Types of Lung Sounds and Auscultation Vector

Types of Lung Sounds and Auscultation: An Overview (2024)

by | Updated: Apr 19, 2024

Abnormal lung sounds, heard during auscultation, are critical indicators for diagnosing respiratory conditions.

These sounds, ranging from wheezes and crackles to stridor and pleural friction rubs, provide valuable insights into the underlying pathology affecting the respiratory system.

This article breaks down the various types of abnormal lung sounds, their clinical significance, and the conditions they’re most commonly associated with.

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What are Lung Sounds?

Lung sounds are specific noises produced by the movement of air through the respiratory tract, identifiable during auscultation with a stethoscope. They include normal breath sounds and abnormal sounds, offering critical insights into pulmonary health and aiding in the diagnosis of various respiratory conditions.

Understanding these sounds is crucial for respiratory therapists and healthcare professionals.

Auscultation lung sounds stethoscope vector

What is Auscultation?

Auscultation is a diagnostic method used by healthcare professionals to listen to the internal sounds of the body, typically using a stethoscope.

It is primarily employed to examine the heart, lungs, and intestines to detect abnormalities in the sounds that these organs make.

For instance, in the lungs, it can help identify the presence of fluid, wheezes, or crackles, which can indicate conditions like pneumonia or asthma.

Auscultation allows for the early detection of many health issues, guiding further diagnostic testing and treatment.

What are Normal Lung Sounds?

Normal or vesicular lung sounds are the sounds of air moving through the small airways and alveoli during respiration, heard through a stethoscope during auscultation.

These sounds are soft and low-pitched, characterized by a gentle rustling quality during inhalation, and are fainter on exhalation.

Present in healthy individuals, vesicular sounds indicate unobstructed airflow and normal lung function.

Types of Abnormal Lung Sounds

The types of abnormal lung sounds can be broadly categorized into several types:

  1. Crackles (Rales)
  2. Wheezes
  3. Rhonchi
  4. Stridor
  5. Diminished
  6. Bronchial
  7. Bronchovesicular
  8. Pleural Friction Rub

Note: These abnormal sounds are critical clues in diagnosing and managing respiratory illnesses, emphasizing the importance of auscultation in clinical practice.

Crackles (Rales)

Crackles (Rales) are abnormal lung sounds that are heard during auscultation as discontinuous, short, popping sounds.

They are caused by the sudden opening of small airways and alveoli that are collapsed or filled with fluid, commonly associated with conditions such as pneumonia, heart failure, or pulmonary fibrosis.

Crackles can be further classified as fine, resembling the sound of hair being rolled between fingers near the ear, or coarse, which are louder and lower in pitch.

Wheezes

Wheezes are high-pitched sounds heard during auscultation, predominantly during expiration but can also be present on inspiration in more severe cases.

They result from the narrowing of the airways, as seen in conditions like asthma, chronic obstructive pulmonary disease (COPD), and bronchitis.

The sound is produced by the turbulent airflow through constricted bronchial tubes, indicating obstruction or constriction within the respiratory tract.

Rhonchi

Rhonchi are low-pitched, snoring or rattling sounds heard during auscultation, primarily during expiration.

They are caused by the obstruction or narrowing of larger airways, often due to mucus, fluid, or foreign bodies.

Rhonchi can indicate conditions such as chronic bronchitis or pneumonia. These sounds may change or disappear after coughing, highlighting their origin from airway secretions.

Stridor

Stridor is a high-pitched, wheezing sound heard during inhalation, though it can sometimes be present during exhalation as well.

It is a sign of upper airway obstruction, indicating a potential blockage in the trachea or larynx. Conditions such as croup, foreign object inhalation, or swelling from an allergic reaction can cause stridor.

This sound is considered a medical emergency when severe, as it may signify a significant restriction of airflow.

Diminished

Diminished lung sounds refer to decreased or absent breath sounds heard during auscultation, indicating reduced airflow to parts of the lungs.

This condition can result from several factors, including severe asthma, emphysema, or pneumothorax, where air or fluid accumulation in the pleural space prevents the lungs from fully expanding.

Diminished sounds can also occur in obesity or in patients with muscular or skeletal issues that restrict chest wall movement, leading to shallow breathing.

Bronchial

Bronchial sounds are abnormal lung sounds characterized by their high-pitched, tubular quality, heard clearly over the trachea and larynx.

When heard over the lung fields, where vesicular sounds are normally expected, they suggest lung consolidation or fibrosis.

