title: Age influences the minimum infusion rate (ED50) for continuous infusions of Althesin and methohexitone.
abstract: The influence of age has been studied on equipotent rates of continuous infusions of two intravenous hypnotic agents. Two end points have been defined; ED50: the rate needed to suppress the initial response to the surgical incision in 50% of patients, and ED95: the corresponding rate in 95% of patients receiving continuous infusion anaesthesia to supplement 67% nitrous oxide in oxygen. All 210 patients included in the study were premedicated with morphine 0.15 mg kg-1. For patients aged 20-40 years (young group), the ED50 values for Althesin (as alphaxalone) and methohexitone were 14.6 micrograms kg-1 min-1 and 59.9 micrograms kg-1 min-1. The ED95 values were 21.0 micrograms kg-1 min-1 and 92.1 micrograms kg-1 min-1. For patients aged 55-80 years (old group), the ED50 values for Althesin and methohexitone were 11.0 micrograms kg-1 min-1 and 44.2 micrograms kg-1 m in-1, while the corresponding ED95 values were 16.4 micrograms kg-1 min-1 and 76.2 micrograms kg-1 min-1.
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging; D000530:Alfaxalone Alfadolone Mixture / Q000008:administration & dosage*; D000771:Anesthesia, Intravenous; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008723:Methohexital / Q000008:administration & dosage*; D008875:Middle Aged; D009020:Morphine; D009609:Nitrous Oxide; D011292:Premedication
chemical_list: D009020:Morphine; D000530:Alfaxalone Alfadolone Mixture; D008723:Methohexital; D009609:Nitrous Oxide