Traumatic Brain Injury (TBI) Monitoring
OVERVIEW
- The core physiological monitor used in TBI is ICP monitoring, in addition to standard monitoring used for any critically ill patient
- Other TBI-specific physiological monitors are less widely used
- BTF guidelines consider ICP monitoring mandatory for severe TBI with an abnormal CT as intracranial hypertension develops in 60%
- Nevertheless, there is currently no evidence of benefit from ICP monitoring in TBI in terms of clinical outcomes
INDICATIONS FOR ICP MONITORING
BTF Guidelines lists the following indications:
- moderate -> severe head injury who can’t be serially neurologically assessed
- severe head injury (GCS < 8) + abnormal CT scan
- severe head injury (GCS < 8) + normal CT if 2 of the following are present:
- Age > 40 yrs
- BP < 90mmHg
- Abnormal motor posturing
BENEFITS OF ICP MONITORING
- useful for CPP guided therapy
- alerts clinicians to changes in the unconscious patient
- easy to measure
- staff familiarity
- number and waveform to evaluate
- continuous measure
RISKS AND LIMITATIONS OF ICP MONITORING
- invasive procedure
- intracranial bleeding < 3% (more with intraventricular catheters)
- infections < 14%
- malfunction/measurement error -> inappropriate or unnecessary investigations/interventions
- might be misleading (not a global measurement)
- no RCTs have demonstrated that ICP-guided therapy improves patient-centered outcomes (including BEST-TRIP)
- some observational studies have noted an association between ICP guided management and prolonged length of stay and worse outcome (Cramer, 2005, Shafi, 2008)
- individual ICP monitors have different limitations:
-> intraparenchymal monitors/subdural bolts: can not be calibrated, subject to drift, does not allow CSF drainage
-> EVD: require expertise and resource availability for placement, infection
EVIDENCE
- There is no high level evidence supportive beneficial outcomes from ICP monitoring
- BEST TRIP (NEJM, 2012)
— MCRCT, 6 sites in Bolivia and Ecuador
— n=324 patients >13y old with severe TBI, or GCS 8 or less within 48 hours
— ICP monitoring (with protcol to keep ICP <20 mmHg) versus clinical exam + CT head only
— outcome: found no difference in ICU LOS or 6 month mortality / neuropsychological and functional recovery
— criticisms: performed in South America, limited generalisability, “it’s not the monitor, but what you do with it that matters”, in practice we use ICP + CTH + clinical exam not any subset thereof
TYPES OF ICP MONITORS
These include:
- CCC — Codman ICP Monitor
- CCC — Extradural ICP Monitors
- CCC — External Ventricular Drain
OTHER MONITORS
- SjO2
- tbO2 — awaiting the BOOST2 trial (ICP vs tbO2)
- microdialysis
- ocular ultrasound for optic nerve sheath diameter
References and Links
CCC Neurocritical Care Series
Emergencies: Brain Herniation, Eclampsia, Elevated ICP, Status Epilepticus, Status Epilepticus in Paeds
DDx: Acute Non-Traumatic Weakness, Bulbar Dysfunction, Coma, Coma-like Syndromes, Delayed Awakening, Hearing Loss in ICU, ICU acquired Weakness, Post-Op Confusion, Pseudocoma, Pupillary Abnormalities
Neurology: Anti-NMDA Encephalitis, Basilar Artery Occlusion, Central Diabetes Insipidus, Cerebral Oedema, Cerebral Venous Sinus Thrombosis, Cervical (Carotid / Vertebral) Artery Dissections, Delirium, GBS vs CIP, GBS vs MG vs MND, Guillain-Barre Syndrome, Horner’s Syndrome, Hypoxic Brain Injury, Intracerebral Haemorrhage (ICH), Myasthenia Gravis, Non-convulsive Status Epilepticus, Post-Hypoxic Myoclonus, PRES, Stroke Thrombolysis, Transverse Myelitis, Watershed Infarcts, Wernicke’s Encephalopathy
Neurosurgery: Cerebral Salt Wasting, Decompressive Craniectomy, Decompressive Craniectomy for Malignant MCA Syndrome, Intracerebral Haemorrhage (ICH)
— SCI: Anatomy and Syndromes, Acute Traumatic Spinal Cord Injury, C-Spine Assessment, C-Spine Fractures, Spinal Cord Infarction, Syndomes,
— SAH: Acute management, Coiling vs Clipping, Complications, Grading Systems, Literature Summaries, ICU Management, Monitoring, Overview, Prognostication, Vasospasm
— TBI: Assessment, Base of skull fracture, Brain Impact Apnoea, Cerebral Perfusion Pressure (CPP), DI in TBI, Elevated ICP, Limitations of CT, Lund Concept, Management, Moderate Head Injury, Monitoring, Overview, Paediatric TBI, Polyuria incl. CSW, Prognosis, Seizures, Temperature
ID in NeuroCrit. Care: Aseptic Meningitis, Bacterial Meningitis, Botulism, Cryptococcosis, Encephalitis, HSV Encephalitis, Meningococcaemia, Spinal Epidural Abscess
Equipment/Investigations: BIS Monitoring, Codman ICP Monitor, Continuous EEG, CSF Analysis, CT Head, CT Head Interpretation, EEG, Extradural ICP Monitors, External Ventricular Drain (EVD), Evoked Potentials, Jugular Bulb Oxygen Saturation, MRI Head, MRI and the Critically Ill, Train of Four (TOF), Transcranial Doppler
Pharmacology: Desmopressin, Hypertonic Saline, Levetiracetam (Keppra), Mannitol, Midazolam, Sedation in ICU, Thiopentone
MISC: Brainstem Rules of 4, Cognitive Impairment in Critically Ill, Eye Movements in Coma, Examination of the Unconscious Patient, Glasgow Coma Scale (GCS), Hiccoughs, Myopathy vs Neuropathy, Neurology Literature Summaries, NSx Literature Summaries, Occulocephalic and occulovestibular reflexes, Prognosis after Cardiac Arrest, SIADH vs Cerebral Salt Wasting, Sleep in ICU
Journal articles
- Chesnut RM, Temkin N, Carney N, Dikmen S, Rondina C, Videtta W, Petroni G, Lujan S, Pridgeon J, Barber J, Machamer J, Chaddock K, Celix JM, Cherner M, Hendrix T. A trial of intracranial-pressure monitoring in traumatic brain injury. N Engl J Med. 2012 Dec 27;367(26):2471-81
- Kirkman MA, Smith M. Intracranial pressure monitoring, cerebral perfusion pressure estimation, and ICP/CPP-guided therapy: a standard of care or optional extra after brain injury? Br J Anaesth. 2014 Jan;112(1):35-46
- Raboel PH, Bartek J Jr, Andresen M, Bellander BM, Romner B. Intracranial Pressure Monitoring: Invasive versus Non-Invasive Methods-A Review. Crit Care Res Pract. 2012;2012:950393
- Smith M. Monitoring intracranial pressure in traumatic brain injury. Anesth Analg. 2008 Jan;106(1):240-8
Critical Care
Compendium
Chris is an Intensivist and ECMO specialist at The Alfred ICU, where he is Deputy Director (Education). He is a Clinical Adjunct Associate Professor at Monash University, the Lead for the Clinician Educator Incubator programme, and a CICM First Part Examiner.
He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives. He was one of the founders of the FOAM movement (Free Open-Access Medical education) has been recognised for his contributions to education with awards from ANZICS, ANZAHPE, and ACEM.
His one great achievement is being the father of three amazing children.
On Bluesky, he is @precordialthump.bsky.social and on the site that Elon has screwed up, he is @precordialthump.
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