Download The Cardiopulmonary System and Movement Dysfunction

The Cardiopulmonary System and
Movement Dysfunction
Physical therapy primarily involves the identification and treatment of
problems related to movement. Movement dysfunction usually is
attributed to impairments of the neuromuscular and musculoskeletal
systems. The cardiopulmonary system plays an important role in
movement because of its function of transporting oxygen to skeletal
muscle. Abnormalities of the cardiovascular and pulmonary systems
can produce limitations in physical function. The purposes of this
article are to describe the steps involved in the transfer of oxygen from
atmospheric air to skeletal muscles and to provide examples of
problems that can occur with each step of the process. Common signs
and symptorns of potential problems involving the cardiovascular and
pulmonary systems also will be discussed. [Peel C. The cardiopulmonary system and movement dysfunction. Phys Ther. 1996;76:448- 455.1
Key Words: Cardiovascular system; Movement disorders; Oxygen transport; Pulmonaly, general.
Claire Peel
448
Physical Therapy. Volume 76 . Number 5 . May 1996
CO, moves into capillary blood. Within the cell, 0,
ovclnent is essential for perfornlance of
moves into mitochondria, allowing adenosine triphosroutine daily tasks and recreational activiphate generation through aerobic melnbolism. The CO,,
ties and is the direct result of many factors.
is returned to the lungs via the lrenous system for
An individual must have the willingrless o r removal from the body. Metabolites, such as hydrogen
motivation to accomplish a task, and the movement must
be supported by the musculoskeletal, ne~lrornuscular, ions (H'), potassium, adenosine, and lactate, also are
removed through the blood syste111 and ar-e either
and cardiopulmonary systems. As experts in the science
excr-eted or used for other functions in the body.
of rnovement dysfunction, physical therapists determine
probable causes of problelns related to nlovernent and
then design programs to improve physical filnctiol~. During exercise, skeletal muscle activity results in an
increase in cell~llar0, requirements and ill the amount
Accomplishing this task requires an understanding not
only of psychology and the roles of' the ~ l e u r o r n ~ ~ s c ~ l l of
a r CO, that must be carried to the lungs for removal
and musculoskeletal systems ill supporting niovenie~~t from the body. To meet the increased 0, needs, both
but also of the role of the cardiopulmonary system.
and cardiac output (CO) must increase
ventilation (i'~)
in propor-tion to the increased n~etabolicrate. \'entilation (in liters per minute) is the product of breathing
The purposes of this introductory article are to describe
frequency and tidal vol~une(VT). Cardiac o u t p ~ l t(in
how the cardiopulmonary system functions to support
liters per minute) is the product of heart rate (HR) and
the increased metabolic needs associated with physical
stroke volume (SV). In individuals witllotrt car-diopulmoactivity and to describe common problerns of the cardionary abnormalities, the increases in (i"~)
and CO are
vascular and pulnlonaiy systems that produce movenlent
closely matched to the increase in metabolic rate, allowdysfunction. Signs and symptoms that are indicative of
potential abnormalities of the cardiopulmonary system
ing arterial blood gas and pH levels to remain close to
baseline values during e x e r c i s e . T h e precision of the
also will be disc.ussed.
