Background and Rationale
Advantages and Disadvantages of each
Evidence
Summary (my practice)
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2 Comments
Jeremy Bragg
22/5/2020 12:29:47 pm
Would a "neuro monitor" (BIS for example) take some of the subjectiveness out of titrating sedation to RASS?
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Idunn Morris
27/5/2020 09:27:40 am
Great question! There are very few trials in the ICU population looking at this, - a recent(ish) Cochrane review in 2018 deemed no benefit but insufficient studies and therefore low level evidence… Overall BIS is validated for well patients under GA with a target based on awareness during surgical intervention. If there was a group it could be useful in in ICU I would have thought it would be those on NMBA infusions where we are going blind with how much sedation to give to be sure they are not aware but without rendering them deeply unconscious for 5days after sedation is later discontinued (associated risks/complications)… I had similar thoughts at one point as to whether TCIs would be useful in ICU for a similar reason, but with renal and hepatic dysfunction, increased volumes of distribution and prolonged duration of infusions the mathematical models they are based on aren't valid…. Ultimately (in my opinion) where both BIS and TCI fall short of being practically useful in most of our ICU patients is that we titrate sedation to that point where patients are not at risk of causing harm (losing lines) or being distressed, but similarly are not deeply unresponsive (and associated harms of this) - and that is based on a clinical assessment - we will respond to a patient at risk of self-extubating say irrespective of what the BIS is (whether 20 or 100 for example).
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![]() About the AuthorIdunn Morris is the Nepean ICU provisional fellow (research). The information provided in these summaries is subject to personal interpretation of the studies touched on. Certainly, the summary 'my practice' section does not correspond to recommended clinical practice, rather 'an approach' based on the information presented. Categories
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About WTETIntensive care medicine is full of unanswered questions, controversies and subtle variations in practice. 'What's the evidence Tuesdays' aims to provide a brief 10-minute oral overview of the rationale and evidence behind an investigation, intervention or approach to management. Whilst based on the fellowship 'critically evaluate' style exam questions it is an MDT forum designed to encourage all clinical staff to know and keep up-to-date with the evidence (or at times lack of!) that guides our day-to-day decisions and where applicable understand why debate amongst the critical care community may still exist. Each week a two-sided written summary of the session is created for those who were unable to attend. Similarly, this summary provides a written resource for fellowship exam candidates to refer to with the understanding these are not model exam answers.
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