Dyspnea
Definition,
Dyspnea is defined as an awareness of difficulty in
breathing It is therefore a symptom,usually described by the
patient as,shortness 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,
Etiology
? Respiratory diseases
? Circulatory diseases
? Poisoning
? Hematology
? Neuropsychogenic factors
Mechanism & clinical feature
? Respiratory dyspnea
1,Inspiratory dyspnea
2,Expiratory dyspnea
3,Mixed dyspnea
Mechanism & clinical feature
? Cardiac dyspnea
Cardiac dyspnea is usually attributable to pulmonary
vascular congestion resulting from the left and/or right
heart failure,
Mechanism & clinical feature
? 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,
Mechanism & clinical feature
? Hematologic dyspnea
In severe anemia,sulf hemoglobinemia,
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,
Mechanism & clinical feature
? Neuro-psychogenic dyspnea
Dyspnea may occur in the 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 respiratory alkalosis,
Accompanied Symptom
? Paroxysmal dyspnea with wheezing,
? Dyspnea with chest pain,
? Dyspnea with fever,
? Dyspnea with cough and purulent sputum,
? Dyspnea with coma,