system is denlollstrated by all appropriate increase i r ~
both (i'~)
and CO as the exercise intensity le\.el ranges
Cardiopulmonary Function at Rest and During
horn light to very heavy.:'
Exercise
The primary purposes of the cardiopulmonary systerli
An effec.tive system for increasing c a r d i o p ~ l l ~ i ~ oactivnar~
are to deliver oxygen (0,)to metabolically active tissues
and to remove carbon dioxide (CO,) and ~netabolites. ity in response to various levels of physical activity
External respiration, or gas exchange between the lungs
involves multiple steps. Figure 2 describes the steps
involved in the transfer of 0, from the atniosphere to
and atmosphere, is linked to internal cell~llarrespiratiorl
skeletal muscle. The initial step is ( i r e ) , which is the
by the cardiovascular system. Interactions between skelmovelnent of air in and out of the I~ulgs.Veiltilation
etal muscle, the heart, and the lungs are character-ized ill
Figure 1. Atnlospheric air is brought into the 111ngs occurs as a result of respiratory muscle activity. W%en
these m ~ ~ s c l econtract,
s
a negative pressure withill the
where 0, rnoves into pulmonary capillaries and CO,
thorax is created, and air moves illward fro111the mouth
rnoves from the blood into alveoli for removal ill expired
to various parts of the I~ulgs.At rest, the primar-y ~n~lscles
air. The heart then pumps 0,-rich blood to peripher-al
tissues. At the capillary level, 0, moves into tissues and
of inspiration are the diaphragm, the scalene n~ilscles,
(: Prrl,
PhD, PT, is A~sociatrProtrssor. Drpartlllrltt of' Ph!sical Therapy, School of'f'har~~iary
atid Allied Health Pri~Sr.;sions.(:rrighto~i Llriivrl-sity, Onlaha, NE (iHliH (LISA) (cperl@>creightol~.rdu)
Physical Theropy . Volume 7 6
.
Number
5 . May 1996
Peel . 449
Figure 1.
A scheme illustrating the gas transport mechanisms for coupling cellular [internal) to pulmonary (external) respiration. Qo,-oxygen
(0,)utilization
output from the alveoli.
by the muscles, &02=carbon dioxide ( C 0 2 ) production by muscles, i/02=0, uptake from the alveoli, VCO,=CO,
[Reprinted with permission from Wasserrnan K, Hansen JE, Sue DY, Whipp BJ. Principles of Exercise Testing and Interpretation. Philadelphia, Pa: Lea
& Febiger; 1987.)
and the parasternal intercostal muscle^.^ These muscles
function to expand the thorax by producing lower rib
cage expansion (diaphragm), elevation of the rib cage
(scalene muscles), and an increase in the anteriorposterior dimension of the rib cage (parasternal muscles) .4 During activity, additional muscles are recruited,
including the sternocleidomastoid and external intercostal muscle^.^ The abdominal muscles indirectly assist
in inspiration by pushing the diaphragm upward, which
increases the length of the diaphragm prior to
in~piration.~
A high degree of compliance is important to facilitate
the movement of blood into the left ventricle. Compliance can decrease with myocardial ischemia and left
ventricular hypertrophy. In these conditions, the ability
to adequately fill the left ventricle may be impaired, and
patients may experience dyspnea o r signs and symptoms
of decreased CO. During systole, the ~nyocardiumcontracts. As the pressure in the left ventricle exceeds the
pressure in the aorta, the aortic valve opens and blood
moves into the arterial system.
The next step involves gas exchange between the alveoli
and pulmonary capillary blood. To accomplish this task,
the alveoli that receive fresh air must be perfused with
blood. The blood must have a sufficiently long transit
time in the pulmonary capillary to allow time for diffilsion of gases. The time needed for CO, to move into the
alveoli and for 0, to move into capillary blood is
approximately 0.25 secondsf5 (Fig. 3). Another critical
factor is that the alveoli that are well ventilated also must
be well perfused. Because of regional differences in the
distributions of both (VE) and perfusion," the possibility
exists to have areas of the lung that are well ventilated
but underperfiised, o r vice versa. During exercise, there
is an increase in both perfusion and (i'~),
which facilitates the matching of (VK)and perfi~sion.
Cardiac output is determined by SV and HR, and varies
depending o n the body's 0, requirements. Increased
activity of the sympathetic nervous system (SNS) produces an increase in CO, which results from increases in
both the rate of contraction and the strength of contraction. Cardiac output also can be increased by greater
venous return reaching the left ventricle, as during
exercise.' The increased volume, or preload, stretches
the ventricular muscle. A stronger contraction is produced because of a more advantageous length-tension
relationship. During exercise, CO is increased because
of increases in both SV and HR, with SV reaching its
ntaxirnal level at approximately 40% of maximal oxygen
consumption (vo2max).X Consequently, for moderateto-heavy exercise (levels greater than 40% of \jo,max),
increases in CO result from increases in HR.
