Breathing is an essential, automatic process that keeps us alive, providing oxygen to our body and removing carbon dioxide. However, when something disrupts this normal rhythm, it can lead to abnormal breathing patterns, each of which can signal underlying health issues.
From rapid, shallow breaths to labored, irregular rhythms, these patterns may be the body’s way of alerting us to problems in the respiratory, cardiovascular, or nervous systems.
In this article, we’ll explore the various types of abnormal breathing patterns, their causes, and why recognizing these signs early can be critical for timely medical intervention.
What is a Breathing Pattern?
A breathing pattern is the rhythm, rate, and depth of breaths that a person takes. In healthy individuals, breathing is usually smooth, consistent, and follows a regular rhythm, allowing the body to efficiently exchange oxygen and carbon dioxide.
This automatic process is controlled by the respiratory centers in the brain, which adjust our breathing rate and depth in response to the body’s needs, such as during exercise, rest, or stressful situations.
Normal breathing patterns can be disrupted due to various factors like illness, emotional stress, or physical conditions, leading to abnormal breathing patterns.
Note: These deviations from the norm can include changes in breath speed, depth, or regularity and are often indicators of underlying health issues in the respiratory, cardiovascular, or nervous systems.
Types of Breathing Patterns
There are several types of breathing patterns, each with unique characteristics that can indicate specific health conditions.
Here are some of the most common types:
- Eupnea
- Hyperpnea
- Bradypnea
- Tachypnea
- Apnea
- Cheyne-Stokes breathing
- Biot’s breathing
- Kussmaul breathing
Review this diagram and keep reading to learn more about the different types of breathing patterns, their causes, and what they might indicate about a patient’s health.
Eupnea
Eupnea refers to normal, unlabored breathing that occurs when the body is at rest. This type of breathing pattern is characterized by regular, steady breaths, typically at a rate of about 12 to 20 breaths per minute in adults.
Eupnea ensures that the body maintains a balanced exchange of oxygen and carbon dioxide, allowing for efficient respiration. It is often the baseline pattern against which other breathing abnormalities are compared, as any deviation from eupnea can indicate underlying health issues.
Hyperpnea
Hyperpnea is characterized by an increase in the depth and rate of breathing, typically occurring in response to increased oxygen demand, such as during exercise or physical exertion. Unlike rapid breathing associated with anxiety, hyperpnea is a controlled, purposeful response that helps the body take in more oxygen to meet heightened metabolic needs.
While it’s a normal response in certain situations, hyperpnea can sometimes occur at rest due to conditions like fever, pain, or certain metabolic disorders, which may require further medical evaluation.
Bradypnea
Bradypnea is a slower-than-normal breathing rate, typically fewer than 12 breaths per minute in adults. This type of breathing pattern can be caused by various factors, including sleep, medication effects (such as sedatives or opioids), and certain medical conditions like hypothyroidism or brain disorders that affect the respiratory center.
While bradypnea may be normal during deep sleep, prolonged or severe bradypnea at rest can lead to inadequate oxygen levels in the body and may signal an underlying health issue that requires attention.
Tachypnea
Tachypnea is a pattern of rapid, shallow breathing, typically defined as more than 20 breaths per minute in adults. Unlike hyperpnea, which involves deep breaths, tachypnea consists of quick, shallow breaths and often occurs as a response to conditions that increase the body’s need for oxygen or reduce its ability to expel carbon dioxide.
This pattern may be triggered by anxiety, fever, pain, or respiratory issues like pneumonia or asthma. Persistent tachypnea can lead to decreased oxygen delivery to tissues and is often a sign that the body is under stress, requiring medical evaluation if it continues.
Apnea
Apnea is the complete cessation of breathing for a temporary period, usually lasting at least 10 seconds. It can occur during sleep, known as sleep apnea, or in other contexts due to medical conditions affecting the respiratory system or brain. Apnea interrupts the normal cycle of oxygen intake and carbon dioxide expulsion, which can lead to oxygen deprivation in the body if it happens frequently or for extended periods.
Conditions such as obstructive sleep apnea, where airway blockage occurs during sleep, and central sleep apnea, where brain signaling fails to initiate breathing, are common forms of apnea that may require medical intervention.