This shift occurs because solid or fluid-filled lung tissues conduct sound more efficiently than air-filled spaces, making the breath sounds more pronounced and similar to those heard over the larger airways.

Conditions such as pneumonia or atelectasis can lead to the presence of bronchial breathing in areas outside the central chest.

Bronchovesicular

Bronchovesicular sounds are intermediate lung sounds that have a quality between vesicular and bronchial breath sounds.

They are normally heard over the major bronchi, around the upper center back and over the sternum, characterized by a mix of soft and harsher qualities, with equal inspiratory and expiratory phases.

When these sounds are heard in areas where vesicular sounds are typically present, it may indicate partial lung consolidation, early pneumonia, or conditions that increase lung density, thereby altering normal airflow patterns and sound transmission.

Pleural Friction Rub

Pleural friction rub is a distinct, abnormal lung sound heard during auscultation, characterized by a low-pitched, grating, or creaking sound.

It occurs when the pleural layers, normally smooth and lubricated, become inflamed and rough, rubbing against each other during respiration. This sound is most commonly associated with pleuritis (pleurisy), where the pleura becomes inflamed due to infections, lung diseases, or chest injuries.

The pleural friction rub sound is akin to walking on fresh snow or leather rubbing together, indicating the presence of pleural irritation.

Causes of Abnormal Lung Sounds

Abnormal lung sounds can arise from various conditions affecting the respiratory system, each indicating different underlying pathologies.

Here’s an overview of common causes associated with each type of abnormal lung sound:

  • Crackles (Rales): These sounds are often caused by fluid accumulation in the airways or alveoli, which can result from conditions such as pneumonia, heart failure, pulmonary fibrosis, or acute respiratory distress syndrome (ARDS).
  • Wheezes: Narrowing of the airways leads to wheezing, typically due to asthma, chronic obstructive pulmonary disease (COPD), bronchitis, or allergic reactions. It can also occur with foreign body aspiration.
  • Rhonchi: Caused by blockages to the larger airways by mucus or foreign bodies, leading to conditions such as chronic bronchitis or cystic fibrosis, where thick secretions are a hallmark.
  • Stridor: This high-pitched sound is indicative of upper airway obstruction and can result from croup, laryngeal edema, foreign object inhalation, or tumors in the airway.
  • Diminished: Reduced breath sounds can be due to a decrease in airflow to the lungs, caused by emphysema, atelectasis, or pneumothorax, as well as obesity or restrictive chest wall diseases that limit lung expansion.
  • Bronchial: Hearing these sounds outside of the trachea indicates areas of lung consolidation from pneumonia, lung abscess, or tumors, as these conditions enhance the transmission of high-pitched sounds.
  • Bronchovesicular: Found in conditions that slightly increase the density of lung tissue, such as in early stages of pneumonia or when there is partial lung consolidation.
  • Pleural Friction Rub: This sound indicates pleural inflammation, which can be due to pleurisy, pulmonary embolism, or pleural effusion, where the friction is caused by the rubbing of pleural surfaces against each other.

Note: Each of these abnormal lung sounds suggests a specific set of respiratory or cardiac conditions, guiding healthcare professionals in their diagnostic and therapeutic approaches.

Treatment for Abnormal Lung Sounds

The treatment for abnormal lung sounds targets the underlying causes and conditions that produce these sounds.

Here’s a general overview based on the type of abnormal lung sound:

  • Crackles (Rales): Treatment may involve addressing heart failure with diuretics to remove excess fluid, antibiotics for pneumonia, or corticosteroids and other medications for pulmonary fibrosis.
  • Wheezes: In the case of asthma or COPD, bronchodilators and inhaled corticosteroids are commonly used to open airways and reduce inflammation. For allergic reactions, antihistamines and epinephrine might be necessary.
  • Rhonchi: Clearing the airway through expectorants, mucolytics, or bronchodilators can help, along with treating the underlying infection if present.
  • Stridor: Immediate treatment is required for stridor due to airway obstruction, potentially involving corticosteroids to reduce inflammation, nebulized epinephrine for swelling, and in severe cases, surgical intervention to secure the airway.
  • Diminished: Enhancing lung expansion through treatments like chest physiotherapy, incentive spirometry, or addressing the underlying cause such as draining a pneumothorax or treating severe asthma.
  • Bronchial and Bronchovesicular: Antibiotics or antivirals for infections causing lung consolidation, along with supportive care like oxygen therapy and hydration, are key treatments.
  • Pleural Friction Rub: Treatment focuses on the underlying cause of the pleurisy or pleural effusion, which may involve antibiotics for infection, anti-inflammatory medications for pleuritis, or procedures to drain excess fluid.

