Pulmonary Function Tests

1. Arrive on time. You may be asked to reschedule if you are late by 30 minutes or more.
2. Do not wear tight clothing that makes it difficult for you to take a deep breath.
3. Do not eat a large meal within 2 hours of the test.
4. Do not exercise heavily for at least 30 minutes before the test.
5. Do not drink alcohol for at least 4 hours before the test.
6. Do not smoke on the day of the test.
7. If you are scheduled for spirometry pre or post bronchodilation, stop using your bronchodilator according to the following table:

Bring a list of your medications with you (include dose, frequency, reason for  taking).  If you are scheduled for a six-minute walk test or exercise test, please wear comfortable shoes and clothing and bring your assistive walking device.

If you have questions or need additional information, contact your medical care team.

Description: Spirometry involves having you take a fast deep inhalation in, then immediately blasting air out to measure total volume as well as the maximum you can exhale at certain timepoints. Sometimes this measurement is made before and after using a bronchodilator medication to dilate your airways.

Length of Test:

1. Spirometry (no bronchodilator)- 15 minutes
2. Spirometry before and after bronchodilator- 30 minutes
3. Sitting and supine spirometry- 30 minutes
4. Preparation- For spirometry ordered before and after bronchodilation, medication must be withheld as indicated below:

Pediatric Considerations: Very young children may have trouble performing spirometry adequately. Animations may be used to engage and encourage the child. Though spirometry data may be more useful, impulse oscillometry (measured by normal tidal breathing) is frequently ordered in patients<5 years who are likely to have difficulty performing adequate spirometry

Description: Diffusion studies measure how well oxygen moves from your lungs into your blood by having you take a deep breath of a gas mixture and hold it for a few seconds. The diffusing capacity of the lung for carbon monoxide (DLCO) , also referred to as the Transfer factor of the lung for carbon monoxide (TLCO), is used to evaluate the transfer of gas from the alveolar air spaces into the pulmonary capillaries.

Length of Test: 15 minutes

Preparation:

1. No smoking or alcohol ingestion the day of test
2. No heavy exercise within 2 hours of test           

Description: This measures the total amount of air in your lungs. The main 4 capacities measured are:

1. TLC (total lung capacity)
2. FRC (functional residual capacity)-volume of gas in the lung at end expiration
3. VC (vital capacity)- change in volume from full inspiration to full expiration
4. IC (inspiratory capacity)-maximum gas inspired from normal end expiration (FRC)

We can measure total lung volume two ways:

1. Method 1(Default): Body Plethysmography-performed in a closed transparent cabin. Body plethysmography is considered the gold standard of lung volume measurement.
   • Length of Test: 15 min
   • Preparation:
     • No smoking within 1 hour of test
     • No restrictive clothing
     • Withhold bronchodilators as described in spirometry section
     • Supplemental oxygen and IV pumps need to be disconnected during measurement
     • Patient should be able to get into plethysmography cabin (with assistance)
   • Considerations: the test has the advantage of measuring airway resistance and of making several measurements within a few minutes. It has the disadvantages of being uncomfortable to claustrophobic patients. IV pumps must be disconnected and oxygen must be removed during closed box measurement. May be difficult for some patients to get in and out of the box.
      
2. Method 2: Nitrogen Washout-patient breathes 100% oxygen for a few minutes to wash out nitrogen in the lung
   • Length of Test: 10 min
   • Preparation:
     • No smoking within 1 hour of test
     • No restrictive clothing
     • Withhold bronchodilators as described in spirometry section
     • If supplemental oxygen is normally worn, be prepared to remove it for at least 15 minutes if feasible
   • Considerations: this test has the advantage of being easier for less mobile patients. It has the disadvantage in that it cannot be repeated quickly, usually just one adequate measurement is obtained. Also, patient that use supplemental oxygen should be breathing room air for at least 15 minutes prior to this test.

