An ICU nurse (also called a critical care nurse) is a registered nurse who cares for the sickest patients in the hospital, people with life-threatening illnesses or injuries who need constant monitoring and advanced support. ICU nurses manage ventilators, titrate powerful IV drips like vasopressors and sedation, care for arterial and central lines, watch every number on the monitor and respond within seconds when a patient's condition changes. They usually care for just one or two patients at a time, and they are often the first to notice when something is wrong.
This guide covers what ICU nurses do, the types of ICUs, the ICU monitor and lines (arterial lines, central lines and Swan-Ganz catheters), vasopressors and mean arterial pressure, ventilators, sedation and the RASS scale, ICU delirium and the ABCDEF bundle, sepsis, ICU vs ER nursing, how to become an ICU nurse, CCRN certification, salary and Critical Care Nurses Day.
In this guide
- What is an ICU nurse?
- What does an ICU nurse do?
- Types of ICUs
- ICU nurse-to-patient ratio
- Arterial lines, central lines and Swan-Ganz catheters
- Vasopressors and mean arterial pressure (MAP)
- Ventilators and airway care
- Sedation, the RASS scale and ICU delirium
- Sepsis in the ICU
- ECMO, CRRT and other advanced therapies
- ICU nurse vs ER nurse
- How to become an ICU nurse
- CCRN certification
- How much do ICU nurses make?
- What is it like to be an ICU nurse?
- A short history of the ICU
- Critical Care Nurses Day and celebrating ICU nurses
- Gifts for ICU nurses
- ICU nurse humor
- Frequently asked questions
What is an ICU nurse?
ICU stands for intensive care unit, the hospital unit for patients who are critically ill or at high risk of becoming unstable. ICU patients may have severe infections and sepsis, respiratory failure, heart attacks or heart surgery, strokes and brain injuries, major trauma, organ failure or complications after surgery.
Critical care nursing is the specialty that cares for these patients. The terms "ICU nurse" and "critical care nurse" are usually used interchangeably, although critical care nurses can also work in step-down units, flight programs and rapid response teams.
What does an ICU nurse do?
- Continuous assessment: head-to-toe and neurologic checks, often every hour, plus constant monitoring of heart rhythm, blood pressure, oxygen and other values
- Titrating drips: adjusting vasopressors, sedation, insulin, heparin and other infusions based on the patient's response and protocols
- Ventilator care: working with respiratory therapists to manage mechanically ventilated patients and prevent complications
- Line and device care: arterial lines, central lines, chest tubes, drains, feeding tubes and specialized devices
- Lab interpretation: drawing and acting on arterial blood gases, electrolytes, lactate and more
- Emergencies: leading or assisting in codes, rapid responses and bedside procedures
- Preventing complications: infections, pressure injuries, blood clots, delirium and muscle weakness
- Family support: updating families, joining care conferences and supporting end-of-life decisions
Types of ICUs
| ICU type | Who it cares for |
|---|---|
| Medical ICU (MICU) | Patients with sepsis, respiratory failure, overdoses, organ failure and other medical illnesses |
| Surgical ICU (SICU) | Patients recovering from major surgery or with surgical complications |
| Cardiovascular ICU (CVICU) and CCU | Patients after open-heart surgery, heart attacks, heart failure and devices like balloon pumps (see our cardiac nurse guide) |
| Neuro ICU | Patients with strokes, brain bleeds, brain injuries and seizures |
| Trauma ICU | Patients with severe injuries (see our trauma nurse guide) |
| Burn ICU | Patients with major burns (see our burn unit nurse guide) |
| Pediatric ICU (PICU) | Critically ill infants, children and teens |
| Neonatal ICU (NICU) | Premature and critically ill newborns (see our NICU nurse guide) |
The MICU vs SICU question comes up a lot: MICU nurses care for patients whose critical illness is medical, while SICU nurses focus on surgical patients, so SICU work includes more wound, drain and post-operative care.
ICU nurse-to-patient ratio
ICU nurses usually care for one or two patients at a time. The most unstable patients, such as those on ECMO, just out of heart surgery or in active shock, often need one-to-one care. California is the only state with a law setting ICU ratios at a maximum of 1:2, while other states rely on hospital policies and staffing standards.
