Children Undergoing Repeated Exposures for Radiation Therapy Do Not Develop Tolerance to Propofol: Clinical and Bispectral Index Data

Background: The purpose of this study was to apply clinical criteria and Bispectral Index® monitor data for evaluating the development of tolerance to propofol in children undergoing repeated drug exposure. Methods: Children undergoing multiple sessions of radiation therapy during anesthesia for various malignancies were given a predetermined dose of propofol at each session. Heart rate, blood pressure, oxygen saturation, respiratory rate, requirement of additional propofol, and time to emergence and discharge were recorded. The Bispectral Index was monitored continuously, and parameters were extracted and averaged for each week of therapy. Results: Fifteen children (aged 2.5-10 yr) were treated for an average of 5 weeks (24 ± 6 sessions). There were no significant differences in physiologic parameters or requirements of additional propofol between the weeks of treatment. Bispectral Index data analysis showed that although a nonlinear change with time for each parameter could not be rejected, the differences between the first and last intervals were nonsignificant. Conclusions: Overall changes with time resulted from random fluctuations without a consistent trend. Combined with clinical data, Bispectral Index parameters showed that tolerance to propofol does not develop in children undergoing repeated exposures to the drug during radiation therapy.