Outline the role, advantages, and disadvantages of the following neuro-monitoring modalities, used in an intubated ICU patient with severe traumatic brain injury.
a) Clinical assessment. (20% marks)
b) ICP monitoring. (30% marks)
c) Cerebral blood flow monitoring. (30% marks)
d) Cerebral function and metabolism. (20% marks)
Aim: To explore the options available for neuromonitoring in TBI.
Key sources include: Paper 2010.1 Q8 compare and contrast EVD and fibre optic. 2009.2 Q25.1 - clinical assessment. CanMEDS Medical Expert.
Discussion: Parts a, b and c are repeat explorations of this topic. Many candidates did not gain marks by not attempting parts of the question. Marks were gained by answering questions discussing first principles. Whilst some techniques described in the question are not available in all centres, the principles underpinning their use are simple and well described in textbooks. Candidates are reminded that there is no negative marking, and it is recommended to attempt all parts of the question. First principle examples would include details on availability, cost, invasiveness, reproducibility, type, and volume of information gathered and complications.
The examiners referenced Question 8 from the first paper of 2010, which asked for a comparison between an EVD and a fiberoptic pressure transducer, and Question 25.1 from the second paper of 2009, which actually asked for the sort of clinical features that would suggest raised intracranial pressure and imply that a head CT would be needed prior to a lumbar puncture. The added twist this time was "role", which would have made some of the candidates think carefully and choose their words. For example, considering c) and d) are not well-accepted or widespread, one could legitimately argue that they have no well-established role. One way of addressing this SAQ could have been to list the possible methods of each assessment and then discuss their advantages and disadvantages (eg. comparing EVD and fibreoptic catheters) but this would have missed an opportunity to showcase some higher-order analysis. What follows is an attempt to answer this question in a way that takes advantage of the stem to discuss the advantages and disadvantages of the whole concept, rather than specific applications of it.
a) Clinical assessment:
b) ICP monitoring:
c) Cerebral blood flow monitoring:
d) Cerebral function and metabolism:
An extension of this SAQ into e) neuroimaging is also a plausible future avenue.
Kirkness, Catherine J. "Cerebral blood flow monitoring in clinical practice." AACN Advanced Critical Care 16.4 (2005): 476-487.
Casault, Colin, et al. "Multimodal brain monitoring following traumatic brain injury: A primer for intensive care practitioners." Journal of the Intensive Care Society 23.2 (2022): 191-202.
Feyen, B. F., et al. "Neuromonitoring in traumatic brain injury." Minerva anestesiologica 78.8 (2012): 949-958.
Lazaridis, Christos, and Brandon Foreman. "Management Strategies Based on Multi-Modality Neuromonitoring in Severe Traumatic Brain Injury." Neurotherapeutics (2023): 1-15.
Ropper, Alexander E., and John H. Chi. "Treatment of traumatic brain injury without direct intracranial pressure monitoring." Neurosurgery 72.4 (2013): N19-N20.