ICU nursing is the specialty practice of caring for patients with life-threatening conditions who require continuous monitoring, advanced technology, and complex pharmacologic management. ICU nurses manage invasive lines, ventilators, vasopressors, and sedation protocols while serving as the primary clinical eyes on patients who cannot advocate for themselves. Nurse-to-patient ratios are 1:1 or 1:2, compared to 1:4–6 on general medical floors. The cognitive and technical demands are substantially higher, and the margin for error is narrower.
This reference covers the core clinical foundations of critical care nursing: hemodynamic monitoring, ventilator management, vasopressors, sedation and analgesia, CRRT, and systematic ICU assessment frameworks. Use it alongside the ARDS nursing reference, sepsis nursing guide, AKI reference, and ABG interpretation guide.
What ICU nurses do – and how ICU nursing differs from floor nursing
ICU nurses manage unstable, critically ill patients who require moment-to-moment physiologic surveillance. Core responsibilities include: continuous hemodynamic monitoring via arterial lines and central venous catheters; managing mechanical ventilation and responding to alarms; titrating vasoactive infusions to MAP targets; monitoring sedation depth and performing daily sedation vacations; coordinating care with intensivists, respiratory therapy, pharmacy, and PT/OT; performing comprehensive head-to-toe assessments every 1–2 hours; preventing VAP, CLABSI, CAUTI, and pressure injuries; and implementing the ABCDEF bundle.
Floor nursing operates on a higher ratio (1:4–6), with patients who are physiologically more stable and require less frequent reassessment. The critical distinctions are:
| Feature | ICU nursing | Floor nursing |
|---|---|---|
| Nurse-to-patient ratio | 1:1 or 1:2 | 1:4–6 |
| Monitoring | Continuous invasive (arterial line, CVP) | Intermittent vital signs |
| Drips | Vasoactive, sedation, paralytic agents | Standard IV fluids, antibiotics |
| Ventilator management | Routine | Rarely (transport only) |
| Assessment frequency | Every 1–2 hours, full systems review | Every 4–8 hours |
| AACN certification | CCRN available | Not applicable |
ICU types. The major ICU subtypes reflect patient population rather than nursing skill set – the core competencies transfer across units:
- MICU (Medical ICU): sepsis, respiratory failure, overdose, ARDS, metabolic crises
- SICU (Surgical ICU): post-operative complications, trauma surgery, bowel perforation
- CVICU (Cardiovascular ICU): post-cardiac surgery, STEMI with cardiogenic shock, IABP/ECMO management
- NICU (Neonatal ICU): premature infants, congenital anomalies, neonatal respiratory failure
- NSICU (Neuroscience ICU): stroke, TBI, subarachnoid hemorrhage, status epilepticus
- Trauma ICU: polytrauma, hemorrhagic shock, crush injuries
AACN CCRN certification is the primary credential for adult critical care nurses. Eligibility requires 1,750 hours of direct critical care practice (875 of those within the preceding two years). The exam covers cardiovascular, pulmonary, neurology, renal, endocrine, and multisystem content. Sub-specialty credentials include CCRN-K (knowledge, non-bedside roles) and subspecialty exams for neonatal and pediatric critical care.
Hemodynamic monitoring
Hemodynamic monitoring measures the pressures and flows that drive oxygen delivery to tissues. In ICU patients, inadequate delivery causes end-organ dysfunction – the goal is to detect and correct hemodynamic deterioration before organ damage becomes irreversible.
