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MIDAZOLAM IMPAIRS MEMORY IN CHILDREN UNDERGOING MYRINGOTOMY

Dalhousie University and IWK Health Centre, 5850 University Ave., Halifax, NS

INTRODUCTION

Benzodiazepines such as midazolam are commonly used as a preoperative medicant for children undergoing surgery (Kain et al., 1997). Lab studies indicate that benzodiazepines impair memory and attention and increase sedation, (Buffett-Jerrott & Stewart, in press). We attempted to extend previous lab findings to the surgery context and to a pediatric sample.

METHODS

Approval was obtained from the hospital REB. Participants were forty 4-6 year olds undergoing myringotomy, randomly assigned, in a double blind fashion, to receive either oral midazolam 0.50 mg/kg mixed with acetaminophen suspension (midazolam group) or acetaminophen alone (placebo group). After drug ingestion, children encoded a set of pictures either well before the theoretical peak blood concentration of midazolam (5 minutes post-drug) or closer to theoretical peak (20 minutes post-drug). Memory for the pictures was tested both pre- and post-surgery with a cued recall test (i.e., items from zoo, kitchen, park, or restaurant; cf. Greenbaum & Graf, 1989). Attention and sedation (observer-rated and objective) were also assessed. After surgery, children freely recalled surgery day events. Events were classified as to whether they likely occurred during the drug influence window.

RESULTS

Midazolam caused impairments relative to placebo on the cued recall test, even when encoding occurred at 5 minutes post-drug (Fig 1). These memory impairments persisted at post-surgery when the acute effects of the drug had worn off (Fig 2). Free recall of post-drug surgery day events was also impaired by midazolam (p< .05). Although midazolam produced impairments relative to placebo on the attention task variables (p's < .05) and was associated with increased levels of sedation on the observer-rated (p < .005) and objective (p < .01) measures, analyses of covariance indicated that midazolam induced amnesia was not completely secondary to these other cognitive effects.

View larger version (15K): [in this window] [in a new window]   FIGURE 1 Cued Recall Performance: Mean number of pictures correctly recalled on the recall test as a function of Drug Group, at each Encoding Time (pre-surgery period). Bars represent standard errors.

View larger version (17K): [in this window] [in a new window]   FIGURE 2 Cued Recall Performance: Mean number of pictures correctly recalled on the cued recall test as a function of Drug Group, at each Encoding Time (post-surgery period). Bars represent standard errors.

Results extend to children and to a surgery context, lab findings that benzodiazepines cause amnesia. Midazolam's amnestic effects appear to occur for material encoded even shortly after the drug is ingested (even highly-salient material), and persist following surgery.

REFERENCES

1 Anaesthesia & Analgesia, 84, 427-432.

2 Current Pharmaceutical Design, in press.

3 Bulletin of the Psychonomic Society, 27, 417-420.

This Article Full Text (PDF) Submit a scholarly reply Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Stewart, S. H. Articles by Loughlin, H. L. Search for Related Content PubMed Articles by Stewart, S. H. Articles by Loughlin, H. L.