Intensive Care Terminology

Use this glossary to explain common terms patients, families, and healthcare professionals may hear when discussing intensive care, critical illness, monitoring, respiratory support, circulation, nutrition, organ support, treatment decisions, and recovery after an ICU stay.

Intensive care, also called critical care, is medical care for people with life-threatening illness or injury. Care is provided by a specially trained multidisciplinary team and includes continuous monitoring, specialized treatments, and support for vital organ functions. Intensive care may be provided in adult, pediatric, neonatal, cardiac, neurological, trauma, or other specialized units.

Core concepts and care providers

Intensive care: Specialized medical care for people with life-threatening illness or injury who need continuous monitoring and advanced treatment.
Critical care: Another term for intensive care and the multidisciplinary specialty that cares for critically ill or injured patients.
Intensive care unit (ICU): A specialized hospital unit with trained staff, monitoring equipment, and treatments for patients who need intensive care.
Critical care unit (CCU): A term that may refer to an intensive care unit or another unit providing high-level monitoring and organ support, depending on the healthcare system.
Intensive therapy unit (ITU): A term used in some countries for an intensive care unit.
High-dependency unit (HDU): A unit that provides a level of monitoring and treatment between a general hospital unit and an ICU.
Step-down unit: A unit for patients who no longer need the full level of ICU care but still require closer monitoring than a general hospital unit provides.
Adult ICU: An intensive care unit for adult patients.
Pediatric intensive care unit (PICU): An intensive care unit for infants, children, and adolescents who need critical care.
Neonatal intensive care unit (NICU): An intensive care unit for newborns who need specialized monitoring or treatment.
Cardiac intensive care unit (CICU): An intensive care unit specializing in patients with serious heart or cardiovascular conditions.
Neuro-intensive care unit: An intensive care unit specializing in serious neurological conditions, brain injury, stroke, or disorders affecting the nervous system.
Intensivist: A physician whose practice focuses on the care of critically ill patients.
Critical care nurse: A nurse with specialized training in caring for patients who need intensive monitoring and treatment.
Respiratory therapist: A healthcare professional who evaluates and treats breathing problems and supports respiratory equipment and therapies.
Critical care pharmacist: A pharmacist who helps select, dose, monitor, and manage medicines for critically ill patients.
Critical care dietitian: A dietitian who assesses nutritional needs and supports nutrition therapy during critical illness.
Physiotherapist: A healthcare professional who supports breathing treatments, movement, strength, mobility, and rehabilitation.
Occupational therapist: A healthcare professional who supports function, communication, daily activities, and recovery after serious illness or injury.
Social worker: A professional who helps patients and families with communication, practical needs, emotional support, care planning, and transitions.
Critical care team: The multidisciplinary group of healthcare professionals involved in assessing, treating, monitoring, and supporting a critically ill patient.
Family-centered care: Care that includes a patient’s family or chosen support people in communication and decision-making when the patient wishes.
Multidisciplinary care: Care provided through collaboration among professionals from different healthcare disciplines.
Level of care: The degree of monitoring, treatment, and organ support a patient needs in a healthcare setting.
Admission: The process of bringing a patient into an ICU or other critical care unit for assessment and treatment.
Transfer: Moving a patient between units, hospitals, or care settings while maintaining appropriate monitoring and treatment.