Normal hemodynamic values
| Parameter | Abbreviation | Normal range | Clinical significance |
|---|---|---|---|
| Mean arterial pressure | MAP | 70–100 mmHg | Minimum 65 mmHg for organ perfusion; target 85–90 mmHg in neurogenic shock |
| Central venous pressure | CVP | 2–8 mmHg | Reflects right atrial pressure; low = hypovolemia; high = RV failure or fluid overload |
| Pulmonary artery pressure (systolic) | PAP-s | 15–30 mmHg | Elevated in pulmonary hypertension, PE, ARDS |
| Pulmonary artery pressure (diastolic) | PAP-d | 8–15 mmHg | Elevated = increased PVR or LV failure |
| Pulmonary artery occlusion pressure (wedge) | PAOP / PCWP | 6–12 mmHg | Estimates LV preload; >18 mmHg suggests cardiogenic pulmonary edema |
| Cardiac output | CO | 4–8 L/min | Total blood pumped per minute |
| Cardiac index | CI | 2.5–4.0 L/min/m² | CO corrected for body surface area; CI <2.2 = cardiogenic shock threshold |
| Systemic vascular resistance | SVR | 800–1,200 dyne·s/cm⁵ | Low in distributive shock (sepsis); high in cardiogenic/hypovolemic shock |
| Mixed venous O₂ saturation | SvO₂ | 60–75% | Reflects O₂ extraction; <60% = supply-demand mismatch; >80% = distributive shock or poor extraction |
Arterial lines
An arterial line (A-line) placed in the radial, femoral, or brachial artery provides continuous beat-to-beat blood pressure monitoring and arterial access for ABG sampling. The waveform displays systolic, diastolic, and mean pressures. Damping (flattened waveform) indicates air, clot, or kinked tubing – troubleshoot before treating the number. Zero the transducer at the phlebostatic axis (4th intercostal space, midaxillary line) at line insertion and with any position change. Monitor the distal limb for ischemia, check the dressing per protocol, and never infuse medications through an arterial line.
Central venous catheter and CVP
A central venous catheter (CVC) in the subclavian, internal jugular, or femoral vein allows CVP measurement, vasopressor infusion, and TPN delivery. CVP reflects right atrial filling pressure – it is a volume-responsiveness surrogate, though dynamic measures (pulse pressure variation, stroke volume variation) are now preferred in many protocols. Low CVP (<2 mmHg) with hypotension suggests hypovolemia; elevated CVP (>12 mmHg) combined with a low CI suggests RV failure or cardiac tamponade.
Pulmonary artery catheter (Swan-Ganz)
The pulmonary artery catheter (PAC) is a flow-directed catheter advanced from a central vein through the right heart into the pulmonary artery. It directly measures CVP, PAP, and PAOP (wedge pressure), and calculates CO via thermodilution – making it the reference standard for complex hemodynamic assessment. Use in ICU has declined with the rise of less-invasive echo-based monitoring, but the PAC remains essential in refractory cardiogenic shock, post-cardiac surgery, and pulmonary hypertension management. Nursing responsibilities: monitor continuous PAP waveform, prevent catheter migration into permanent wedge position (causes infarction), and prepare for balloon inflation for wedge readings.
Mechanical ventilation
Mechanical ventilation supports or replaces a patient’s breathing work when respiratory failure prevents adequate gas exchange. ICU nurses do not independently adjust ventilator settings, but they must understand modes, alarms, and protective strategies – they are the first clinicians to identify ventilator-patient dyssynchrony, deteriorating compliance, or accidental extubation.
Ventilator modes
| Mode | Full name | How it works | Primary use |
|---|---|---|---|
| AC/VC | Assist-control, volume-cycled | Delivers a set tidal volume with every breath (patient-triggered or machine-triggered at set rate) | Initial ventilation of most patients; guarantees minute ventilation |
| AC/PC | Assist-control, pressure-cycled | Delivers a set pressure; tidal volume varies with lung compliance | When volume delivery needs to vary with compliance changes (e.g., ARDS) |
| SIMV | Synchronized intermittent mandatory ventilation | Delivers mandatory breaths synchronized to patient effort; patient breathes spontaneously between them | Weaning; less common now – evidence shows AC may be faster for weaning |
| PSV | Pressure support ventilation | Augments patient's spontaneous breaths with a set pressure boost; patient controls rate, timing, and effort | Weaning; spontaneous breathing trials (SBTs) |
| CPAP | Continuous positive airway pressure | Provides constant positive pressure throughout breathing cycle; no mandatory breaths | Spontaneous breathing trials; sleep apnea management |
Key ventilator settings and lung-protective ventilation
Lung-protective ventilation (LPV) is the evidence-based standard for ARDS and is applied broadly in most mechanically ventilated ICU patients. The NHLBI ARDS Network trial (ARDSnet, 2000) demonstrated reduced mortality with lower tidal volumes – this is one of the most consequential ventilator trials in critical care history.
Core LPV parameters:
- Tidal volume (Vt): 6–8 mL/kg of ideal body weight (IBW). IBW, not actual body weight – this distinction is critical. For a 70 kg IBW patient, target Vt is 420–560 mL.
