In this episode, I’ll discuss what if it is not the sedative class that causes delirium – just the depth of sedation?
Both the 2013 and 2018 SCCM guidelines for sedation in the ICU recommend avoiding benzodiazepine infusions for sedation in the ICU. The reason for this is in part concern that benzodiazepines cause more delirium than non-benzodiazepine-based sedatives.
These guidelines also recommend using light sedation over deep sedation whenever possible for the same purpose – avoiding delirium.
These are conditional recommendations which the guideline authors state is based on low quality of evidence, but it was the most reasonable conclusion to draw from available evidence at the time the guidelines were written.
A group of researchers recently published in Critical Care Medicine a retrospective cohort study involving over 10,000 patients to compare propofol and benzodiazepine-based ICU sedation to determine the risk of each strategy on post-extubation delirium.
The authors sought to prove the hypothesis that benzodiazepine versus propofol-based sedation is associated with fewer delirium-free days within 14 days after extubation. They also look at deep sedation which was defined as the ratio of days with a mean Richmond Agitation-Sedation Scale of less than or equal to –3 during the course of mechanical ventilation.
The patient cohort studied ranged from admissions during 2008 all the way through 2018. On average just under one-third of the time on mechanical ventilation was spent under deep sedation.
The mean number of delirium-free days was just under 10. The analysis found that a higher proportion of days under deep sedation was associated with 3 fewer delirium-free days post-extubation. The interesting finding was that the use of benzodiazepines compared with propofol only increased the risk of post-extubation delirium in patients who received a high proportion of deep sedation. The cohort of benzodiazepine patients who received a low proportion of deep sedation did not have a higher risk of delirium compared with patients who received propofol.
Even when the dose of sedative was used to predict risk of delirium, the GABAergic drug-induced proportion of deep sedation for the endpoint post-extubation delirium was a better predictor of delirium.
The authors concluded:
Benzodiazepine compared with propofol-induced deep sedation during mechanical ventilation is associated with increased post-extubation delirium risk. Our data do not support the view that benzodiazepine-based compared with propofol-based sedation in the ICU adds an independent risk of delirium, as long as deep sedation can be avoided. It is probably easier to avoid deep sedation when infusions of the short-acting drug propofol are given rather than long-acting benzodiazepines. Clinicians should try to avoid using benzodiazepines if deep sedation is required for a prolonged period
and should avoid deep sedation whenever possible.
While this data will not lead to benzodiazepines becoming 1st line sedatives in ICU patients, it does provide useful information that when benzos are used, care should be taken to limit or eliminate the time spent in deep sedation.
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