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SUMMARY
This randomised, double-blinded, placebo-controlled study was primarily aimed to evaluate the potential of risperidone to prevent postoperative delirium following cardiac surgery with cardiopulmonary bypass and the secondary objective was to explore clinical factors associated with postoperative delirium.
One-hundred-and-twenty-six adult patients undergoing elective cardiac surgery with cardiopulmonary bypass were randomly assigned to receive either 1 mg of risperidone or placebo sublingually when they regained consciousness. Delirium and other outcomes were assessed. The confusion assessment method for intensive care unit was used to assess postoperative delirium.
The incidence of postoperative delirium in the risperidone group was lower than the placebo group (11.1% vs. 31.7% respectively, P=0.009, relative risk-0.35, 95% confidence interval [CI]=0.16-0.77). Other postoperative outcomes were not statistically different between the groups. In exploring the factors associated with delirium, univariate analysis showed many factors were associated with postoperative delirium. However multiple logistic regression analysis showed a lapse of 70 minutes from the time of opening eyes to following commands and postoperative respiratory failure were independent risk factors (P=0.003, odds ratio [OR]=4.57, 95% CI=1.66-12.59 and P=0.038, OR=13.78, 95% CI=1.15-165.18 respectively).
A single dose of risperidone administered soon after cardiac surgery with cardiopulmonary bypass reduces the incidence of postoperative delirium. Multiple factors tended to be associated with postoperative delirium, but only the time from opening eyes to following commands and postoperative respiratory failure were independent risk factors in this study.
Key Words: delirium, postoperative, cardiac surgery, risperidone, antipsychotic
Delirium is a disturbance of consciousness characterised by an acute onset and fluctuating course of impaired cognitive function caused by the direct physiological consequences of general medical conditions'. Postoperative delirium is one of the most common neuropsychiatrie problems following cardiac surgery23. Current management is generally to identify and correct the underlying medical conditions with symptomatic control after the diagnosis was made. Due to the frequency of occurrence and the associated increased morbidity and mortality, intervention to control this complication is important. However, there is limited data supporting effective measures for the prevention of postoperative delirium4.
Risperidone is a second generation antipsychotic in the chemical class of benzisoxazole derivatives. Risperidone is approved by the Food and Drug Administration for the treatment of bipolar I disorder. Previous studies of risperidone in treating delirium revealed favourable efficacy with few side-effects5 8.
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