The skull is a rigid, non-expandable container. Total intracranial volume is fixed. Any increase in one component must be compensated by a decrease in another — or ICP rises.
Early: displacement of CSF into spinal subarachnoid space
Early: reduction in cerebral venous blood volume
Late: once compensation exhausted, small volume increases → steep ICP rise (decompensation)
Clinical Significance
The "flat" part of the pressure-volume curve allows initial tolerance of expanding lesions. Once on the steep part, even minor volume changes (e.g., coughing, suctioning) cause dangerous ICP spikes.
📊 Normal ICP Values
Population
Normal ICP
Mildly Raised
Significantly Raised
Severe
Adults
5–15 mmHg
16–20 mmHg
21–40 mmHg
>40 mmHg
Children
3–7 mmHg
8–15 mmHg
>15 mmHg
>20 mmHg
Neonates
1.5–6 mmHg
—
>6 mmHg
—
Treatment Threshold
ICP >20 mmHg sustained requires active treatment in TBI (BTF Guidelines). Some centres use >22 mmHg (BTF 4th edition).
Optimal CPP (CPPopt) monitoring can guide targeted therapy
Nursing Implication
In severe TBI with lost autoregulation, avoid both hypertension AND hypotension. Keep MAP and ICP tightly controlled. Avoid activities that spike ICP (suctioning without pre-treatment, painful stimulation without analgesia).
📈 Lundberg Waves
Wave
Description
ICP Level
Duration
Significance
A Waves (Plateau waves)
Sustained ICP elevation with flat top
50–100 mmHg
5–20 min
Loss of autoregulation — CRITICAL. Requires immediate intervention.
B Waves
Rhythmic oscillations at 0.5–2/min
20–50 mmHg
0.5–2 min
Reduced compliance; may precede A waves
C Waves
Smaller rhythmic waves at 4–8/min
Normal–mildly raised
~1 min
Related to Traube-Hering-Mayer vasomotor waves; less clinically significant
A Waves = Emergency
Sustained plateau waves indicate critical loss of cerebrovascular compliance. Notify neurosurgery immediately. Apply first-tier ICP management NOW.
⭐ Intraventricular Catheter (EVD) — Gold Standard
Advantages
Accurate continuous ICP measurement
Can drain CSF therapeutically to reduce ICP
CSF sampling for culture/analysis
Intrathecal drug administration
Disadvantages
Invasive insertion — risk of haemorrhage (~1–2%), infection (ventriculitis ~5–10%)
Challenging insertion if ventricles compressed/shifted
Blockage by clot or debris
Transducer Zeroing
Zeroing Reference Point
The external reference (air-fluid interface) must be levelled at the Foramen of Monroe = tragus of the ear (external auditory meatus). Zero with stopcock open to air. Re-zero with every position change.
EVD Management Key Points
Drain height: set above Foramen of Monroe — e.g., 20 cmH₂O above tragus. Higher = less drainage. Lower = more drainage. Never set below unless prescribed.
Clamping for transport: clamp EVD during any patient transport/movement — prevents over-drainage and risk of haemorrhage
NPi <3: abnormal — correlates with raised ICP and herniation risk
NPi <2: strongly associated with uncal herniation
More sensitive than manual pupil assessment for subtle changes
Trending NPi over time more important than single reading
Non-Invasive Use
ONSD and pupillometry are valuable adjuncts, particularly for initial assessment, triage, and monitoring where invasive ICP monitoring is not yet in place. They do NOT replace invasive monitoring in severe TBI.
ICP >20 mmHg Sustained: Activate Protocol
Treat systematically — tier 1 first, escalate only if not controlled. Always target CPP 60–70 mmHg alongside ICP reduction.
Targeted temperature management (TTM): cooling to 35–36°C — reduces metabolic demand; risks: infection, coagulopathy, electrolyte shifts
CSF drainage via EVD: if already monitoring with EVD — drain 5–10 ml CSF slowly
Repeat osmotherapy boluses: with serum osmolality monitoring
3️⃣ Third-Tier / Surgical Escalation
Decompressive craniectomy: surgical removal of skull bone to allow brain to expand — DECRA and RESCUEicp trial evidence for refractory ICP; improves survival but functional outcome variable
Evacuation of haematoma: acute subdural/epidural haematoma causing ICP rise
Ventriculostomy insertion: if not already present
🧮 CPP Calculator
Cerebral Perfusion Pressure
—
🎯 ICP Management Tier Selector
Herniation = Neurosurgical Emergency
Any herniation syndrome requires immediate senior medical and neurosurgical response. Nurse must know signs and initiate emergency response.
⚠️ Transtentorial (Uncal) Herniation
Uncus of temporal lobe herniates through the tentorium cerebelli, compressing CN III and cerebral peduncle.
