Respiratory Therapy Terms and Definitions

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AARC – the abbreviation for the American Association for Respiratory Care, a professional organization dedicated to advancing the field of respiratory care through education, advocacy, research, and credentialing.

ABG Calculator – a medical tool designed to interpret arterial blood gas analyses, educating healthcare professionals in assessing a patient’s oxygenation, ventilation, and acid-base balance.

Accessory Muscles of Breathing – muscles of the neck, back, and abdomen that assist the diaphragm when a patient has an increased work of breathing.

Acid-Base Balance – the process by which the body maintains a proper equilibrium of acids and bases and refers to the degree of acidity and alkalinity.

Acute Exacerbation of COPD – a worsening state of COPD that usually indicates that the patient is in need of increased medication dosages or other forms of care.

Acute Respiratory Distress Syndrome (ARDS) – a severe lung condition characterized by rapid onset of widespread inflammation in the lungs, leading to respiratory failure.

Adult Croup – a rare respiratory condition characterized by inflammation of the larynx and trachea, leading to a distinctive barking cough and difficulty breathing.

Advanced Cardiac Life Support (ACLS) – an advanced form of emergency life support for the treatment of cardiac arrest, stroke, myocardial infarction, and other life-threatening cardiovascular emergencies.

Advanced Directive – a legal document that allows a patient to specify what medical care he or she does or does not want to receive if they were no longer able to make decisions on their own. It’s typically in the form of a living will or durable power of attorney.

Aerophagia – the excessive swallowing of air, which can lead to bloating, belching, and discomfort in the digestive tract.

Aerosol Medication – a medication that can be dispersed as solid or liquid particles in a gas which allows for inhalation into the airways of the respiratory tract.

Agonal Breathing – an irregular, gasping respiratory pattern that occurs as a reflexive response to severe physiological distress.

Air Bronchograms – a pattern on a chest radiograph that shows air-filled bronchi surrounded by areas of consolidation.

Airway Clearance Therapy – a type of therapy that uses noninvasive techniques to help mobilize and remove secretions in order to improve gas exchange.

Airway Management – the process of maintaining ventilation in a patient by using an artificial airway. This ensures that gas exchange can occur by establishing a link between the patient and the ventilator.

Airway Obstruction – a complete or partial blockage of an airway that prevents or limits ventilation and air movement to and from the lungs.

Airway Pharmacology – a term that refers to the deliverance of aerosol medications to the respiratory tract of the lungs.

Airway Pressure Release Ventilation (APRV) – a mode of mechanical ventilation in which two levels of continuous positive airway pressure are applied with an intermittent release phase for spontaneous breaths. This mode is often recommended to improve oxygenation and treat refractory hypoxemia.

Airway Resistance – the measurement of impedance to the movement of air through the respiratory tract during inspiration and expiration.

Airway Suctioning – a method of using negative pressure to remove secretions from a patient’s airway through a collecting tube or catheter.

Albuterol – an inhaled beta-2-agonist bronchodilator that is administered to prevent and treat wheezing, chest tightness, and shortness of breath caused by pulmonary diseases, such as asthma and chronic obstructive pulmonary disease (COPD).

Alveolar-Capillary Membrane – a layer of tissue that serves as a barrier through which gas exchange occurs between the alveoli and pulmonary capillaries.

Alveolar Ventilation – the ventilatory process that takes place in the alveoli of the lungs, where the body is able to take in oxygen and remove carbon dioxide.

Alveoli – tiny, balloon-like sacs in the lungs where the exchange of oxygen and carbon dioxide occurs between the air and the bloodstream.

Ambulation – the process of helping a patient gain the ability to walk without any type of assistance.

Anticholinergic Bronchodilators – a drug that acts on the parasympathetic nervous system by blocking the mechanism of action of the neurotransmitter acetylcholine (ACh) to promote relaxation of the smooth muscles in the airways of the lungs.

Antimicrobial Agents – a class of drugs that work to eliminate potentially harmful microorganisms and prevents them from growing or spreading in the lungs.

Anti-Mucus Diet – a dietary approach focused on minimizing the intake of foods believed to increase mucus production, favoring instead those that are thought to reduce or not contribute to mucus formation in the body.

Apgar Score – a numerical assessment conducted one and five minutes after birth to evaluate a newborn’s health across five vital signs.

Apnea – the absence of spontaneous breathing.

Apnea of Prematurity – a disorder that occurs in preterm infants which results in frequent periods of apnea. It is caused by a physiologically underdeveloped respiratory control center in the brain.

Apneustic Breathing – an abnormal breathing pattern that results from an injury to the upper pons in the brain that results in a prolonged inspiratory time followed by inadequate expiration.

Arterial Blood Gas (ABG) – a test that measures the blood levels of oxygen (PaO2), carbon dioxide (PaCO2), and acid-base balance (pH) in the body that is used to assess how well oxygen is being distributed and how well carbon dioxide is being removed.

Artificial Airway – a tube that is inserted into a patient’s trachea in order to maintain breathing and ventilation.

Assist/Control Mode (A/C) – a mode of mechanical ventilation in which a minimum number of preset mandatory breaths are delivered by the ventilator but the patient can also trigger assisted breaths. The patient makes an effort to breathe and the ventilator assists in delivering the breath.

Asthma – a chronic, obstructive, and inflammatory respiratory condition characterized by recurring episodes of dyspnea, wheezing, and chest tightness.

Atelectasis – a medical condition characterized by the partial or complete collapse of one or more areas of the lung, leading to reduced oxygen exchange.

Auscultation – a non-invasive procedure for listening to the internal sounds of the body using a stethoscope.

Automatic External Defibrillator (AED) – a portable electronic device that can be used outside of the hospital to detect cardiac arrhythmias and perform defibrillation in order to re-establish a normal heart rhythm.

Auto-PEEP – a complication of mechanical ventilation that occurs when positive pressure remains in the alveoli at the end-exhalation phase of the breathing cycle.


Barotrauma – an injury to lung tissue that results from overexpansion and increased levels of pressure.

Barrel Chest – a term used to describe a patient with an increased anterior-posterior diameter of the chest wall that is often seen in patients with emphysema.

Base Excess (BE) – a value obtained during an arterial blood gas (ABG) analysis that refers to the difference between the normal and actual buffer base in a sample of blood.

Beta-2 Agonist – a type of medication that is administered for the treatment of acute bronchospasm and works by causing relaxation of smooth muscle tissue in the airways.

Bicarbonate (HCO3-) – a byproduct of the body’s metabolism that represents the total carbon dioxide content that is transported in the blood. Once it reaches the lungs, it can be exhaled as carbon dioxide.

Bilevel Positive Airway Pressure (BiPAP) – a form of noninvasive ventilation that distributes two levels of pressure in order to provide ventilatory support and help avoid invasive mechanical ventilation.

Biot’s Respirations – a breathing pattern characterized by deep breaths that alternate with irregular periods of apnea. It often results from damage to the medulla or pons in the brain.

Bland Aerosol Therapy – a treatment modality that involves the inhalation of sterile water or saline aerosols to hydrate the respiratory tract and facilitate airway clearance.

Body Plethysmography – a pulmonary function test that measures the amount of air that is inhaled and the amount of air that remains in the lungs after exhalation.

Bourdon Gauge – a flow meter device that uses a fixed orifice and operates under variable pressures that can be adjusted with a pressure-reducing valve.

