Sedation with Flunitarazepam at Magnetic Resonance Imaging in the Elderly Patients with Dementia

Magnetic resonance imaging (MRI) of the brain is useful in diagnosing senile dementia, but to avoid the creation of artifacts the patient should be kept immobile. We studied the effects of pretreatment with flunitrazepam, a sleep inducer of the benzodiazepine class, as a sedative prior to imaging. The subjects consisted of 108 patients with senile dementia admitted to the Dementia Ward of Kyoto Higashiyama Geriatric Hospital. Their ages ranged from 64-95 years (mean, 81) and the mean body weights of the 76 women and 32 men were 36 and 47kg, respectively. Immediately before undergoing MRI the patients were given a slow intravenous injection of flunitrazepam (2mg/ml diluted in 19ml of saline). Immediately before the patients fell asleep, administration was discontinued and the dose was noted: mean 0.008mg/kg. In all patients sleep induction and sedation were achieved. No adverse reactions such as apnea were observed. The flunitrazepam dose in our study was much lower than that in previous reports on adults. As body weights of the elderly are also lower than those of younger adults, the optimum dose of flunitrazepam for the elderly may be much lower. Intravenous flunitrazepam may be a useful and safe premedication for MRI in elderly patients with dementia. To avoid serious adverse reactions the dose should be minimized by: 1) determining body weight before MRI, 2) administering diluted flunitrazepam, and 3) discontinuing the drug before the patient falls asleep.