- 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
- 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
- tbO2 — awaiting the BOOST2 trial (ICP vs tbO2)
- ocular ultrasound for optic nerve sheath diameter
References and Links
- CCC – Traumatic Brain Injury: Assessment
- CCC – Traumatic Brain Injury: Management
- CCC – Traumatic Brain Injury: Monitoring
- CCC – Traumatic Brain Injury: Prognosis
- CCC – Traumatic brain injury: Overview
- CCC – Increased ICP in TBI
- CCC – Limitations of CT in Traumatic Brain Injury
- CCC – Cerebral Perfusion Pressure (CPP) in TBI
- 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. PMC3565432.
- 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. PMID: 24293327.
- 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. PMC3376474.
- Smith M. Monitoring intracranial pressure in traumatic brain injury. Anesth Analg. 2008 Jan;106(1):240-8. PMID: 18165584.
Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also the Innovation Lead for the Australian Centre for Health Innovation at Alfred Health, a Clinical Adjunct Associate Professor at Monash University, and the Chair of the Australian and New Zealand Intensive Care Society (ANZICS) Education Committee. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.
After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.
He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE. He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of LITFL.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.
His one great achievement is being the father of two amazing children.
On Twitter, he is @precordialthump.