Bradycardia – an abnormally decreased heart rate of fewer than 60 beats per minute.

Bradypnea – an abnormal breathing pattern characterized by a respiratory rate that is less than 12 breaths per minute.

Breath Sounds – the sounds that come from the lungs during inhalation and exhalation that can be heard during auscultation. An abnormality in breath sounds is an indication of other health issues.

Breathing Pattern – the ventilatory pattern by a patient over a period of time that accounts for the respiratory rate and amount of air that is cycled.

Breathing Treatment – a therapeutic modality that involves inhaling medications directly into the lungs using a nebulizer to manage and alleviate respiratory conditions.

Breathometer – a startup company that developed a compact, smartphone-enabled breathalyzer intended to offer users a convenient way to measure their blood alcohol content, but it faced severe regulatory backlash and eventual shutdown due to significant inaccuracies in its product’s readings.

Bronchiectasis – a chronic respiratory condition characterized by the irreversible widening and scarring of the bronchial tubes due to recurrent infections and inflammation.

Bronchitis – inflammation of the bronchial tubes in the lungs, typically resulting from a viral infection, characterized by coughing, mucus production, and sometimes shortness of breath.

Bronchoalveolar Lavage (BAL) – a diagnostic technique that uses a bronchoscope and saline solution to collect specimens from the lower respiratory tract for testing.

Bronchoconstriction – an abnormal contraction of the smooth muscle tissue in the airways of the lungs that results in narrowing and difficulty breathing.

Bronchodilator – a medication that relaxes and widens the air passages in the lungs, making it easier to breathe.

Bronchoprovocation Study – a test that uses methacholine, a cholinergic drug, to access airway hyperresponsiveness in order to diagnose a patient with asthma.

Bronchopulmonary Dysplasia (BPD) – a chronic respiratory disorder in premature and low birth weight infants characterized by a reduction in the overall surface area for gas exchange.

Bronchoscopy – an endoscopic procedure that involves passing a bronchoscope into the airways of the lungs for diagnostic and therapeutic purposes.

Bubble Humidifier – a medical device that adds moisture to oxygen, making it more comfortable for patients to breathe during supplemental oxygen therapy.


Cape Cyanosis – a specific pattern of bluish discoloration affecting the upper extremities and face, resembling a cape draped over the shoulders and upper chest, often indicating underlying circulatory or respiratory issues.

Capillaries – the smallest blood vessels in the body that form a connection between arterioles and venules, and allow the exchange of blood, nutrients, and waste.

Capnography – a process of measuring and monitoring the amount of carbon dioxide in exhaled air.

Carbon Dioxide Transport – the movement of CO2 from bodily tissues to the lungs for exhalation, facilitated by dissolution in plasma, conversion to bicarbonate ions, and binding to hemoglobin.

Carbon Monoxide Poisoning – a potentially fatal condition caused by inhaling carbon monoxide gas, which inhibits the blood’s capacity to carry oxygen.

Carboxyhemoglobin – a chemical compound formed when carbon monoxide binds with hemoglobin in the blood, hindering the blood’s ability to carry and deliver oxygen to the body.

Cardiac Electrophysiology – the study and treatment of the heart’s electrical activity and related rhythm disorders.

Cardiac Output – a measurement of the volume of blood that is pumped by the heart per minute.

Cardiac Tamponade – a medical condition characterized by the accumulation of blood, fluid, or gas in the pericardial sac of the heart.

Cardiogenic Pulmonary Edema – a type of pulmonary edema that is caused by increased pressures in the heart and is associated with congestive heart failure.

Cardiopulmonary Diseases – a group of conditions that affect the heart and lungs, often impacting the body’s ability to adequately circulate blood and oxygenate tissues.

Cardiopulmonary Rehabilitation – an organized program that is designed to improve the status of patients with conditions of the heart and lungs with a goal to improve their overall quality of life.

Cardiopulmonary Resuscitation (CPR) – an emergency medical procedure for life support that involves repeated chest compressions and artificial ventilation in an effort to restore spontaneous breathing and blood circulation in a patient who is in cardiac or respiratory arrest.

Cardiovascular Life Support – a set of medical procedures and interventions designed to provide immediate care for life-threatening cardiac emergencies.

Cardioversion – a medical procedure that uses an electrical shock to restore an abnormal heart rhythm back to normal.

Carina – the bifurcation of the trachea that separates into the right and left mainstem bronchi.

Central Sleep Apnea – a disorder characterized by the absence of breathing while asleep that is caused by a medullary depression that inhibits an inspiratory effort.

Centrilobular Emphysema – a subtype of emphysema characterized by enlargement and damage of the air sacs, primarily in the central parts of the lung’s secondary lobules.

Chest Physical Therapy (CPT) – a form of therapy that is designed to help clear secretions, improve ventilation, and strengthen the respiratory muscles of breathing.

Chest Radiograph – a radiographic imaging technique used for the assessment of the heart, lungs, and structures within the thoracic cavity.

Chest Trauma – any type of trauma or injury to the chest wall.

Cheyne-Stokes Respiration – an abnormal breathing pattern characterized by gradual periods of deep and shallow breaths with a period of apnea.

Chronic Bronchitis – a condition characterized by long-term inflammation of the bronchial tubes, leading to persistent coughing and production of mucus.

Chronic Cough – a persistent cough lasting more than eight weeks in adults or four weeks in children, often indicating an underlying medical condition.

Chronic Obstructive Pulmonary Disease (COPD) – a progressive lung disorder characterized by obstructed airflow and breathing difficulties.

Cilia – microscopic hairlike structures that line the cells within the airways of the lungs that help mobilize mucus and secretions.

Clinical Sims Exam Diseases – a set of medical conditions and scenarios crucial for students to study and understand thoroughly to effectively diagnose, manage, and treat during the simulated patient interactions and problem-solving challenges presented on the Clinical Simulation Exam (CSE).

Clinical Simulation Exam (CSE) – a practical assessment used in respiratory care education to evaluate a student’s clinical competencies, decision-making, and procedural skills through simulated patient interactions and clinical scenarios.

Code of Ethics – a set of guiding principles and standards designed to ensure professional conduct and high-quality patient care in the field of respiratory care.

Committee on Accreditation for Respiratory Care (CoARC) – an accrediting committee that establishes education standards and oversees the approval of respiratory care programs.

Complete Blood Count – a group of medical laboratory tests for screening and diagnostic purposes that analyzes the counts of red blood cells, white blood cells, and platelets, as well as the concentration of hemoglobin and hematocrit.

Computed Tomography (CT) – a radiographic imaging technique that generates cross-sectional images of an organ or tissue structure.

Congenital Cardiac Defect – a condition of the heart that develops before an infant is born.

Congenital Diaphragmatic Hernia – a developmental birth defect characterized by a hole in the diaphragm of a fetus that results in severe respiratory distress.

Congestive Heart Failure (CHF) – a chronic condition where the heart muscle weakens and loses the ability to pump blood effectively, leading to symptoms such as shortness of breath, edema, and fatigue.

Contact Precautions – safety measures used to reduce the risk of transmitting infectious diseases and microorganisms that can be spread by direct or indirect contact.

Continuous Positive Airway Pressure (CPAP) – a mode of ventilatory support in which a continuous pressure that is above atmospheric pressure is maintained throughout the breathing cycle.

Control Mode Ventilation (CMV) – a mode of mechanical ventilation where the machine delivers a preset tidal volume at a set time-triggered frequency.