Cheyne-Stokes Breathing
Cheyne-Stokes breathing is an abnormal breathing pattern characterized by a cyclical pattern of gradual increases and decreases in breathing depth and rate, followed by periods of apnea. This pattern often occurs during sleep and is most commonly associated with heart failure, stroke, traumatic brain injury, or other conditions affecting the brainstem, which regulates breathing.
Cheyne-Stokes breathing can result in disrupted oxygenation, especially if apneic episodes are prolonged, and is typically considered a sign of severe underlying health issues that warrant medical assessment.
Biot’s Breathing
Biot’s breathing is an irregular breathing pattern characterized by groups of quick, shallow breaths followed by unpredictable periods of apnea. Unlike Cheyne-Stokes, which has a regular cyclic pattern, Biot’s breathing is erratic, with no consistent rhythm.
This pattern is often associated with damage to the medulla oblongata due to conditions such as head trauma, stroke, or central nervous system infections like meningitis. Biot’s breathing can significantly disrupt the body’s oxygen and carbon dioxide balance and usually indicates a critical need for medical intervention.
Kussmaul Breathing
Kussmaul breathing is a deep, labored breathing pattern often associated with metabolic acidosis, particularly diabetic ketoacidosis. This type of breathing is characterized by rapid, deep breaths that help the body expel carbon dioxide to reduce blood acidity.
Unlike hyperpnea, which may occur during exercise, Kussmaul breathing is a response to severe metabolic disturbances and is typically a sign of an urgent medical condition. Its distinctive pattern is a compensatory mechanism to maintain blood pH balance, and its presence often indicates a need for immediate medical evaluation and intervention.
Watch this video or keep reading to learn more about the different types of breathing patterns, their causes, and what they might indicate for a patient’s respiratory health.
Other Types of Abnormal Breathing Patterns
In addition to the more common types, several other abnormal breathing patterns can signal various health conditions. Here are a few:
Dyspnea
Dyspnea, commonly known as shortness of breath, is a sensation of uncomfortable or labored breathing. It may feel like a tightness in the chest or a sense that the air taken in is insufficient.
Dyspnea can be triggered by physical exertion, anxiety, high altitudes, or medical conditions such as asthma, chronic obstructive pulmonary disease (COPD), heart failure, or lung infections. Persistent dyspnea at rest is a serious symptom that often requires medical evaluation to identify and manage the underlying cause.
Orthopnea
Orthopnea is a type of dyspnea that specifically occurs when a person is lying flat and typically improves when sitting or standing up. This abnormal breathing pattern is often associated with heart failure, as lying down can cause fluid to pool in the lungs, making breathing more difficult.
Patients with orthopnea often sleep propped up on pillows to alleviate their symptoms. It can also be seen in respiratory conditions where lung function is compromised, and it typically indicates a need for further medical assessment.
Apneustic Breathing
Apneustic breathing is a prolonged, gasping inhalation followed by a short, insufficient exhalation, resulting in irregular and labored breaths. This pattern often indicates severe neurological damage, especially to the brainstem, as it disrupts the normal rhythm and control of breathing.
Apneustic breathing can be seen in cases of stroke, trauma, or specific brain lesions and is typically a sign of a critical condition requiring immediate medical intervention.
Agonal Breathing
Agonal breathing is an abnormal and often distressing type of breathing marked by gasping, labored breaths that are irregular and shallow. It typically occurs as a body’s last effort to breathe in response to a severe lack of oxygen and often precedes cardiac arrest or death.
Agonal breaths do not effectively support oxygen exchange and are a medical emergency, requiring immediate intervention such as cardiopulmonary resuscitation (CPR).
Ataxic Breathing
Ataxic breathing is an irregular and unpredictable pattern of breathing characterized by periods of shallow and deep breaths that may be followed by apnea. This pattern is typically associated with damage to the medulla oblongata, the part of the brain responsible for regulating breathing.
Ataxic breathing is often seen in cases of severe head trauma, brain tumors, or central nervous system disorders and usually indicates a critical condition requiring urgent medical care.
Paradoxical Breathing
Paradoxical breathing occurs when the chest and abdomen move in opposite directions during breathing—where the chest falls on inhalation and rises on exhalation, which is the reverse of the normal pattern.