Description: The measurement of respiratory muscle forces (or strength), maximum inspiratory pressure (MIP or PImax), and maximum expiratory pressure (MEP or PEmax), are direct tests that are simple to perform, and are well tolerated by patients. The test assesses the aggregate force or pressure that respiratory muscles can generate against an occlusion at the mouth . PImax is an index of diaphragm strength, while PEmax measures the strength of abdominal and intercostal muscles.

Length of Test: 15 minutes

Preparation: The patient should refrain from heavy exercise immediately before testing.

Pediatric Considerations: Alternate methods that may be preferable in children are:

1. SNIP (sniff nasal inspiratory pressure)- maximal inspiratory pressure is measured via foam nasal probe rather than a mouthpiece.
2. PmW (whistle mouth pressure)- a sharp maximal exhalation though a whistle device provides auditory stimulation.

Description: The peak cough flow measured peak expiration flow (L/sec) when the patient exerts a maximal cough effort. This is typically performed in patient with suspected neuromuscular weakness.

Length of Test: 5 minutes

Description: Maximal Voluntary Ventilation (MVV) is the volume of air exhaled in 12 seconds during rapid forced breathing. MVV tests the overall function of the respiratory system. It is influenced by airway resistance, respiratory muscles, compliance of the lungs and/or chest wall, and ventilatory control mechanisms.

Length of Test: 20 minutes

Preparation: The patient should refrain from heavy exercise immediately before testing.

Considerations: Hyperventilation from the measurement may cause lightheadedness, dizziness, and syncope

Description: Improvement in airflow following inhalation of a bronchodilator is generally accepted as indicative of reversible airway obstruction. However, the evaluation of airway hyperresponsiveness is often indicated, especially in patients with unclear or nonspecific symptoms (e.g., symptoms of asthma with normal spirometry and no bronchodilator response). Bronchial provocation (challenge) testing may be performed with a variety of agents and methods including aerosolized nonspecific pharmacological agents such as methacholine. We will have you perform a few spirometry measurements (take a deep breath in and blow it out as fast as you can). You will then be asked to inhale different doses of the methacholine medication at different intervals. Your spirometry will be measured again after each dose.

Length of Test: 60 minutes

Preparation:

1. Pulmonary medications should be withheld as follows:

2. Do not use alcohol within 4 hours of the test, or smoke within 1 hour of the test.
3. If you use any of the medications listed in the table above, please withhold using them for the time mentioned in the table unless your physician has directed you otherwise. These medications can affect the results of the test.
4. You may continue to use these medications unless you physician state otherwise:

• Cromones
• Inhaled corticosteroids
• Leukotriene modifiers
• Antihistamines

5. If you have any questions regarding your medications, please consult with your NIH study team.

Description: The purpose of this airway challenge test is to determine whether the patient has exercise-induced airway narrowing. The identification of hyperreactive airways using an exercise stimulus can play an important role in the diagnosis and management of asthma . The preferred term for bronchoconstriction that occurs during or after short-term exercise is exercise-induced bronchoconstriction (EIB). Although historically referred to as exercise induced asthma (EIA), it is probably more appropriate to call this condition EIB, because the response to exercise is actually bronchoconstriction and not all people with asthma have EIB .However, EIB has been reported to occur in up to 90% of children with asthma in some selected series, but population-based studies indicate a prevalence of about 50% . Several cross-sectional screening studies have found rates of EIB between 10 and 18% in the general population. Data from published studies suggest that the severity of asthma correlates with the severity and degree of EIB . Atopy is a recognized risk factor for EIB, suggesting that patients with allergic rhinitis or atopic dermatitis with exercise-related symptoms may have EIB. We will make a few spirometry measurements first (take a deep breath in and blow it out as fast as you can).

You will either ride a stationary bike or run on a treadmill for the test. We will closely monitor your heart rate/rhythm (electrocardiogram), blood pressure, breathing, and oxygen saturation during the test. We will have you exercise at a level that keeps your heart rate and respiratory rate within a few minutes. After exercise, we will perform more spirometry measurements at certain time intervals (up to 30 min).