Treatment strategies are tailored to the individual’s specific condition, severity, and overall health status.

They can range from pharmacological interventions, lifestyle modifications, to surgical procedures, aiming to alleviate symptoms, treat the underlying cause, and prevent complications.

Close monitoring and follow-up care are essential to adjust treatments as needed and ensure the best possible outcomes.

How to Perform Auscultation of the Lungs

Auscultation of the lungs is a critical component of the physical examination, allowing healthcare providers to assess respiratory function and identify potential abnormalities.

Here are the essential steps to perform auscultation of the lungs effectively:

  • Prepare the Patient: Ensure the patient is in a comfortable position, ideally sitting upright with arms slightly forward to maximize lung exposure. Provide privacy and explain the procedure to the patient to ensure cooperation and comfort.
  • Use a Good Quality Stethoscope: Position the earpieces correctly and use the diaphragm of the stethoscope for auscultation, ensuring a tight seal over the area being examined to isolate lung sounds effectively.
  • Follow a Systematic Pattern: Begin at the apex of the lungs and move systematically down to the bases, comparing symmetric areas on both sides of the chest. This includes anterior, lateral, and posterior lung fields.
  • Instruct the Patient to Breathe Deeply Through the Mouth: Deep breaths enhance the detection of lung sounds. Listen to at least one full respiratory cycle (inhalation and exhalation) at each site.
  • Listen for Normal and Abnormal Sounds: Identify normal breath sounds (vesicular, bronchovesicular, bronchial) and note any abnormal sounds (crackles, wheezes, rhonchi, stridor), including their location, timing, and characteristics.
  • Pay Attention to Breath Sounds Intensity: Assess whether the breath sounds are normal, decreased, or increased, which can indicate various conditions such as obstruction, consolidation, or pleural effusion.
  • Document Findings: Record the auscultation findings accurately in the patient’s medical record, noting any deviations from normal lung sounds and any suspected conditions based on the auscultation.

Note: By following these steps, healthcare professionals can conduct a thorough and effective lung auscultation, contributing to the accurate assessment of respiratory health and aiding in the diagnosis of various lung conditions.

FAQs About Lung Sounds and Auscultation

What are Adventitious Breath Sounds?

Adventitious breath sounds are abnormal lung sounds heard during auscultation. They are not present in healthy lungs and include sounds such as crackles, wheezes, rhonchi, and stridor.

These sounds can indicate various respiratory conditions, from airway obstruction to fluid in the lungs.

What is the Difference Between Wheezing and Crackles?

Wheezing is a high-pitched musical sound caused by airway obstruction, often heard in asthma and COPD.

Crackles, or rales, are short, discontinuous sounds occurring when air opens small airways and alveoli that are collapsed or filled with fluid, commonly heard in conditions like pneumonia or heart failure.

Are Lung Sounds Objective or Subjective?

Lung sounds can be considered both objective and subjective. They provide objective evidence of the presence or absence of respiratory conditions when interpreted by a trained listener.

However, their interpretation can be subjective, varying between observers based on experience and skill level.

Where to Listen for Lung Sounds With a Stethoscope?

Listen for lung sounds in a systematic pattern covering the anterior, lateral, and posterior chest. Anteriorly, auscultate above the clavicles and between the ribs down to the sixth rib.

Laterally, listen from the axilla down to the seventh or eighth rib. Posteriorly, cover the area from the upper back down to the lower lobes near the tenth rib.

What are Coarse Breath Sounds?

Coarse breath sounds are a type of adventitious breath sound, similar to crackles but louder and lower in pitch.

They are heard during both inhalation and exhalation and are caused by the presence of fluid or mucus in the larger airways.

Conditions like severe pneumonia or chronic bronchitis often produce coarse breath sounds.

What are Stridor Breath Sounds?

Stridor breath sounds are high-pitched, wheezing sounds heard primarily during inhalation.

They indicate a blockage or narrowing in the upper airway, such as the trachea or larynx, often resulting from conditions like croup, foreign body aspiration, or swelling from an allergic reaction.

Stridor is considered a medical emergency when severe, as it can significantly restrict airflow.

What Type of Lung Sounds are Heard With Pneumonia?