This abnormality can be caused by a weakened or paralyzed diaphragm, rib fractures, or lung conditions such as a collapsed lung (pneumothorax). Paradoxical breathing compromises effective air exchange and often signals a respiratory emergency requiring immediate medical assessment.
Hypopnea
Hypopnea is a breathing pattern characterized by shallow or reduced breathing, with a decrease in airflow and oxygen intake that is less severe than apnea. Hypopnea often occurs during sleep and can lead to reduced oxygen saturation levels in the blood, commonly observed in sleep disorders such as obstructive sleep apnea syndrome.
If left untreated, hypopnea can contribute to daytime fatigue, cardiovascular issues, and other health complications, highlighting the need for proper diagnosis and management.
Hyperventilation
Hyperventilation is a rapid or deep breathing pattern that causes an excessive expulsion of carbon dioxide, leading to a decrease in blood CO₂ levels and an increase in blood pH (respiratory alkalosis). It is often triggered by anxiety, panic attacks, pain, or medical conditions affecting the respiratory system.
Symptoms of hyperventilation include lightheadedness, tingling in the fingers, and even loss of consciousness in severe cases. Controlled breathing techniques or addressing the underlying cause can often help manage hyperventilation episodes.
Hypoventilation
Hypoventilation is a slow or shallow breathing pattern that results in inadequate ventilation, leading to an increase in blood carbon dioxide levels (hypercapnia) and a decrease in oxygen levels. This pattern can be caused by factors such as respiratory muscle weakness, obesity, neuromuscular diseases, or certain medications that depress breathing.
Hypoventilation can cause symptoms like fatigue, headaches, and confusion and, if left untreated, may result in respiratory acidosis, a potentially life-threatening condition that requires medical intervention.
Sighing
Sighing is a breathing pattern that includes frequent deep breaths interspersed within regular breathing. Sighs are typically deeper than normal breaths and are often associated with the release of tension or relief, but excessive sighing can indicate underlying respiratory issues, such as anxiety, fatigue, or even lung disease.
While occasional sighing is normal, frequent sighs may point to emotional stress or physiological conditions affecting lung function.
Gasping
Gasping is an abnormal breathing pattern characterized by quick, forceful inhalations, often occurring as a reflexive response to a lack of oxygen. It is commonly associated with respiratory distress or extreme exertion and may be a sign of life-threatening situations, such as cardiac arrest or severe asthma attacks.
Gasping typically indicates a critical lack of oxygen and requires immediate medical attention to prevent further complications.
Obstructive Breathing
Obstructive breathing occurs when airflow is partially blocked during inhalation or exhalation, making it difficult for air to move through the respiratory passages. This pattern is often associated with conditions such as asthma, chronic obstructive pulmonary disease (COPD), or obstructive sleep apnea, where narrowing or obstruction in the airways disrupts normal breathing.
Obstructive breathing can cause wheezing, labored breaths, and reduced oxygen intake, necessitating treatment to clear the obstruction and support normal respiration.
Asthmatic Breathing
Asthmatic breathing is characterized by wheezing, shortness of breath, and prolonged exhalation, typically resulting from airway inflammation and constriction during an asthma attack. This breathing pattern can be triggered by allergens, respiratory infections, physical activity, or stress, leading to difficulty moving air in and out of the lungs.
Asthmatic breathing often requires medical intervention, such as bronchodilators or corticosteroids, to reduce inflammation and ease breathing.
Central Neurogenic Hyperventilation
Central neurogenic hyperventilation is an abnormal breathing pattern marked by rapid and deep breaths, often caused by a neurological injury or damage to the brainstem. This condition can result from traumatic brain injury, stroke, or increased intracranial pressure, leading to continuous hyperventilation that reduces blood carbon dioxide levels.
This type of breathing pattern is typically a sign of a severe neurological condition and often requires urgent medical attention.
Paroxysmal Nocturnal Dyspnea
Paroxysmal nocturnal dyspnea (PND) is a sudden onset of shortness of breath that occurs at night, often waking the person from sleep. It is typically caused by heart failure, where fluid builds up in the lungs while lying down, making it difficult to breathe.
Individuals with PND often find relief by sitting or standing up, which helps redistribute fluid and ease breathing. PND is an important symptom of heart failure and requires medical evaluation to address the underlying condition.
