Residual Functional Capacity Assessment for Lung Disease
What Is RFC?
If your lung disease is not severe enough to meet or equal a listing at Step 3 of the Sequential Evaluation Process, the Social Security Administration will need to determine your residual functional capacity (RFC) to decide whether you are disabled at Step 4 and Step 5 of the Sequential Evaluation Process. RFC is a claimant’s ability to perform work-related activities. In other words, it is what you can still do despite your limitations. An RFC for physical impairments is expressed in terms of whether the Social Security Administration believes you can do heavy, medium, light, or sedentary work in spite of your impairments. The lower your RFC, the less the Social Security Administration believes you can do. Claimants close to the listing should be restricted to no higher than sedentary exertion.
Claimants with Both Lung and Heart Disease
The close physiological relationship between the cardiovascular and pulmonary systems means an impairment in one of these systems influences the other. For example, it is very common for a claimant with COPD caused or aggravated by cigarette smoking to also have significant cardiac disease or peripheral vascular disease as separate impairments. Thus, if you have both heart and respiratory impairments, you will have a much worse functional restriction than if you had either alone. For example, if you would be restricted to medium work on the basis of cardiovascular disease and medium work because of respiratory disease, you should receive a RFC for no higher than light work.
Removal of Lung Tissue
Removal of lung tissue (pulmonary resection) can also limit the RFC. The most frequent type of pulmonary resection is a lobectomy associated with surgery for lung cancer. Sometimes, a pneumonectomy involving the removal of an entire right or left lung is performed.
In otherwise healthy lungs, a lobectomy usually results in an exertional restriction to medium work when the results of spirometry are evaluated. In cases of pneumonectomy, an RFC is always required, and even with a healthy remaining lung is usually no higher than light work.
As with other pulmonary impairments, environmental restrictions from exposure to excessive dust and fumes would be indicated on the RFC.
The fact that a treating surgeon may say something in his or her medical notes like, “The patient has fully recovered from surgery and has no difficulty breathing,” does not mean that spirometry does not have to be performed. When significant amounts of lung tissue are removed, there will be some degree of pulmonary limitation.
Most claimants with pulmonary resection associated with removal of a lung cancer are operated on because they have cancer caused by cigarette smoking. Claimants who have smoked long enough to develop lung cancer always have chronic obstructive pulmonary disease and will have pulmonary deficits worse than would be expected if the remaining lung tissue were normal (see Figure 5 below). This is another reason it would be improper for the Social Security Administration to guess about remaining lung function without obtaining spirometry (unless the claim is otherwise allowable). Whether or not a claimant post-resection for lung cancer complains of shortness of breath, the Social Security Administration has a responsibility to evaluate the residual breathing impairment.
Figure 5: Smoker's lung.
Lung Disease With Gas Exchange Impairment
If you have a lung disease that produces gas exchange impairment, you should not receive RFC levels of exertion that could cause you to desaturate (lose oxygen from the blood), so that you become so hypoxemic (oxygen deprived) that you are in danger of a cardiac arrhythmia (and consequent sudden death), or in danger of loss of consciousness. Desaturation can happen so quickly that you have no reliable symptom warning signs.
Whether exercise produces hypoxemia depends on the amount of exercise and severity of the underlying disease, as well as environmental factors such as extreme heat and cold. Exercise arterial blood gas studies (ABGS) that produce actual PaO2 measurements correlated with known levels of exercise is useful. In these instances, your RFC determination should be at least one level below the exercise level at which limiting symptoms or hypoxemia appears. In other words, you should never receive a RFC that corresponds to the exercise test exertional level alone, unless there is no hypoxemia.
To further illustrate, suppose claimant A, with heart disease but no lung disease, reaches an exercise level on a treadmill that indicates the ability to perform light level work. Now consider claimant B, with restrictive lung disease but no heart disease, who does as much exercise on the treadmill, but who develops hypoxemia as measured with ABGS. The latter claimant should receive no higher than a sedentary RFC.
In addition to the objective medical evidence, the opinion of your treating physician about your exercise capacity and symptoms and your own observations and those of your family can be helpful in determining RFC.
Information About Your Activities
You should take care to provide the Social Security Administration with a clear picture regarding the speed at which you can carry out various activities, particularly as limited by shortness of breath. If you state you can climb two flights of stairs, the Social Security Administration might use that information but it is incomplete. There are several pieces of information missing: 1) Are the stairs climbed at a normal pace? 2) Do you have to stop and rest on the way up, limited by shortness of breath?
Similarly, it is misleading to say you can walk 1 block or 2 blocks or 3 blocks. If the pace is slow enough, some people with chronic pulmonary disease can walk several miles. But if it’s a slow struggle, it hardly represents any practical functional capacity.
Use of the arms can bring on rapid shortness of breath. So it is important to provide times for completion of daily activities, if possible. If not, comparisons to normal individuals can help define functional limitation. For example, “I can walk a block before I get short of breath, but I can’t keep up with my wife” is a much more revealing statement than “I get short of breath walking.”
The ability to do heavy, medium, light, or sedentary work is not correlated to any particular pulmonary function test results. However, spirometric or other test values of 80% or more of predicted normal are generally considered a strong argument for a “not severe” impairment that requires no RFC limitations. Intermediate results must be interpreted on a case by case basis considering all of the evidence, including your symptoms. The Social Security adjudicator should keep in mind where along the numerical spectrum your test results lie between meet-level severity and normal values.
Symptoms of shortness of breath correlate only loosely with severity of pulmonary disease as measured by pulmonary function studies. For example, a claimant whose lung function would suggest a capacity for medium work might credibly have shortness of breath that limits him or her to light work—symptoms can certainly produce a greater restriction than is present from a purely physiological standpoint. Some SSA adjudicators may mechanically apply particular test values to particular RFCs. This is improper and not supported by any official policy.
All claimants with respiratory disorders severe enough to warrant a RFC should receive limitations from exposure to excessive dust and fumes. Furthermore, work at cold temperatures can increase symptoms of shortness of breath and decrease exercise capacity in individuals with COPD such as asthma, emphysema, and chronic bronchitis.