Monitoring and assessment

Vital signs: Measurements such as heart rate, blood pressure, breathing rate, temperature, and oxygen saturation that help show how the body is functioning.
Continuous monitoring: Ongoing measurement and display of physiological information, often using sensors, electrodes, catheters, and bedside monitors.
Bedside monitor: An electronic device that displays and records measurements such as heart rhythm, blood pressure, breathing rate, and oxygen saturation.
Telemetry: Remote or continuous monitoring of heart rhythm or other physiological measurements.
Heart rate: The number of times the heart beats in a defined period.
Blood pressure: The force of blood against the walls of the arteries.
Mean arterial pressure (MAP): An estimate of the average pressure in the arteries during one cardiac cycle.
Oxygen saturation: The percentage of hemoglobin carrying oxygen in the blood, commonly measured with a pulse oximeter.
Pulse oximeter: A noninvasive sensor that estimates blood oxygen saturation and pulse rate, often placed on a finger, toe, ear, or other site.
Respiratory rate: The number of breaths taken in a defined period.
Temperature monitoring: Measurement of body temperature to identify fever, low body temperature, or changes that may require attention.
Electrocardiogram (ECG or EKG): A test that records the electrical activity and rhythm of the heart.
Arterial blood gas (ABG): A blood test that measures oxygen, carbon dioxide, acidity, and other information about respiratory and metabolic function.
Blood gas: A blood measurement used to assess oxygenation, ventilation, and acid-base balance.
Capnography: Continuous measurement and display of carbon dioxide in exhaled air, often used to assess ventilation.
Hemodynamic monitoring: Measurement of blood flow, blood pressure, heart function, and circulation.
Arterial line: A catheter placed in an artery to measure blood pressure continuously and collect blood samples.
Central venous pressure (CVP): A pressure measurement that may help assess blood volume, venous return, and right-sided heart function in selected patients.
Glasgow Coma Scale (GCS): A standardized scale used to assess levels of consciousness based on eye opening, verbal response, and motor response.
Neurological assessment: Evaluation of consciousness, pupils, movement, sensation, speech, and other signs of nervous system function.
Pain assessment: A structured evaluation of pain intensity, location, quality, and effect on function or comfort.
Sedation assessment: Evaluation of how awake, calm, or responsive a patient is after receiving sedating medication.
Delirium assessment: Evaluation for sudden changes in attention, awareness, thinking, or behavior.
Fluid balance: The comparison between fluid taken into the body and fluid removed from the body over a defined period.
Urine output: The amount of urine produced over a defined period, often monitored as an indicator of kidney function and fluid balance.
Laboratory monitoring: Repeated blood, urine, or other tests used to assess organ function, infection, blood counts, electrolytes, and response to treatment.

Breathing and respiratory support

Respiratory failure: A condition in which the lungs cannot provide enough oxygen, remove enough carbon dioxide, or perform both functions adequately.
Oxygen therapy: Treatment that provides additional oxygen through a device such as a nasal cannula, mask, or ventilator.
Nasal cannula: A device with small prongs placed in the nostrils to deliver supplemental oxygen.
High-flow nasal cannula (HFNC): A device that delivers warmed, humidified oxygen and air at a high flow rate through nasal prongs.
Face mask: A device placed over the nose and mouth to deliver oxygen or support breathing.
Noninvasive ventilation (NIV): Breathing support delivered through a mask or similar interface without placing a breathing tube into the windpipe.
Continuous positive airway pressure (CPAP): Noninvasive breathing support that provides continuous pressure to help keep the airways and lungs open.
Bilevel positive airway pressure (BiPAP): Noninvasive breathing support that provides different pressure levels during inhalation and exhalation.
Mechanical ventilation: Use of a machine to assist or replace a patient’s breathing.
Ventilator: A machine that moves air and oxygen into the lungs and helps remove carbon dioxide.
Invasive ventilation: Mechanical ventilation delivered through an endotracheal tube or tracheostomy tube.
Endotracheal tube (ET tube): A breathing tube placed through the mouth or nose into the trachea to support ventilation and protect the airway.
Intubation: The procedure of placing an endotracheal tube into the trachea.
Extubation: Removal of an endotracheal tube when the patient can safely breathe and protect the airway without it.
Tracheostomy: A surgically created opening in the neck that leads to the trachea and may hold a breathing tube.
Tracheostomy tube: A tube placed through a tracheostomy to support breathing, airway access, or secretion management.
Airway: The passages that carry air from the nose and mouth to the lungs.
Airway protection: The ability to keep materials such as saliva, food, or stomach contents from entering the lungs.
Aspiration: Entry of food, fluid, saliva, stomach contents, or another substance into the airway or lungs.
Suction: Removal of mucus, secretions, blood, or other material from the airway or a tube using a suction device.
Fraction of inspired oxygen (FiO2): The concentration of oxygen in the air or gas delivered to a patient.
Positive end-expiratory pressure (PEEP): Pressure maintained in the lungs at the end of exhalation to help keep air sacs open.
Tidal volume: The amount of air moved into or out of the lungs with each ventilator breath or spontaneous breath.
Ventilator mode: The method a ventilator uses to deliver breaths and respond to a patient’s breathing effort.
Spontaneous breathing trial: A monitored period during which a patient breathes with reduced ventilator support to assess readiness for extubation.
Weaning: The gradual reduction of mechanical ventilation or other respiratory support as a patient’s breathing improves.
Respiratory physiotherapy: Techniques used to support breathing, mobilize secretions, improve lung expansion, and assist recovery.
Prone positioning: Placing a patient on their abdomen to improve oxygenation in selected patients with serious respiratory failure.
Acute respiratory distress syndrome (ARDS): A serious form of lung injury that causes severe difficulty exchanging oxygen and may require advanced respiratory support.
Ventilator-associated pneumonia (VAP): Pneumonia that develops in a patient who has received mechanical ventilation through an endotracheal tube.

