Document ID: chunk:federal_register_of_legislation:F2023C00151:front:0:p12
Version: federal_register_of_legislation:F2023C00151
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11–12). However, if a respiratory component is present, measurements of lung function, such as forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and maximal expiratory flow (MEF 25–75) are to be used in addition to exercise tolerance. FEV1 and FVC are to be measured by spirometry. For the purposes of assessment in accordance with this Guide, the terms "MEF 25–75" and "FEF 25–75" (forced expiratory flow between 25% and 75% of the vital capacity) are to be taken as equivalent.

The conversion of loss of exercise tolerance and measurements of lung function into an impairment rating is set out in Table 1.2 and Table 1.3.

Certain cardiorespiratory conditions cannot be rated by applying exercise tolerance. These include:
    conditions that do not decrease exercise tolerance;
    conditions that do not produce symptoms; and
    intermittent conditions.

"Exercise tolerance" refers to a person's ability to exercise from a cardiorespiratory point of view rather than to a person's total ability to exercise. For example, a veteran who has osteoarthritis of both knees may be greatly limited in walking but may still be able to swim a considerable distance. Such a veteran would still have good exercise tolerance from a cardiorespiratory point of view, though total ability to exercise would be reduced.

A veteran whose ability to exercise has been significantly reduced by other conditions (such as musculoskeletal conditions or being grossly overweight), or who no longer has cardiac or respiratory symptoms on exercise, cannot always be given an appropriate impairment rating for reduced exercise tolerance. However, the need to apply Chapter 19 (Partially Contributing Impairment) should always be considered before disregarding exercise tolerance figures.

Calculation of the impairment rating for accepted cardiorespiratory conditions

Follow the steps below to determine the impairment rating for cardiorespiratory conditions:

(Each step is elaborated in the following pages.)

Step 1  Establish what cardiorespiratory conditions are present.                                                                Page 7
Step 2  Assess the information that is available and decide whether it is reliable and sufficient.                              Page 8
Step 3  Determine the impairment rating based on effort tolerance.                                                              Page 9
Step 4  (Omit this step if no respiratory disease is present.)                                                                  Page 13

        Determine the impairment rating based on measure­ments of lung function.
Step 5  Determine the total accepted cardiorespiratory functional impairment rating.                                            Page 21
Step 6  Consider the effects of cardiac failure (if any).                                                                       Page 24
Step 7  Moderate the total cardiorespiratory functional impairment rating to allow for effects of any non-accepted conditions.  Page 24
Step 8  Determine whether any ratings from the relevant Other Impairment tables apply (Tables 1.7, 1.8, 1.9, 1.10).             Page 25

Step 1: Establish what cardiorespiratory conditions are present.

For the purpose of assessing cardiorespiratory impairment, both the accepted and the