Arterial lines, central lines and Swan-Ganz catheters
| Line | What it is | Why ICU nurses use it |
|---|---|---|
| Arterial line (art line) | A thin catheter in an artery, usually in the wrist | Shows blood pressure beat by beat and allows frequent blood draws, including arterial blood gases |
| Central line (central venous catheter) | A catheter in a large vein in the neck, chest or groin, ending near the heart | Safely delivers vasopressors and other medications that can damage small veins, plus fluids, blood and nutrition |
| PICC line | A central line placed through a vein in the upper arm | Longer-term IV access |
| Pulmonary artery (Swan-Ganz) catheter | A specialized catheter threaded through the heart into the pulmonary artery | Measures pressures inside the heart and lungs and cardiac output to guide treatment of shock and heart failure |
Central line infections are dangerous, so ICU nurses follow strict central line bundles: hand hygiene, sterile dressing changes, scrubbing the hub before every access and asking every day whether the line is still needed.
Vasopressors and mean arterial pressure (MAP)
Vasopressors ("pressors") are powerful IV medications that tighten blood vessels and raise blood pressure in patients with shock. Common vasopressors include norepinephrine (often the first choice in septic shock), vasopressin, epinephrine, phenylephrine and dopamine. ICU nurses titrate them up and down, often every few minutes, to reach a blood pressure goal.
That goal is usually a mean arterial pressure (MAP), the average pressure pushing blood to the organs during one heartbeat:
Example: a blood pressure of 120/80 gives a MAP of about (120 + 160) ÷ 3 = 93 mmHg. A normal MAP is usually about 70 to 100 mmHg. In septic shock, guidelines generally target a MAP of at least 65 mmHg so the brain, kidneys and other organs get enough blood flow.
This guide is educational and simplified. Medication decisions follow provider orders, current guidelines and facility protocols.
Ventilators and airway care
Many ICU patients need a mechanical ventilator to breathe, usually through an endotracheal tube. ICU nurses work closely with respiratory therapists to monitor common ventilator settings:
- Mode: such as assist-control, SIMV or pressure support
- FiO2: the percentage of oxygen delivered
- PEEP: pressure that keeps the small air sacs open at the end of each breath
- Tidal volume: the size of each breath, often kept small to protect the lungs
- Respiratory rate: how many breaths the ventilator gives each minute
Nurses help prevent ventilator-associated pneumonia by keeping the head of the bed raised, providing frequent oral care and supporting daily breathing trials to get patients off the ventilator as soon as possible. For patients with severe ARDS, ICU teams may use prone positioning, carefully turning the patient onto their stomach for long periods to improve oxygen levels.
Sedation, the RASS scale and ICU delirium
Ventilated patients often need sedation and pain medication, but too much sedation can slow recovery. ICU nurses measure sedation with the Richmond Agitation-Sedation Scale (RASS):
| RASS score | Meaning |
|---|---|
| +4 | Combative |
| +3 | Very agitated |
| +2 | Agitated |
| +1 | Restless |
| 0 | Alert and calm |
| -1 | Drowsy, wakes to voice for more than 10 seconds |
| -2 | Light sedation, briefly wakes to voice |
| -3 | Moderate sedation, moves to voice but no eye contact |
| -4 | Deep sedation, responds only to physical stimulation |
| -5 | Unarousable |
Many ICUs aim for light sedation (around 0 to -2) when it is safe, and use daily sedation vacations (spontaneous awakening trials) to check whether a patient still needs sedation.
