Critical Care Nursing Study Notes

Critical care nursing is one of the most technically demanding areas of nursing practice. ICU nurses manage patients who are hemodynamically unstable, mechanically ventilated, receiving multiple vasoactive infusions, and at constant risk of rapid deterioration. This guide covers the high-yield content for nurses working in or studying critical care — including the topics most commonly tested on NCLEX and critical care certification exams.

ICU Patient Assessment: The Systems Approach

In the ICU, assessment follows a head-to-toe systems approach, performed every 1–2 hours on unstable patients. Use a consistent sequence so nothing is missed:

• Neurological: Level of consciousness, GCS or FOUR score, RASS sedation level, pupil response, motor strength
• Cardiovascular: HR, rhythm, BP (arterial line vs cuff), MAP, peripheral pulses, capillary refill, edema, CVP trend
• Respiratory: RR, SpO2, breath sounds, work of breathing, ventilator settings and waveforms if intubated
• GI: Bowel sounds, abdomen distention, NG tube output, enteral feeding tolerance, last BM
• Renal: Hourly urine output (goal ≥0.5 mL/kg/hr), urine color, BUN/creatinine trend, fluid balance
• Skin/lines: All IV and invasive line sites, wound assessment, pressure injury risk, restraint checks

Critical ICU Assessment Scales

• GCS (Glasgow Coma Scale): Eye (1–4) + Verbal (1–5) + Motor (1–6) = 3–15. Score ≤8 = severe impairment, typically intubated
• RASS (Richmond Agitation-Sedation Scale): −5 (unarousable) to +4 (combative). Target for most ICU patients: −2 to 0
• CPOT (Critical Care Pain Observation Tool): Used when patient cannot self-report pain. Assesses facial expression, body movements, muscle tension, compliance with ventilator (0–8; ≥3 = significant pain)

Hemodynamic Monitoring

Hemodynamic monitoring provides real-time data on cardiac function and fluid status. ICU nurses interpret these values to guide vasopressor titration, fluid resuscitation, and medication decisions.

• Arterial line (A-line): Continuous BP monitoring, frequent ABG sampling. Normal MAP: 70–100 mmHg. Target MAP ≥65 in septic shock
• Central venous pressure (CVP): Reflects right ventricular preload. Normal: 2–8 mmHg. Elevated in fluid overload or right heart failure; low in hypovolemia
• Pulmonary artery catheter (Swan-Ganz): Measures PAWP (pulmonary artery wedge pressure, reflects left ventricular preload), cardiac output, cardiac index. Normal CI: 2.5–4 L/min/m²
• ScvO2 (central venous O2 saturation): Reflects oxygen delivery vs consumption balance. Normal ≥70%; low ScvO2 in high-demand states (sepsis, hemorrhage)

Mechanical Ventilation: What ICU Nurses Need to Know

Nurses do not independently adjust ventilator settings, but they must understand what the settings mean, recognize alarms, and know when to call respiratory therapy or the provider.

Key Ventilator Settings

• FiO2: Fraction of inspired oxygen (0.21–1.0). Titrate to keep SpO2 92–96% (or 88–92% in ARDS/COPD)
• PEEP: Positive end-expiratory pressure. Keeps alveoli open between breaths. Normal: 5 cmH2O. Higher PEEP used in ARDS
• Tidal volume (Vt): Volume per breath. In ARDS: 6 mL/kg ideal body weight (lung-protective strategy)
• RR: Set rate — patient may breathe above this on assisted modes
• Mode: AC (assist-control), SIMV, PSV (pressure support for weaning)

Ventilator Alarms and Nursing Response

• High-pressure alarm: Secretions, biting tube, bronchospasm, pneumothorax → suction, assess breath sounds, call provider
• Low-pressure/low-volume alarm: Circuit disconnect, cuff leak → check connections, check cuff pressure
• Apnea alarm: Patient not triggering breaths → assess patient immediately, escalate

Ventilator-associated pneumonia (VAP) prevention bundle: HOB elevation 30–45°, oral care with chlorhexidine every 4 hours, daily sedation vacation, daily weaning readiness assessment, hand hygiene.

