notes by dr Claudio Italiano
The dyspnoic patient presents a series of symptoms that vary according to the
diseases that afflict him. In fact, dyspnea, ie the sensation of lack of air, is
not always associated with respiratory diseases; in fact, it may be dyspnea
related to cardiac pathologies, e.g. we can classically have the dyspnoic
patient for a cardiac asthma. The doctor proceeds with the patient's visit,
starting with the objective examination and requesting the appropriate
investigations.
Eg practical. A middle-aged patient comes to our observation in the grip of
severe dyspnea. We visit: at the physical examination we appreciate a thoracic
finding characterized by basal wet noises at the base of the right and poor
bilateral ventilation with O2 saturation of 90% masked; to the auscultation of
the heart of tachyarrhythmia, PA 180/100; the patient performs an ecg that
documents atrial fibrillation with high ventricular response; at a blood count
of 26,000 Gb with a positive formula for neutrophilic leukocytosis; the
glucotest control documents 350 mg%. We begin to work and, in the meantime, we
check the chest that at the chest-Xray documents congestion with suspected lesions at
the middle right lobar field and right ile congesto. The picture is complex. We
set up a double antibiotic therapy, a diuretic, IV therapy with amiodarone (4
vials into 250 cc of glucose at 20 ml / hour), Venturi mask oxygen therapy,
methylprednisolone. The respiratory picture will normalize only after ten days
of treatment. As you can see the clinical picture was complex.
Important indications of the underlying etiology may derive from the evaluation
of the general conditions of patients and vital signs, from the measurement of
body weight, respiratory flow peaks and arterial oxygenation through pulsed
oximetry. The feedback of a paradoxical pulse (excessive variations of arterial
pressure with respiratory acts) may suggest COPD, asthma, pericardial
pathologies. A tachycardia can be associated with heart failure or an anemia
condition. Jugular vein distension suggests congestive heart failure.
The doctor must look for a possible use of accessory muscles of the respiration,
decreases of diaphragm excursion, unilateral obtuseness to the percussion of the
thorax, hyperrisance, abnormal respiratory noises, such as hiss or rales. In
patients with bronchiectasis, the dominant finding on target examination is
crackles or rales, usually bilateral. A decrease in breathing sounds and the
presence of hisses suggest COPD.
A decrease in cardiac sounds can be caused by pulmonary hyperplasia, obesity, cardiac tamponade. A tone or S4 may indicate a reduced sinister ventricular response, while the finding of breaths suggests valvular pathologies, or possibly an interatrial defect hitherto undiagnosed. A rubbing noise can indicate a pleural effusion. Hepatomegaly, ascites, hepato-jugular reflux or edema can be caused by right heart decompensation by pulmonary hypertension. The finding of digital Hippocratism must lead to the execution of exams aimed at excluding pulmonary carcinomas, bronchiectasis, idiopathic pulmonary fibrosis.
Laboratory exams
The initial assessment must include a complete blood count and some blood
chemistry tests. Anemia can cause dyspnea, while a polycythemia may be a
consequence of a condition of chronic hypoxia. Leukocytosis, neutropenia,
alterations of the leukocyte formula may suggest underlying inflammatory or
infectious diseases. A retention of carbon dioxide suggests an alteration of the
pulmonary gaseous exchange, compatible with COPD or with advanced interstitial
lung disease. The brain natriuretic hormone (brain natriuretic peptide, BNP) is
a neuro-hormone that is secreted by the myocardium in response to the
ventricular wall tension. For patients with dyspnea, plasma N-terminal pro-BNP
concentrations are increased in patients with left ventricular dilatation or
hypertrophy, systolic or diastolic dysfunction, but not in patients with lung
diseases. BNP and L-terminal pro-BNP levels may therefore be useful for
distinguishing between heart failure and pulmonary causes of dyspnoea. D-dimer
is a marker of fibrin degradation. Plasma D-dimer levels are directly related to
the severity of pulmonary embolisms, and may be useful for determining the risk
of thromboembolic relapses. In a patient with low pre-test probability, a
negative result at D-dimer level determination may be useful to exclude a
pulmonary embolism. Following the medical history and physical examination, the
initial diagnostic tests must include pulsed oximetry, blood count, blood
chemistry, electrocardiogram, chest x-ray and usually a spirometry. In cases
where even after these tests the diagnosis remains uncertain, consideration
should be given to the diagnosis of anxiety, hyperventilation syndrome, physical
deconditioning, neuromuscular disorders.