COPD – the abbreviation for chronic obstructive pulmonary disease, a disease that causes progressive airway obstruction.

Cor Pulmonale – a condition that causes failure of the right ventricle and often results from pulmonary hypertension.

Coronary Artery Bypass Graft (CABG) – a surgical procedure that aims to improve blood flow to the heart and is often performed on patients with coronary artery disease.

Coronary Artery Disease – a disease that develops when there is narrowing or a blockage of the coronary arteries. It is usually caused by plaque build-up that results in decreased blood flow to the heart.

Coughing Up Mucus – a reflex action where the body expels mucus, a viscous secretion produced by the mucous membranes, to clear the airways of irritants, infections, or debris.

COVID-19 – a respiratory illness caused by the SARS-CoV-2 virus with symptoms ranging from mild cold-like to severe pneumonia-like.

CPAP Belly Syndrome – bloating or discomfort in the abdomen that some people experience when using a continuous positive airway pressure (CPAP) machine, due to the swallowing of air during therapy.

Crackles – also known as rales, are abnormal sounds that are heard as air moves through secretions in the small or middle airways of the lungs.

Cricothyrotomy – an emergency surgical procedure where an incision is made through the skin and cricothyroid membrane in order to access the trachea so that ventilation can occur.

Croup – a viral infection of the upper airway that results in subglottic swelling and an obstruction below the vocal cords.

Croup Tent – a child-friendly enclosure used to deliver mild aerosol treatments to infants and young children struggling with respiratory conditions like croup.

CRT – the abbreviation that stands for certified respiratory therapist.

Cyanosis – a physical sign characterized by a bluish discoloration of the skin and mucous membranes, indicating insufficient oxygenation of the blood.

Cystic Fibrosis – a genetic disorder characterized by the production of thick and sticky mucus that can clog the airways and lead to respiratory and digestive problems.


Dead Space – the volume of ventilated air that does not participate in gas exchange.

Dead Space/Tidal Volume Ratio (VD/VT) – a ratio that shows the percentage of each breath that does not participate in gas exchange.

Defibrillation – the act of delivering an electrical shock to the heart for the treatment of a life-threatening cardiac arrhythmia.

Depth of Respiration – the volume of air that is inhaled or exhaled during each breath.

Diaphoresis – a medical term characterized by abnormal, excessive sweating.

Diaphragm – a muscle of respiration located below the lungs that continually contracts and assists with ventilation.

Diffusing Capacity of the Lungs for Carbon Monoxide (DLCO) – a pulmonary function test that is performed to assess the extent to which carbon monoxide can diffuse from air into the bloodstream.

Diminished Breath Sounds – a type of lung sounds that are heard (or not heard) when there is decreased air movement in the lungs.

Disease X – a hypothetical, unknown pathogen that could cause a future epidemic or pandemic, as designated by the World Health Organization to emphasize the need for preparedness and research for unknown diseases.

Diuretic Agents – a class of medication that stimulates urine production to promote the excretion of excess water and sodium in patients who are fluid overloaded.

DOPE Mnemonic – a clinical tool used to quickly identify and address common causes of ventilation problems in intubated patients, including displacement, obstruction, pneumothorax, and equipment failure.

Dorsal Recumbent Position – a position in which a patient lies on their back with their knees bent, legs separated, and feet flat on the bed or examining table, often used to facilitate medical examination or a surgical procedure.

Droplet Precautions – safety measures used to reduce the risk of transmitting infectious diseases and microorganisms that can be spread by droplet particles in the air after coughing, sneezing, or talking.

Drug Overdose – when a person takes too much of a medication that is more than the recommended medical dose. The medication could be prescription, over-the-counter, or illegal. It could be intentional or accidental.

DuoNeb – a combination bronchodilator medication used to treat bronchospasm in patients with obstructive lungs diseases.

Dyspnea – a term that refers to shortness of breath or difficulty breathing as perceived by the patient.


Elasticity – a characteristic of a tissue that allows it to return to its original shaped after being stretched.

Electrocardiogram (EKG) – a noninvasive diagnostic procedure that measures the electrical activity of the heart.

Emphysema – a chronic lung condition characterized by the irreversible damage of the alveoli in the lungs, leading to breathing difficulties.

Endotracheal Tube – an artificial airway that is inserted into the trachea as a means to establish a connection for mechanical ventilatory support.

Epiglottis – an acute upper airway infection that causes severe supraglottic swelling.

Erythrocyte – red blood cell.

Expiratory Reserve Volume (ERV) – the total amount of air that can be exhaled after a normal expiration.

Extracellular Fluid – the body fluid outside cells, encompassing components such as blood plasma and interstitial fluid, crucial for delivering nutrients and removing waste.

Extracorporeal Membrane Oxygenation (ECMO) – a type of extracorporeal life support that involves pumping blood out of the body through a membrane for the gas exchange of oxygen and carbon dioxide.

Extubation – a procedure that involves the removal of an endotracheal tube from the trachea.


Fenestrated Tracheostomy Tube – a tracheostomy tube that has an opening above the cuff that allows airflow to pass through so that the patient is able to talk with the airway in place.

Fetal Circulation – the process that facilitates the exchange of oxygen, nutrients, and waste products between the mother and the fetus.

Fetal Lung Development – a process in newborns involving multiple developmental phases that lead to the formation of the lungs and alveoli so that gas exchange and breathing can occur.

FEV1 – a measurement of the maximum volume of air that a patient can exhale during the first second of a forced vital capacity maneuver.

FEV1/FVC Ratio – a ratio that reflects a percentage of the amount of forced expiratory volume that can be exhaled in the first second of a forced vital capacity maneuver.

Fick’s First Law of Diffusion – a law which states that the rate of diffusion of a substance across a membrane is proportional to the concentration gradient, area of the membrane, and membrane permeability, and inversely proportional to the thickness of the membrane.

Flail Chest – a traumatic injury where a portion of the rib cage is fractured and becomes detached from the chest wall.

Flexible Bronchoscopy – a procedure that involves the insertion of a flexible bronchoscope into the airways of the lungs for diagnostic and therapeutic purposes.

Flowmeter – a device that regulates and measures the flow of therapeutic gases to patients, ensuring precise and safe delivery.

Flow Rate – a measurement of a patient’s maximum speed of inspiration or expiration.

Flutter Valve – a small, handheld device that uses positive expiratory pressure and vibrations to help clear mucus from the lungs.

Forced Expiration Technique (FET) – a breathing exercise used to clear mucus from the lungs by combining controlled breathing, deep inhalation, and forceful exhalation.

Forced Vital Capacity (FVC) – the total volume of air that can be rapidly and forcefully exhaled after a maximum inspiration.

Fraction of Inspired Oxygen (FiO2) – the concentration of oxygen that is being inhaled by a patient.

Functional Residual Capacity (FRC) – the volume of air exhaled after a normal tidal volume breath in addition to the volume remaining in the lungs after maximum expiration.


Gas Distribution Tests – pulmonary tests that measure the volume and distribution of air within the lungs to assess respiratory function.

Gas Exchange – the physiological process of diffusion where oxygen moves from the lungs to the bloodstream during inhalation and carbon dioxide moves from the blood to the lungs for removal during exhalation.

Glasgow Coma Scale (GCS) – a scoring system used to classify a patient’s level of consciousness after a brain injury.