Postictal Breathing
Postictal breathing refers to the altered breathing pattern that occurs following a seizure. After a seizure, individuals may experience labored, slow, or irregular breathing as the body recovers from the intense neurological activity.
This pattern is often accompanied by confusion, drowsiness, or other postictal symptoms. Postictal breathing typically resolves on its own as the person recovers, but monitoring is essential to ensure normal breathing returns without further complications.
Pursed-Lip Breathing
Pursed-lip breathing is a technique where individuals breathe in slowly through the nose and exhale through pursed lips, as if blowing out a candle. This method is often adopted by individuals with chronic obstructive pulmonary disease (COPD) or other respiratory conditions as it helps to keep the airways open longer during exhalation, promoting better airflow and reducing shortness of breath.
Pursed-lip breathing can be both a symptom of respiratory distress and a therapeutic technique to help control breathing.
Diaphragmatic Breathing
Diaphragmatic breathing, also known as belly breathing, involves using the diaphragm for deeper, fuller breaths that expand the abdomen rather than the chest. This type of breathing pattern is often encouraged in respiratory therapy, as it enhances oxygen intake and reduces shallow, inefficient breathing.
While it’s typically a beneficial breathing technique, the inability to perform diaphragmatic breathing effectively may indicate respiratory muscle weakness or a restrictive lung condition.
Air Trapping
Air trapping occurs when air becomes trapped in the lungs during exhalation, often due to narrowed or obstructed airways. This pattern is common in conditions like chronic obstructive pulmonary disease (COPD) and asthma, where air remains in the lungs after each breath, leading to an overinflated chest and difficulty taking in fresh air.
Air trapping can cause breathlessness, reduced exercise tolerance, and requires treatment to improve airway function and breathing efficiency.
Platypnea
Platypnea is a rare breathing pattern where a person experiences shortness of breath while sitting or standing, which improves when lying down. This unusual pattern is often associated with certain heart or lung conditions, such as atrial septal defects or hepatopulmonary syndrome, where blood flow or gas exchange is affected by body position.
Platypnea is an important symptom that typically indicates a need for further medical investigation to determine the underlying cause.
Mouth Breathing
Mouth breathing is a pattern where a person predominantly breathes through their mouth instead of the nose. This pattern may be due to nasal congestion, enlarged tonsils, or other obstructions that make nasal breathing difficult.
Chronic mouth breathing can lead to dry mouth, dental issues, and may also be associated with conditions like sleep apnea. Addressing the cause of mouth breathing is essential for restoring normal nasal breathing and preventing complications.
How to Assess a Patient’s Breathing Pattern
Assessing a patient’s breathing pattern is essential for identifying abnormalities and understanding underlying health conditions.
Here’s a step-by-step guide on how to effectively evaluate a patient’s breathing pattern:
- Observe the Patient’s Position and Comfort Level: Note the patient’s posture and whether they appear comfortable or distressed. Some patients may adopt specific positions, like leaning forward or propping themselves up, to ease breathing.
- Count the Respiratory Rate: Measure the number of breaths per minute while the patient is at rest. A normal adult rate is 12-20 breaths per minute. Deviations from this range, like tachypnea (rapid) or bradypnea (slow), may indicate underlying issues.
- Assess the Depth of Breathing: Observe the depth of each breath. Shallow breaths can indicate pain, anxiety, or restrictive lung conditions, while deep, labored breaths may suggest metabolic acidosis or hypoxemia.
- Evaluate the Rhythm of Breathing: A normal breathing rhythm is regular and even. Irregular rhythms, such as in Cheyne-Stokes or Biot’s breathing, may suggest neurological or metabolic conditions.
- Observe Chest and Abdomen Movement: Watch for symmetrical expansion of the chest and any signs of accessory muscle use, which may indicate respiratory distress. Paradoxical movement, where the chest and abdomen move in opposite directions, is often a sign of respiratory compromise.
- Listen for Any Audible Sounds: Observe for any sounds, such as wheezing, stridor, or gasping, which can provide clues about airway obstruction or other respiratory issues.
- Check for Signs of Accessory Muscle Use: Look for involvement of muscles around the neck, shoulders, and abdomen, which can signal difficulty breathing. Accessory muscle use is often seen in patients with obstructive conditions like asthma or COPD.