From the lungs, oxygenated blood enters the left side of
the heart. The heart then must be able to generate a
force great enough to propel blood to various parts of
the body. During diastole, when blood moves into the
left ventricle, the myocardium is relaxed and compliant.
As the blood leaves the heart, adjustments in the vascular
system direct blood proportionally to the tissues with the
highest metabolic needs. Contraction and relaxation of
smooth muscle in the walls of arteries and arterioles
produce changes in the size of these vessels. Increasing
450 . Peel
Physical Therapy . Volume 7 6
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Air moves into the lungs as a result of contraction
of respiratory muscles
+
+
+
+
+
Inspired air is distributed to alveoli
Diffusion of 0, from alveoli to
pulmonary capillary blood
Ejection of blood containing 0, from lefi ventricle
Distribution of cardiac output to
active skeletal muscles
Movement of 0,from peripheral capillaries
to mitochondria of muscle cells
Figure 2.
Steps invcllved in the transfer of oxygen (0,)
skeletal muscle.
from the atmosphere to
the size of a vessel's lumen, o r vasodilation, allows
greater blood flow to the area of the body supplied by
those vessels. During activity, CO is directed to active
skeletal muscles and to the skin to allow dissipation of
heat, with vasoconstriction occurring in inactive muscles
arid vibc-elal organs. The degree of vasodilation verstls
constriction is controlled centrally by the SNS and locally
by cellular metabolites. As muscles become more active,
there is an increase in the local concentration of metabolites, such as CO, and H + , which produces vasodilation."
The increase in temperature also facilitates vasodilation.
This local mechanism allows blood to be shunted to
muscles with the greatest metabolic activity. Having
reached the tissue level, 0, moves from capillaries into
muscle cells, with CO, moving in the opposite direction.
Another ir~iportantfactor for an adequate 0, delivery
system is the 0,-canying capacity of the blood. The 0,
content of the blood is determined by the amourit of
hemoglobin in the blood and by the partial pressure of
oxygen (Po,) in the blood.ti l ' h e oxyhemoglobin dissociation curve, as demonstrated in Figure 4, describes the
relationship between the Po, and the saturation of
hemoglobin. Factors that alter the oxyhemoglobin dissociation curve will affect 0, delivery to skeletal muscle.
A shift of the cunTeto the left impairs the amount of 0,
extracted by muscle, whereas a shift to the right facilitates tlie unloading of 0, from hemoglobin." Increased
concentration of carboxyhemoglobin, which occurs with
smoking, produces a leftward shift of the curve, impairPhysical Therapy . Volume 7 6
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1996
a
-
t
EXERCISE
0.
0
I
.25
1
.50
I
.75
Figure 3.
Oxygen time courses in the pulmonary capillary when diffusion is
normal and abnormal. Under normal conditions, blood reaches a
parfial pressure of oxygen (PO,) of 100 rnm Hg within 0.25 seconds
even though the time course of travel through the capillary is 0.75
seconds. When there is a limitation in diffusion, the time to reach a PO,
of 100 mm Hg i s prolonged, as noted by the "abnormal" line. When
diffusion is severely limited, blood exiting the pulmonary capillary will
not achieve a normal PO, level, as indicated by the "grossly abnormal"
line. The time course i s shortened during exercise (as noted by the
arrow) and may result in below-normal PO, levels when limitations in
diffusion are present. (Reprinted with permission from West JB. Respiratory Physiology. 4th ed. Baltimore, Md: Williams & Wilkins Co; 1990.)
ing 0, delivery. Acidosis and increased body temperature, which occur with exercise, facilitate the unloading
of 0, from hemoglobin and the diffusion of 0, from
capillaries to muscle cells.
