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

FAST HUGS BID - Daily ICU Checklist

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

Clinical Pearl

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

Warning

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

Warning

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

Clinical Pearl

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

Warning

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

DELIRIUM Causes

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.