- Plateau pressure: Keep ≤30 cmH₂O (measures lung compliance; high plateau pressure = over-distension injury)
- Driving pressure: Plateau pressure minus PEEP; target <15 cmH₂O – emerging evidence suggests this is the strongest predictor of ARDS mortality
- PEEP (positive end-expiratory pressure): Maintains alveolar recruitment between breaths; typical range 5–10 cmH₂O; higher PEEP (10–20 cmH₂O) used in moderate-severe ARDS to reduce derecruitment
- FiO₂: Fraction of inspired oxygen; wean toward 0.40–0.60 to minimize oxygen toxicity; target SpO₂ 92–96% in most ARDS patients
- Respiratory rate: 12–20 breaths/min; may be higher in ARDS to maintain adequate minute ventilation at low tidal volumes
VAP bundle
Ventilator-associated pneumonia (VAP) develops in 9–27% of mechanically ventilated patients and carries substantial mortality. Bundle compliance reduces VAP incidence by 50–70%.
VAP prevention bundle (AACN):
- Head of bed elevation 30–45°
- Daily sedation interruption (spontaneous awakening trial)
- Daily spontaneous breathing trial assessment for extubation readiness
- Deep vein thrombosis prophylaxis
- Stress ulcer prophylaxis
- Oral care with chlorhexidine every 4 hours
- Subglottic suctioning (in intubated patients with specialized ETT)
Vasopressors and inotropes
Vasopressors restore blood pressure by increasing vascular resistance or cardiac output. ICU nurses titrate these agents continuously based on MAP targets – typically MAP ≥65 mmHg – and monitor for adverse effects. All vasoactive infusions require central venous access; peripheral administration carries extravasation risk and should be limited to emergencies with the most dilute concentration possible.
| Drug | Mechanism | Primary use | Key nursing considerations |
|---|---|---|---|
| Norepinephrine | α1 >> β1 agonist – increases SVR and MAP with moderate increase in CO | First-line vasopressor in septic shock (Surviving Sepsis Campaign); distributive shock | Monitor for peripheral vasoconstriction (cool/mottled extremities); central line strongly preferred; assess for extravasation if peripheral |
| Vasopressin | V1 receptor agonist – pure vasoconstriction; increases SVR without affecting heart rate or contractility | Add-on to norepinephrine in refractory septic shock; also used in vasodilatory shock post-cardiac surgery | Fixed dose 0.03–0.04 units/min (not titrated); monitor for mesenteric ischemia and hyponatremia with prolonged use |
| Epinephrine | Equal α1 and β agonist – increases HR, contractility, SVR, and CO | Anaphylactic shock (first-line); cardiogenic shock with bradycardia; cardiac arrest | High risk for tachyarrhythmias; monitor lactate (epinephrine causes lactic acidosis independent of perfusion) |
| Dopamine | Dose-dependent: low dose = dopaminergic (renal vasodilation); mid dose = β1 (inotropy/chronotropy); high dose = α1 (vasoconstriction) | Second-line vasopressor; some use in cardiogenic shock with bradycardia | Higher risk of arrhythmias versus norepinephrine in septic shock – avoid as first-line; monitor HR continuously |
| Dobutamine | β1 > β2 > α agonist – increases contractility and CO with modest decrease in SVR | Cardiogenic shock when cardiac output is critically low; acute decompensated heart failure with low CI | May cause hypotension if patient is vasodilated; monitor for tachyarrhythmias; CI threshold for use typically <2.2 L/min/m² |
| Milrinone | Phosphodiesterase-3 inhibitor – increases cAMP → increased CO and vasodilation | Cardiogenic shock; right ventricular failure; pulmonary hypertension; post-cardiac surgery low-output syndrome | Significantly lowers SVR – may worsen hypotension; renally cleared, so reduce dose in AKI; not appropriate if BP already low without another vasopressor running |
Titration principle: use the lowest effective dose. Higher doses increase adverse effect risk without necessarily improving perfusion. Once MAP targets are achieved and the patient is hemodynamically stable, wean vasopressors gradually – typically reducing by 20–30% increments, monitoring for recurrent hypotension.
Sedation, analgesia, and delirium management
Sedation and analgesia management has shifted fundamentally over the past decade. The 2018 SCCM PADIS (Pain, Agitation/Sedation, Delirium, Immobility, Sleep Disruption) guidelines – updated in 2025 – establish analgesia-first, light-sedation protocols as the standard of care. Deep sedation is associated with prolonged mechanical ventilation, delirium, muscle wasting, and higher mortality.