Chest x-ray is important in the evaluation of patients with chronic dyspnea of
suspected lung origin; the indications deriving from radiography must be
interpreted in association with other findings of the objective examination. A
negative X-ray does not rule out the presence of infiltrative pneumopathy.
Radiographic examination is also indicated in patients with heart failure who
have new signs or symptoms. In about half of patients with chronic carboxiatic
disease, the test shows cardiomegaly; Magnification marks of individual cardiac
chambers are useful in the diagnosis of valvular pathologies.6
The electrocardiogram can confirm the presence of rhythm alterations, possible
causes of dyspnoea; the examination must be requested when heart failure is
suspected. The doctor must take into consideration any underlying cardiopathies,
electrolyte abnormalities, systemic diseases. A history of atrial fibrillation
increases the likelihood of congestive heart failure. The electrocardiogram can
show an ischemia in case of previous infarcts. A decrease in the voltage of QRS
complexes in precordial derivations can be attributed to pericardial effusions,
infiltrative cardiopathies, COPD, hypothyroidism, obesity. The electrocardiogram
has a high sensitivity, but a low specificity, in the diagnosis of systolic
dysfunction of the left ventricle.
In patients with dyspnoea, spirometry should be performed to document any
obstruction of airflow in the airways. A decrease in forced expiratory volume in
the first second (VEMS) or in the VEMS / forced vital capacity (CVF) ratio
indicates an obstructive pathology of the airways, such as COPD, chronic
bronchitis or asthma. A restrictive pneumopathy is instead suggested by a
decrease in CVF and a normal or increased VEMS / CVF ratio; for the diagnostic
confirmation the measurement of the pulmonary volumes is necessary.
Further tests may be required according to the diagnostic aspect, and may
include other pulmonary function tests, echocardiography, computed tomography
(CT), perfusional and ventilatory scinrigrafia, stress test, bronchoscopy;
catheterization of the right or left heart can be performed in some patients.
In addition to spirometry, further lung function tests may include blood gas
analysis, determination of lung volumes (eg, residual volume, residual
functional capacity, total lung capacity), pulmonary diffusion capacity of
carbon monoxide (DLCO). Total pulmonary capacity is reduced in patients with
restrictive parenchymal diseases, while it is normal or increased in patients
with obstructive diseases and "entrapment" of air in the lungs. In a patient
with normal spirometric examinations and lung volumes, but a reduced DLCO, the
differential diagnosis should include anemia, early interstitial lung disease,
vascular pneu- mopathy. Patients with emphysema typically have lower DLCO values.
In patients with bronchiectasis, dyspnoea is more closely related to pulmonary
hyperinflation than to variables indicating pulmonary obstruction. A decrease in
maximal inspiratory and expiratory pressure suggests a neuromuscular cause of
dyspnea.
American College of Cardiology and the American Heart Association recommend
performing an ultrasound (or alternative imaging methods) in patients suspected
of heart failure. Like chest radiography, transthoracic echocardiography is also
indicated in patients with dyspnea of suspected cardiac origin. The data
obtainable with the test, useful for the diagnosis, include the pressures in the
right ventricle and in the polmonar artery, the ejection fraction, the thickness
and the compliance of the ventricular wall, as well as the detection of valve
changes.
In cases of chronic dyspnoea of uncertain diagnosis, presumably attributable to widespread pulmonary diseases, the most suitable imaging examination is the high resolution chest CT without contrast medium. A CT angiography with contrast medium may be required to exclude acute or chronic pulmonary embolism. CT is useful in the diagnosis of inflammatory pathologies, malignant neoplasms, interstitial pneumopathies, mediastinal pathologies, occult emphysemes.
Ventilation / perfusion scintigraphy is indicated for patients with pulmonary
hypertension due to an undefined cause, to rule out chronic thromboembolic
pulmonary hypertension. The examination is more sensitive than pulmonary
angiography with CT in the diagnosis of this pathology.
A cardiovascular effort test, whether or not associated with imaging tests, can
provide information on the presence of coronary ischemia. The car-diopulmonary
stress test allows an assessment of pulmonary gas exchange during exercise and
of metabolic oxygen requirements. The information can be useful to clarify the
cause of dyspnea.
In patients with interstitial lung disease, sarcoidosis or malignant neoplasms,
diagnostic bronchoscopy, associated with bronchiolar lavage or biopsy
examination may be useful; the test can confirm atypical or mycotic ineffective
processes. A right-heart catheterization is necessary to confirm a diagnosis of
pulmonary arterial hypertension. Scanning with gallium may be useful to identify
neoplastic processes, apart from targeted biopsies.
index pneumology