ICU delirium is a sudden state of confusion that affects many critically ill patients, especially those on ventilators. Nurses screen for it with tools like the CAM-ICU. To prevent it, ICU teams use the ABCDEF bundle:
- A: Assess, prevent and manage pain
- B: Both spontaneous awakening and spontaneous breathing trials
- C: Choice of analgesia and sedation
- D: Delirium: assess, prevent and manage
- E: Early mobility and exercise
- F: Family engagement and empowerment
Sepsis in the ICU
Sepsis is the body's extreme response to an infection, which can lead to organ failure and septic shock. It is one of the most common reasons patients are admitted to the ICU. Early treatment saves lives, so ICU nurses work quickly to:
- Measure lactate levels
- Draw blood cultures before antibiotics
- Give broad-spectrum antibiotics as ordered
- Give IV fluids for low blood pressure or high lactate
- Start vasopressors if blood pressure stays low, usually targeting a MAP of 65 or higher
ECMO, CRRT and other advanced therapies
- ECMO (extracorporeal membrane oxygenation): a machine that pumps blood outside the body to add oxygen and remove carbon dioxide, taking over for the lungs (VV ECMO) or the heart and lungs (VA ECMO) while they heal
- CRRT (continuous renal replacement therapy): slow, continuous dialysis for unstable patients with kidney failure (see our dialysis nurse guide)
- Intra-aortic balloon pumps and Impella devices: devices that support a failing heart
- Targeted temperature management: carefully controlling body temperature after cardiac arrest
- Intracranial pressure monitoring: watching pressure inside the skull in neuro ICU patients
ICU nurse vs ER nurse
| ICU nurse | ER nurse | |
|---|---|---|
| Patients | 1 to 2 critically ill patients | Several patients with every kind of emergency |
| Length of care | Days to weeks | Minutes to hours, then patients are admitted, transferred or discharged |
| Focus | Deep, continuous monitoring and titration | Rapid triage, assessment and stabilization |
| Key certification | CCRN | CEN |
Both specialties are a common path to flight nursing and CRNA school. Learn more in our ER nurse guide.
How to become an ICU nurse
- Earn a nursing degree (ADN or BSN) and pass the NCLEX-RN. Many ICUs prefer a BSN.
- Get acute care experience in med-surg or telemetry, or apply directly to a new graduate ICU residency program.
- Get BLS and ACLS certified, plus PALS for pediatric ICUs.
- Complete ICU orientation, which often lasts several months and includes critical care courses.
- Earn the CCRN once you have enough critical care hours.
- Consider advancing to charge nurse, flight nurse, acute care nurse practitioner or CRNA. Critical care experience is required for CRNA school (see our CRNA guide).
CCRN certification
The CCRN is the main critical care nursing certification, offered by the American Association of Critical-Care Nurses (AACN) for adult, pediatric and neonatal populations. To be eligible, nurses need a current RN or APRN license and one of two clinical practice options:
- Two-year option: at least 1,750 hours of direct care of acutely or critically ill patients in the past 2 years, with 875 of those hours in the most recent year
- Five-year option: at least 2,000 hours in the past 5 years, with 144 of those hours in the most recent year
Nurses must then pass the CCRN exam. Related AACN credentials include the CCRN-K for nurses who influence critical care without direct bedside care, the PCCN for progressive care and the CMC and CSC cardiac subspecialties. Check AACN for current requirements.
How much do ICU nurses make?
The U.S. Bureau of Labor Statistics does not publish a separate salary for ICU or critical care nurses, because it groups them with all registered nurses. The median annual wage for registered nurses was $97,550 in May 2025, and RNs working in hospitals, where nearly all ICUs are, earned a median of $100,220, according to the BLS.
ICU nurse pay depends on location, hospital, shift differentials, experience and certification. Many hospitals pay a differential for the CCRN, and ICU experience opens doors to some of the best paying roles in nursing, including travel ICU contracts, flight nursing and CRNA. See where critical care roles rank in our guide to the highest paying nursing jobs.
What is it like to be an ICU nurse?
- Detail-oriented: ICU nurses track dozens of numbers, drips and devices for every patient.
- Autonomy and teamwork: ICU nurses work closely with intensivists, respiratory therapists and pharmacists, and their judgment is highly trusted.
- High stakes: small changes can mean big problems, so ICU nurses learn to trust their gut.
- Emotional weight: ICU nurses support families through some of the hardest moments of their lives, including end-of-life care.
- Incredible saves: watching a patient come off the ventilator and walk out of the unit is unforgettable.
- Lifelong learning: new devices, drugs and evidence keep critical care nursing constantly changing.
A short history of the ICU
- 1850s: during the Crimean War, Florence Nightingale places the most seriously injured soldiers closest to the nurses' station so they can be watched more closely.
- 1923: neurosurgeon Walter Dandy creates a special three-bed unit for post-operative neurosurgery patients at Johns Hopkins Hospital.
- 1952 and 1953: during a polio epidemic in Copenhagen, patients are kept alive by hand ventilation, and anesthesiologist Bjørn Ibsen opens what is widely considered the first modern ICU.
- 1958: Dr. Peter Safar opens one of the first physician-staffed ICUs in the United States, in Baltimore.