Gastroesophageal Reflux Disease (GERD) – a chronic medical condition characterized by the backward flow of stomach acid into the esophagus, leading to symptoms such as heartburn and regurgitation.

GlideScope – a video laryngoscope that provides an enhanced, indirect view of the larynx for efficient endotracheal intubation.

Grunting – a noisy, irregular breathing pattern in infants that serves as an indication of respiratory distress.

Guillain-Barré Syndrome – a rapid-onset disease characterized by ascending paralysis in which the patient’s autoimmune system attacks and causes inflammation and deterioration of the peripheral nervous system.


Head Trauma – any physical injury to the head, ranging from minor bumps and bruises to more serious brain injuries, affecting brain function.

Heart Rate (HR) – a measurement of the number of heart beats per minute.

Heat and Moisture Exchanger (HME) – a device that provides humidification during mechanical ventilation by recirculating heat and moisture from a patient’s exhaled breath.

Heliox – a medical gas mixture of helium and oxygen that is used to treat patients with a severe airway obstruction.

Hemodynamic Monitoring – the continuous measurement and analysis of cardiovascular parameters to assess heart function and fluid status.

Hemoglobin – a protein in red blood cells that transports oxygen molecules from the lungs to body tissues.

Hemoptysis – the coughing up of blood from the respiratory tract.

Hemothorax – the accumulation of blood in the pleural cavity that occurs from a traumatic thoracic injury.

High-Flow Nasal Cannula (HFNC) – an oxygen delivery system that can supply heated and humidified oxygen with flows u to 60 L/min.

High-Frequency Chest Wall Compression (HFCW) – a type of airway clearance therapy commonly used in patients with Cystic Fibrosis that uses an inflatable vest to help mobilize secretions. It works by creating oscillations against the patient’s thorax and chest wall.

High-Frequency Oscillatory Ventilation (HFOV) – a type of mechanical ventilation that delivers very small tidal volumes at an extremely fast rate which minimizes the chances of a lung injury.

History of Respiratory Care – refers to the development and evolution of practices, methodologies, and technologies used to assess and treat patients with respiratory conditions.

Humidification Therapy – a medical treatment that adds moisture to the air inhaled by patients to maintain optimal respiratory tract conditions.

Hypercapnia – a condition characterized by elevated carbon dioxide levels in the blood.

Hyperpnea – an abnormal breathing pattern characterized by an increased respiratory rate, rhythm, and depth of breathing.

Hypertension – high blood pressure.

Hyperventilation – a respiratory pattern characterized by an increased rate or depth of breathing that results in a decreased PaCO2.

Hypotension – low blood pressure.

Hypoventilation – a respiratory pattern characterized by a decreased rate or depth of breathing that results in an increased PaCO2.

Hypoxemia – a medical condition characterized by abnormally low levels of oxygen in arterial blood.

Hypoxia – a medical condition characterized by abnormally low levels of oxygen in body tissues.


Incentive Spirometry – a type of lung expansion therapy that encourages patients to take slow, deep breaths in order to help avoid atelectasis.

Indoor Plants – vegetation cultivated within interior spaces that contribute to improved air quality by filtering pollutants and enhancing oxygen levels.

Inhaled Anti-Infective Agents – a class of medications that work to inhibit the spread of infections by eliminating potentially harmful organisms.

Inhaled Corticosteroids – a class of drugs that have anti-inflammatory effects on the airways and are effective for the maintenance of obstructive diseases such as asthma.

Inhaled Nitric Oxide (iNO) – a colorless, odorless gas that causes vascular smooth muscle relaxation which improves blood flow to ventilated alveoli.

Inhaled Pulmonary Vasodilators – medications administered through inhalation to dilate the blood vessels in the lungs, improving oxygenation and reducing pulmonary arterial pressure.

Inspiratory Capacity (IC) – the volume of air that can be inhaled in addition to a normal tidal volume breath.

Inspiratory-to-Expiratory Ratio (I:E Ratio) – refers to the ratio of the inspiratory portion compared to the expiratory portion of the breathing cycle.

Inspiratory Reserve Volume (IRV) – the volume of air that can be inhaled after a tidal volume breath.

Intermittent Positive Pressure Breathing (IPPB) – a patient-triggered, pressure-cycled form of noninvasive positive pressure ventilation that can assist with lung expansion.

Interstitial Fluid – a component of the body’s extracellular fluid that bathes the cells in tissues, providing a medium for nutrient and waste exchange.

Interstitial Lung Disease (ILD) – a term that describes any respiratory disorder that causes scarring of the tissues within the lungs.

Intrapulmonary Percussive Ventilation (IPV) – a type of airway clearance therapy that uses a pneumatic machine to deliver small pressurized breaths at a fast rate to help mobilize secretions.

Intubation – the process of inserting a tube into the trachea in order to establish an airway and facilitate breathing support via mechanical ventilation.

Inverse Ratio Ventilation – a mode of mechanical ventilation that uses an inverse I:E ratio to improve oxygenation and gas exchange.

Iron Lung – a negative pressure ventilator that was invented in the 1920s that was primarily used to treat patients with polio.


Joint Commission – a nonprofit organization that is responsible for the accreditation and certification of hospitals and healthcare organizations in the United States.

Jugular Venous Distention – the abnormal bulging of the jugular veins in a patient’s neck that is often a sign of heart failure.


Kennel Cough – a highly contagious respiratory disease in dogs, characterized by a persistent, dry, hacking cough, caused by a combination of viral and bacterial infections.

Kerley B Lines – the thin lines that can be seen on a chest x-ray near the pleural edge of the lungs that are caused by increased pulmonary capillary pressures.

Kussmaul Respiration – an abnormal breathing pattern characterized by an increased respiratory rate and depth of breathing with an irregular rhythm.

Kyphoscoliosis – a condition characterized by an abnormal curvature of the sagittal and coronal planes of the spine.


Laminar Flow – a type of fluid flow in which the fluid travels smoothly or in regular paths, in contrast to turbulent flow in which the fluid undergoes irregular fluctuations and mixing.

Laryngopharyngeal Reflux – a medical condition in which stomach acid flows back into the throat, causing irritation and symptoms such as hoarseness, throat clearing, and cough.

Larynx – an organ in the anterior neck that helps produce sound and protects the vocal cords and trachea.

Leukocyte – white blood cell.

Life2000 Ventilator – a lightweight, wearable, noninvasive ventilator designed to support individuals with respiratory conditions that make it challenging to lead an active lifestyle.

Lobar Atelectasis – the collapse of an entire lobe of the lung, often due to blockages in the bronchial tubes or external pressure on the lung tissue.

Lung Cancer – a type of cancer that forms in the tissues of the lungs that most often occurs in those who smoke tobacco-related products.

Lung Capacity – the maximum amount of air that the lungs can hold during the process of inhalation and exhalation.

Lung Compliance – a measurement of the lung’s ability to expand.

Lung Consolidation – a term that refers to an area of the lungs that is filled with liquid instead of air.

Lung Damage – any injury or harm to the lung tissues that impairs their function, leading to breathing difficulties and potentially serious respiratory conditions.

Lung Expansion Therapy – a set of techniques designed to improve lung function by encouraging the full expansion of lung tissues, often used to prevent or treat atelectasis and improve oxygenation.

Lung Fissure – a deep groove in the lung tissue that separates the different lobes within each lung.

Lung Infection – a condition where pathogens such as bacteria, viruses, or fungi invade the lung tissue, causing inflammation and impaired respiratory function.

