Respiratory
disturbances
DYSPNEA
In
early HF, dyspnea is observed only during exertion, when it may simply represent
an aggravation of the breathlessness that occurs normally. As HF advances, dyspnea
occurs with progressively less strenuous activity and ultimately it is present
even at rest.
The principal difference between exertional dyspnea occurs
with progressively less strenuous activity and ultimately it is present even at
rest. The principal difference between exertional dyspnea in normal persons and
in patients.
With HF is the degree of exertion necessary to induce this
symptom. Cardiac dyspnea is observed most frequently in patients with elevations
of pulmonary vessels and interstitial accumulation of interstitial fluid.
The activation of receptors in the lungs results in the rapid, shallow breathing
characteristic of cardiac dyspnea. The oxygen cost of breathing is increased by
the excessive work of the respiratory muscles required to move air into and out
of the congested lungs.
This is coupled with the diminished delivery
of oxygen to these muscles, a consequence of a reduced cardiac output. This imbalance
may contribute to fatigue of the respiratory muscles and the sensation of shortness
of breath.
Orthopnea
This
symptom, i.e. dyspnea in the recumbent position, is usually a later manifestation
of HF than exertional dyspnea. Orthopnea results form the redistribution of fluid
from the abdomen and lower extremities into the chest during recumbency,
Which
increase the pulmonary capillary pressure, combined with elevation of the diaphragm.
Patients with orthopnea must elevate their head on several pillows at night and
frequently awaken short of breath and coughing if their head slips off the pillows.
Orthopnea is usually relieved by sitting upright, and some patients
reports that they find relief from sitting in front of an open window. In advanced
HF, patients cannot lie down at all and must spend the entire night in a sitting
position.
Paroxysmal
(nocturnal) dyspnea
This
term refers to attacks of severe shortness of breath and coughing that generally
occurs at night, usually awaken the patient from sleep, and may be quite frightening.
Though simple orthopnea may be relived by sitting upright at the side
of the bed with legs dependent, in the patients with paroxysmal nocturnal dyspnea,
coughing and wheezing often persist even in this position.
Paroxysmal
nocturnal dyspnea may be caused in part by the depression of the respiratory center
during sleep, which may reduce ventilation. Sufficiently to lower arterial oxygen
tension, particularly in patients with interstitial lungs edema and reduced pulmonary
compliance.
Cardiac asthma is closely related to paroxysmal nocturnal
dyspnea and nocturnal cough and is characterized by wheezing secondary to bronchospasm-most
prominent at night.
Acute pulmonary edema is a severe form of cardiac
asthma due to marked elevation of pulmonary capillary pressure leading to alveolar
edema, associated with extreme shortness of breath, rales over the lungs fields,
and the expectoration of blood –tinged fluid. If not treated promptly, acute
pulmonary edema may be fatal.
Cheyne-stokes
respiration
Also known as periodic respiration or cyclic respiration,
Cheyne - Stokes respiration is characterized by diminished sensitivity of the
respiratory center to arterialpco2. There is an apneic phase, during which the
arterial po2 falls and the arterial pco2 rises.
These changes in the
arterial blood stimulate the depressed respiratory center, resulting in hyperventilation
and hypocapian, followed in turn by recurrence of apnea.
Cheyne - Stokes
respiration occurs most often in patients with cerebral atherosclerosis and other
cerebral lesions, but the prolongation of the circulation time from the lung to
the brain that occurs in HF, particularly in patients with hypertension and coronary
artery disease, also appears to contribute to this form of disordered breathing.
Other
symptoms
Fatigue and weakness
These nonspecific
but common symptoms of HF are related to reduction of skeletal muscle perfusion.
Exercise capacity is reduced to the limited ability of the failing heart to increase
its output and deliver oxygen to the exercising muscles.
Abdominal
symptoms
Anorexia and nausea associated with abdominal pain and
failure are frequent complains and may be related to the congested liver and portal
venous system.
Cerebral
symptoms
Patients with severe HF, particularly elderly patients with cerebral arteriosclerosis,
reduced cerebral perfusion, and arterial hypoxemia, may develop alterations in
the mental state characterized by confusion, difficulty in concentration, impairment
of memory, headache, and anxiety. Nocturia is common in HF and may contribute
to insomnia.
