The edition · Anaesthesiology
Remimazolam read 11 BIS units higher than propofol at the same sedation depth
A crossover trial in volunteers found 57.6 against 46.5 at deep sedation — a gap wide enough to matter if a propofol-derived target is used to titrate. Plus cannabis and anaesthetic dosing in 341,199 patients, a dexmedetomidine recall, and supraglottic airways in the child with a recent upper respiratory infection.
The edition in brief
In a randomised double-blind crossover trial, 16 healthy volunteers received remimazolam and propofol at least seven days apart, each titrated to moderate and deep sedation by a clinical scale. At deep sedation mean bispectral index was 57.6 with remimazolam against 46.5 with propofol, an adjusted difference of 11.1 units (95% CI 7.3-14.8). The offset was present at moderate sedation and at loss of the eyelash reflex too. Emergence time did not differ; processing speed and executive function recovered faster after remimazolam at 30 minutes, converging by 120. A retrospective cohort of 341,199 adults found cannabis use associated with higher anaesthetic doses: non-medical use +6.85 µg/kg/min propofol (95% CI 6.07-7.63) and +0.01 MAC of volatile agent, rising to +8.41 µg/kg/min among daily recreational users. The authors note the effects were smaller than previously reported. The FDA lists an ongoing Class II recall of dexmedetomidine hydrochloride in 0.9% sodium chloride, 400 µg per 100 mL, in Galaxy single-dose containers made by Baxter Healthcare, for deviations from good manufacturing practice. In 62 women with breast cancer at a Delhi centre, autonomic dysfunction was present in 79% but showed no association with post-induction hypotension, which occurred in 32% (sympathetic OR 1.04, 95% CI 0.35-3.07). In 4,878 weighted paediatric encounters with airway hyperresponsiveness, supraglottic airway use at induction was associated with fewer respiratory adverse events than tracheal intubation (adjusted risk ratio 0.41, 95% CI 0.19-0.62).
The bispectral index reads higher on remimazolam at the same depth
Titrate remimazolam to clinical endpoints — at matched depths its bispectral index ran about 11 units higher than propofol's, so a propofol target oversedates.
Cannabis users needed more anaesthetic, but less than the folklore says
Ask about cannabis use and expect modestly higher anaesthetic requirements, but titrate to effect — the measured differences were small enough to sit inside routine adjustment.
Class II recall of premixed dexmedetomidine bags for manufacturing deviations
Check whether your unit holds the recalled Baxter premixed dexmedetomidine bags, and guard the dilution step if you have to fall back to compounding from concentrate.
Autonomic dysfunction was near-universal, and predicted nothing
Formal autonomic testing did not predict post-induction hypotension despite a 79% prevalence of dysfunction — prepare for hypotension in about a third of these patients instead.
Preoxygenate to an end-tidal oxygen target, not to a clock
Preoxygenate to an end-tidal oxygen fraction of 0.9, fix the mask seal rather than adding time, and leave nasal oxygen running through apnoea.
In the child with a recent chest infection, the supraglottic airway had fewer respiratory events
Where the case allows either, choose a supraglottic airway over intubation at induction in a child with recent respiratory illness — adjusted risk of respiratory adverse events was less than half.
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