Page 878 - Cardiac Nursing

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854 PA R T V / Health Promotion and Disease Prevention
about this change. Although the AHA guidelines suggest ECG encouraged for participants in cardiac rehabilitation programs.
4
monitoring for the first 6 to 12 sessions, recommendations on Again, however, an effective exercise prescription must consider
this issue have varied widely. Patients who should be considered the patient’s goals, health status, and availability of time in ad-
for longer ECG monitoring include those with a history of seri- dition to practical considerations such as cost, availability of
ous rhythm disorders, implantable cardioverter defibrillator im- equipment, and facilities.
plantation, CHF, and abnormal hemodynamic responses to exer- Much of the art of exercise prescription clearly involves indi-
cise testing (e.g., exercise-induced hypotension). vidualizing the exercise intensity. Typically, exercise intensity is ex-
pressed as a percentage of maximal capacity, either in absolute
terms (i.e., workload or watts) or in relation to the maximal HR,
Exercise Prescription for maximal oxygen uptake, or perceived effort. Training benefits have
Outpatient Rehabilitation been shown to occur with exercise intensities ranging from 40% to
85% of maximal oxygen uptake, which are generally equivalent to
Exercise prescription essentially describes the process whereby a 50% to 90% of the maximal HR. However, the intensity that a
person’s recommended regimen of physical activity is designed in given individual can maintain for a specified period of time varies
a systematic and individualized manner. An “individualized man- widely. In general, the most appropriate intensity for most patients
ner” implies specific strategies to optimize return to work or in rehabilitation programs is 50% to 70% of maximal capacity.
ADLs, reduction of risk factors for future cardiac events, and max- The actual prescribed exercise intensity for the patient should nat-
imization of the patient’s capacity to maintain an active lifestyle. urally depend on goals, health status, length of time since infarc-
The development of an appropriate exercise prescription to meet tion or surgery, symptoms, and initial state of fitness.
the individual patient’s needs has a sound scientific foundation, Training is a general phenomenon; there is no true threshold
but there is also an art to effective exercise programming. beyond which patients achieve benefits. Thus, as long as patients
The art of exercise prescription has become increasingly im- exercise safely, setting the exercise intensity is a less rigid practice
portant in this era of cost containment (shorter rehabilitation), than it was years ago. In addition, the patient’s ability to tolerate
surgical and technologic advances (larger numbers of transplanta- activities can change daily. Other factors, such as time of day, en-
tions, pacemaker, or CHF participants than ever before), and the vironment, and time since medications were taken, can influence
multitude of new medicines available. There is no single program the patient’s response to exercise, and the exercise prescription
that is best for all patients or even one patient over time; capa- must be adjusted accordingly. It is also useful to use a window of
bilities, vocational needs, and expectations differ among patients intensity that ranges approximately 10% above and 10% below
and can change with the passing of time. Thus, the art of exer- the desired level.
cise prescription relies on the nurse’s abilities to synthesize the The graded exercise test is the foundation on which a safe and
patient’s pathophysiologic, psychosocial, and vocational factors effective exercise prescription is based. To achieve a desired train-
and tailor them to the patient’s needs and realistic goals. A final ing intensity, oxygen uptake or some estimate of it must be quan-
but important consideration is the selection of activities that the tified during a maximal or symptom-limited exercise test. Because
individual enjoys, which will provide the best chance that he or HR is easily measured and is linearly related to oxygen uptake, it
she will continue to perform safely after the formal rehabilitation has become a standard by which training intensity is estimated
program ends.
during exercise sessions. The most useful method uses a meas-
ure known as the HR reserve. This method uses a percentage of
Principles of Exercise Prescription the difference between maximum HR and resting HR and adds
Training implies adaptations of the body to the demands placed this value to the resting HR. For example, for a patient who
on it. A training effect is best measured as an increase in maximal achieves a maximum HR of 150 beats per minute, has a resting
ventilatory oxygen uptake, but not all institutions have gas ex- HR of 70 beats per minute, and wishes to exercise at intensity
change equipment and there are many ways to quantify functional equivalent to 60% of maximum:
outcomes of rehabilitation. For example, some patients after reha-
bilitation may be better suited to perform submaximal levels of ac- Maximum HR 150 bpm
tivity for longer periods, remain independent, continue working, Resting HR 70
or rejoin their friends on the golf course. All of these can be im-
portant goals for a given patient and may occur even with a min- HR range 80
imal change in maximal oxygen uptake. Desired intensity (60%)
The major ingredients of the exercise prescription are fre-
quency, intensity, duration, mode, and rate of progression. In 48
general, these principles apply for both the patient with heart
Resting HR 70
disease and the healthy adult; however, the ways in which they
are applied differ. On the basis of numerous studies performed Training HR 118
since the 1950s, it is generally accepted that increases in maxi-
mal oxygen uptake are achieved if a person exercises dynamically A reasonable training HR range for this individual would be
for a period ranging from 15 to 60 minutes, three to five times 115 to 125 beats per minute. This is also referred to as the Kar-
per week, at an intensity equivalent to 50% to 80% of the max- vonen formula and is reliable for patients in normal sinus rhythm
imum capacity. Dynamic exercises are those that use large mus- whose measurements of resting and maximum HRs are accurate.
cle groups in a rhythmic manner, such as treadmill walking, cy- An estimated target HR for exercise should be supplemented by
cle ergometry, rowing, stepping, and arm ergometry. As considering the patient’s MET level relative to his or her maxi-
mentioned, short warm-up and cool-down periods are strongly mum, the perceived exertion, and symptoms.