aka rales. abnormal, discontinuous, adventitious lung sounds heard on insp. sounds like velcro opening. doesn't clear with coughing. produced when fluid inside a bronchus causes a collapse of the distal airways and alveoli. causes: atelectasis, pneumonia, fibrosis, heart failure, pulmonary edema.
atelectatic crackles are not patholgic. heard when sections of the alveoli that weren't fully aerated and deflate slightly and accumulate secretions during sleep or in the elderly, expand by a few deep breaths