Circulation, vascular access, and organ support

Intravenous (IV) access: A route into a vein used to give fluids, medicines, blood products, or nutrition.
Peripheral IV: A short catheter placed in a peripheral vein, commonly in the hand or arm.
Central venous catheter: A catheter placed in a large vein to give medicines or fluids, measure selected pressures, or provide other treatments.
Central line: Another term for a central venous catheter.
Peripherally inserted central catheter (PICC): A catheter inserted through a peripheral vein and advanced until its tip is near the heart.
Intraosseous (IO) access: A route for giving fluids or medicines through the bone marrow when IV access cannot be obtained quickly.
Infusion pump: A device that delivers fluids or medicines at a controlled rate.
Syringe pump: A device that delivers a medication or fluid from a syringe at a controlled rate.
Vasopressor: A medicine that constricts blood vessels and raises blood pressure when circulation is inadequate.
Inotrope: A medicine that changes the strength of the heart’s contraction.
Fluid resuscitation: Administration of fluids to support circulation and organ perfusion when a patient has lost fluid or has inadequate circulating volume.
Blood transfusion: Administration of donated blood or a blood component, such as red blood cells, platelets, or plasma.
Shock: A life-threatening condition in which the circulatory system cannot provide enough blood flow and oxygen to the body’s tissues.
Septic shock: Shock associated with infection and severe circulatory or cellular dysfunction.
Cardiogenic shock: Shock caused by the heart’s inability to pump enough blood to meet the body’s needs.
Hypovolemic shock: Shock caused by an inadequate volume of circulating blood or fluid, such as after major bleeding or fluid loss.
Obstructive shock: Shock caused by a physical blockage that prevents adequate blood flow through the heart or major vessels.
Anaphylactic shock: A severe allergic reaction that can cause airway narrowing, low blood pressure, and other life-threatening effects.
Cardiac arrest: A sudden loss of effective heart activity that stops the heart from pumping blood normally.
Cardiopulmonary resuscitation (CPR): Emergency chest compressions and other interventions used when a person is in cardiac arrest.
Return of spontaneous circulation (ROSC): The return of a sustained heartbeat and circulation after cardiac arrest and resuscitation.
Extracorporeal membrane oxygenation (ECMO): A form of life support that circulates blood through a machine that adds oxygen and removes carbon dioxide before returning the blood to the body.
Renal replacement therapy: Treatment that takes over some functions of the kidneys, including removal of waste and excess fluid.
Dialysis: A treatment that removes waste products and excess fluid from the blood when the kidneys cannot do so adequately.
Continuous renal replacement therapy (CRRT): A slow, continuous form of renal replacement therapy often used for critically ill patients who may not tolerate intermittent dialysis.
Hemofiltration: A process that removes fluid and dissolved substances from blood through a filter and may be used as part of renal replacement therapy.
Urinary catheter: A flexible tube placed in the bladder to drain urine and monitor urine output.
Chest tube: A tube placed in the chest to remove air, blood, or fluid from around the lung or heart.
Drain: A tube or device used to remove fluid, blood, air, or secretions from a body area.
Organ support: Treatment or technology that temporarily supports the function of an organ, such as the lungs, heart, or kidneys.
Multiorgan dysfunction syndrome (MODS): A condition in which two or more organ systems function abnormally during serious illness or injury.

