The presence of expiratory phase wheezing signifies that the patient's peak expiratory flow rate is less than 50% of normal. Distal airway obstruction predominantly produces expiratory sounds. Intrathoracic major airway obstruction produces inspiratory as well as expiratory sounds. As a rule, extrathoracic airway obstruction produce inspiratory sounds. Bronchiolar disease usually causes wheezing that occurs in the expiratory phase of respiration. The fraction of the respiratory cycle during which a wheeze is produced roughly corresponds to the degree of airway obstruction. Wheezes occupy different portions of the respiratory cycle depending on the site of airway obstruction and its nature.

The term 'wheeze' is also used as a clinical condition describing wheezing in preschool children, termed as 'preschool wheeze'. The differential diagnosis of wheezing is wide, and the reason for wheezing in a given patient is determined by considering the characteristics of the wheezes and the historical and clinical findings made by the examining physician. Wheezing is commonly experienced by persons with a lung disease the most common cause of recurrent wheezing is asthma, though it can also be a symptom of lung cancer, congestive heart failure, and certain types of heart diseases. For wheezes to occur, part of the respiratory tree must be narrowed or obstructed (for example narrowing of the lower respiratory tract in an asthmatic attack), or airflow velocity within the respiratory tree must be heightened. Virus, bacteria, common cold, allergy, pneumonia, asthma, tuberculosisĪ wheeze is a clinical symptom of a continuous, coarse, whistling sound produced in the respiratory airways during breathing.

The sound of wheezing as heard with a stethoscope

Wheeze lung sounds