- Evaluate Oxygen Saturation (SpO2): Measure oxygen levels using a pulse oximeter. Low oxygen saturation may indicate hypoxemia, suggesting impaired gas exchange or respiratory compromise.
- Assess for Skin Color and Condition: Cyanosis (a bluish discoloration of the skin, especially around the lips and fingertips) can indicate inadequate oxygenation. Pallor or sweating may also signal respiratory distress.
- Ask the Patient About Symptoms: Inquire if they feel shortness of breath, chest tightness, or any discomfort. Patient feedback can provide valuable insight into the presence and severity of respiratory symptoms.
Note: By systematically following these steps, healthcare providers can gain a comprehensive understanding of a patient’s breathing pattern and identify any abnormalities that may require intervention or further evaluation.
FAQs About the Breathing and the Patterns of Respiration
What Does Abnormal Breathing Indicate?
Abnormal breathing can indicate a range of underlying health issues, from respiratory and cardiovascular conditions to neurological or metabolic imbalances.
For example, rapid, shallow breaths might signal anxiety or a lung issue, while deep, labored breathing could indicate metabolic acidosis.
Persistent abnormal breathing patterns often warrant further evaluation, as they can be signs of conditions like chronic obstructive pulmonary disease (COPD), heart failure, stroke, or brain injury.
What Are the Abnormal Breathing Patterns While Sleeping?
Abnormal breathing patterns during sleep include sleep apnea, where breathing repeatedly stops and starts, and Cheyne-Stokes respiration, a cyclic pattern of shallow breathing followed by deep breaths and pauses.
These patterns are often associated with sleep disorders, heart failure, and neurological conditions. Monitoring and addressing these patterns is important, as they can disrupt sleep quality and lead to further health complications if untreated.
What Are Abnormal Breath Sounds?
Abnormal breath sounds are sounds heard during breathing that differ from normal, clear lung sounds. Common types include wheezing (a whistling sound often associated with asthma or obstruction), crackles (a crackling or popping sound suggesting fluid in the lungs), rhonchi (a coarse sound indicating mucus), and stridor (a high-pitched sound caused by airway obstruction).
Note: Each abnormal sound can provide clues to specific respiratory issues and may require further investigation or treatment.
What Breathing Pattern is Common with Increased Intracranial Pressure?
Cheyne-Stokes breathing is a common breathing pattern associated with increased intracranial pressure. This pattern features a cyclical increase and decrease in breathing depth, followed by periods of apnea.
Increased intracranial pressure can disrupt the brain’s ability to regulate breathing, leading to this irregular pattern, which is often seen in patients with head trauma, stroke, or brain swelling.
What Breathing Pattern Occurs at the End of Life?
At the end of life, a common breathing pattern observed is agonal breathing, which involves irregular, gasping breaths. Cheyne-Stokes respiration is also common, featuring cycles of deep and shallow breaths followed by pauses.
These patterns indicate a natural process as the body begins to shut down, and while they may appear distressing, they are often painless for the patient. Comfort care measures are typically prioritized during this time.
What Breathing Patterns Are Common After a Stroke?
After a stroke, abnormal breathing patterns can include Cheyne-Stokes respiration, especially if the stroke affects brain areas involved in respiratory control.
Other irregular breathing patterns, such as Biot’s breathing or ataxic breathing, may also occur, depending on the location and severity of brain injury. These patterns are often signs of disrupted neurological control over breathing and may require careful monitoring and supportive care.
What Breathing Pattern Occurs After a Seizure?
Postictal breathing, or the breathing pattern following a seizure, can vary but often includes slow, irregular, or labored breaths as the body recovers. This pattern typically normalizes as the postictal state (the recovery period following a seizure) resolves.
Monitoring postictal breathing is important to ensure that normal breathing resumes and that no complications, such as respiratory distress, occur.
What Are the Causes of Kussmaul Breathing?
Kussmaul breathing is typically caused by metabolic acidosis, particularly diabetic ketoacidosis (DKA). In this condition, the body attempts to reduce blood acidity by exhaling more carbon dioxide through deep, rapid breathing.
Kussmaul breathing may also be seen in other conditions causing severe metabolic acidosis, such as kidney failure or certain poisonings, where the body needs to regulate blood pH levels.
How Can Kussmaul Breathing Be Prevented?