- 1960s: coronary care units spread, and nurses take on heart monitoring and defibrillation.
- 1969: the American Association of Critical-Care Nurses is founded.
- 1976: the first CCRN certification exam is offered.
- 2020: the COVID-19 pandemic puts ICU nurses in the national spotlight.
Critical Care Nurses Day and celebrating ICU nurses
AACN recognizes Critical Care Nurses Day on February 14, and May is Critical Care Awareness and Recognition Month, which overlaps with National Nurses Week (May 6 to 12).
Ideas for celebrating ICU nurses
- Bring food for both day and night shift, since ICU nurses rarely leave the unit.
- Share thank-you notes and updates from former patients (with permission).
- Sponsor CCRN exam fees or review courses.
- Provide debriefing time and wellness support after hard shifts.
- Recognize the respiratory therapists, pharmacists and techs on the ICU team.
Looking for more ideas? See our guide to the best gifts for ICU nurses.
Gifts for ICU nurses
A throwback design for critical care nurses who wear their specialty with pride. $29.99
Shop now →
For the coffee that gets reheated three times between titrations. $15.99
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Because every ICU nurse knows “stable” always has a few asterisks. Great for report notes and CCRN studying. $17.99
Shop now →Browse the full ICU nurse collection for shirts, notebooks and stickers.
ICU nurse humor
- "Sickest patients, steadiest hands." (Now a sticker.)
- "Powered by caffeine and cardiac rhythms." (Also a sticker.)
- "Stable comes with footnotes."
- "I titrate drips, not my opinions."
- "My patient has more lines than a subway map."
- "Never say the Q word in the ICU."
Frequently asked questions
What does an ICU nurse do?
ICU nurses care for critically ill patients. They monitor patients continuously, manage ventilators, titrate vasopressors and sedation, care for arterial and central lines, respond to emergencies, prevent complications and support families.
How much do ICU nurses make?
BLS does not report ICU nurse pay separately. Registered nurses overall earned a median of $97,550 in May 2025, and RNs in hospitals earned a median of $100,220. ICU pay varies by location, experience, shift and certification.
What is the CCRN certification?
The CCRN is a critical care nursing certification from the American Association of Critical-Care Nurses (AACN) for adult, pediatric or neonatal nurses. It requires an RN license and either 1,750 hours of direct critical care in the past 2 years or 2,000 hours in the past 5 years, plus passing an exam.
What is the ICU nurse-to-patient ratio?
ICU nurses usually care for 1 or 2 patients at a time. Very unstable patients, such as those on ECMO or just out of heart surgery, may need one-to-one care. California is the only state that sets a legal ICU ratio of 1:2.
What is a normal mean arterial pressure (MAP)?
A normal MAP is usually about 70 to 100 mmHg. In septic shock, guidelines generally target a MAP of at least 65 mmHg. MAP can be estimated as (systolic + 2 x diastolic) / 3.
Can new grads work in the ICU?
Yes. Many hospitals hire new graduate nurses into ICU residency programs with long orientations, though spots are competitive. Others prefer a year or more of med-surg or step-down experience first.
What is the difference between an ICU nurse and an ER nurse?
ER nurses rapidly assess and stabilize patients with every kind of emergency, then move them on. ICU nurses care for the sickest patients for days or weeks, with 1 or 2 patients and deeper monitoring of drips, ventilators and lines.
When is Critical Care Nurses Day?
AACN recognizes Critical Care Nurses Day on February 14 each year, and May is Critical Care Awareness and Recognition Month.
Exploring other specialties? See our full guide to nurse specialties and the types of nurses.
Celebrate the ICU nurses in your life
For Critical Care Nurses Day, a new CCRN or the nurse who never left your loved one's bedside.
Shop the ICU Collection →Sources
- U.S. Bureau of Labor Statistics, Occupational Outlook Handbook: Registered Nurses
- American Association of Critical-Care Nurses (AACN), CCRN Exam Handbook
- Society of Critical Care Medicine, Surviving Sepsis Campaign Guidelines and ICU Liberation (ABCDEF) Bundle
- Sessler CN et al. The Richmond Agitation-Sedation Scale. American Journal of Respiratory and Critical Care Medicine, 2002.
- California Code of Regulations, Title 22, Nurse-to-Patient Ratios