What are beta blockers and how do they work? Beta blockers, also known as beta-adrenergic blocking agents, are a class of drugs that works by blocking the neurotransmitters norepinephrine and epinephrine from binding to receptors. There are three known types of beta receptors, known as beta1 (Î²1), beta2 (Î²2) and beta3 (Î²3).
Although many newer imaging techniques for the evaluation of lung pathology have been developed, auscultation of the chest remains an invaluable clinical tool and is still probably the most common method of evaluating the lung. Evaluation of lung sounds is a routine part of a clinical examination. Breath sounds can be classified into 2 broad categories: normal breath sounds and adventitious (or abnormal) sounds. Adventitious breath sounds include wheezes, coarse crackles, fine crackles, and rhonchi. See the video of breath sound assessment, below.
Abnormal sounds may resemble a musical wind instrument or be more rough in quality like a grating noise. Some conditions may cause crackling, creaking, bubbling or even clicking breathing sounds. Identifying the type of abnormal breath sound is important to assist with a diagnosis. More than one type of abnormal sound may be present at the same time. Since the causes may overlap, other criteria as well as further diagnostic testing may be necessary for a final diagnosis.