RASS scale (Richmond Agitation-Sedation Scale)
The RASS quantifies sedation depth on a –5 to +4 scale. Target for most ventilated patients is RASS –1 to 0 (lightly sedated, easily arousable):
| Score | Label | Description |
|---|---|---|
| +4 | Combative | Overtly combative, violent, danger to staff |
| +3 | Very agitated | Pulls tubes/lines, aggressive |
| +2 | Agitated | Frequent non-purposeful movement |
| +1 | Restless | Anxious, apprehensive, movements not aggressive |
| 0 | Alert and calm | – |
| –1 | Drowsy | Not fully alert; sustained eye opening >10 sec to voice |
| –2 | Light sedation | Brief eye opening to voice; no eye contact |
| –3 | Moderate sedation | Movement or eye opening to voice; no eye contact |
| –4 | Deep sedation | No response to voice; movement to physical stimulus |
| –5 | Unarousable | No response to voice or physical stimulus |
CAM-ICU delirium assessment
The Confusion Assessment Method for the ICU (CAM-ICU) screens for delirium in non-verbal patients. Delirium affects 60–80% of ICU patients on mechanical ventilation and is independently associated with longer ICU stays and higher 6-month mortality. CAM-ICU is positive (delirium present) when the patient has all of: (1) acute change or fluctuating mental status, AND (2) inattention, AND (3) either altered consciousness OR disorganized thinking.
Prevention strategies include early mobility (ABCDEF bundle), minimizing anticholinergic medications, maintaining sleep-wake cycles, reorientation, family presence, and hearing/vision aid availability.
Common ICU sedation and analgesic agents
| Agent | Class | Onset | Key advantages | Key disadvantages / nursing watch |
|---|---|---|---|---|
| Propofol | Sedative-hypnotic (GABA-A) | Rapid (30–60 sec) | Short-acting, titratable, anticonvulsant properties; easy sedation vacation | Propofol infusion syndrome (PIS) with doses >4 mg/kg/h or >48 hrs – monitor triglycerides, metabolic acidosis, CK; high lipid load (1.1 kcal/mL) |
| Dexmedetomidine | α2 agonist | Moderate (15 min) | Preserves respiratory drive; reduces delirium vs. benzodiazepines; patient can be aroused and follow commands | Bradycardia and hypotension; not for use when patient needs deep sedation (RASS –3 or below) |
| Midazolam | Benzodiazepine (GABA-A) | Moderate (2–5 min IV) | Useful for acute agitation; amnestic properties | Associated with increased delirium – PADIS guidelines recommend against routine use; accumulates in renal/hepatic failure; prolonged awakening |
| Fentanyl | Opioid (μ-receptor) | Rapid (1–2 min IV) | Preferred opioid in critical care – potent, titratable, minimal histamine release | Respiratory depression; ileus; chest wall rigidity at high bolus doses; use CPOT or NRS pain scale for assessment in non-verbal patients |
| Morphine | Opioid (μ-receptor) | Moderate (5 min IV) | Effective analgesia; useful when cost is a constraint | Active metabolite (morphine-6-glucuronide) accumulates in renal failure; histamine release → hypotension; avoid in AKI/CKD |
| Ketamine | NMDA antagonist | Rapid (1 min IV) | Bronchodilator properties; maintains hemodynamics; useful in asthma/bronchospasm, procedural sedation, multimodal analgesia | Dissociative emergence reactions; increased secretions; may increase ICP – avoid in TBI without careful monitoring |
Sedation vacation (daily spontaneous awakening trial, SAT): Every morning, sedation infusions are interrupted while the patient is monitored for awakening. The SAT is paired with a spontaneous breathing trial (SBT) – the SAT-SBT combination reduces time on ventilator and ICU length of stay. Restart sedation at half the prior dose if the patient shows distress, agitation, or hemodynamic instability during the SAT.
