PFTs measure two components of the respiratory system: the mechanical ability of the respiratory system to move air in and out of the lungs; and the effectiveness of the respiratory system in exchanging oxygen and carbon dioxide with the atmosphere. A PFT includes three possible components:
1. Spirometry (94010, 94060, 94070)
2. Lung Volume Determination (94250, 94726, 94727 and 94728)
Lung Volume tests cannot be measured directly using Spirometry because these volumes and capacities include air that cannot be expelled from the lungs. Lung Volume is generally determined in one of four ways:
Closed circuit helium equilibration
Open circuit nitrogen washout
Whole body plethysmography
3. Diffusion Capacity Tests (94729)
The PFT will be considered medically necessary for the following conditions:
· Preoperative evaluation of the lungs and pulmonary reserve when:
– thoracic surgery will result in loss of functional pulmonary tissue (i.e., lobectomy) or
– patients are undergoing major thoracic and/or abdominal surgery and the physician has some reason to believe the patient may have a pre-existing pulmonary limitation (e.g., long history of smoking); or
– the patient’s pulmonary function is already severely compromised by other diseases such as chronic obstructive pulmonary disease (COPD).
· Initial diagnostic workup for the purpose of differentiating between obstructive and restrictive forms of chronic pulmonary disease. Obstructive defects (e.g., emphysema, bronchitis, asthma) occur when ventilation is disturbed by an increase in airway resistance. Expiration is primarily affected.
Restrictive defects (e.g., pulmonary fibrosis, tumors, chest wall trauma) occur when ventilation is disturbed by a limitation in chest expansion. Inspiration is primarily affected.
· To assess the indications for and effect of therapy in diseases such as sarcoidosis, diffuse lupus erythematosus, and diffuse interstitial fibrosis syndrome.
· Evaluate patient’s response to a newly established bronchodilator anti-inflammatory therapy.
· To monitor the course of asthma and the patient’s response to therapy (i.e., especially to confirm home peak expiratory flow measurements).
· Evaluate patients who continue to exhibit increasing shortness of breath (SOB) after initiation of bronchodilator anti-inflammatory therapy.
· Initial evaluation for a patient that presents with new onset (within 1 month) of one or more of the following symptoms: shortness of breath, cough, dyspnea, wheezing, orthopnea, or chest pain.
· Initial diagnostic workup for a patient whose physical exam revealed one of the following: overinflation, expiratory slowing, cyanosis, chest deformity, wheezing, or unexplained crackles.
· Initial diagnostic workup for a patient with chronic cough. It is not expected that a patient would have a repeat spirometry without new symptomatology.
· Re-evaluation of a patient with or without underlying lung disease who presents with increasing SOB (from previous evaluation) or worsening cough and related qualifying factors such as abnormal breath sounds or decreasing endurance to perform Activities of Daily Living (ADL’s).
· To establish baseline values for patients being treated with pulmonary toxic regimens (e.g., Amiodarone).
· To monitor patients being treated with pulmonary toxic regimens when any new respiratory symptoms (e.g., exertional dyspnea, non-productive cough, pleuritic chest pain) may suggest the possibility of pulmonary toxicity.
· To evaluate cystic fibrosis patients with pulmonary manifestations.
It is expected that procedure code 94070 will only be performed to make an initial diagnosis of asthma.
Also, it is expected that procedure code 94060 be utilized during the initial diagnostic evaluation of a patient. Once it has been determined that a patient is sensitive to bronchodilators, repeat bronchospasm evaluation is usually not medically necessary, unless one of the following circumstances exist:
(1) a patient is exhibiting an acute exacerbation and a bronchospasm evaluation is being performed to determine if the patient will respond to bronchodilators;
(2) the initial bronchospasm evaluation was negative for bronchodilator sensivity and the patient presents with new symptoms which suggest the patient has a disease process which may respond to bronchodilators; or
(3) the initial bronchospasm evaluation was not diagnostic due to lack of patient effort. Repeat spirometries performed to evaluate patients’ response to newly established treatments, monitor the course of asthma/COPD, or evaluate patients continuing with symptomatology after initiation of treatment should be utilized with procedure code 94010.