Classic Triad
Unilateral fixed dilated pupil — ipsilateral to herniation (CN III compression → loss of parasympathetic constriction → pupil dilates and fixes)
EMERGENCY PROTOCOL — Uncal Herniation
1. Call neurosurgery STAT
2. Hyperventilate: target pCO₂ 30–35 mmHg (temporary bridge ONLY)
3. Mannitol 20%: 100 ml IV bolus over 15 min (or 3% NaCl 100 ml if haemodynamically unstable)
4. Ensure HOB 30°, head neutral
5. Maintain MAP — do not allow hypotension
6. Prepare for emergency CT / surgery
⬇️ Central Herniation
Bilateral downward displacement of cerebral hemispheres through the tentorium. Occurs with diffuse brain swelling or midline lesions.
Progression of Signs
Stage
Level of Brain Affected
Pupils
Motor
Breathing
Diencephalic (early)
Diencephalon
Small, reactive
Paratonia
Cheyne-Stokes
Midbrain-pons
Midbrain/Upper pons
Midpoint, fixed
Bilateral Babinski; decorticate → decerebrate
Central neurogenic hyperventilation
Medullary
Medulla
Dilated, fixed
Flaccid
Ataxic / apnoea
Bilateral Babinski sign is an important early sign of central herniation.
🔻 Tonsillar (Cerebellar) Herniation
Cerebellar tonsils herniate through the foramen magnum, directly compressing the brainstem (medulla).
Late and Ominous Sign
Cushing's triad indicates catastrophic ICP rise. By the time Cushing's appears, herniation is imminent or occurring. Do NOT wait for Cushing's to act — intervene at ICP >20 mmHg.
Hypertension is a compensatory response (baroreceptor-mediated attempt to increase MAP above ICP)
Bradycardia: reflex bradycardia from baroreceptors responding to hypertension + direct vagal activation
Irregular respiration: medullary respiratory centre compression
Do NOT treat the hypertension with antihypertensives — this will reduce CPP further
ABG monitoring; correlate EtCO₂ with ABG; ventilator settings
Avoid hypotension
SBP >100 mmHg; CPP 60–70
Continuous arterial line; vasopressors per order
Avoid hypoxia
SpO₂ ≥95%
Continuous SpO₂; ABG; suction only as needed with pre-oxygenation
Normonatraemia → hypernatraemia
Na 136–145 (135–155 if ICP raised)
6-hourly electrolytes; administer HTS per order; accurate I&O
ICP monitoring
ICP <20 mmHg
Continuous display; document hourly; alert >20 mmHg >5 min
Glycaemic control
6–10 mmol/L
Hourly BGL in insulin infusion; avoid hypoglycaemia
Seizure prophylaxis
Per neurosurgery order
Levetiracetam administration; observe for seizure activity
Neutral head position
Midline, no flexion/rotation
Ensure ETT tape not compressing neck; cervical collar check
⚡ Seizure Management in Neurocritical Care
Seizure Prophylaxis in TBI
Levetiracetam 500–1000 mg IV BD — first-line prophylaxis in TBI (7 days post-injury, BTF guidelines)
Phenytoin: older alternative — more drug interactions, monitoring required
Prophylaxis reduces early seizures (not late seizures >7 days)
Non-Convulsive Status Epilepticus (NCSE)
Common in neurocritical care — no visible convulsions but ongoing seizure activity on EEG
Suspect if: failure to improve, fluctuating consciousness, unexplained ICP spikes
Continuous EEG monitoring recommended in coma/sedated patients with TBI/SAH
Treatment: levetiracetam, valproate, lacosamide per neurologist — escalate to propofol/midazolam infusion if refractory
Acute Seizure Protocol
Protect airway; position lateral if not intubated; O₂ 15L NRB mask
Lorazepam 0.1 mg/kg IV (max 4 mg/dose) — or midazolam 10 mg buccal/IM if no IV access
If persistent >5 min: repeat benzodiazepine ONCE
If >10 min: levetiracetam 60 mg/kg IV (max 4500 mg) over 10 min, or valproate 40 mg/kg IV
If >20 min (status epilepticus): RSI + intubation, phenobarbitone or propofol infusion
ICP monitoring — seizures cause ICP spikes; paralyse only with continuous EEG
🧂 Sodium Disorders in Neurocritical Care
Both CSW and SIADH cause hyponatraemia but require OPPOSITE treatment — misdiagnosis is dangerous.
Feature
Cerebral Salt Wasting (CSW)
SIADH
Volume status
HYPOVOLAEMIC — depleted
EUVOLAEMIC
Serum Na
Low
Low
Serum osmolality
Low
Low
Urine Na
High (>20 mmol/L)
High (>20 mmol/L)
Urine osmolality
High
High
BUN/Cr
Raised (hypovolaemia)
Low-normal
Uric acid
Low
Low
CVP/PCWP
Low
Normal-high
Mechanism
Renal Na wasting (BNP-mediated) → volume depletion
ADH excess → water retention
Common setting
Subarachnoid haemorrhage (most common)
CNS disease, drugs, pain
Treatment
Salt + fluid REPLACEMENT (0.9% NaCl ± fludrocortisone)
Fluid RESTRICTION ± tolvaptan
Treating CSW with fluid restriction = DANGEROUS
In post-SAH patients: CSW is most common. Fluid restriction worsens vasospasm and can cause cerebral ischaemia. When in doubt, treat as CSW (fluid replete) while awaiting senior review.