The ABCDEF bundle
The ABCDEF (ICU Liberation) bundle from the Society of Critical Care Medicine translates PADIS guidelines into six bedside-actionable elements. Studies of over 25,000 ICU patients show that higher bundle compliance reduces hospital mortality, shortens mechanical ventilation duration, decreases delirium and coma days, and cuts ICU readmissions in half.
| Element | Component | Core action |
|---|---|---|
| A | Assess, prevent, and manage pain | Use validated scale (CPOT, NRS); treat pain before sedation – analgesia-first |
| B | Both SAT and SBT | Daily sedation interruption + spontaneous breathing trial; coordinate with respiratory therapy |
| C | Choice of analgesia and sedation | Target lightest effective sedation (RASS –1 to 0); prefer non-benzodiazepine sedation |
| D | Delirium: assess, prevent, manage | CAM-ICU every shift; minimize anticholinergics; reorientation; family presence |
| E | Early mobility and exercise | PT/OT consultation; passive ROM progressing to ambulation as early as hemodynamic stability allows |
| F | Family engagement and empowerment | Include family in rounds; liberal visitation; family as partners in reorientation and sleep |
CRRT: continuous renal replacement therapy
CRRT is used in ICU patients with acute kidney injury who cannot tolerate the rapid fluid and electrolyte shifts of conventional intermittent hemodialysis – typically due to hemodynamic instability. CRRT runs continuously at low flow rates (typically 25–35 mL/kg/h effluent dose), allowing gentle, slow solute clearance and fluid removal over 24 hours. See the AKI nursing reference for full KDIGO staging and AKI management.
When CRRT is used instead of intermittent hemodialysis:
- Hemodynamic instability (MAP <65 despite vasopressors – patient cannot tolerate rapid fluid shifts)
- Large fluid removal required (severe fluid overload in AKI Stage 3)
- Severe electrolyte and acid-base correction needed at controlled rate
- Acute liver failure with cerebral edema (CRRT controls ICP by avoiding osmotic shifts)
CRRT modalities:
- CVVH (continuous venovenous hemofiltration): solute removal by convection; replacement fluid given pre- or post-filter
- CVVHD (continuous venovenous hemodialysis): solute removal by diffusion; dialysate flows counter-current to blood
- CVVHDF (continuous venovenous hemodiafiltration): combines both; most commonly used modality
Nursing responsibilities during CRRT:
- Access monitoring: Assess the dialysis catheter (typically large-bore dual-lumen in femoral or internal jugular vein) for kinking, position, and signs of infection every shift
- Circuit pressure monitoring: Trend access pressure, return pressure, filter pressure, and transmembrane pressure (TMP). Rising TMP signals impending filter clotting – notify provider or initiate per protocol
- Anticoagulation: Regional citrate anticoagulation (RCA) is now preferred over systemic heparin in most centers. With citrate, monitor ionized calcium every 4–6 hours – calcium infusions run concurrently through a separate line. Systemic ionized calcium <1.0 mmol/L requires citrate rate adjustment
- Fluid balance: Calculate CRRT net fluid removal against the physician order every hour. Critically ill patients in CRRT are often in positive fluid balance – target net removal is explicitly ordered (e.g., –100 mL/hr)
- Electrolyte and acid-base monitoring: Draw BMP/electrolytes every 4–6 hours. CRRT removes potassium, phosphate, and bicarbonate – replacement is added to the dialysate or replacement fluid bags as ordered. Monitor for hypophosphatemia (common in CRRT), hypokalemia, hypomagnesemia
- Temperature: CRRT causes significant heat loss – use circuit warmer; monitor patient temperature every 2 hours; hypothermia masks fever in sepsis
- Drug dosing: Many medications are dialyzed out by CRRT – notify pharmacy of CRRT initiation so dosing adjustments can be made (antibiotics, anticoagulants, antiepileptics)
Systematic ICU assessment: FASTHUG-S and head-to-toe
ICU nurses perform a systematic head-to-toe assessment at least every 2 hours, with continuous surveillance between assessments. Two frameworks help ensure nothing is missed.