A final critical factor is the need for a method of
regulation that prevents large fluctuations in arterial
blood gases and pH. It is well known that changes in the
-partial pressure of oxygen in arterial blood (Pao,), the
partial pressure of carbon dioxide in arterial blood
(Paco,), and H + concentration stimulate the respiratory
system and produce changes in (VE) that serve to return
blood gas values to n ~ r m a lThe
. ~ increase in metabolism
with exercise results in an increase in CO, production
so that arterial blood gases and pH remain close to
baseline during mild and moderate exercise."he
exact
mechanism of control is unknown and rnay involve the
rate of CO, flow to the lurigs o r the central ncrvous
system.
In summary, the cardiopulmonary system plays a critical
role in delivering 0, to skeletal muscles to support
movement. Consequently, problems involving either the
cardiopulmonaly system o r the musculoskeletal system
can adversely affect a person's ability to perform routine
Peel . 45 1
Ventilation-Perfusion (v/Q) Mismatching
SAT
Figure 4.
Effects of temperature, partial pressure of carbon dioxide in arterial
and pH on the oxygen dissociation curve. The large arrow
blood (Pco,),
in the center indicates that increases in temperature and PCO, and
decreases in p H will shift the curve to the right, focilitoting the dissociation of oxygen with hemoglobin (Hb). Po,=partial pressure of oxygen.
(Reprinted with permission from West JB. Respirotory Physiology. 4th
ed. Baltimore, Md: Williams 8 Wilkins Co; 1990.)
furlctional activities. Because of the multiple steps that
are involved in the transfer of 0, from the atnlosphere
to skeletal nluscles, there are a variety of problems that
can have an adverce effect.
Respiratory Muscle Dysfunction and Chest
Wall Deformities
Respiratory muscle dysfunction and chest wall deformities limit the ability of the thorax to expand, and
therefore pulmonary ventilation is compromised. Respiratory muscle dysfunction can be caused by paralysis o r
partial paralysis of the respiratory rrruscles and often
occurs with cervical spinal cord injuries and GuillainRarre syr~drome.l'.~:'
Progressive n~usculardiseases, such
as m~iscttlartlystrophy and amyotrophic lateral sclerosis,
can cause myopathy of respiratory muscle^.^^ Chest wall
defornlities occur with ankylosing spondylitis, kyphosis,
ancl scoliosis.' A noncompliant o r rigid chest wall also
cau l i ~ r ~thoracic
it
expansion, a condition that occurs
wit11 aging. I' If the condition is severe, VT at rest may be
decreased, requiring a n increased breathing frequency
for adequate (VK). With less severe conditions, individuals may be li~rlitedin their ability to increase (VT) o r
breathing frequency during exercise, resulting in a
decrease in maximal excrcise capacity.
452
. Peel
In conditions in which parts of the lung are perfused but
not ventiIated, or ventilated with poor perfusion, effective gas exchange cannot occur. The term "vencilatio~iperfusion (v/Q) mismatching" is used to describe inequalities between areas of (VE) and perfusion. This
condition can occur with the obstructive lung diseases of
enlphyserna and chronic bronchitis because (VE) is not
evenly distributed to parts of the lungs and blood flow is
affected by destruction of portions of the capillary bed.'"
The result is a decrease in Pao, o r an increase in Paco,.
Perfusion of parts of the lungs could be decreased
because of vascular abnormalities such as pulmonary
emboli. The result of this condition is an increase in
alveolar dead space, o r "wasted" (VF.). Alveolar dead
space is the volume of gas in alveoli that are ventilated,
but poorly perfused o r urlderperfused.I7 This condition
occurs when blood flow is blocked by a p u l m o n a r ~
embolus. The opposite condition occurs with pulmonary
fibrosis, where selected alveoli are replaced with scar
tissue, decreasing (vE.) to areas with normal perft1sion.l"
Adequate perfusion without (VE) is referred to as a
shunt.
