A 59-year-old male is admitted to the ICU following a severe traumatic brain injury
sedated, intubated and ventilated.
a) List the arguments for and against intracranial pressure (ICP) monitoring in this
b) Explain the term "secondary brain injury" and list the steps to avoid this.
- This patient has about a 50 – 60% chance of developing raised ICP.
- It is critical that CPP is maintained and to know the CPP need to know the ICP.
- ICP is a strong predictor of outcome after severe TBI.
- Several studies have shown substantial lowering of mortality after ICP monitoring and
control was introduced.
- Numerous studies have also shown that patients who respond to ICP-lowering therapies
have a lower mortality compared to those who don't, allowing some prognostication.
- Internationally accepted BTF Guidelines advise ICP monitoring in patients with severe
TBI (GCS < 9) and an abnormal CT scan.
- Doesn't lead to greater intensity of treatment or ICU LOS compared to no ICP
- If EVD allows CSF drainage and analysis.
- Early diagnosis of secondary surgically correctable lesion e.g.: delayed subdural
- Risks associated with brain injury associated coagulopathy.
- Other risks – infection, false readings and risks of avoidable interventions (osmotherapy,
falsely elevating CPP, deep sedation).
- BEST TRIPPS study showing no difference in outcome.
- May require transfer to OT for insertion.
- Secondary injury occurs at any time after the primary injury, and thus should theoretically
be preventable and is caused primarily by:
Ensure a PaO2 > 80 and/or SpO2 > 92%
PaCO2 35 - 40mmHg
SBP > 90 mmHg and/MAP > 70 mmHg / CPP > 50 mmHg
o Metabolic disturbance (Na, glucose, osmo)
Na+ of 140 – 150 mmol/L, glucose 6 – 10, Serum osmo 320 mOsm/L
Phenytoin x 72hrs
o Raised ICP
ICP lowering therapy (head up 30o, neck neutral alignment, sedation and
paralysis, osmotherapy, drain CSF, surgical decompression)
o Secondary surgical lesion (delayed subdural/parenchymal haemorhage)
Repeat CT, surgical therapy
a) is a list of arguments for and against ICP monitoring. The debate about indications for intracranial pressure monitoring (strictly, whether there are any) is discussed in the Required Reading section.
To simplify revision, and because the author has succumbed to sloth, large greyish boxes have been lifted from that section and planted here with zero modification.
A precise definition of "secondary brain injury" is remarkably difficult to find, as occurs often with frequently used terminology of which everybody has some assumed intuitive understanding. Go on everyone, define "injury" in general. The college, in its model answer, does not define the term, but rather frames it in terms of problems and solutions.
Prevention of secondary brain injury - colloquially referred to as "neurprotective measures" - is discussed elsewhere, both as a brief summary and as a rambling dialogue. Salient points from the brief summary are lazily pasted below.
Maintaining cerebral oxygen supply:
Decreasing cerebral oxygen demand:
Our beloved Oh's Intensive Care manual has two excellent chapters to dedicate to this topic:
Chapter 43 (pp. 563) Cerebral protection by Victoria Heaviside and Michelle Hayes, and
Chapter 67 (pp. 765) Severe head injury by John A Myburgh.
However, the discerning reader will recognise this book as an antique, and look instead to the frequently updated Brain Trauma Organisation Guidelines for Management of Traumatic Brain Injury.
Narayan, Raj K., et al. "Intracranial pressure: to monitor or not to monitor? A review of our experience with severe head injury." Journal of neurosurgery 56.5 (1982): 650-659.
Forsyth, Rob J., Susanne Wolny, and Beryl Rodrigues. "Routine intracranial pressure monitoring in acute coma." Cochrane Database Syst Rev 2 (2010).
Badri, Shide, et al. "Mortality and long-term functional outcome associated with intracranial pressure after traumatic brain injury." Intensive care medicine 38.11 (2012): 1800-1809.
Farahvar, Arash, et al. "Increased mortality in patients with severe traumatic brain injury treated without intracranial pressure monitoring: Clinical article."Journal of neurosurgery 117.4 (2012): 729-734.
Chesnut, Randall M., et al. "A trial of intracranial-pressure monitoring in traumatic brain injury." New England Journal of Medicine 367.26 (2012): 2471-2481.
Farahvar, Arash, et al. "Response to intracranial hypertension treatment as a predictor of death in patients with severe traumatic brain injury: Clinical article."Journal of neurosurgery 114.5 (2011): 1471-1478.
Meythaler, Jay M., et al. "Current concepts: Diffuse axonal injury - associated traumatic brain injury." Archives of physical medicine and rehabilitation 82.10 (2001): 1461-1471.
Tasker, R. C., et al. "Monitoring in non-traumatic coma. Part I: Invasive intracranial measurements." Archives of disease in childhood 63.8 (1988): 888-894.
Cremer, Olaf L., et al. "Effect of intracranial pressure monitoring and targeted intensive care on functional outcome after severe head injury*." Critical care medicine 33.10 (2005): 2207-2213.