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.
Crackles are the sounds you will hear in a lung field that has fluid in the small airways. As stated before, crackles and rales are the same thing, and this can often lead to confusion among health care providers. Crackles come in two flavours: fine and coarse. Fine crackles sound like salt heated on a frying pan or the sound of rolling your hair between your fingers next to your ear. Coarse crackles sound like pouring water out of a bottle or like ripping open Velcro. This lung sound is often a sign of adult respiratory distress syndrome, early congestive heart failure, asthma, and pulmonary oedema. Rhonchi, rales, wheezes, rubbing or stridor? â Listening for lung sounds.