The presence of working memory without explicit recall in a critically ill patient

We describe an intubated patient sedated with propofol who interacted with caregivers, demonstrating intact "working memory." When neuromuscular blockade and bispectral index (BIS) monitoring were instituted, a greatly reduced amount of sedative achieved BIS values less than 60. Neither the sedation that allowed working memory nor the lighter sedation that produced BIS values less than 60 resulted in recall. This experience suggests that working memory demonstrated when BIS values are less than 60 is unlikely to lead to recall.

The presence of intact working memory during sedation is a poor predictor of explicit recall when bispectral index values are maintained less than 60.