FASTHUG-S (daily ICU care checklist)
| Letter | Element | What to assess/ensure |
|---|---|---|
| F | Feeding | Is enteral nutrition running? Is NG/OG tube in correct position? Meeting caloric target? Hold ordered pre-procedure? |
| A | Analgesia | Pain scale score (CPOT or NRS); analgesia infusions at appropriate dose; PRN orders available |
| S | Sedation | RASS target documented and achieved; SAT due today? Sedation vacation documented |
| T | Thromboembolic prophylaxis | DVT prophylaxis ordered (pharmacologic or mechanical SCDs); contraindications documented |
| H | Head of bed | Elevated 30–45° for VAP prevention; exception documented if contraindicated |
| U | Ulcer prophylaxis | Stress ulcer prophylaxis ordered (PPI or H2 blocker) in high-risk mechanically ventilated patients |
| G | Glucose control | Blood glucose checked; insulin drip or sliding scale per protocol; ICU glucose target typically 140–180 mg/dL per NICE-SUGAR evidence |
| S | Spontaneous breathing trial | SBT readiness criteria checked; trial performed or documented rationale for deferral |
ICU head-to-toe assessment priorities
Neurological: RASS score, GCS, pupillary response (size, reactivity, equality), CAM-ICU, pain score, limb strength, cranial nerve deficits if applicable
Cardiovascular: Heart rate, rhythm (continuous telemetry), MAP, CVP if applicable, peripheral pulses, capillary refill, skin temperature and color, edema, vasoactive drip rates
Respiratory: RR, SpO₂, ETCO₂ (if monitored), ventilator settings and alarms, breath sounds bilaterally, ETT position and cuff pressure (target 20–30 cmH₂O), sputum character and amount, suction frequency
Renal/GU: Hourly urine output (≥0.5 mL/kg/h target), urine color and character, creatinine trend, fluid balance for past 24 hours, BUN, electrolytes
GI: Bowel sounds, abdominal distension, NG/OG tube position and residual volume, stool output, signs of GI bleeding, enteral feeding tolerance
Integumentary: Pressure injury risk (Braden scale), skin integrity at all bony prominences, IV and invasive line sites (redness, drainage, dressing integrity), ETT and tube-related pressure injuries
Lines and devices: Verify all lines – type, location, date of insertion, dressing integrity, patency, necessity (remove unnecessary lines to reduce CLABSI risk)
Electrolyte monitoring in the ICU
ICU patients are at high risk for electrolyte disturbances due to organ dysfunction, diuretics, enteral feeding, CRRT, and massive fluid shifts. For a comprehensive reference, see the electrolyte imbalances reference. The table below summarizes ICU-specific intervention thresholds.
| Electrolyte | Normal range | Critical low – act immediately | Critical high – act immediately | ICU-specific concern |
|---|---|---|---|---|
| Potassium (K⁺) | 3.5–5.0 mEq/L | <3.0 (arrhythmia risk) – replace IV | >6.0 – cardiac monitoring, kayexalate, insulin/dextrose, dialysis | Hypokalemia with diuretics/CRRT; hyperkalemia in AKI/rhabdomyolysis |
| Sodium (Na⁺) | 136–145 mEq/L | <125 with symptoms – controlled correction, 0.9% NaCl or hypertonic 3% | >155 – calculate free water deficit; correct slowly (≤8–10 mEq/L per 24 hr) | Overcorrection of hyponatremia → osmotic demyelination syndrome |
| Calcium (Ca²⁺ ionized) | 1.12–1.32 mmol/L | <0.8 – IV calcium gluconate; CRRT citrate accumulation | >1.5 – hydration, loop diuretics, calcitonin if severe | Hypocalcemia in CRRT (citrate); pancreatitis; massive transfusion |
| Magnesium (Mg²⁺) | 1.7–2.4 mg/dL | <1.2 – IV magnesium sulfate; risk of arrhythmia and seizure | >5.0 – respiratory depression; calcium gluconate as antidote | Hypomagnesemia with diuretics, aminoglycosides, CRRT |
| Phosphate (PO₄³⁻) | 2.5–4.5 mg/dL | <1.5 – IV sodium or potassium phosphate; respiratory muscle weakness | >5.0 in AKI – CRRT or dialysis | Hypophosphatemia: CRRT, refeeding syndrome, sepsis; causes ventilator dependence if severe |
| Glucose | 70–100 mg/dL (fasting) | <70 – D50W IV push; recheck in 15 min | >180 – insulin per protocol; target 140–180 in ICU (NICE-SUGAR) | Hyperglycemia worsens outcomes; tight control <110 increases hypoglycemia risk |
Common ICU conditions – quick reference
The site has dedicated reference pages for each of these conditions – this section provides the ICU-specific framing and links to the full content.
ARDS (acute respiratory distress syndrome): Hypoxemic respiratory failure from diffuse alveolar injury; Berlin definition (P/F ratio <300); lung-protective ventilation is the cornerstone of management; prone positioning for P/F <150; high PEEP strategy; avoid fluid overload.
Sepsis and septic shock: Sepsis-3 definitions (organ dysfunction from infection); septic shock = MAP <65 despite fluids requiring vasopressors, plus lactate >2 mmol/L; 1-hour bundle – blood cultures, lactate, broad-spectrum antibiotics, 30 mL/kg crystalloid if hypotensive/lactate ≥4; norepinephrine first-line vasopressor.
