title: "ICU Rotation Deep Dive"
ICU Rotation Deep Dive
This page consolidates key ICU concepts from across the Critical Care curriculum. Use it as your go-to reference when starting your ICU rotation.
1. ICU Basics
Who Gets Admitted to ICU?
ICU Admission Criteria:
- Requires organ support (ventilation, vasopressors, RRT)
- High risk of deterioration requiring close monitoring
- Post-operative high-risk patients
- Failure to improve on ward despite maximal therapy
Levels of Care
| Level | Description | Examples |
|---|---|---|
| Level 0 | Normal ward care | Stable patients |
| Level 1 | Ward + additional monitoring/intervention | Post-op, single organ support |
| Level 2 | HDU - single organ support or step-down from ICU | NIV, single vasopressor |
| Level 3 | ICU - multiple organ support or advanced respiratory | Ventilated, multiple vasopressors |
Daily ICU Assessment
- F - Feeding: Is nutrition adequate? Enteral preferred.
- A - Analgesia: Pain controlled?
- S - Sedation: Target RASS? Can we lighten?
- T - Thromboprophylaxis: DVT prevention (heparin + SCDs)
- H - Head of bed: Elevated 30-45° (VAP prevention)
- U - Ulcer prophylaxis: PPI/H2 blocker if high risk
- G - Glycaemic control: BSL 6-10 mmol/L target
- S - Spontaneous breathing trial: Ready to wean?
- B - Bowels: Moving? Constipation common with opioids
- I - Indwelling catheters: Still needed? Remove early
- D - Deescalation: Antibiotics, sedation, support
The ICU bundle approach: Evidence-based bundles reduce VAP, CLABSI, and mortality. Compliance with ALL elements matters more than any single intervention.
2. Haemodynamic Monitoring
Basic Parameters
| Parameter | Normal Range | What It Tells You |
|---|---|---|
| MAP | 65-90 mmHg | Perfusion pressure |
| CVP | 2-8 mmHg | Right heart filling (not reliable for volume status) |
| HR | 60-100 | Compensatory response, rhythm |
| UO | >0.5 mL/kg/hr | Renal perfusion |
| Lactate | <2 mmol/L | Tissue oxygenation |
MAP Target: Generally ≥65 mmHg. Higher targets (75-80) may be needed in chronic hypertension or traumatic brain injury.
Source: Surviving Sepsis Campaign / local ICU protocol.
Advanced Monitoring
| Tool | What It Measures | When to Use |
|---|---|---|
| Arterial line | Continuous BP, ABG access | Vasopressors, frequent ABGs |
| Central line | CVP, drug delivery | Vasopressors, TPN, access |
| PAC (Swan-Ganz) | CO, PCWP, SVR | Refractory shock, unclear cause |
| Echo (TTE/TOE) | LV/RV function, valves | Shock assessment |
| PiCCO/FloTrac | CO, SVV, extravascular lung water | Goal-directed therapy |
CVP is NOT a good marker of fluid responsiveness! Use dynamic measures: pulse pressure variation, passive leg raise, fluid challenge response.
3. Shock in the ICU
See the [[shock]] wiki article for detailed pathophysiology.
The 4 Types
| Type | Mechanism | CVP | CO | SVR | Examples |
|---|---|---|---|---|---|
| Hypovolaemic | ↓ Preload | ↓ | ↓ | ↑ | Haemorrhage, dehydration |
| Cardiogenic | ↓ Pump function | ↑ | ↓ | ↑ | MI, cardiomyopathy |
| Distributive | ↓ SVR | ↓/N | ↑ | ↓ | Sepsis, anaphylaxis |
| Obstructive | ↓ Venous return | ↑ | ↓ | ↑ | PE, tamponade, tension pneumo |
Vasopressor Choice
First-line vasopressors:
- Septic shock: Noradrenaline (α1 > β1)
- Cardiogenic shock: Dobutamine (β1 > β2) ± noradrenaline
- Anaphylaxis: Adrenaline (α + β)
| Drug | Receptors | Effect | Use |
|---|---|---|---|
| Noradrenaline | α1 >> β1 | Vasoconstriction, ↑HR/contractility | Sepsis, distributive |
| Adrenaline | α + β | Vasoconstriction + inotropy | Anaphylaxis, refractory shock |
| Vasopressin | V1 | Vasoconstriction (non-catecholamine) | Adjunct in sepsis |
| Dobutamine | β1 > β2 | Inotropy, mild vasodilation | Cardiogenic shock |
| Dopamine | Dose-dependent | Low: renal; Mid: β; High: α | Rarely used now |
4. Mechanical Ventilation
See the [[mechanical-ventilation]] wiki article for detailed ventilator modes and settings.