Diffusion Abnormalities
Movement of gases across the alveolar-capillary membrane may be limited because of abnormalitics in the
membranes or because of an accumulation of fluid in
the alveoli or interstitial spacc. Pulmonary diseases that
result in thickening of the alveolar capillary membrane
cause an impairment in diffusion. A colninori example is
idiopathic pulmonary fibrosis.lq In pulmonary edema o r
congestivc hcart failure, fluid fills the space between the
capillaries and alveoli. Both of these conditions result in
impaired diffusion of O2from the alveoli to the capillary
blood, resulting in an abnormally low Pao,. The condition worsens with activity because blood moves faster
through the pulmonary capillaries and there is less time
fol- diffusion. In Figure 3, the effect of exercise on 0,
transfer in the pulmonary capillary is illustrated.
Inadequate Cardiac Output
Cardiac abnormalities have the potential to impair cardiac output either at rest o r during activity. Common
problems involving the heart include myocardial ischemia, heart failure, valvular abnormalities, and cardiac dysrhythmias. Myocardial ischemia can result from
either atherosclerosis o r vasospasm of coronary artcries.2') Chronic heart Failure involves impaired contractile
function of cardiac muscle and can occur as a result of
many causes including coronary artery disease, myocarditis, hypertension, and sorllc systemic diseases." Valvular abnormalities prevent the normal flow of blood
through the heart and rcsult from a variety of causes
including rheumatic fever, myocardial infarction, and
cotlgerlital abnormalities.'Of the marly types of cardiac
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arrhythmias, those that have the greatest potential to
dysrhythmias and heart
limit CO include ventric~~lar
blocks." If any of these conditions is severe, CO at rest
may not be sufficient to meet the needs of the body.
With less severe conditions, CO may he adequate at rest
but inadequate during the stress of physical activity.
Consequently, O 2 delivery to active skeletal muscles is
impaired, requiring an increase in energy generation
using anaerobic metabolic pathways. Blood levels of
lactic acid increase, producing metabolic acidosis, which
can Ile manifested as fatigue, clyspnea, or limited exercise tolerance. Other signs and symptoms of inadequate
CO include skin color changes such as pallor or cyanosis,
light-headedness or dizziness, and weakness.
Table.
Signs and Symptoms Associated With Abnormalities of the
Cardiovascular and Pulmonary Systems
Condition
Signs/Symptoms
Respiratory distress
Difficulty breothing as demonstrated by
shortness of breath, increased breothing
rate, use of accessory muscles, and nasal
flaring
Chronic coughing
Changes in skin color (pallor or cyanosis)
Abnormal responses to activity such an
excessively high or low heort rate,
decreasing systolic blood pressure,
increased diastolic blood pressure,
changes in electrocardiographic activity
or heort sounds, excessive fatigue
Chest pain
Dvs~nea
,
Intermittent claudication
Decreased or absent peripheral pulses
Changes in the appearance of involved
extremities, which may include dry or
cool skin, hair loss, or muscular atrophy
Cardiac dysfunction
Limitations in Peripheral Blood Flow
If the ability to either vasodilate or vasoconstrict in parts
of the circulation is impaired, then 0, delivery to active
skeletal ~nusclenlay be impaired. In persons with atherosclerosis involving peripheral arteries, blood flow may
be decreased by the atherosclerotic lesion or by the
inability of sclerotic vessels to vasodilate.'" Ischemia,
producing pain and limiting physical activity, results
when muscles become active and require additional 0,.
In persons with spinal cord injuries, normal SNS control
of peripheral blood vessels may not be present. Without
sympathetic control, the reflex vasoconstriction in inactive skeletal muscle and in visceral organs that normally
occurs with activity will not occur.2Wonseqiiently, blood
flow to skeletal lnuscle rnay be limited because blood is
not being diverted from other tissues. The inability to
vasoconstrict in appropriate parts of the vascular system
also can affect skin blood flow and limit heat dissipation.
Without adequate 0,, active skeletal muscles must
increase their use of anaerobic enerby-generating pathways. The outcome is fatigue and dyspnea because of
increased lactic acid and metabolic acidosis.
