You are called to review a 55-year-old female following difficult, prolonged surgery for clipping of a left middle cerebral artery aneurysm. She returned to the ICU intubated, ventilated and with an external ventricular drain (EVD) in situ three hours earlier.
She now has frank blood in the EVD. Her blood pressure is 180/100 mmHg, and her intracranial pressure has increased to 57 mm Hg.
Outline your approach to her initial management
- This is a very urgent situation
- Likely diagnosis is a surgical catastrophe
- Will need urgent CT +/- angiogram
- Contact surgical team
- Control ICP and defend CPP
- Prepare for OT
- Contact family once urgent situation settled
- PaO2 >90 mmHg, O2 sats >95%
- CO2 32 – 38 mmHg
- Check ETT ties
- Check BP for accuracy, probably allow BP to be a bit on the high side initially (SBP 150 – 170) but not excessively. Avoid hypotension. Treat hypotension carefully (probably noradrenaline rather than metaraminol boluses) to prevent large swings in BP
Urgent CT +/- Angiogram
- Get junior to call CT
- Start packing, obtaining equipment, medications
Contact Surgical Team
- Check reading; level, zero, draining
- ETT ties not tight
- Head up 45 degrees
- Mild hyperventilation (CO2 34 – 38 mmHg)
- Thiopentone bolus 2 – 5 mg/kg
- Lower drain (5 – 10 cm above foramen magnum) and drain CSF
- Consider osmolar therapy
- Mannitol (100 mL 20%)
- Hypertonic saline (dose)
- Target osm 320
- Maintain CPP if able
- Probably target CPP of 50-60
- Prepare for OT
- Check G+H
- Check coags
- Contact anesthestic/OT co-ordinator
- Cease feeds
Additional Examiners’ Comments:
Some candidates failed to recognise this as an emergency situation and treat appropriately in collaboration with the neurosurgeon.
This college model answer is an interesting exercise, which offers a glimpse into the mind of the examiner. The candidates would be forgiven for thinking that writing something like "this is a very urgent situation" would be a useless motherhood statement in an ICU final. We are all critical care staff here. Upon seeing an ICP of 57 and an EVD full of blood, none of us would say "This is a non-urgent benign situation, and I will have a cup of tea". However, the apparent failure of some of the candidates to write such a statement has led the examiners to conclude that they failed to recognise this hideous situation as an emergency.
The rest of the college answer is also interesting, as it introduces some weird micromanagement of intra-hospital logistics (eg. "Contact anesthestic/OT co-ordinator" and "Get junior to call CT"). One might conclude on the basis of this that the marking breakdown included such minutae.
If all the "pack the patient, wipe their bottom, fold the sheets" bullshit is trimmed away one recognises that the meat of this question is in the management of ICP. The stereotypical approach to ICP management is described elsewhere, and is repeated here to simplify revision:
Stereotypical steps in ICP management:
- Position the head (45 °head up, facing straight)
- Loosen the ETT ties
- Remove the C-spine collar
- Decrease PEEP as much as possible
- Increase sedation
- Propofol sedation to decrease distress and thus decrease ICP
- Benzodiazepines may be of use (but they do not decrease the CMRO2 as much as propofol)
- Drain some CSF from the EVD
- Paralysis with neuromuscular junction blocker
- Mannitol 20%
- Hypertonic saline
- Super-refractory ICP
- Controversial measures
- Barbiturate coma if other methods of lowering ICP have failed
- Decompressive craniectomy
Interestingly, the college recommends defending the CPP, which sounds unusual, because one will inevitably end up pushing more blood out of the EVD, with the MCA clip lost and the artery hosing away. This is actually the least stupid move of the possible moves you could make here, but it is a valid point that blood loss would likely be suibstantial, if not immediately then in theatre. According to this MRI study of cerebral blood flow by Enzmann et al (1994), the MCA blood flow at rest is about 127 ml/min. Let's say that the entire MCA output is being pushed out of the EVD. At that rate, one would lose 1L of blood every 8 minutes or so. As such, to organise a massive transfusion protocol might appear as a reasonable. Of course, one would not practice permissive hypotesion here to limit the blood loss, because that would produce brain hypoperfusion.
Enzmann, Dieter R., et al. "Blood flow in major cerebral arteries measured by phase-contrast cine MR." American journal of neuroradiology 15.1 (1994): 123-129.