Case of the Month #39 Traumatic Brain Injury

ICP is influenced by age, body position and clinical context. Thus, it is difficult to give a ‘normal value’. However, most consensus sources agree ICP >22mmHg in the context of an acute brain injury should be treated. Cerebral perfusion pressure (CPP) should be maintained between 60-70 mmHg. Given that CPP = Mean Arterial Pressure (MAP)-ICP, having excluded life-threatening haemorrhage and in the absence of ICP monitoring, a MAP of 90mmHg should be targeted.  

There is no one consensus algorithm when attempting to treat either a clinically or monitor-diagnosed rise in ICP. However, the following can serve as a rough guide: 

 

Initial measures 

1. For an acute change, give osmotherapy, either: 

20% Mannitol by bolus (0.25-1.0g/kg) or, 

 Hypertonic saline by bolus (concentrations vary e.g. 3% at 2ml/kg) 

N.B. ensure volume resuscitation when giving mannitol as it can prompt hypotension and therefore a decrease in CPP. 

 

2. Early intubation:  

In the awake patient, consider the need for early mechanical ventilation for physiological control and airway protection. 

 

3. Optimise the drainage of CSF and venous pressure: 

- Relieve venous outflow obstruction (e.g. avoid neck ties, nurse head up at 30o) 

- Consider the need for early CSF diversion (i.e. an EVD) 

- Address agitation and pain (sedation and analgesia) 

- Prevent hypercarbia 

 

4. Consider equipment issues: 

If a monitor-diagnosed rise in ICP is observed, check for measurement confounders such as transducer malfunctions and ensuring the external auditory meatus is being used as the zero point for ICP measurement.  

 

5. Consider other surgical options early 

 

If a sustained rise in ICP is refractory to your efforts, the following tiered approach in treatment escalation can be considered: 

Tier 1 

- Increase analgesia and/or sedation 

- Maintain PaCO2 at the lower end of normal (4.5-5.0 kPa) 

- Blood pressure support to maintain CPP 60-70mmHg 

 

Tier 2 

- Achieve normothermia (pharmacologically or external device) 

- If not done already, placement of EVD for CSF drainage 

- A further increase in sedation e.g. midazolam 

- Give a further bolus of osmotic therapy as above 

- Consider neuromuscular blockade 

- Consider repeating a CT scan 

 

Tier 3 

- Escalate osmotic therapy within limits of Na+ < 155 mmol/L and serum Osmolarity <320 mOsm/L 

- Brain oximetry: increase PEEP and FiO2. Aim Hb >100g/L. 

- Optimise CPP (if hyperaemia is evident, aim for a lower CPP) 

- Consider EEG and the treatment of seizures 

- Consider the possibility of both systemic and CNS infections 

 

As/before aggressive treatment measures are discussed it is important to evaluate the patient’s prognosis, their functional baseline, previous wishes and the neurological outcome which is felt achievable. Is this a Devastating Brain Injury (DBI)? 

 

Tier 4 

- Activate cooling to 35 degrees 

- Barbiturate coma 

Suggested method: Ensure CO monitoring. Give a test dose 500mg thiopentone. If an ICP response is seen and sustained, start a thiopentone infusion with continuous EEG to burst suppression 

- Decompressive craniectomy