Bruce Protocol

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Bruce Protocol -

A protocol for exercise testing of cardiac patients developed by Robert A. Bruce.

Before the development of the Bruce Protocol there was no safe, standardized protocol that could be used to monitor cardiac function in exercising patients. Master's Two-Step Test was sometimes used, but it was too strenuous for many patients, and inadequate for the assessment of respiratory and circulatory function during varying amounts of exercise. Most physicians relied upon patients' complaints about exertion, and examined them only at rest.

To address these problems, Dr. Bruce and Dr. Paul Yu began work on developing a treadmill exercise test. The test made extensive use of relatively new technological developments in electrocardiographs and motorized treadmills.

A Bruce exercise test involved walking on a treadmill while the heart was monitored by an electrocardiograph with various electrodes attached to the body. Ventilation volumes and respiratory gas exchanges were also monitored, before, during and after exercise. Because the treadmill speed and inclination could be adjusted, this physical activity was tolerated by most patients.

Initial experiments involved a single-stage test, in which subjects walked for 10 minutes on the treadmill at a fixed workload. Bruce's first paper on treadmill exercise tests, published in 1949, analyzed minute-by-minute changes in respiratory and circulatory function of normal adults and patients with heart or lung ailments.

In 1950 Bruce joined the University of Washington, where he continued research on the single-stage test, particularly as a predictor of the success of surgery for valvular or congenital heart disease. Later he developed the multistage test, consisting of several stages of progressively greater workloads. It was this multistage test, a description of which was first published in 1963, that became known as the Bruce Protocol. In the initial paper, Bruce reported that the test could detect signs of such conditions as angina pectoris, a previous heart attack, or a ventricular aneurysm. Bruce his and colleagues also demonstrated that exercise testing was useful in screening apparently healthy people for early signs of coronary artery disease.

Bruce Protocol 

Stage   Min     % grade MPH     METS
1       3       10      1.7     4.7
2       6       12      2.5     7.0
3       9       14      3.4     10.1
4       12      16      4.2     12.9
5       15      18      5.0     15.0