Page 448 - Cardiac Nursing

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424 P A R T III / Assessment of Heart Disease

■ Figure 19-2 Stages, workloads, and oxygen cost per stage of some commonly used protocols. USAFSAM,
United States Air force School of Aerospace Medicine; ACIP, Asyptomatic Cardiac Ischemia Pilot; CHF, con-
gestive heart failure (modified Naughton); kpm/min, kilopond meters/minute; %GR, percent grade; MPH,
miles per hour.

therapy, and possibly even lowered sensitivity for detecting coro- and prognostic comparative data. The Naughton test, however,
nary disease. 22,25,27,36,37 can result in tests of excessive duration among more fit subjects.

Balke Treadmill Protocol Cycle Ergometer Protocols
The Balke protocol, and modifications of it, has been widely used Although there are specific bicycle protocols named after early
for clinical exercise testing. It uses constant walking speeds (2.0 or researchers in Europe, such as Astrand and Rodahl, 40 bicycle er-
3.0 mph) and modest increments in grade (2.5% or 5.0%), and it gometer protocols tend to be more generalized than those for the
has been used particularly often in studies assessing angina re- treadmill. For example, 15- to 25-W increments per 2-minute stage
sponses. Modifications of the original Balke treadmill protocol are commonly used for patients with cardiovascular disease, whereas
have become widespread. One modification, developed by the for apparently healthy adults or athletic individuals, appropriate
38
United States School of Aerospace Medicine (Balke–Ware) con- work rate increments might typically be between 40 and 50 W per
sists of 5% grade increases every 2 minutes and a constant brisk stage. Most modern, electronically braked cycle ergometers have
walking speed of 3.3 mph (after an initial warm-up of 2.0 mph), controllers that permit ramp testing in which the work rate incre-
which has been considered the most efficient speed for walking. ments can be individualized in continuous fashion (see next section).
The constant speed is advantageous in that it requires only an ini-
tial adaptation in stride. Ramp Testing
An approach to exercise testing that has gained interest in recent
Naughton Treadmill Protocol years is the ramp protocol, in which work increases constantly and
The Naughton treadmill protocol 39 is a low-level test that has be- continuously. In 1981, Whipp et al. 41 first described cardiopul-
come common for multicenter trials in patients with chronic monary responses to a ramp test on a cycle ergometer, and many
heart failure. The test begins with 2-minute stages at 1 and 2 mph of the gas exchange equipment manufacturers now include ramp
and 0% grade, then continually increases grade in approximately software. Treadmills have also been adapted to conduct ramp
1-MET increments at a constant speed of 2 mph for the next tests. 25,42,43 The ramp protocol uses a constant and continuous
8 minutes. Speed then increases to 3 mph with a slight decrease in increase in metabolic demand that replaces the “staging” used in
grade, followed by increases in grade equivalent to approximately conventional exercise tests. The uniform increase in work allows
1 MET. The Naughton protocol provides reasonable and gradual for a steady increase in cardiopulmonary responses and permits a
work rate increases for patients with more advanced heart disease. more accurate estimation of oxygen uptake. 25 The recent call for
Because this protocol has been used extensively in patients with “optimizing” exercise testing 4,22,27,30 would appear to be facilitated
chronic heart failure, it provides a substantial amount of functional by the ramp approach, because large work increments are avoided