Lung Infiltrates – substances or cells that fill the lung, appearing denser on medical imaging, indicating various possible lung conditions.

Lung Lobe – a section of the lung, each distinctly separated by fissures, and functioning as a unit within the overall respiratory system.

Lymph – a clear fluid circulating through the lymphatic system, carrying white blood cells, especially lymphocytes, and draining into the bloodstream.


Magnetic Resonance Imaging (MRI) – an imaging technique that uses magnetic fields and radio waves to generate detailed images of organs and body tissues.

Mallampati Score – a test that is used to inspect the upper airway in order to predict the ease of endotracheal intubation.

Mandatory Breath – a breath in mechanical ventilation that is initiated and controlled by the machine.

Mandatory Minute Ventilation (MMV) – a feature of some ventilators that causes an increase in the mandatory breaths that are delivered when the patient’s spontaneous breathing level becomes inadequate.

Mean Airway Pressure – the average pressure applied to the airway over time during mechanical ventilation.

Mechanical Insufflation-Exsufflation – a type of airway clearance therapy that uses a device to provide alternating positive and negative pressure to give an artificial cough in order to help mobilize and remove secretions.

Mechanical Ventilation – a therapeutic method that uses a machine to provide positive pressure to the lungs of patients who are unable to breathe on their own.

Mechanical Ventilation Monitoring – the continuous assessment of a patient’s ventilatory status and the performance of the ventilator machine to ensure optimal respiratory support and patient safety.

Mechanical Ventilator – a device used to provide positive pressure ventilation in order to facilitate breathing.

Meconium Aspiration Syndrome – a neonatal respiratory condition caused by the inhalation of meconium-stained amniotic fluid into the lungs.

Medical Gas Therapy – the controlled administration of medical gases like oxygen, nitric oxide, and heliox to treat various respiratory conditions.

Metabolic Acidosis – an acidotic condition caused by non-respiratory processes that results in abnormally low bicarbonate levels.

Metabolic Alkalosis – an alkalotic condition caused by non-respiratory processes that results in abnormally high bicarbonate levels.

MetaNeb – a therapeutic system used to improve respiratory function by expanding the lungs, moving secretions, and providing supplemental oxygen.

Methacholine Challenge Test – a diagnostic procedure that assesses bronchial hyperreactivity by measuring lung function response to inhaled methacholine.

Methylxanthine – a class of bronchoactive agents used for the long-term control of asthma symptoms.

Military Respiratory Therapist – a healthcare professional who specializes in providing comprehensive respiratory care and emergency support to military personnel across various branches of the armed forces.

Minute Ventilation – a measurement of the volume of air that enters or leaves the lungs per minute.

Modified Allen Test – a test that evaluates the adequacy of blood circulation in the radial and ulnar arteries prior to performing an arterial blood gas stick.

Modified Borg Dyspnea Scale (MBS) – a numerical scale from 0 to 10 that is used to measure the severity of dyspnea as perceived by the patient.

Morning Cough – a persistent coughing episode that occurs predominantly upon waking, often indicative of underlying health conditions.

Mucolytic Agents – a class of drugs that are administered to help control copious amounts of thick secretions that are common in respiratory diseases such as cystic fibrosis and bronchiectasis.

Mucus – a slippery, protective secretion produced by mucous membranes, aiding in trapping pathogens, hydrating tissues, and facilitating bodily functions.

Mucus Disorders – are health conditions characterized by the abnormal production or secretion of mucus, affecting respiratory and digestive tracts.

Mucus Plug – a collection of mucus that results in an occlusion of the airway.

Muscular Dystrophy – a group of genetic diseases that results in progressive muscle weakness and leads to difficulty breathing and the inability to walk.

Myasthenia Gravis – a chronic neuromuscular disease that leads to descending paralysis and muscular weakness in the face, throat, and respiratory system.

Myocardial Infarction – a medical emergency caused by the interruption of blood flow to a part of the heart, resulting in the death of heart muscle cells.


Nasal Flaring – a clinical sign characterized by the widening of nostrils while breathing that is often a sign of respiratory distress.

Nasopharynx – the upper portion of the pharynx behind the nasal cavity that allows breathing through the nose.

National Board for Respiratory Care (NBRC) – a nonprofit organization in the United States that provides and maintains credentials for Respiratory Therapists upon earning a passing score on the certification board examinations.

Nebulizer – an aerosol delivery device that creates particles out of a liquid medication to facilitate absorption in the airways of the lungs.

Negative Pressure Ventilation – a method of mechanical ventilation in which a sub-atmospheric pressure environment is created around the patient’s chest or body, causing air to be drawn into the lungs, mimicking the natural process of inhalation.

Neonatal Mechanical Ventilation – the medical procedure used to assist or fully take over the breathing of newborns who are unable to breathe sufficiently on their own, by delivering air and oxygen into their lungs through a machine.

Neonatal/Pediatric Patient Assessment – the specialized evaluation of infants and children’s health status and needs.

Neonatal Respiratory Distress Syndrome (NRDS) – a lung condition primarily in premature infants caused by a deficiency of surfactant, leading to difficulty breathing shortly after birth.

Neuromuscular Blocking Agents – a class of drugs that cause respiratory muscle paralysis by altering the action of postsynaptic acetylcholine receptors.

Newborn Grunting – a clinical sign in infants characterized by expiratory sounds while breathing that is often a sign of respiratory distress.

Nic Sick – the symptoms of nausea, dizziness, and increased heart rate experienced after consuming excessive amounts of nicotine.

Noninvasive Positive Pressure Ventilation (NPPV) – a therapeutic method of providing positive pressure to a patient’s lungs without the insertion of an endotracheal tube.

Noninvasive Ventilation – a type of mechanical ventilation performed without the insertion of an endotracheal tube.

Nonsteroidal Anti-Asthma Agents – a type of medication used for the prophylactic management of mild persistent asthma.

Normal Breathing – the effortless, rhythmic inhalation and exhalation of air, sufficient to meet the body’s oxygen and carbon dioxide exchange needs.

Nosocomial Pneumonia – a type of pneumonia that is acquired inside of the hospital more than 48 hours after being admitted.

Nutrition Assessment – a comprehensive evaluation conducted to determine a patient’s overall nutritional status to inform personalized healthcare plans.


Obstructive Lung Diseases – respiratory conditions characterized by airflow obstruction due to narrowed or blocked airways.

Obstructive Sleep Apnea (OSA) – a disorder characterized by the absence of breathing while asleep that is caused by a blockage of the upper airway.

Oropharynx – the portion of the pharynx behind the oral cavity that allows air, liquid, and food to pass through.

Orthopnea – difficulty breathing while lying down.

Over-the-Counter Oxygen – a non-prescription product typically sold in portable canisters, designed for recreational use or temporary relief in situations like high altitudes or polluted environments.

Oxygenation – the process by which oxygen from inhaled air is transferred to the bloodstream in the lungs.

Oxygen Concentrator – a medical device that extracts and purifies oxygen from ambient air to deliver it to patients requiring supplemental oxygen.

Oxygen Face Tent – a medical device designed to administer oxygen to patients who cannot comfortably use a traditional oxygen mask or nasal cannula.

Oxygen Therapy – any type of therapy in which oxygen is delivered to a patient for the treatment of hypoxemia.

Oxygen Transport – the process by which oxygen is carried from the lungs to tissues throughout the body, primarily via hemoglobin in red blood cells.