Preventing Kussmaul breathing involves managing underlying conditions that cause metabolic acidosis, especially diabetes. Keeping blood sugar levels under control and preventing diabetic ketoacidosis (DKA) through regular monitoring, proper medication use, and a healthy diet can reduce the risk.
For other causes, such as kidney disease, adhering to treatment plans and regular check-ups can help prevent metabolic imbalances that might lead to Kussmaul breathing.
What is the Difference Between Kussmaul Breathing and Hyperventilation?
While both Kussmaul breathing and hyperventilation involve rapid breathing, they differ in cause and pattern. Kussmaul breathing is a deep, labored form of hyperventilation specifically in response to metabolic acidosis, helping to reduce blood acidity by expelling CO2.
In contrast, general hyperventilation is typically a response to stress, anxiety, or other non-metabolic factors and usually involves faster, shallow breaths rather than deep, labored ones.
What is the Difference Between Kussmaul Breathing and Cheyne-Stokes Respirations?
Kussmaul breathing is a continuous, deep, and labored breathing pattern that occurs in response to metabolic acidosis. It is steady and does not include pauses. Cheyne-Stokes respiration, however, is characterized by a cyclic pattern of gradual increases and decreases in breath depth, followed by periods of apnea.
Note: Cheyne-Stokes is often associated with heart failure or neurological conditions, while Kussmaul breathing is linked to metabolic issues like diabetic ketoacidosis.
What is Pursed-Lip Breathing?
Pursed-lip breathing is a technique where individuals breathe in slowly through the nose and exhale through pursed lips, as if blowing out a candle.
This method is often adopted by individuals with chronic obstructive pulmonary disease (COPD) or other respiratory conditions as it helps to keep the airways open longer during exhalation, promoting better airflow and reducing shortness of breath.
Pursed-lip breathing can be both a symptom of respiratory distress and a therapeutic technique to help control breathing.
What is Diaphragmatic Breathing?
Diaphragmatic breathing, also known as belly breathing, involves using the diaphragm for deeper, fuller breaths that expand the abdomen rather than the chest.
This type of breathing pattern is often encouraged in respiratory therapy, as it enhances oxygen intake and reduces shallow, inefficient breathing.
While it’s typically a beneficial breathing technique, the inability to perform diaphragmatic breathing effectively may indicate respiratory muscle weakness or a restrictive lung condition.
What is Lateral Costal Breathing?
Lateral costal breathing is a technique focusing on expanding the lower ribs laterally (side-to-side) during inhalation to maximize lung capacity and improve oxygen intake.
This breathing pattern is often used in respiratory therapy to strengthen the diaphragm and improve lung function. It encourages better ventilation and can be particularly useful for patients with restrictive lung diseases or those recovering from surgery.
What Are the Types of Abnormal Respiratory Patterns in Newborns?
In newborns, abnormal respiratory patterns can include periodic breathing, where the baby has short pauses between breaths, and apnea, which involves a longer pause in breathing (typically more than 20 seconds).
Other patterns, such as grunting (caused by partial closure of the vocal cords) or nasal flaring, may indicate respiratory distress. Rapid or shallow breathing, retractions (pulling in of the chest muscles during breaths), and wheezing are also common signs of potential respiratory issues in newborns, often requiring close monitoring and medical evaluation.
Which Abnormal Breathing Patterns Require Treatment?
Several abnormal breathing patterns may require treatment, depending on their cause and severity. Patterns like apnea, Kussmaul breathing, Cheyne-Stokes respiration, and agonal breathing often indicate serious underlying conditions and need prompt medical intervention.
Obstructive breathing, seen in asthma or COPD, and breathing irregularities related to heart failure or neurological issues also generally require treatment. The goal of treatment is to address the underlying condition, improve oxygenation, and restore normal breathing patterns.
Final Thoughts
Understanding the abnormal breathing patterns is crucial for identifying potential health issues before they escalate. While some patterns may be temporary or linked to anxiety, others could indicate serious conditions that require immediate attention.
By learning about these patterns, you’re better equipped to recognize unusual changes in breathing and take appropriate action when necessary.
Early detection can make a significant difference in health outcomes, highlighting the importance of awareness and proactive care in respiratory health.
Written by:
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
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- Faarc, Kacmarek Robert PhD Rrt, et al. 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.