Low Oxygen-Carrying Capacity
The most common condition producing a decrease in
0,-carrying capacity is anemia. In persons with anemia,
as the blood moves through the circlilatory system, the
Po, drops faster than usual as 0, leaves the limited
amount of hemog1obin.l As the blood reaches skeletal
muscle, the low Po, levels may not provide a sufficient
gradient. for diffusion of 0, from blood to skeletal
muscle. Consequently, lactic acid increases, and metabolic acidosis and fatigue result. A common compensatory ~nechanismis tachycardia, which assists in increasing CO. A potential consequence is all exaggerated
increase in HR in response to low-intensity activities.
Signs and Symptoms of Cardiovascular or
Pulmonary Abnormalities
When the cardiovascular or pulmonary system cannot
respond appropriately to the increased demand of exer-
Physical Therapy . Volume 7 6
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1996
8
Peripheral vascular
disease
cise, abnormal physiological responses or synlptolns ot
activity intolerance occur. The abnormalities provide
clues to the underlying patholo#. Problems often
become symptomatic first during activity when the cardiopulmonary systerrl is stressed. AS the co~ldition
becomes more severe, higns and symptoms also rrlay
occur at rest. By carefully observi~~g
symptoms and
documenting responses during activity, early detection
of cardiopulmonary problems is possible. A summary of
common signs and sympto~nsis presented in the Table.
Signs and Symptoms of Respiratory Distress
One of the most common symptoms of r e s p i r a t o ~
distress is dyspnea, or the sensation of difficult or
labored breathing. Having diffic~ultybreathing, or being
"out of breath," is expected when working at or near
maximal capacity but not when working at low or
moderate levels of effort. Dyspnea also can occur at rest
and is easily detected because patients cannot complete
a full sentence without stopping to breathe. Another
symptom of a problelrl involving the respiratory system is
a chronic cough. Whether the cough is productive or
not, characteristics of sputum such as collsistency, color,
and smell are important to identifying the problenl.'"
A rapid breathing rate, or tachypnea, also may indicate
distress. Persons who are unable to increase (VK) 1,y
increasing VT or depth of breathing rely on their ability
to increase the breathing rate. Increasing the breathing
rate, rather than VT, is a less efficient stratqy of increasing (i'~)
because there is a relative increase in deadspace (i'r;). A change in the regularity of hreathing also
may indicate abnormal function. Normal hreathing
involves regular inspiration and expiration, with a deep
Peel . 453
breath o r sigh interspersed periodically. An example of
an abnormal breathing pattern is Cheyne-Stokes respiration, which involves increasing and decreasing the
depth of breathing, with periods of apnea interspersed.Z7
This pattern often occurs in patients with heart failure or
cerebrovascular disease.Zx
Other signs of respiratory distress include use of accessory breathing muscles, changes in skin color, behavioral
changes, and nasal flaring. Increased use of neck muscles for inspiration o r abdominal muscles for expiration
is abnormal when resting o r performing low levels of
exercise. Cyanosis or pallor is an indication of abnormal
oxygenation, o r hypoxernia. Behavioral changes, such as
confusion o r agitation, also can indicate hypoxemia.
Nasal flaring is a sign of severe distress and occurs when
individuals exert increased effort during inspiration.