Indications
When to intubate:
- Failure to protect airway (GCS ≤8)
- Failure to oxygenate (refractory hypoxia)
- Failure to ventilate (rising CO2, fatigue)
- Anticipated deterioration (burns, anaphylaxis)
See also: [[intubation]], [[burns]], [[anaphylaxis]]
Basic Vent Settings
| Parameter | Initial Setting | What It Does |
|---|---|---|
| Mode | SIMV or A/C | Mandatory vs supported breaths |
| FiO2 | Start 1.0, wean to <0.6 | Oxygen delivery |
| PEEP | 5-10 cmH2O | Prevents alveolar collapse |
| Vt | 6-8 mL/kg IBW | Tidal volume (lung protective) |
| RR | 12-16 | Minute ventilation |
Lung protective ventilation:
- Vt ≤6-8 mL/kg IBW (ideal body weight, not actual)
- Plateau pressure ≤30 cmH2O
- PEEP to keep alveoli open
High Vt causes ventilator-induced lung injury (VILI).
Source: ARDSNet lung-protective ventilation / local ICU protocol.
ARDS Management
See the [[ards]] wiki article for detailed ARDS pathophysiology and management.
| Severity | PaO2/FiO2 Ratio |
|---|---|
| Mild | 200-300 |
| Moderate | 100-200 |
| Severe | <100 |
ARDS Bundle:
- Lung protective ventilation (low Vt, limit Pplat)
- Moderate PEEP
- Conservative fluid strategy
- Prone positioning if P/F <150
- Consider neuromuscular blockade in severe ARDS
5. Sedation and Analgesia
The "Analgesia First" Approach
Pain before sedation: Treat pain first, then add sedation only if needed. Pain causes agitation - treating the cause is better than masking it.
Common ICU Agents
| Drug | Class | Onset | Duration | Notes |
|---|---|---|---|---|
| Fentanyl | Opioid | 1-2 min | 30-60 min | Short-acting, ideal for bolus |
| Morphine | Opioid | 5-10 min | 3-4 hr | Histamine release, accumulates in renal failure |
| Propofol | Sedative | 30 sec | 5-10 min | Easy titration, hypotension, PRIS risk |
| Midazolam | Benzo | 2-3 min | 1-2 hr | Accumulates, delirium risk |
| Dexmedetomidine | α2-agonist | 15 min | Variable | Arousable sedation, less delirium |
Q: Propofol key characteristics/risks? A: Rapid on/off; hypotension; PRIS risk with high-dose, prolonged infusions.
Q: Midazolam downside with prolonged use? A: Accumulates and increases delirium risk.
Q: Dexmedetomidine sedation profile? A: Arousable sedation with less delirium than benzodiazepines.
Q: PRIS risk threshold and key features? A: Risk increases with >4 mg/kg/hr for >48 hours; features include metabolic acidosis, rhabdomyolysis, hyperkalaemia, and cardiac failure.
Source: Surviving Sepsis Campaign / local ICU protocol.
