmonary exercise testing?
- To diagnose obstructive CAD
- To differentiate between cardiac and pulmonary limitations to exercise
- to determine whether arterial desaturation occurs with exercise
What would be the estimated max HR at peak exercise for a 60 y/o male?
What does PFT testing involve?
- Group of procedures that measure the function of the lungs
- Spirometry, lung volumes, gas transfer, bronchial challenge.
what are some Contraindications of PFT testing?
Hemoptysis, pneumothorax, unstable angina, recent MI, thoracic aneurysms, abdominal aneurysms, cerebral aneurysms, recent eye surgery
What is Spirometry?
- creating the loop
- measure of airflow and lung volumes during a forced expiratory maneuver from full inspiration
How long should bronchodilators be held before the test?
SABA for 4 hours
LABA for 8 hours
STEROIDS for 12 hours
What is the volume-time graph?
- the volume is plotted against the time, it displays expiration.
- Y-axis is volume
- X-axis is time
What is included in the flow-volume loop?
- FEF 25-75%
- FEF 200-1200 ml
What is forced Vital capacity (FVC)?
The total amount of air expired as quickly as possible after taking the deepest possible breath
What is Forced expiratory volume (FEVT)
- max volume of gas that can be exhaled over a period of time
- obtained from an FVC measurement
- most common used time is 1 sec (FEV1)
What are normal values for FEV1?
What does the FEV1 measure?
the volume of air which can be forcibly exhaled from the lungs in the first second of a FVC maneuver
What is FEV1%?
Indicates the % of the total FVC expelled from the lungs during the first second of forced exhalation.
- 1st indicator if pt is obstructive or restrictive
- < 70% think obstructive
What is FEF25%?
amount of air that was forcibly expelled in the first 25% of the total forced vital capacity
What is FEF75%?
amount of air expelled from the lungs during the first 75% of the FVC test
What is the FEF 25-75%?
- assesses MD to Small airways
- amount of air expelled from the lungs during the middle half of the FVC test
What is the FEF200-1200?
- assesses LG upper airways
- measures the average flow rate between 200-1200 mL of an FVC
What is a Peak expiratory flow rate (PEFR)?
- very top peek of the loop
- maximal flow rate generated during an FVC
- used by pts w/ Asthma to monitor evidence of bronchospasm (measure 3 times, give bronchodilator and repeat)
What are the average PEFR?
Adult Male: 10 L/s or 600 L/min
Adult Female: 7.5 L/s or 450 L/min
What is Maximal Voluntary Ventilation (MVV)?
- max vol. of air a pt can breathe over a specific period of time (12 sec)
- the 12-sec volume is then multiplied by 5
What does the MVV test?
- muscle strength of the diaphragm
- compliance of the lungs and thorax
- inspiratory/expiratory airway resistance
- pt motivation/effort
What is the normal value for an MVV?
- 160-170 L/min for young adult males
- 90 or less L/min for elderly females
What are Flow-Volume loops?
plot of inspiratory/expiratory flow in the vertical axis against volume in the horizontal axis, taken during a max forced inspiratory and expiratory maneuver
What can be included in a Flow-Volume loop test?
- instantaneous flow at any given lung volume during Forced inhalation/exhalation
What can the shape of the loop mean?
- loop contour assists in dx and localization of airway obstruction
- skinny loop = restrictive
- scooped out loop=obstructive
What are good indicators of Obstructive disorders on a flow-volume loop?
- Normal to increased TLC
- Increased RV
- Reduced FEV1
- PEFR more than 6 seconds
- Reduced FVC
What are good indicators or Restrictive disorders on a flow-volume loop?
- Normal to decreased TLC
- Decreased RV
What diseases are Obstructive?
- Cystic Fibrosis
- Chronic Bronchitis
What is a normal FEV1 for an OLD?
FEV1 > 80% of predicted
What is a mild obstruction FEV1 of an OLD?
FEV1 60-80% of predicted
What is a moderate obstruction FEV1 of an OLD?
FEV1 40-60% of predicted
What is a severe obstruction FEV1 of an OLD?
FEV1 <40% of predicted
What values indicate OLD when reading the FEV1%?
If it is <70$ predicted
How does Age factor into predicting OLD or RLD?
FVC and Flow rates decline with age
How does height factor into predicting OLD or RLD?