Signs and Symptoms of Cardiac Dysfunction
O n e of the most common symptoms of a cardiac problem is angina, or chest pain. Angina may be described by
patients as a feeling of heaviness, pressure, or burning
rather than as a painful sensation. The discomfort
associated with angina may occur in areas other than the
chest, such as the arms, cervical region, jaw, o r upper
back. The term exertional angina is used if the pain occurs
during activity and is relieved when the individual stops
the activity. Exertional angina is thought to result from
myocardial ischemia due to an increase in myocardial 0,
demand that cannot be met because atherosclerosis
limits an increase in blood flow to the heart. Chest pain
that occurs at rest can indicate a coronary artery spasrn
or an impending myocardial infarction.g!' Chest pain
also car1 result from other causes, including pericarditis,
pleural effusion, o r a musculoskeletal injury. Differentiating angina from other problenls associated with chest
pain is an important part of the clinical asses~ment.:~)
Other symptoms of cardiac dysfunction include dyspnea,
light-headedness o r dizziness, and fatigue. Dyspnea, typically associated with piilmonary dysfunction, often
occurs with ~~lyocardial
ischemia and heart failure. Dyspnea also can occur in patients with left ventricular
hypertrophy, which often is caused by hypertension o r
aortic valve disease and results in impaired ventricular
relaxation. Light-headedness o r dizziness is associated
with heart failure o r myocardial ischemia, and also with
hypoterlsioli. Fatigue that results from routine activities,
or that occurs with low-intensity exercise, is associated
with heart fa1'I ure.
Signs of cardiac dysfunction include abnormal responses
to exercise. An HR that is either excessively high o r
exceptionally low during exercise may indicate heart
disease. The amount of increase in HR with activity is
related to the intensity of the activity, age of the individ-
454 . Peel
ual, medications, and ambient temperature.:" Heart rate
responses that are either higher o r lower than would be
expected based o n these factors could indicate an abnormality. Abnormal blood pressure responses include
either a systolic blood pressure that does not rise progressively as work level increases o r a systolic blood
pressure that falls during exercise. An increase in diastolic blood pressure during exercise that is greater than
15 to 20 inm Hg also is considered abn~rrnal.:~'
Other
signs include electrocardiographic changes such as dysrhythmias o r ST-segment depression and changes in
heart sounds.
The patients's age, medications, and corresponding
symptoms must be considered when interpreting abnormal responses to exercise. A single abnormal finding in
a patient who is asymptomatic may not be indicative of a
problem, whereas multiple abnormal findings in a
patient who is symptomatic provide support for a cardiac
abnormality. An example is a rapid HR, a falling blood
pressure response, and the appearance of a third heart
sound, a combination of abnormal findings that suggests
heart failure.
Signs and Symptoms of Inadequate Peripheral
Blood Flow
Intermittent claudication is one of the most common
symptoms of inadequate peripheral blood flow. Pain
resulting from ischemia occurs when 0, delivery cannot
meet the increased 0, requirements of active skeletal
muscle. Discomfort typically occurs during walking and
is relieved when the individual stops to rest. Pain also
may occur when the lower extremities are elevated, with
relief occurring when the extremities are rrioved to a
dependent position.
Chronic deprivation of 0, often produces trophic
changes, which inolude muscle atrophy, hair loss, and
dry skin.:':' The skin may feel cool, and peripheral pulses
in corresponding arteries may be weak o r absent.
Changes in skin color with elevation of the involved
extremities also may occur. Typically, there is blanching
of the skin with elevation, followed by redness when the
extremity is returned to the dependent position. The
tinling of the changes in skin color can be used to
estimate the severity of the co~ldition:"~
Summary
The cardiovascular and pulmonary systems are essential
to normal movement because of their role in delivering
0, from the atmosphere to active skeletal muscle. There
are multiple steps involved in the transfer of O2 from the
air to blood and in the delivery of 0,-rich blood to
lnetabolically active tissues. An impairment in any of the
steps can result in inadequate 0, delivery. By understanding and identifying the mecharlism involved when
Physical Therapy
. Volume 76 . Number 5 . M a y 1996
0, delivery is inadequate, therapists can determine
optimal methods of patient management.
In the early stages of cardiovascular and pulmonary
diseases, the signs and symptoms may be subtle. Careful
observation and monitoring of responses during and
after physical activity is important to be able to identify
potential problems. Because of their role in physical
rehabilitation, physical therapists are in a position to
identify problems. Early identification of problems may
lead to treatment that may arrest or slow the progression
of the disease.
References
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3 Saltin B, Astrand PO. Maximal oxygen uptake in athletes. J AH11
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