Optimal propofol plasma concentration during upper gastrointestinal endoscopy in young, middle-aged and elderly patients

Background: Suitable propofol plasma concentrations during gastroscopy have not been determined for suppressing somatic and hemodynamic responses in d ifferent age groups. Methods: Propofol sedation at target plasma concentrations from 0.5 to 4.0 mu g/ml were performed randomly in three groups of patients (23 per group) who were undergoing elective outpatient gastroscopy: ages 17-49 yr (group 1 ), 50-69 yr (group 2), and 70-89 yr (group 3). Plasma propofol concentratio n in which 50% of patients do not respond to these different stimuli were d etermined by logistic regression: verbal command (Cp(50)ls), somatic respon se to gastroscopy (Cp(50)endo), and gag response to gastroscopy (Cp(50)gag) . Hemodynamic responses were also Investigated in the different age groups. Results: Cp(50)ls concentrations were 2.23 mu g/ml (group 1), 1.75 mu g/ml (group 2), and 1.40 mu g/ml (group 3), The Cp(50)endo values in groups 1 an d 2 were 2.87 and 2.34 mu g/ml, respectively, which were significantly high er than their respective Cp(50)ls values. Cp(50)endo value in group 3 was 1 .64 mu g/ml, which was close to its Cp(50)ls value. Because of a high degre e of Interpatient variability, Cp(50)gag could not be defined. Systolic blo od pressure response decreased with Increasing propofol concentrations. Conclusions: The authors determined the propofol concentration necessary fo r gastroscopy and showed that increasing age reduces it, Propofol concentra tion that suppresses somatic response induces loss of consciousness in almo st all young patients.