Dyspnea
Definition,
Dyspnea is defined as an awareness of difficulty in
breathing It is therefore a symptom,usually described
by the patient as,short of breath,” whether the
sensation is due to actual difficulty in breathing or is
essentially an awareness of hyperventilation,If the
symptom becomes striking,it always companies with
dilatation of nares,cyanosis,use of accessory
muscles of respiration and abnormalities of
respiratory rate,depth or rhythm,
?Respiratory diseases
? Circulatory diseases
? Poisoning
? Hematology
? Neuropsychogenic factors
Etiology
Respiratory dyspnea
? Caused by abnormal ventilation and gas exchange,
reduction in ventilatory capacity,hypercapnia and
hypoxemia resulting from respiratory disease,
? Three clininal types,Inspiratory dyspnea
Expiratory dyspnea
Mixed dyspnea
Inspiratory dyspnea
? Tends to occur primarily when there is obstruction
( such as inflammation,edema,tumor and foreign
body) in larynx,trachea and major bronchi,
? Characterized by the depression sigh,in which
visible indrawing over the sternal notch,the
supraclavioular spaces,the intercostal spaces and
the epigastrium in the inspiration can be seen,
? Often accompanied by a coarse,low pitched
inspiratory wheezing and dry cough,
Expiratory dyspnea
? Expiratory dyspnea is due to the decrease of lung
elasticity and spasm narrowing of the bronchioles
and smaller bronchi as in emphysema,bronchial
asthma and asthmatic bronchitis,
? Expiration is prolonged and laboured with
wheezing,
Mixed dyspnea
? Occurs with the extensive lung disease,such as
severe pneumonia,pulmonary fibrosis,massive
atelectasis,pleural effusion and pneumothorax,
? Results in the decrease of ventilators and gas
exchange capacity,
? Breathing is difficult during both inspiration and
expiration,
Cardiac dyspnea
Cardiac dyspnea is usually
attributable to pulmonary vascular
congestion resulting from the left
and/or right heart failure,
Cardiac dyspnea
? In Left-sided heart failure,compliance is
reduced,and therefore,ventilation is decreased
to the edematous lung regions and vital capacity
reduced,Alveoli are stiff and more work is
needed to overcome elastic recoil,the high
alveolar pressure will stimulate stretch receptor
and initiate the inflation reflex resulting in early
turning off of inspiration and an increase in
respiratory rate,
Cardiac dyspnea
? The dyspnea caused by right-sided heart failure is
less severe than that one caused by left-sided,
? Mechanism,
(1) The pressure of right atrial and superior vena
cava is the natural stimulus of respiratory center,
(2) The decrease of oxygen content and the
accumulation of the acid metabolites,such as
lactic,stimulate respiratory center,
(3) The restriction of the respiratory movement
caused by enlargement of liver resulting from
congestion,ascites and pleural effusion,
Cardiac dyspnea
Symptoms of congestive heart failure
can cause orthopnea and paroxysmal
nocturnal dyspnea when elevated-
filling pressure is present,
orthopnea
? Orthopnea is difficulty in breathing in the supine
position,this may be relived by sitting up,which
reduces the degree of pulmonary congestion by
pooling blood in the lower extremities and
lowering left ventricular filling pressures,
improving the diaphragmatic movement,
increasing vital capacity,
paroxysmal nocturnal dyspnea
? Symptoms,The patient awakes short of breath at
night,but often obtain relief by sitting up for a
period of time,In the most advanced cases,the
patients become acutely dyspneic,cyanotic and
very frequently produce foamy sputum tinged with
blood,
? Signs,Moist rales at the both lung bases,
tachycardia,wheezing and bronchospasm,the
markedly accentuated second heart sound in the
pulmonic area,
? Mechanism,Supine posture for sleep results in
resorbtion of extracellular fluid into the
intravascular space,causing arise in filling
pressure,
? The paroxysmal dyspnea is termed as cardiac
asthma,It can be seen in the hypertensive heart
disease and coronary heart disease,
paroxysmal nocturnal dyspnea
Toxic dyspnea
? In the metabolic acidosis (uremia and diabetic
ketosis),the acid metabolites stimulate the
respiratory center,causing deep and regular
respiration with snoring,
? The overdose of morphine and pentobarbital
can depress respiratory center causing deep
respiration or Cheyne-Stokess respiration
Neuro-Psychogenic dyspnea
? In patients suffering from cerebrovascular
diseases (intracranial hemorrhage,elevated
intracerebral pressure),the respiratory center
loses the blood supply or is compressed,The
respiration becomes deep,slow and irregular,
? In some cases the dyspnea may be psychogenic,
which is characterized by repetitive deep,sighing
respiration with numbness of extremities or lips,
cheiropedal spasm,These are also manifestations
of acute hypocapnia and respiratory alkalosis,
Hematological dyspnea
? In severe anemia,sulfhemoglobinemia,
methaemoglobinemia or carbon monoxide
poisoning the decrease of oxygen-carrying
capacity and oxygen content develop abnormal
respiration and increased heart rate,
? The respiration rate also increases in shock which
stimulates respiration center because of
hypotension,
Accompanied Symptom
?Paroxysmal dyspnea with wheezing,
? Dyspnea with chest pain,
? Dyspnea with fever,
? Dyspnea with cough and purulent sputum,
? Dyspnea with coma,
? Paroxysmal dyspnea with wheezing
It is present in bronchial asthma and cardiac
asthma,Paroxysmal severe dyspnea is often
seen in acute larynx edema,foreign body in
bronchi,massive pulmonary embolism,and
spontaneous pneumothorax,
? Dyspnea with chest pain,
It is frequently observed in lobar pneumonia,
pulmonary infarction,spontaneous
pneumothorax,acute exudative pleurisy,
acute myocardial infarction,and bronchial
carcinoma,
? Dyspnea with fever,
It is commonly noted in pneumonia,lung
abscess,pulmonary tuberculosis,pleurisy,
acute pericarditis,and nervous system
diseases,
? Dyspnea with cough and purulent sputum,
It is often present in chronic bronchitis,
obstructive pulmonary emphysema with
infection,purulent pneumonia,and lung abscess;
Dyspnea with large amount of foamy sputum is
often seen in acute left ventricular heart failure
and organophosphorus poisoning,
? Dyspnea with coma,
It suggests cerebral hemorrhage,
meningitis,pneumonia with shock,
uremia,diabetic ketoacidosis,and acute
poisoning,