Paradoxical Breathing – an abnormal respiratory pattern characterized by an inward movement of the chest wall during inhalation followed by an outward movement during exhalation.

Parietal Pleura – the membrane that covers the entire surface of the diaphragm and thoracic cavity.

Patient Assessment – a systematic evaluation of a patient’s health status through the collection and analysis of medical history, physical examination, and diagnostic tests.

Patient-Ventilator Asynchrony – the inappropriate timing of delivered breaths between a patient and the mechanical ventilator.

Pediatric Advanced Life Support (PALS) – an advanced form of emergency life support for the treatment of cardiovascular emergencies in pediatric patients.

Penetrating Chest Trauma – a type of chest trauma where there is a singular puncture of the thoracic cavity that most often results from a knife or gunshot wound.

Peripheral Cyanosis – an abnormal bluish discoloration of the skin caused by inadequate oxygenation that can be seen on the patient’s extremities.

Persistent Pulmonary Hypertension of the Newborn (PPHN) – a condition in newborn infants that is characterized by abnormally increased pulmonary hypertension caused by failed circulatory adaptation at birth.

Personal Protective Equipment (PPE) – protective garments and equipment worn by healthcare professionals to minimize exposure to hazards and infections during patient care.

P/F Ratio (PaO2/FiO2) – a value that is used to assess a patient’s oxygenation status and level of hypoxemia that can be calculated by dividing the PaO2 by the FiO2.

PFT Equipment – a set of medical devices used to measure lung function, including lung volume, capacity, rates of flow, and gas exchange.

Pharynx – a muscular tube in the throat that connects the mouth and nasal passages to the esophagus and larynx, facilitating breathing, swallowing, and speech.

Phlegm – a viscous substance secreted by the mucous membranes of the respiratory tract, aiding in trapping and expelling foreign particles and pathogens from the body.

Pin-indexed Safety System (PISS) – a yoke-type connection system for small high-pressure gas cylinders and their attachments that reduces the risk of administering the wrong gas to the wrong patient.

Plateau Pressure – a pressure measurement during mechanical ventilation that is taken during an inspiratory pause at peak inspiration.

Pleural Diseases – conditions that affect the pleura, which can result from various factors such as infection, inflammation, trauma, or malignancy and often manifest as chest pain, cough, and shortness of breath.

Pleural Effusion – a respiratory condition characterized by an abnormal accumulation of fluid in the pleural space.

Pleural Friction Rub – a loud grating lung sound that is heard when inflamed pleura rub together that is caused by decreased fluid in the pleural space.

Pleurisy – a respiratory condition characterized by pain and inflammation in the pleura that usually results from a viral infection.

Pneumonia – an infection that causes inflammation in the lungs and results in fluid build-up, fever, cough, and difficulty breathing.

Pneumothorax – a condition characterized by the presence of air in the pleural space, which causes the lung to collapse.

Positive End Expiratory Pressure (PEEP) – the positive pressure above atmospheric pressure that remains in the lungs at the end of expiration.

Positive Expiratory Pressure (PEP) – an airway clearance technique where the patient exhales against back-pressure which helps mobilize secretions into the larger airways so that they can be removed via coughing or suctioning.

Positron Emission Tomography (PET) – a test that uses radioactive substances to examine the metabolic activity of various parts of the body.

Postnasal Drip – a condition where excess mucus accumulates in the back of the throat or nose, often leading to a sensation of mucus dripping downward from the nasal passages.

Postural Drainage – an airway clearance technique that involves positioning the patient in a way that allows gravity and mechanical energy to drain secretions into the central airways to help with removal by coughing or suctioning.

Pressure Controlled Ventilation – a mode of mechanical ventilation in which a specific inspiratory pressure can be set and delivered.

Pressure Support Ventilation (PSV) – a mode of mechanical ventilation in which the patient’s spontaneous breaths are supported by the ventilator during the inspiratory phase of breathing.

Principles of Respiratory Care – the fundamental laws and theories from physics and fluid dynamics that govern the mechanics, energy transformations, and airflow patterns involved in breathing and lung function.

PRN – an abbreviation for “pro re nata,” is a Latin phrase that translates to “as needed” and is commonly used in medical prescriptions to indicate that a medication should be taken only when necessary for a specific condition or symptom.

Prone Positioning – a body position where the patient lies face down with their back up.

Proportional Assist Ventilation (PAV) – a mode of mechanical ventilation where the machine uses variable pressure to provide pressure support for a patient’s spontaneous breaths.

Pulmonary Diffusion – the process by which oxygen and carbon dioxide exchange between the lungs’ alveoli and the bloodstream.

Pulmonary Edema – a condition characterized by the accumulation of fluid in the alveoli, leading to impaired gas exchange and breathing difficulty.

Pulmonary Embolism – a condition characterized by a blood clot blocking one or more arteries in the lungs, impairing blood flow and oxygenation.

Pulmonary Fibrosis – a lung disease characterized by the thickening and scarring of the lung tissue, leading to decreased oxygen absorption and difficulty breathing.

Pulmonary Function Testing (PFT) – a set of noninvasive tests used to examine a patient’s respiratory system and identify the severity of pulmonary impairment.

Pulmonary Rehabilitation – a multidisciplinary program for patients with chronic lung diseases that includes breathing techniques, exercise training, and health education.

Pulmonary Vascular Disease – a group of conditions that affect the blood vessels in the lungs, impairing blood flow and gas exchange.

Pulse Oximetry – a noninvasive technique for monitoring a patient’s oxygen saturation.

Pulsus Paradoxus – an abnormal decrease in blood pressure with each inspiratory effort.


Quality Assurance – a program with policies and standards designed to achieve desirable clinical outcomes and patient satisfaction levels.

Quality Control – a method in healthcare that uses a systematic approach to provide quality care and achieve desirable clinical outcomes.


Radiograph – an x-ray image.

Radiolucent – a term that describes objects of an x-ray that appear black because they do not block the passage of radiation.

Radiopaque – a term that describes objects of an x-ray that appear white because they do not allow the passage of radiation.

Rales – also known as crackles, are abnormal sounds heard as air moves through secretions in the small or middle airways of the lungs.

Rare Lung Disease – an uncommon respiratory condition that often goes undiagnosed or misdiagnosed, leading to significant health impacts and the need for specialized medical care.

Refractory Hypoxemia – a severe type of hypoxemia where an adequate PaO2 cannot be maintained with an FiO2 greater than 50%.

Regulation of Breathing – the physiological process controlled by the brainstem, involving various receptors and mechanisms, to maintain optimal levels of oxygen and carbon dioxide in the body.

Renal Insufficiency – a medical condition characterized by the kidneys’ diminished ability to filter waste products and excess fluids from the blood.

Residual Volume (RV) – the volume of air remaining in the lungs after a complete exhalation.

Respiration – the process by which cells utilize oxygen to produce energy from nutrients, releasing carbon dioxide as a byproduct.

Respiratory Abbreviations – shortened forms of medical terms and phrases used in the field of respiratory care to facilitate quick and efficient communication among healthcare professionals.

Respiratory Acidosis – an acidotic condition caused by hypoventilation.

Respiratory Alkalosis ­– an alkalotic condition caused by hyperventilation.

Respiratory Calculations – the use of mathematical formulas and equations to assess, diagnose, and manage patients’ pulmonary function and ventilation needs.