Nutrition, comfort, and mobility

Enteral nutrition: Nutrition delivered through the gastrointestinal tract, usually through a feeding tube.
Parenteral nutrition: Nutrition delivered into the bloodstream when the gastrointestinal tract cannot be used adequately.
Feeding tube: A tube used to deliver nutrition, fluids, or medicines to the stomach or intestine.
Nasogastric tube (NG tube): A tube passed through the nose into the stomach.
Orogastric tube (OG tube): A tube passed through the mouth into the stomach.
Gastric decompression: Removal of air, fluid, or stomach contents through a tube to reduce pressure or vomiting.
Aspiration precautions: Measures used to reduce the chance of food, fluid, or secretions entering the lungs.
Analgesia: Treatment used to relieve pain.
Sedation: Medication used to reduce anxiety, distress, awareness, or discomfort and to help a patient tolerate certain treatments.
Delirium: A sudden change in attention, awareness, thinking, or behavior that may be associated with illness, medication, infection, sleep disruption, or the ICU environment.
Agitation: Restlessness, distress, or increased physical or verbal activity that may have many possible causes.
Restraint: A physical or medication-based intervention used under defined clinical and legal safeguards to prevent harm when less restrictive measures are not sufficient.
Neuromuscular blockade: Medication-induced temporary paralysis used in selected situations to support mechanical ventilation or other critical care treatments.
Pressure injury: Damage to the skin and underlying tissue caused by sustained pressure, friction, shear, or a combination of factors.
Deep vein thrombosis (DVT): A blood clot in a deep vein, often in the leg.
Venous thromboembolism (VTE): A condition that includes deep vein thrombosis and pulmonary embolism.
VTE prophylaxis: Measures used to reduce the risk of blood clots, such as medication, compression devices, or mobilization.
Early mobilization: Carefully planned movement or activity during critical illness when clinically appropriate.
Range-of-motion exercise: Movement of a joint through its available motion to help maintain flexibility and function.
ICU-acquired weakness: New muscle weakness that develops during or after critical illness and may affect mobility and recovery.
Fluid overload: Excess fluid in the body that may cause swelling or affect organ function.
Electrolyte imbalance: An abnormal level of minerals such as sodium, potassium, calcium, or magnesium in the body.
Sleep promotion: Care practices intended to support rest and normal sleep patterns during critical illness.

Common conditions and emergencies in intensive care

Critical illness: A serious illness or injury that may impair vital organ function and requires close monitoring or advanced treatment.
Infection: Invasion and multiplication of microorganisms in the body that may or may not cause illness.
Sepsis: A life-threatening response to infection that can cause organ dysfunction.
Severe infection: An infection that causes significant illness, organ dysfunction, or a need for advanced medical treatment.
Systemic inflammatory response syndrome (SIRS): A generalized inflammatory response that may be caused by infection or other conditions. Clinical definitions and use vary.
Acute kidney injury (AKI): A sudden decline in kidney function that can affect fluid balance, electrolytes, and waste removal.
Chronic kidney disease: Long-term loss of kidney function that may affect how the body manages fluid, electrolytes, and waste.
Respiratory infection: An infection involving the nose, throat, airways, or lungs.
Pneumonia: An infection or inflammation of the lungs that can interfere with oxygen exchange.
Chronic obstructive pulmonary disease (COPD): A group of long-term lung conditions that obstruct airflow and may worsen during a serious illness.
Heart failure: A condition in which the heart cannot pump or fill adequately to meet the body’s needs.
Myocardial infarction: Injury to heart muscle caused by inadequate blood flow, commonly called a heart attack.
Stroke: A sudden injury to the brain caused by interrupted blood flow or bleeding.
Traumatic brain injury (TBI): Brain injury caused by an external force, such as a fall, collision, or blow.
Coma: A state of profound unresponsiveness in which a person cannot be awakened and does not respond normally to the environment.
Seizure: A sudden episode of abnormal electrical activity in the brain that may cause changes in movement, sensation, behavior, or awareness.
Status epilepticus: A prolonged seizure or repeated seizures without adequate recovery between them that requires urgent treatment.
Acute liver failure: Rapid loss of liver function that may affect blood clotting, metabolism, brain function, and other systems.
Gastrointestinal bleeding: Bleeding in the digestive tract that may cause blood loss, anemia, or circulatory instability.
Pancreatitis: Inflammation of the pancreas that may range from mild illness to a serious condition requiring intensive care.
Burns: Tissue injuries caused by heat, chemicals, electricity, radiation, or other sources that may require specialized critical care.
Multiple trauma: Serious injuries involving more than one body region or organ system.
Cardiac arrest: A sudden loss of effective heart activity requiring immediate resuscitation.
Respiratory arrest: A failure of breathing that may lead rapidly to cardiac arrest without treatment.
Hospital-acquired infection: An infection that develops during healthcare and was not present or incubating when care began.
Multidrug-resistant organism (MDRO): A microorganism that is resistant to multiple medicines used to treat it.
Isolation precautions: Measures used to reduce the spread of infection to or from a patient.
Infection prevention: Practices such as hand hygiene, protective equipment, cleaning, and device-care protocols used to reduce infection risk.