AKI and CRRT indication: KDIGO staging; CRRT initiated at Stage 3 with hemodynamic instability; see CRRT section above for nursing management.
TBI and ICP management: ICP target <20–22 mmHg; CPP target 60–70 mmHg (CPP = MAP – ICP); head of bed 30°; avoid hypoxia (SpO₂ <90%) and hypercarbia (PaCO₂ >45); osmotic therapy with mannitol or hypertonic saline; continuous ICP monitoring via external ventricular drain (EVD) or intraparenchymal monitor.
Post-cardiac surgery ICU: Hemodynamic monitoring via PA catheter or TEE; manage coagulopathy with FFP/platelets/cryoprecipitate; chest tube output monitoring (>200 mL/hr for 2+ hours = surgical re-exploration threshold); temporary pacing wire awareness; mediastinal shift recognition (hemodynamic collapse after cardiac surgery = rule out tamponade first).
Frequently asked questions
What does an ICU nurse do?
An ICU nurse provides continuous bedside care for critically ill patients who require monitoring that cannot be safely provided on a general medical floor. Core tasks include managing mechanical ventilators, titrating vasoactive infusions to hemodynamic targets, performing hourly assessments, maintaining invasive monitoring lines, administering sedation and analgesia protocols, preventing healthcare-associated infections (VAP, CLABSI, CAUTI), implementing the ABCDEF bundle, and communicating changes in patient condition to the medical team.
How is ICU nursing different from floor nursing?
The primary differences are patient acuity, nurse-to-patient ratio, monitoring intensity, and pharmacologic complexity. ICU nurses manage 1–2 patients with continuous invasive monitoring and complex vasoactive infusions. Floor nurses manage 4–6 patients with intermittent vital signs and standard IV medications. ICU patients have little physiologic reserve – deterioration can be rapid and irreversible – so the cognitive and surveillance demands are substantially higher.
What certifications do ICU nurses need?
CCRN (Critical Care Registered Nurse), awarded by the American Association of Critical-Care Nurses (AACN), is the standard credential for adult critical care nurses. It requires 1,750 hours of direct critical care practice with at least 875 hours in the preceding two years. Other relevant certifications: CCRN-K for advanced practice/non-bedside roles, CMC (Cardiac Medicine Certification), CSC (Cardiac Surgery Certification), and subspecialty credentials for neonatal and pediatric critical care.
What is the ABCDEF bundle?
The ABCDEF bundle is a structured, evidence-based care protocol from the Society of Critical Care Medicine that operationalizes the PADIS guidelines at the bedside. The six elements are: Assess/prevent/manage pain; Both SAT and SBT; Choice of analgesia and sedation; Delirium assessment/prevention/management; Early mobility and exercise; and Family engagement. Research in over 25,000 ICU patients demonstrates that higher bundle compliance reduces mortality, delirium days, and mechanical ventilation duration.
What is lung-protective ventilation?
Lung-protective ventilation (LPV) limits ventilator-induced lung injury by using low tidal volumes (6–8 mL/kg IBW), targeting plateau pressures ≤30 cmH₂O, and applying appropriate PEEP to maintain alveolar recruitment. The NHLBI ARDSnet trial established 6 mL/kg IBW tidal volumes as the standard in ARDS, reducing 28-day mortality from 39.8% to 31.0% versus 12 mL/kg conventional ventilation.
What is a Swan-Ganz catheter used for?
A Swan-Ganz (pulmonary artery) catheter provides direct measurement of CVP, pulmonary artery pressures, and pulmonary artery occlusion pressure (wedge pressure), along with thermodilution cardiac output. It allows differentiation of cardiogenic from non-cardiogenic pulmonary edema (PAOP >18 mmHg suggests cardiogenic etiology) and guides vasopressor and inotrope therapy in complex shock states. Its use has declined with advances in echocardiography, but it remains valuable in refractory shock and post-cardiac surgery patients.
Clinical content reviewed against AACN critical care nursing standards, SCCM PADIS guidelines (2018, updated 2025), NHLBI ARDSnet tidal volume protocol, Surviving Sepsis Campaign guidelines, and NIH/NCBI StatPearls vasopressor and inotrope reference (NBK482411). This reference is for educational purposes and does not substitute for institutional protocols or clinical judgment.