Length of Test: 90 minutes

Preparation:

1. A completed pre-screening questionnaire may be required prior to the test. We ask that you not smoke for at least 8 hours prior to testing, avoid caffeine intake for 12 hours and avoid eating 3 hours before the test. Take medications as instructed. Patients should wear clothes and sneakers appropriate for activity and refrain from exercise before their appointment on the day of their test.
2. Medications that should be withheld include:
   • Inhaled beta-agonists in conventional doses
     • Short-acting (e.g. albuterol), withhold 6 hours before test
     • Long-acting (e.g. salmeterol), withhold 36 hours before test
   • Inhaled anticholinergics
     • Short-acting (e.g. ipratropium), withhold 12 hours before test
     • Long-acting (e.g. tiotropium, withhold 48 hours before test
   • Antihistamines
     • Short-acting, withhold 48 hours before test
     • Long-acting, withhold 3 days before test
3. If you have any questions regarding your medications, please consult with your NIH study team.

Description: The cardiopulmonary exercise test (CPET) involves the assessment of cardiopulmonary function during incremental exercise and combines the routine measurements of the electrocardiogram (ECG), blood pressure and power output with the analysis of exhaled gases. It is useful in a wide spectrum of clinical settings and helpful in clinical decision making. In practice, CPET is considered when specific questions persist after consideration of basic clinical data (e.g., physical examination, chest radiograph, pulmonary function tests, and ECG).

You will either ride a stationary bike or run on a treadmill for the test. We will closely monitor your heart rate/rhythm (electrocardiogram), blood pressure, breathing, and oxygen saturation during the test. You will generally be asked to exercise to your maximal level unless you feel you cannot continue. The actual time spent exercising is usually around 10-20 minutes with the majority of time spent preparing you for the test.

Length of Test: 60 minutes

Preparation:

• A completed pre-screening questionnaire may be required prior to the test. We ask that you not smoke or use alcohol for at least 4 hours prior to testing, and avoid eating 3 hours before the test. You should continue to take your normal medications as usual, unless your physician has instructed you otherwise. Patients should wear clothes and sneakers appropriate for activity and refrain from exercise before their appointment on the day of their test.

Description: You will breathe normally in and out through a mouthpiece. The equipment measures your respiratory resistance with normal breathing. The assessment of the measured values and the analysis of the curves allow differentiation between obstructive and restrictive ventilation defects. Impulse ocillometry complements conventional tests such as spirometry, body plethysmography, and lung diffusion. Impulse oscillometry requires only little patient cooperation so that patients from the age of 2 and up can be examined. Thus, this procedure is particularly suitable for measurements in the field of pediatrics.

Length of Test:

1. 15 minutes : measurement without pre/post bronchodilator comparison
2. 30 minutes: pre/post bronchodilator comparison iii. Preparation- Withhold bronchodilators as with spirometry if pre/post testing is needed

Preparation: Withhold bronchodilators as with spirometry if pre/post testing is needed

Description: Oral exhaled nitric oxide measurement are used as an indicator of eosinophilic airway inflammation. It is frequently used to monitor the response to antiinflammatory medications, to verify adherence to therapy, and to predict upcoming asthma exacerbations. Nasal nitric oxide measurements are very high relative to the lower respiratory tract. Nasal NO may have physiologic roles, such as preserving sinus sterility and modulating ciliary motility. Nasal nitric oxide is clinically useful in accessing primary ciliary dyskinesia where nitric oxide levels are extremely low.