Recovery, communication, and care decisions

Weaning: The gradual reduction of a treatment or form of organ support as the patient improves.
ICU discharge: Transfer from the ICU to another hospital unit or care setting when the patient no longer needs the ICU’s level of monitoring or support.
Step-down care: Ongoing care in a unit that provides more monitoring than a general hospital unit but less support than an ICU.
Hospital discharge: The process of leaving the hospital with a follow-up plan, medications, instructions, and arrangements for ongoing care.
Rehabilitation: Services that support recovery of strength, movement, communication, thinking, self-care, and participation after serious illness or injury.
Post-intensive care syndrome (PICS): New or worsening physical, cognitive, or emotional symptoms that may occur during or after critical illness and affect patients or family members.
ICU diary: A record kept during an ICU stay to help a patient understand what happened during a period they may not remember clearly.
Family meeting: A structured conversation among healthcare professionals, the patient when able, and family or chosen support people about condition, treatment, goals, and next steps.
Shared decision-making: A collaborative process in which healthcare professionals and the patient or decision-makers discuss options, evidence, values, and preferences.
Capacity: The ability to understand, consider, and communicate a specific healthcare decision.
Surrogate decision-maker: A person authorized to help make healthcare decisions when a patient cannot make or communicate those decisions.
Advance directive: A document that records a person’s preferences for future healthcare decisions if they become unable to communicate or decide.
Goals of care: The outcomes and priorities that guide treatment decisions, based on the patient’s values, condition, preferences, and likely benefits and burdens of treatment.
Code status: Documentation of the treatments to be attempted or not attempted if a patient’s heart or breathing stops.
Do not resuscitate (DNR) or do not attempt resuscitation (DNAR): A medical order stating that CPR should not be attempted if the patient experiences cardiac arrest. Terminology and policies vary by location.
Life-sustaining treatment: A treatment that supports or replaces a vital body function, such as mechanical ventilation, dialysis, or medications that support blood pressure.
Treatment limitation: A decision not to start, or to reduce or stop, a treatment when it no longer meets the patient’s goals or is unlikely to provide the intended benefit.
Palliative care: Specialized support focused on comfort, symptom relief, communication, and quality of life at any stage of serious illness. It may be provided alongside life-prolonging treatment.
End-of-life care: Care focused on comfort, dignity, communication, and support when a person is approaching the end of life.
Comfort-focused care: Care that prioritizes relief of pain, breathlessness, anxiety, and other distressing symptoms rather than burdensome treatments that do not match the patient’s goals.
Care transition: The movement from one healthcare setting, team, or level of care to another.
Care plan: A coordinated plan describing diagnoses, treatments, medicines, monitoring, goals, follow-up, and support needs.
Follow-up: Ongoing assessment, treatment, education, rehabilitation, or support after an ICU stay or critical illness.
Health equity: The goal of ensuring that all people have a fair opportunity to receive understandable, respectful, and appropriate critical care.
Language access: Interpretation, translation, or other communication support that helps patients and families understand information and participate in care decisions.
Culturally responsive care: Care that respects a patient’s culture, language, identity, values, communication preferences, and lived experience.

Intensive care terminology, unit names, clinical protocols, treatment options, and care-decision processes may vary by country, healthcare system, facility, clinical specialty, and individual circumstances. A member of the critical care team can explain which terms, treatments, and decisions apply to a particular patient or family.

Intensive Care Terminology

A glossary of common terms related to critical illness, intensive care units, monitoring, life support, organ support, recovery, and patient-centered care.