Next Unit: Pulmonary Shunting and V/Q Mismatch
16 minute read
During both the rapid assessment of a patient's ABCs and the head-to-toe secondary survey the assessment of the patient's breath sounds via auscultation is vital to the recognition and treatment of several emergencies. In the EMS setting the detailed analysis of breath sounds can be restricted by environmental noise, time constraints, and limitations to patient mobility. Regardless of these practical limitations, the description of breath sounds is a vital component of many national registry exam questions and may help guide your care in the field.
This section will begin by reviewing the importance of hearing bilateral breath sounds followed by defining and describing stridor, wheezing, crackles, and several special sounds that may appear on an exam.
Breath sounds should be assessed in three locations, the apex of each lung (right above the clavicle), the mid lung (mid sternal), and at the bases (Roughly at the level of the xiphoid process).
Vesicular Breath Sounds (Normal)
Normal breath sounds over the lung fields are called VESICULAR breath sounds: low-pitched and soft.
(Over the trachea, in contrast, the breath sounds are high-pitched and loud; over the mainstream bronchi, between the scapulae, and below the clavicles they are medium-pitched sounds--a combination of vesicular and bronchial--called bronchovesicular sounds.)
Inspiration to expiration length ratio is 3:1, or longer: shorter.
The Absence of Breath Sounds
The presence of breath sounds over both sides of the chest is an essential element of the "A" in the ABCs. The presence of equal bilateral breath sounds indicates that both lungs are inflating equally with a given breath, which means the airways leading from the mouth to alveoli are likely to be intact and the chest cavity is free from air/blood that would prevent lung expansion.
The presence of absent or unequal sounds in one side of the chest is a common finding in pneumothorax and/or hemothorax. In young individuals, there may be minimal other symptoms to indicate the presence of these potentially deadly conditions due to the ability of the second lung to compensate. But in elderly or ill patients this condition can be rapidly fatal.
The absence of bilateral breath sounds can indicate a lack of breathing or poor air movement; while absent breathing is obvious from lack of chest rise, poor air movement can occur in many diseases (asthma, pneumonia, airway obstruction). If you cannot auscultate breath sounds in an ill-appearing patient who has chest rise it is reasonable to assume that effective breathing is not occurring, and high-flow oxygen or positive pressure ventilation may be required.
Upper airway obstructions can lead to stridor, a high-pitched harsh-sounding whistle that is loudest when auscultating close to the mediastinum and neck. Stridor is most commonly seen in young children who aspirate small objects and the elderly who have head/neck tumors that are leading to progressive obstruction.
As stridor can indicate significant upper airway obstruction, the next best step in a responsive patient is to visually examine the oral cavity for obstruction then provide high-flow oxygen and raid transport with potential ALS intercept in the event of patient decompensation.
Obstruction of the small airways within the lungs leads to wheezing, a high-pitched whistling sound, greatest on expiration, that is generally louder as you get further away from the mediastinum. It occurs as the small airways collapse when a patient attempts to exhale, this collapse results from swelling in the airways from chronic or acute illness. Wheezing is seen in all age groups.
Wheezing is often a sign of diseases such as COPD or Asthma, but is not always a sign of severe illness. Wheezing must be taken in the context of the patient's overall condition and there is not one best "next step" in the event you hear wheezing. As with all respiratory illnesses oxygen is likely to be the best next step and in the case of severe asthma or COPD patients will likely have short-acting "beta-agonists," such as albuterol, that can help to rapidly open the airways.
Obstruction of the alveoli by fluid or mucus will lead to crackles, as per their name crackles are often said to sound like "popcorn" or "velcro" and are loudest when the patient is inhaling. Crackles occur as the collapsed fluid-filled alveoli in the collapsed lung "pop open." Crackles can be heard all throughout the lung or can be localized in one small area.
As in wheezing, crackles must be taken in the context of the patient's clinical condition, they can be present in mild illnesses that do not require EMS care and in severe situations that could rapidly lead to death. The most common cause of localized crackles is pneumonia while the most common cause of bilateral crackles is pulmonary edema. These conditions can present in a massive number of ways and are reviewed in the other airway/respiratory units.
Other Lung Sounds
In some special situations, you may hear sounds in the lungs that you do not expect to be there, in these cases look at the patients overall clinical condition and do not be afraid to contact medical command or transport the patient to a higher level of care if you are uncertain of the cause or significance of your findings.
One of the most commonly tested abnormal lung sounds are the presence of intestinal GI sounds in the left lung field, this can be related to rupture of the diaphragm (which separates the abdomen and chest cavities) during trauma, leading to the movement of the intestines up into the lung cavity alongside hemothorax.
A "Friction rub" is the presence of a grating, sandpaper-like, or velcro-like sound that is localized to a small area of the lung that is present on both inspiration and expiration. This results from inflammation of the lung lining (the pleura). This inflammation increases friction between the layers resulting in pain and the aftermentioned rubbing sound.
The other abnormal chest sound is a "gurgling" noise that comes and goes with each breath, this is the sign of an open pneumothorax or "sucking chest wound" which can lead to a tension pneumothorax if not identified and treated. These injuries are often obvious as they require penetrating trauma to the chest.