🌊 Diabetes Insipidus (DI) Post Head Injury
Features
Damage to posterior pituitary/hypothalamus → ADH deficiency → hypotonic polyuria
Urine output >250 ml/hr for 2 consecutive hours, or >3 L/day
Urine osmolality <300 mOsm/kg; urine specific gravity <1.005
Rising serum Na and osmolality
Sign of severe brain injury — especially brainstem/pituitary damage, or impending brain death
Management
Desmopressin (DDAVP): 1–2 mcg IV/SC/intranasal — replaces ADH activity
Replace fluid losses with 0.45% NaCl or D5W (hypotonic) — avoid rapid correction of hypernatraemia
Monitor Na every 2–4 hours during acute phase; urine output hourly
Distinguish from nephrogenic DI (no response to DDAVP) and osmotic diuresis
🥗 Nutritional Support in Neurocritical Care
Early enteral nutrition within 24–48 hours of injury — reduces infection, preserves gut integrity, improves outcome
Nasogastric or NJ tube feeding; gastric residuals ≤500 ml before holding (per protocol)
Target 25 kcal/kg/day; 1.2–2 g protein/kg/day (hypermetabolic state post-TBI)
HOB 30° during feeding — applies to both ICP management AND aspiration prevention. If ICP unstable at 30°, pause feed and alert team.
Selenium, zinc, vitamins B1 (thiamine) important — especially in malnutrition, alcohol history
Percutaneous endoscopic gastrostomy (PEG) for long-term nutrition if prolonged coma expected
🚗 TBI Burden in the GCC
Road traffic accidents (RTAs) remain the leading cause of traumatic death in the GCC. The region has among the highest per-capita RTA fatality rates globally.
Key Statistics
UAE: RTAs account for ~24 deaths per 100,000 population annually
Saudi Arabia: RTAs are the second leading cause of death overall; leading cause in ages 15–44
Qatar: High expatriate worker population — occupational and RTA TBI prominent
Motorbike and pedestrian injuries contribute significantly (helmets not universally worn)
Young male expatriate workers over-represented in TBI statistics
Nursing Implication
GCC nurses must be highly competent in TBI and ICP management. Language barriers with patients/families are common — use trained interpreters, not family members, for consent and neurological assessment discussions.
🏥 Neurosurgical Centres in the GCC
Centre
Country
Level / Speciality
Sheikh Khalifa Medical City (SKMC)
Abu Dhabi, UAE
Level 1 Trauma; full neurosurgical + neurocritical care
Cleveland Clinic Abu Dhabi
Abu Dhabi, UAE
Quaternary; comprehensive neurological institute
Rashid Hospital
Dubai, UAE
Level 1 Trauma; busiest trauma centre in UAE
Hamad Medical Corporation (HMC) / Hamad General Hospital
Doha, Qatar
Level 1 Trauma; national neurosciences centre
King Fahad Medical City (KFMC)
Riyadh, KSA
Tertiary; neurosciences centre of excellence
King Faisal Specialist Hospital & Research Centre
Riyadh, KSA
Quaternary neurosciences + neuro-oncology
Salmaniya Medical Complex
Manama, Bahrain
National trauma; neurosurgery services
Sultan Qaboos University Hospital
Muscat, Oman
Tertiary; academic neurosciences
Note: Provision of neurocritical care is expanding across the GCC. Patients at smaller hospitals may require transfer — time-critical decision-making is essential.
High mortality if not decompressed within 4 hours of ictus (Seelig criterion)
Venous + cortical artery bleeds; often with underlying brain injury
ASDH + GCS <8 = craniotomy consideration
Decompressive Craniectomy (DC)
Removal of large skull flap to allow swollen brain to expand outside skull
Indications: refractory ICP >20 mmHg despite all medical management; malignant MCA infarction
DECRA trial (2011): DC improved ICP control but increased unfavourable outcomes in moderate TBI
RESCUEicp trial (2016): DC reduced mortality in refractory ICP — more survivors but more in vegetative/severe disability state
Decision requires shared decision-making with family — senior neurosurgeon + neurointensivist + family conference
🩸 Subarachnoid Haemorrhage (SAH) in GCC
Key Management Points
Intervention
Details
Nimodipine
60 mg orally/NG 4-hourly × 21 days — reduces vasospasm morbidity; do not miss doses; monitor for hypotension
Euvolaemia
Current standard — Triple H therapy (hypertension + hypervolaemia + haemodilution) no longer recommended routinely; euvolaemia preferred; avoid hypovolaemia