When I was in nursing school, it was very hard for me to differentiate the types of lung sounds. I guess you can’t just hear rales or rhonchi anytime you want to – you have to wait until the patient and the particular illness presents itself. To start with the basics, breath sounds are the noises produced by the structures of the lungs during breathing. The lung sounds are best heard with a stethoscope, and this is called auscultation. Normal lung sounds occur in all parts of the chest area, including above the collarbones and at the bottom of the rib cage. Using a stethoscope, you can hear normal breath sounds, decreased or absent breath sounds and abnormal breath sounds. After about a year on the med/surg floor at the hospital, it became quite clear to me that there were several diseases that caused different lung sounds, and those sounds were easily detected when I had some experience.
Bronchial (or tracheal) sounds are heard on the chest at sites which are close to large airways. In contrast to vesicular sounds, they are relatively louder in expiration than inspiration. This type of breath sound is heard best over the trachea, but they can also be heard on the back, between the scapulae and at the lung apices especially on the right. Vesicular sounds are the most common sounds heard over the chest. They are present at sites that are at a distance from large airways. The vesicular sound is a soft sound that has been compared to that of wind blowing through trees. It is louder in inspiration than expiration. The vesicular sound is commonly decreased in chronic obstructive lung disease. It is also decreased over sites of pneumonia in the early stages of the illness. It is usually, but not always, decreased or absent in conditions where the ventilation to an area of the lung is impaired, for example, in pneumothorax, misplaced endotracheal tube or mucus plugging.
When we refer to the term adventitious breath sounds, we mean extra or additional sounds that are heard over normal breath sounds. There are several types of abnormal breath sounds, but the three most common are rales (crackles), rhonchi and wheezing. Rales, or crackles, are caused by fluid in the small airways or atelectasis. Crackles are referred to as discontinuous sounds; they are intermittent, nonmusical and brief. Crackles may be heard on inspiration or expiration. These sounds are often associated with inflammation or infection of the small bronchi, bronchioles and alveoli. Crackles that don’t clear after a cough may indicate pulmonary edema or fluid in the alveoli due to heart failure or adult respiratory distress syndrome (ARDS). Wheezes are sounds that are heard continuously during inspiration or expiration, or during both inspiration and expiration. They are caused by air moving through airways narrowed by constriction or swelling of the airway or partial airway obstruction.
Wheezes that are relatively high pitched and have a shrill or squeaking quality may be referred to as sibilant rhonchi. They are often heard continuously through both inspiration and expiration and have a musical quality. These wheezes occur when airways are narrowed, such as may occur during an acute asthmatic attack. Wheezes that are lower-pitched sounds with a snoring or moaning quality may be referred to as sonorous rhonchi. Secretions in large airways, such as occurs with bronchitis, may produce these sounds; they may clear somewhat with coughing. Rhonchi are continuous adventitious breath sounds detected by auscultation. Although rhonchi are usually louder and lower pitched than crackles (more like a hoarse moan or a deep snore) they may be described as rattling, bubbling, rumbling or musical.
In sum, the detection of adventitious sounds is an important part of the respiratory examination, often leading to a diagnosis of cardiac and pulmonary conditions. It is important as caregivers that we differentiate these most important lung sounds and chart them accordingly. We, as nurses, need to note that absent or decreased sounds can mean air or fluid in or around the lungs (pneumonia, heart failure or pleural effusion), increased thickness of the chest wall, over-inflation of a part of the lungs (emphysema) or reduced airflow to part of the lungs. Further, we should be aware that several other conditions can cause abnormal or decreased breath sounds, including acute bronchitis, asthma, bronchiectasis, chronic bronchitis, interstitial lung disease, foreign body obstruction of the airway, pulmonary edema and tracheobronchitis.