High-Yield ICU Medications

Vasopressors and Inotropes

• Norepinephrine (Levophed): First-line vasopressor for septic shock. Alpha-1 dominant (vasoconstriction). Titrate to MAP ≥65
• Dopamine: Low dose (1–5 mcg/kg/min): dopaminergic (renal dilation); Moderate (5–10): beta-1 (inotropy); High (>10): alpha-1 (vasoconstriction)
• Epinephrine: Anaphylaxis, cardiac arrest. Increases HR, BP, bronchodilation
• Dobutamine: Pure inotrope (beta-1). Increases cardiac output. Used in cardiogenic shock — can drop BP, monitor closely
• Vasopressin: Added to norepinephrine in refractory septic shock. Fixed dose (0.03–0.04 units/min)

Sedation and Analgesia

• Propofol: Rapid onset/offset, ideal for short-term sedation and neurological assessment. Monitor triglycerides (>72-hr use). Can cause propofol infusion syndrome (rare, severe)
• Dexmedetomidine (Precedex): Sedative without respiratory depression. Patient remains arousable. Causes bradycardia and hypotension — monitor
• Midazolam: Benzodiazepine, longer-acting. Used in refractory agitation or seizures. Risk of delirium with prolonged use
• Fentanyl: First-line opioid analgesic for intubated patients. Rapid onset. Assess with CPOT if nonverbal
• Ketamine: Dissociative analgesic; bronchodilator. Used for procedural pain, refractory bronchospasm. Can cause emergence reactions

Sepsis: Recognition and Nursing Management

Sepsis is life-threatening organ dysfunction caused by a dysregulated host response to infection. Septic shock = sepsis + persistent hypotension requiring vasopressors + lactate ≥2 mmol/L despite adequate fluid resuscitation.

Sepsis-3 Criteria (qSOFA)

Screen with qSOFA (quick SOFA): altered mental status + RR ≥22 + systolic BP ≤100. Two or more = high risk for sepsis.

Surviving Sepsis Bundle (Hour-1)

1. Measure lactate (re-measure if initial >2 mmol/L)
2. Obtain blood cultures before antibiotics
3. Administer broad-spectrum antibiotics
4. 30 mL/kg IV crystalloid for hypotension or lactate ≥4 mmol/L
5. Start vasopressors if hypotensive during/after fluids (MAP target ≥65)

Nursing priorities in sepsis: Establish IV access (large-bore or central line), draw cultures from two separate sites before first antibiotic dose, administer antibiotics within 1 hour, monitor urine output hourly, reassess mental status and vital signs frequently.

ARDS: Nursing Care and Ventilator Strategy

Acute Respiratory Distress Syndrome (ARDS) is diffuse lung injury characterized by bilateral pulmonary infiltrates, severe hypoxemia (PaO2/FiO2 <300), and non-cardiogenic pulmonary edema.

• Lung-protective ventilation: Tidal volume 6 mL/kg IBW, plateau pressure <30 cmH2O, higher PEEP settings
• Prone positioning: Improves V/Q matching. Requires 2+ nurses to turn safely. Monitor pressure points, ETT position, lines
• SpO2 target: 88–93% — acceptable in ARDS (avoiding oxygen toxicity)
• Fluid management: Conservative — excess fluid worsens pulmonary edema
• Nursing concern: Watch for pneumothorax (sudden high-pressure alarm, decreased breath sounds, tracheal deviation)

NCLEX Tips: Critical Care

• MAP = (SBP + 2×DBP) ÷ 3. Target ≥65 in shock states
• When a ventilator alarm sounds: first assess the patient, then troubleshoot the machine
• Elevated CVP + bilateral crackles = fluid overload, not hypovolemia — don’t give more fluid
• Dobutamine increases cardiac output but can drop BP — don’t use alone in hypotension without vasopressor coverage
• Daily sedation vacation + spontaneous breathing trial = best evidence for successful extubation
• Lactate clearance (not just a single value) guides resuscitation in sepsis

Official Resources and Further Reading

External References

• American Association of Critical-Care Nurses (AACN) — critical care practice standards and resources
• Surviving Sepsis Campaign Guidelines — evidence-based sepsis management protocols

Related Articles on Lectures Note

• Cardiac Nursing Study Notes — MI, heart failure, dysrhythmias, and cardiac medications
• Respiratory Nursing Study Guide — COPD, pneumonia, ABG interpretation, and ventilator management

Frequently Asked Questions: Critical Care Nursing

What is the target MAP in septic shock?

The standard target is MAP ≥65 mmHg. Higher targets (≥75–80) may be used for patients with chronic hypertension to maintain adequate organ perfusion.

What is a normal urine output in the ICU?

≥0.5 mL/kg/hr. In a 70 kg patient, that’s ≥35 mL/hr. Urine output below this threshold (oliguria) signals potential renal hypoperfusion and requires immediate assessment and provider notification.

What’s the difference between sedation and analgesia-first approaches in the ICU?

Current ICU guidelines (PADIS) favor analgesia-first: treat pain before adding sedation. Uncontrolled pain drives agitation. This approach reduces overall sedative requirements and shortens time on the ventilator.

What is ICU delirium and how is it managed?

ICU delirium is acute brain dysfunction — characterized by altered attention, disorganized thinking, and fluctuating level of consciousness. Assess with CAM-ICU. Non-pharmacological management first: reorientation, natural light/dark cycle, early mobility, remove restraints when safe, minimize sedation. Pharmacological treatment is limited — haloperidol is commonly used but evidence is mixed.