• Types of nitric oxide tests:
  • Single flow: You take a deep breath in , then exhale slowly. The computer screen has animations that help you keep your exhaled flow in the right target range.
  • Multiple flow: This is done the same way as the single flow measurement with the exception of having you exhale at different flow rates. This is sometimes used by researchers to obtain more specific information on alveolar vs airway nitric oxide exchange dynamics
  • Nasal nitric oxide: We insert a foam plug in your nostril, then have you exhale through a restrictor mouthpiece until we see a plateau in your nitric oxide reading. We typically make a few measurements in both you left and right nostril. This is used primarily in the assessment of primary ciliary dyskinesia

Length of Test:

1. 15 minutes: Single flow nitric oxide
2. 30 minutes: Multiple flow nitric oxide
3. 30 minutes: Nasal nitric oxide

Preparation:

1. No taxing respiratory maneuvers within 1 hour prior (exercise, spirometry)
2. Ideally no eating/drinking 1 hour prior, particularly nitrate containing foods ( leafy greens, root vegetables)
3. No smoking within 1 hour prior
4. Upper and lower respiratory tract infections increase nitric oxide
5. Medications that can reduce nitric oxide include corticosteroids, NO synthase inhibitors, leukotriene-axis modifiers. Medications that can increase include NO donor drugs and L-arginine.

Description: A pulmonary shunt is a pathological condition which results when the alveoli of the lungs are perfused with blood as normal, but ventilation (the supply of air) fails to supply the perfused region. In other words, the ventilation/perfusion ratio (the ratio of air reaching the alveoli to blood perfusing them) is zero. A pulmonary shunt often occurs when the alveoli fill with fluid, causing parts of the lung to be unventilated although they are still perfused.

Intrapulmonary shunting is the main cause of hypoxemia (inadequate blood oxygen) in pulmonary edema and conditions such as pneumonia in which the lungs become consolidated. The shunt fraction is the percentage of blood put out by the heart that is not completely oxygenated.

In pathological conditions such as pulmonary contusion, the shunt fraction is significantly greater and even breathing 100% oxygen does not fully oxygenate the blood.

The procedure is performed by having the patient breath 100% oxygen via face mask for 20 minutes. An arterial blood sample is are generally drawn prior to the procedure on room air, and again after breathing 20 minutes of 100% oxygen. The latter blood gas is used in the calculation of the shunt fraction. This blood sample is usually drawn from the radial artery in your wrist.

Length of Test: 90 minutes

Preparation: No specific preparation.

Description: The high altitude simulation test (HAST) is a diagnostic test to screen patients at risk for hypoxia at higher altitudes and determine if supplemental oxygen is needed during plane travel or travel to high altitude. The HAST simulates a plane cabin pressure at 5,000 to 8,000 feet which results in oxygen concentrations of approximately 17.1% and 15.1 %.

The procedure is performed by having the patient breath 15% oxygen via face mask for 20 minutes. Your breathing, oxygen saturation and heart rate are monitored throughout the test. An arterial blood sample is are generally drawn prior to the procedure on room air, and again after breathing 20 minutes of 15% oxygen. This blood sample is usually drawn from the radial artery in your wrist.

Length of Test: 90 minutes

Preparation: No specific preparation

Description: The six minute walk test is a way to measure your functional exercise capacity. The 6MWT is a self-paced test of walking capacity. Patients are asked to walk as far as possible in 6 min along a flat corridor. Your distance walked will be measured. Your oxygen saturation and heart rate will be monitored throughout the test. In addition, we will measure your blood pressure before and after the test and you will be asked to rate your shortness of breath and fatigue on a scale before and after the test.

This test can be done with you wearing oxygen if needed. Your provider may request an oxygen titration walk, in which case, we will adjust oxygen level as needed during the test.

Length of Test: 30 minutes

Preparation: 

1. The patient should refrain from heavy exercise immediately before testing.
2. The patient should arrive with their usual aids to mobility (e.g. cane, walker).
3. If the patient normally uses portable oxygen (portable tank or concentrator), they should arrive with their usual source of oxygen. Otherwise, the PFT lab will supply a portable E cylinder of oxygen for use during the test if needed.