- most effect
- all spirometric measurements increase w/ height due to an increase in # or size of the alveoli relative to airways
How does Sex factor into predicting OLD or RLD?
- most PFT are lower in female vs. the males
How does Weight factor into predicting OLD or RLD?
- increased weight means growth or muscle mass
- in obesity, lung values (esp. ERV) decrease with greater weight
What would a Flow-volume loop look like in pts with ASTHMA?
- Reduced PEFR
- Airflow reduces rapidly w/ the reduction in the lung volumes because the airways narrow and the loops becomes concave
- Concavity may present before the change in FEV1 or FEV1%
What would a Flow-volume loop look like in pts with EMPHYSEMA?
- reduced flow at low lung volumes creating a dog-leg to the flow volume curve
- airways may collapse during Forced expiration due to destruction of supporting lung tissue
What is reversibility?
- characteristic feature of asthma
- if repeated FEV1 improves by 12-15% or 200 ml after administering Sulbutamol 2.5 mg or Ipratropium Bromide
- this is called a significant change and means the trx worked for them
- plug the Liters into the formula to see if there is a significant change (post-pre)/pre
Interpreting a PFT
- FEV1 > 80% predicted
- FVC > 80% predicted
- FEV1% >70% predicted
- FEF25-75% > 60% predicted
FEV1, FEV1%, and FEF25-75% are all normal then you have a normal PFT
PFT with Obstruction
(think early obstruction or small airway obstruction)
- FEV1% is reduced
- FEF25-75% is <60%
- FVC Normal or <80%
- FEV1 is <80%
PFT with Restriction
- FEV1 is Normal or <80%
- FVC <80%
- FEV1% is Normal or >70%
PFT with mixed Restriction/Obstruction
- FEV1 <80%
- FVC <80%
- FEV1% <70%
What is DLCO?
Diffusion of Lung Carbon Monoxide
What does D LCO measure?
- the amount of CO that moves across the AC-membrane
- hallmark of Emphysema
- can determine pulmonary fibrosis
- Will show up as Normal or decreased in Obstructive or Restrictive disorders
What are the ranges for D LCO?
Female: slightly lower
How do you tell if a patient is air trapping?
RV/TLC will be <35% on a PFT
What is a normal RV/TLC on a PFT?
Equal to or >35%
What does Body Plethysmography help look at?
FRC, RAW, RV, TLC, Thoracic Gas Volume
What can looking at Raw help determine?
It can help determine bronchospasms & tumors
What are 3 indirect measurements of the RV and Capacities containing the RV?
- Closed-circuit helium dilution test
- open0curcuit nitrogen washout test
- Body Plethysmography
What will a Flow-Volume loop look like with a large airway obstruction?
(post extubation stenosis, goiter, endotracheal neoplasms)
- No high PEFR, and very round.
- Limited airflow during inspiration and expriation
What will a Flow-volume loop look like with a variable extrathoracic obstruction?
(vocal cord paralysis, reduced pharyngeal cross-section area)
- Small FVC, bigger volume
- Obstruction worsens in inspiration bc negative pressure narrows trachea and inspiratory flow is reduced to a greater extent than expiratory flow
What will a flow-volume loop look like w/ a variable intrathoracic obstruction?
(tracheomalacia, polychondritis, tumors of lower trachea)
- Very big FVC, very flattened PEFR, larger volume, reduction in expiratory phase
- the narrowing is in max inspiration bc increased intrathoracic pressure compressing the airway
What effect does smoking have on a PFT?
- In pts w/ COPD there is a decline in FEV1 of 90-150 ml/yr
- Smoking cessation increases FEV1 the first year and then a decline of 30 ml/year
What are some intrinsic restrictive lung disorders?
- idiopathic pulm. fibrosis
- interstitial pneumonitits
What are some extrinsic restrictive lung disorders?
- scoliosis, kyphosis
- ankylosing spondylitis
- pleural effusion
- gross obesity
- pain on inspiration- pleurisy, rib fractures
What are some neuromuscular restrictive lung disorders?
- Generalized weakness
- paralysis of diaphragm
- myasthenia gravis
- amyotrophic lateral sclerosis
What are some key indicators of restrictive disorders?
- full expansion is limited therefore FVC is reduced
- FEV1 may be reduced bc the stiffness of fibrotic lungs increases the expiratory pressure
- FEV1% will be normal or increased
- Check TLC if restriction is suspected