In addition, it is not expected that a pulse oximetry (procedure code 94760 or 94761) for oxygen saturation would routinely be performed with spirometry. Pulse oximetry is considered medically necessary when the patient has a condition resulting in hypoxemia and there is a need to assess the status of a chronic respiratory condition, supplemental oxygen and/or a therapeutic regimen (e.g., acute symptoms).
Usually during an initial evaluation, there is no reason to obtain a spirometry after the administration of bronchodilators in patients who have normal spirometry, normal flow volume loop and normal airway resistance unless there is reason to believe (e.g., symptoms, exam) that a patient has underlying lung disease.
The residual volume (RV) cannot be measured by spirometry because this includes air that cannot be expelled from the lungs, and, therefore, is determined by subtracting the expiratory reserve volume (ERV) from the functional residual capacity (FRC). The FRC cannot be measured by simple spirometry either; therefore, procedure code 94726 or 94727 will be performed when the RV and FRC need to be determined.
The Maximum Voluntary Ventilation (MVV; procedure code 94200) is a determination of the liters of air that a person can breathe per minute by a maximum voluntary effort. This test measures several physiologic phenomena occurring at the same time. The results and success of this test are effort dependent, therefore, routine performance of this test is not recommended, except in cases such as: pre-operative evaluation, neuromuscular weakness, upper airway obstruction, or suspicion of Chest Bellows disease.
The Respiratory Flow Volume Loop (procedure code 94375) is used to evaluate the dynamics of both large and medium size airways. This test is more useful than the conventional spirogram. The procedure is the same for spirometry except for the addition of a maximal forced inspiration at the end of the force expiratory measures.
Pulmonary Stress Testing (94620, 94621)
The pulmonary stress testing procedures range from simple to complex. The simple procedure (Stage 1) consists of BP, ECG, and ventilation measurements at timed increments during exercise. The complex procedure includes Stage 2 and Stage 3. Stage 2 involves all of Stage 1 measurements in addition to the mixed venous CO2 tension (production) by means of rebreathing technique and O2 uptake. Stage 3 requires the following: (a) blood gas sampling and analysis, (b) an indwelling catheter is inserted into the brachial or radial artery, and (c) in addition to Stage 2 tests, measurements for cardiac output, alveolar ventilation, ratio of dead space to tidal volume, alveolar-arterial O2 tension difference, venous admixture ratio and lactate levels are determined.
Exercise testing is done to evaluate functional capacity and to assess the severity and type of impairment of existing as well as undiagnosed conditions. The Pulmonary Stress Test will be considered medically necessary for the following conditions:
· To determine whether the patient’s exercise intolerance is related to pulmonary disease, cardiac disease, or due to lack of conditioning or poor effort.
· Initial diagnostic workup when symptoms (generally dyspnea) are out of proportion to findings on static function (spirometry, lung volume, diffusion capacity).
· Detection of interstitial lung disease (fibrosis) or exercise-induced broncho-spasm which are only manifested by exercise.
· Evaluate patient’s response to a newly established pulmonary treatment regimen.
The majority of clinical problems can be assessed during the simple procedures included in Stage 1, and should be completed before more complex tests are performed. Abnormal results indicate that more precise information is required through more complex Stage 2 protocols. If Stage 3 protocols are implemented, arterial blood analysis is necessary. In 75% of patients, Stage 1 is sufficient. Oxygen titration can be done during graded exercise to determine the oxygen needs for improving exercise tolerance and increased functional capacity.
Absolute contraindications to exercise testing include:
· Acute febrile illness
· Pulmonary edema
· Systolic BP > 250mm Hg
· Diastolic BP > 120mm Hg
· Acute asthma attack
· Unstable angina
· Acute Myocarditis
Lung Compliance (94750)
Lung compliance measures the elastic recoil or stiffness of the lungs. It is more invasive than other PFTs, because the patient is required to swallow an esophageal balloon.
Compliance studies are performed only when all other PFTs give equivocal results, or the results require confirmation by additional data.