RASS Score
| Score | Term | Description |
|---|---|---|
| +4 | Combative | Overtly combative, danger to staff |
| +3 | Very agitated | Pulls/removes tubes, aggressive |
| +2 | Agitated | Frequent non-purposeful movement |
| +1 | Restless | Anxious but movements not aggressive |
| 0 | Alert & calm | TARGET for most patients |
| -1 | Drowsy | Not fully alert, sustained awakening to voice |
| -2 | Light sedation | Briefly awakens to voice |
| -3 | Moderate sedation | Movement to voice but no eye contact |
| -4 | Deep sedation | No response to voice, movement to physical stim |
| -5 | Unarousable | No response |
Daily sedation holds: Stop sedation each morning to assess neurological status and readiness to wean. Reduces duration of ventilation and ICU stay.
6. Sepsis Management
Sepsis-3 Definitions
Sepsis: Life-threatening organ dysfunction caused by dysregulated host response to infection.
Septic Shock: Sepsis + vasopressors required to maintain MAP ≥65 + lactate >2 despite adequate fluid resuscitation.
The Hour-1 Bundle
Sepsis Hour-1 Bundle (start immediately):
- Measure lactate (remeasure if >2)
- Blood cultures before antibiotics
- Broad-spectrum antibiotics within 1 hour
- 30 mL/kg crystalloid for hypotension or lactate ≥4
- Vasopressors if hypotensive during/after fluid resuscitation
Source: Surviving Sepsis Campaign (Hour-1 bundle) / local sepsis pathway.
qSOFA (Quick SOFA)
| Criterion | Points |
|---|---|
| RR ≥22 | 1 |
| Altered mentation | 1 |
| SBP ≤100 | 1 |
≥2 points → high risk of poor outcome, consider ICU
7. Common ICU Problems
ICU Delirium
- D - Drugs (benzos, opioids, anticholinergics)
- E - Electrolyte disturbance
- L - Lack of sleep
- I - Infection
- R - Reduced sensory input (no glasses, hearing aids)
- I - Intracranial pathology
- U - Urinary retention, constipation
- M - Myocardial (hypoxia, hypotension)
Prevention > Treatment:
- Early mobilisation
- Sleep hygiene (lights off, minimise night interventions)
- Orientation (clocks, calendars, family)
- Avoid deliriogenic drugs (benzos, anticholinergics)
- Treat pain adequately
Thrombocytopenia
Thrombocytopenia is defined as platelet count <150 × 10^9/L.
Severe thrombocytopenia is typically <50 × 10^9/L (higher bleeding risk).
VTE Prophylaxis in ICU
| Strategy | Options | Notes |
|---|---|---|
| Pharmacologic | LMWH (enoxaparin), UFH, fondaparinux | LMWH preferred; UFH if severe renal impairment |
| Mechanical | SCDs, compression stockings | Use when bleeding risk is high or anticoagulation is contraindicated |
Default ICU VTE prevention is pharmacologic prophylaxis unless bleeding risk is high.
First-line agent is LMWH (e.g., enoxaparin) if renal function allows.
Use UFH for prophylaxis when CrCl <30 mL/min or rapid reversal is needed.
If anticoagulation is contraindicated, use mechanical prophylaxis (SCDs).
Perioperative VTE prevention combines early mobilisation, mechanical devices (TEDS/SCDs), and pharmacologic prophylaxis when safe.
Highest perioperative VTE risk is in major orthopedic surgery (hip/knee arthroplasty).
Ventilator-Associated Pneumonia (VAP)
VAP Prevention Bundle:
- Head of bed 30-45°
- Daily sedation vacation
- DVT prophylaxis
- Peptic ulcer prophylaxis
- Oral care with chlorhexidine
- Subglottic secretion drainage
AKI Prevention in ICU
Prevent worsening AKI by avoiding nephrotoxins, optimising fluid status, and maintaining MAP ≥65 mmHg.
Aim for urine output ≥0.5 mL/kg/hr and monitor electrolytes closely.
8. Practice Questions
What is the first-line vasopressor?
Which is the most appropriate first step?
What is the next step?
What is the diagnosis?
What is the first-line treatment?
ICU Study Checklist
Click to expand or view deep dives