In pneumonia, the type of lung sounds typically heard are crackles (or rales) and can include bronchial breath sounds over the affected area.

Crackles result from fluid or secretions in the airways, while bronchial breath sounds indicate consolidation or infection within the lung tissue.

What are the Types of Crackles?

Crackles are classified into two types: fine and coarse. Fine crackles are short, high-pitched, and heard during the end of inspiration, often associated with interstitial lung disease or early heart failure.

Coarse crackles are louder, lower in pitch, and can be heard during both inspiration and expiration, typically indicating more severe conditions such as pneumonia or pulmonary edema.

What Does Rhonchi Sound Like?

Rhonchi sound like low-pitched, snoring, or rattling noises heard during auscultation. They are caused by the passage of air through an obstruction in the larger airways, often due to mucus or secretions.

Rhonchi is commonly associated with conditions causing airway blockage, such as bronchitis or COPD.

Is Rhonchi Concerning?

Rhonchi can be concerning as they often indicate the presence of blockages or secretions in the larger airways, suggesting underlying conditions like chronic bronchitis, COPD, or pneumonia.

However, the clinical significance of rhonchi depends on the overall clinical context and other findings. In some cases, rhonchi can clear after coughing, which may indicate less severe airway obstruction.

What is the Most Concerning Lung Sound?

Stridor is often considered the most concerning lung sound because it indicates a potential obstruction in the upper airway, which can be life-threatening if not promptly treated.

It requires immediate medical attention to prevent severe breathing difficulties.

What Lung Sounds are Heard With Emphysema?

In emphysema, diminished lung sounds or decreased breath sounds are commonly heard due to the loss of alveolar walls and the collapse of small airways, which reduces the effective transmission of sound.

Occasionally, wheezes may also be present due to airway narrowing.

What Lung Sounds are Wet?

Wet lung sounds typically refer to crackles (or rales), which are discontinuous, popping sounds heard during inhalation.

They are associated with fluid accumulation in the airways or alveoli, seen in conditions like pneumonia, heart failure, or pulmonary edema.

Can You Listen to Your Own Lung Sounds?

Yes, it is possible to listen to your own lung sounds using a stethoscope. However, accurately interpreting these sounds requires training and experience.

Healthcare professionals are skilled in differentiating between normal and abnormal lung sounds and understanding their potential clinical significance.

Which Lung Sounds are Associated With Atelectasis?

In atelectasis, diminished or absent breath sounds are commonly associated, especially over the affected area, due to the collapse of part or all of a lung, reducing airflow and sound transmission.

Additionally, bronchial breath sounds may be heard if there is lung consolidation near the collapse.

What Lung Sounds are Heard With COPD?

In chronic obstructive pulmonary disease (COPD), wheezing and diminished breath sounds are commonly heard due to airflow obstruction and hyperinflation of the lungs. Rhonchi may also be present due to mucus in the larger airways.

What Lung Sounds are Heard With CHF?

In congestive heart failure (CHF), fine crackles are often heard at the lung bases due to pulmonary edema, a condition where fluid backs up into the lungs.

These sounds are typically more pronounced at the end of inspiration.

What is the Best Stethoscope for Auscultation?

The 3M Littmann Classic III Stethoscope is widely regarded as one of the best stethoscopes for auscultation.

It offers high acoustic sensitivity for both high and low-frequency sounds, a tunable diaphragm, and a comfortable fit, making it a popular choice among healthcare professionals for lung and heart auscultation.

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Final Thoughts

The ability to accurately identify and interpret abnormal lung sounds during auscultation is an indispensable skill in the diagnosis and management of respiratory conditions.

Mastery of this skill allows healthcare professionals to make informed decisions, leading to early detection and treatment of potentially life-threatening diseases.

The precise interpretation of these sounds contributes significantly to improving patient care, reducing morbidity, and enhancing the quality of life for those suffering from respiratory disorders.

John Landry, BS, RRT

Written by:

John Landry, BS, RRT

John Landry is a registered respiratory therapist from Memphis, TN, and has a bachelor's degree in kinesiology. He enjoys using evidence-based research to help others breathe easier and live a healthier life.

References

  • Egan’s Fundamentals of Respiratory Care. 12th ed., Mosby, 2020.
  • Faarc, Heuer Al PhD Mba Rrt Rpft. Wilkins’ Clinical Assessment in Respiratory Care. 8th ed., Mosby, 2017.
  • Zimmerman B, Williams D. Lung Sounds. [Updated 2023 Aug 28]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024.

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