PART A: SYSTEM SPECIFIC ASSESSMENT

CHAPTER 1

CARDIORESPIRATORY IMPAIRMENT

INTRODUCTION

Cardiorespiratory impairment results from conditions that affect the function of the heart or lungs. The procedures described in this chapter are to be applied in assessing most conditions of the heart and lungs, and will usually also be appropriate for conditions affecting the function of the thorax or diaphragm, lesions of the nerves that supply the muscles of respiration, and conditions such as anaemia. The principal exception is any condition which is predominantly intermittent in nature and which would be better assessed by applying Chapter 15 (Intermittent Impairment).

Different procedures (described in Chapter 2) are to be applied to assess hypertension and non-cardiac vascular conditions (such as aortic aneurysm and varicose veins).

In general, cardiorespiratory impairment is to be measured by reference to exercise tolerance. Exercise tolerance is quantified in terms of METs (see pages 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.