Respiratory Care in Alternative Settings – refers to the diagnosis, treatment, and management of respiratory disorders in non-hospital environments such as subacute facilities, long-term acute care hospitals, rehabilitation centers, skilled nursing facilities, and patients’ homes.

Respiratory Care Plan – a comprehensive strategy designed to manage and treat a patient’s respiratory condition, detailing specific interventions, treatments, and goals to improve breathing and lung function.

Respiratory Care Practitioner – a licensed and certified medical professional who provided treatment from patients with cardiopulmonary disorders.

Respiratory Care Research – the scientific study of methods and interventions aimed at diagnosing, treating, and managing respiratory diseases.

Respiratory Care Week – an annual observance dedicated to recognizing the contributions of respiratory therapists and promoting awareness about lung health.

Respiratory Failure – a life-threatening condition where the lungs fail to exchange gases effectively, leading to inadequate oxygen levels or carbon dioxide elimination in the blood.

Respiratory Management – the coordinated medical interventions and therapies aimed at maintaining or restoring optimal lung function, gas exchange, and breathing in patients with respiratory issues.

Respiratory Rate – the number of breaths that are taken per minute.

Respiratory System – a complex set of organs responsible for inhaling oxygen and exhaling carbon dioxide, facilitating gas exchange to sustain life.

Respiratory System Laws – scientific principles that govern the mechanics of breathing and gas exchange in the lungs.

Respiratory Zone – the region of the lungs where actual gas exchange occurs between the air and the bloodstream.

Restrictive Lung Diseases – conditions that reduce lung volume and hinder the lungs’ ability to expand fully during inhalation.

Rhonchi – an abnormal breath sound that can be heard when air moves through the large airways when there is excess mucus or secretions.

Rhonchal Fremitus – coarse vibrations that can be felt by palpitating the chest wall during normal breathing.

Rigid Bronchoscopy – a procedure that involves the insertion of a rigid bronchoscope into the airways of the lungs for therapeutic purposes.


Safety Indexed Connector Systems – standardized connection systems for high and low-pressure gas delivery sources that are used to reduce the risk of administering the wrong gas to the wrong patient.

Sensitivity –  a ventilator setting that determines how much effort (negative pressure) the patient must generate in order to trigger on a breath from the machine.

Severe Epidemic Enterovirus Respiratory Syndrome (SEERS) – a hypothetical or fictional respiratory illness caused by a new strain of enterovirus, characterized by rapid transmission and severe respiratory symptoms, posing a significant global public health threat.

Shock – a medical condition characterized by a significant reduction in blood flow throughout the body, leading to decreased organ perfusion and cellular oxygen supply, often resulting in serious and potentially life-threatening consequences.

Shunt – a condition where blood passes from the right side to the left side of the heart without being oxygenated in the lungs.

Sickle Cell Anemia – a blood condition that causes erythrocytes to break down and lose their shape and oxygen-carrying capacity.

Silicosis – a chronic lung disease caused by inhaling silica dust, leading to inflammation, scarring, and impaired lung function.

Silverman Score – a test that is used to determine an infant’s level of respiratory distress by assessing their chest movement, intercostal retractions, xiphoid retractions, nasal flaring, and expiratory grunting.

Simple Face Mask – a device that fits over the nose and mouth, used to deliver a controlled amount of oxygen to individuals who require supplemental oxygen.

Sinusitis – a condition characterized by inflammation of the mucus membranes that line the paranasal sinuses which results in nasal congestion and facial pain or pressure.

Sleep Apnea – a sleep disorder characterized by repeated interruptions in breathing for 10 seconds or longer.

Sleep Disorder – a medical condition characterized by disruptions in the normal sleep patterns, leading to adverse effects on health, well-being, and daytime functioning.

Sleep Physiology – the study of the processes and mechanisms underlying the different stages and cycles of sleep, examining how the body functions and maintains homeostasis during rest.

Sleep Study – a diagnostic test that monitors and records various parameters during sleep to diagnose and evaluate sleep disorders.

Small Particle Aerosol Generator (SPAG) – a large-volume jet nebulizer primarily used for the administration of ribavirin.

Smoking Cessation – the process of discontinuing tobacco use.

Sphygmomanometer – a device that is used to measure the blood pressure of an artery. It uses a cuff that wraps around the arm and a bulb to pump air into the cuff in order to constrict blood flow. As the air is released, the pressure reading is displayed on a manometer and can be heard using a stethoscope.

Spirometer – a diagnostic tool used in pulmonary function testing that measures the volume of air inhaled and exhaled by the lungs.

Spirometry – a diagnostic test that measures the volume and speed of air a person can inhale and exhale, helping to assess lung function.

Spontaneous Breathing Trial (SBT) – a technique used on patients who are receiving mechanical ventilatory support in order to test their readiness for weaning.

Sputum – the mucus and saliva mixture coughed up from the respiratory tract, often used to diagnose and monitor respiratory diseases.

Status Asthmaticus – a severe asthma attack that does not respond to bronchodilator therapy that lasts for more than 24 hours.

Sternal Rub – a medical technique used to assess a patient’s consciousness by applying pressure to the breastbone to elicit a response.

Sternum – a long, flat bone located in the center of the chest, connecting to the ribs via cartilage and forming the front part of the rib cage, providing protection to vital organs like the heart and lungs.

Stethoscope – a medical device for that is used during auscultation in order to listen to the sounds of the body.

Stridor – a high-pitched adventitious lung sound that is heard when an upper airway obstruction is present.

Stroke – a condition that occurs when there is a lack of blood supply to the brain.

Stroke Volume – the volume of blood that is pumped out of the left ventricle during each cardiac contraction.

Subcutaneous Emphysema – a medical condition characterized by the presence of air or gas in the subcutaneous tissue, often resulting from trauma, lung disease, or medical procedures.

Supplemental Oxygen – oxygen delivered for therapeutic purposes that exceeds a concentration of 21%.

Surfactant – a substance that forms a layer over the surface of alveoli in the lungs to reduce surface tension and prevent alveolar collapse.

Surfactant Replacement Therapy – a treatment modality that is often used in preterm infants with surfactant deficiency that involves the deliverance of exogenous surfactant in order to improve alveolar expansion.

Swan-Ganz Catheter – a thin tube that is inserted and positioned in the pulmonary artery to monitor and measure the blood pressure of cardiac and pulmonary circulation.

Synchronous Intermittent Mandatory Ventilation (SIMV) – a mode of ventilatory support in which the ventilator delivers a preset number of mandatory breaths but allows the patient to initiate spontaneous breaths in between the mandatory breaths.


Tachycardia – an abnormally increased heart rate of greater than 100 beats per minute.

Tachypnea – an abnormal breathing pattern characterized by a respiratory rate that is greater than 20 breaths per minute.

Tension Pneumothorax – a severe condition that occurs when air leaks into the pleural space and results in a collapsed lung.

Tetanus – a neuromuscular disorder that stems from a bacterial infection that affects the nerves, causes muscle spasms, and can be life-threatening.

Theophylline – a methylxanthine medication that serves as a bronchodilator in patients with asthma and COPD.

Thoracentesis – a procedure that involves the insertion of a large needle into the pleural space to remove fluid or air for therapeutic or diagnostic purposes.

Thoracic Imaging – a specialized branch of diagnostic radiology focused on visualizing and diagnosing diseases of the chest, including the heart, lungs, and surrounding structures.

Thorax – the structure that encloses the thoracic cavity, which consists of the ribs, sternum, and vertebral column.

Thorpe Tube – a flow meter device that is attached to a 50-psig gas source that facilitates accurate flow adjustments calibrated in liters per minute.

Tidal Volume – the volume of air that is inhaled and exhaled from during normal breathing.

TMC Exam – a standardized test that evaluates the knowledge and competencies of respiratory therapy students, covering a broad range of topics essential for safe and effective patient care and serving as a qualifying exam for credentialing as a respiratory therapist.

Total Lung Capacity (TLC) – the volume of air that is inhaled and exhaled in addition to the volume remaining in the lungs after maximum expiration.

Trachea – a rigid tube-like structure in the human respiratory system that transports air from the throat to the lungs and vice versa, facilitating the exchange of oxygen and carbon dioxide.

Tracheal Disorder – any medical condition that affects the trachea, potentially impacting air flow and respiratory function.

Tracheostomy – a surgical opening in the neck and trachea that provides access for the insertion of an artificial airway.

Tracheostomy Tube – an artificial airway that is surgically placed directly into the trachea through an opening in the throat as a means to establish a connection for breathing or mechanical ventilatory support.

Transtracheal Catheter – a flexible tube that is inserted into the trachea through the neck to deliver supplemental oxygen directly to the lungs.

Trigger – a term that refers to how much effort (negative pressure) a patient must generate in order to initiate a breath during mechanical ventilation.

Tuberculosis – a contagious bacterial infection, primarily affecting the lungs, caused by Mycobacterium tuberculosis.

Turbulent Flow – a type of fluid flow characterized by irregular movements and chaotic changes in pressure and velocity, as opposed to the smooth and regular patterns of laminar flow.


Ultrasonic Nebulizer – a type of nebulizer that uses an electrical signal and high-frequency vibrations to break a drug solution into aerosol particles for inhalation.

Ultrasound – an imaging test that uses high-frequency sound waves to create a visual of the organs and structures of the body for assessment.

Upper Airway Stimulation – a technique for treating obstructive sleep apnea that involves the implantation of a device that can monitor breathing patterns and provide stimulation to maintain an open airway.

Upper Respiratory Infection – an illness caused by an acute infection that primarily affects the nose, throat, sinuses, or larynx.


Vagus Nerve – a cranial nerve in the brain that is part of the autonomic nervous system which controls involuntary bodily functions.

Vallecula – an anatomic depression behind the base of the tongue that serves as an important landmark during intubation.

Ventilation – the movement of air in and out of the lungs, facilitating the exchange of oxygen and carbon dioxide.

Ventilation-Perfusion (V/Q) Ratio – a ratio of the relationship between the amount of air reaching the alveoli (ventilation) and the amount of blood flowing through the capillaries of the lungs (perfusion).

Ventilator Alarms – a safety mechanism on a mechanical ventilator that uses set parameters to provide alerts whenever there is a potential problem related to the patient-ventilator interaction.

Ventilator-Associated Pneumonia (VAP) – a lung infection that develops 48 hours or more after a patient has been intubated and placed on the ventilator.

Ventilator-Induced Lung Injury (VILI) – an acute lung injury that occurs while a patient is receiving mechanical ventilatory support.

Ventilator Management – the process of adjusting and overseeing mechanical ventilation to support or replace a patient’s respiratory function.

Ventilator Mode – a way of describing how a mechanical ventilator assists a patient with inspiration. The characteristics of a particular mode essentially control how the ventilator functions.

Ventilator Settings – the controls on a mechanical ventilator that can be set or adjusted in order to determine the amount of support that is delivered to the patient.

Ventilator Weaning – the gradual reduction and eventual removal of mechanical ventilation support as a patient’s respiratory function improves, transitioning them toward independent breathing.

Ventricular Fibrillation – a life-threatening cardiac arrhythmia that results in a rapid heart rate due to erratic quivering of the muscles of the ventricles.

Ventricular Tachycardia – a cardiac arrhythmia that results in an abnormally fast heart rate due to improper electrical activity in the ventricles.

Vesicular Breath Sounds – a term that refers to the normal breath sounds that you would expect to hear as air flows through an open airway.

Vital Capacity (VC) – the volume of air that can be exhaled after a maximum inhalation.

Volume-Controlled Ventilation – a mode of mechanical ventilation in which a specific tidal volume can be set and delivered.

Volume Support – a mode of mechanical ventilation in which the ventilator delivers a supported breath to help the patient reach a set tidal volume. This mode is commonly used to wean patients from anesthesia.

V/Q Scan – an imaging test that uses a radiographic substance to assess the ventilation and perfusion of the lungs. It’s typically indicated to check for a pulmonary embolism.


Water Vapor Pressure – the pressure at which water is in equilibrium with its gaseous state.

Wet Drowning – a type of drowning that occurs due to the inhalation of a large amount of water into the lungs.

Wheezing – a high-pitched whistling sound made while breathing, typically caused by narrowed or obstructed airways.

Whispered Pectoriloquy – a diagnostic examination method where a patient whispers a phrase while a healthcare provider auscultates their chest with a stethoscope, listening for changes in clarity and volume.

Winter Cough – a persistent cough that occurs during the colder months, often caused by viral infections, dry air, or indoor allergens.

Winters’ Formula – an equation used to calculate a patient’s expected PaCO2 and evaluate respiratory compensation in response to metabolic acidosis.

World Lung Day – a global initiative that occurs annually on September 25th aimed at raising awareness about lung health and advocating for research and policies to prevent and treat lung diseases.

Work Of Breathing (WOB) – the energy and force that is required in order to inhale a volume of gas into the lungs.


Xiphoid Process – the section of the lower end of the sternum that sits just above the diaphragm.

Xopenex – an inhaled short-acting Beta-2 agonist bronchodilator that is administered to provide relief for acute reversible airflow obstructions as seen in patients with asthma or COPD.


Yankauer – an oral catheter made of hard plastic with an angled head that is designed for suctioning the mouth and throat.

Y-connector – an adapter in the circuit of a mechanical ventilator that connects the inspiratory and expiratory limbs together


Zafirlukast – an orally administered antileukotriene agent that is used for the treatment of chronic asthma and is effective in inhibiting episodes that are caused by certain triggers.

Zone Valve – a valve that controls the medical gas distribution of the central piping system to a specific zone of the hospital that typically contains an on/off switch for oxygen, air, and vacuum.


  • Egan’s Fundamentals of Respiratory Care. 12th ed., Mosby, 2020.
  • Clinical Application of Mechanical Ventilation. 4th ed., Cengage Learning, 2013.
  • Pilbeam’s Mechanical Ventilation: Physiological and Clinical Applications. 6th ed., Mosby, 2015.
  • Mosby’s Respiratory Care Equipment. 10th ed., Mosby, 2017.
  • Rau’s Respiratory Care Pharmacology. 10th ed., Mosby, 2019.
  • Wilkins’ Clinical Assessment in Respiratory Care. 8th ed., Mosby, 2017.
  • Cardiopulmonary Anatomy & Physiology: Essentials of Respiratory Care. 7th ed., Cengage Learning, 2019.
  • Clinical Manifestations and Assessment of Respiratory Disease. 8th ed., Mosby, 2019.
  • Ruppel’s Manual of Pulmonary Function Testing. 11th ed., Mosby, 2017.
  • Neonatal and Pediatric Respiratory Care. 5th ed., Saunders, 2018.