• T Kazama, K Takeuchi, K Ikeda, T Ikeda, M Kikura, T Iida, S Suzuki, H Hanai, and S Sato.
• Departments of Anesthesiology and Intensive Care and Endoscopic and Photodynamic Medicine, Hamamatsu University School of Medicine, and the Center for Digestive Disease, Hamamatsu South Hospital, Hamamatsu, Japan. tkazama@hama-med.ac.jp
• Anesthesiology. 2000 Sep 1; 93 (3): 662-9.

BackgroundSuitable propofol plasma concentrations during gastroscopy have not been determined for suppressing somatic and hemodynamic responses in different age groups.MethodsPropofol sedation at target plasma concentrations from 0.5 to 4.0 microgram/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 concentration in which 50% of patients do not respond to these different stimuli were determined by logistic regression: verbal command (Cp50ls), somatic response to gastroscopy (Cp50endo), and gag response to gastroscopy (Cp50gag). Hemodynamic responses were also investigated in the different age groups.ResultsCp50ls concentrations were 2.23 microgram/ml (group 1), 1.75 microgram/ml (group 2), and 1.40 microgram/ml (group 3). The Cp50endo values in groups 1 and 2 were 2.87 and 2.34 microgram/ml, respectively, which were significantly higher than their respective Cp50ls values. Cp50endo value in group 3 was 1.64 microgram/ml, which was close to its Cp50ls value. Because of a high degree of interpatient variability, Cp50gag could not be defined. Systolic blood pressure response decreased with increasing propofol concentrations.ConclusionsThe authors determined the propofol concentration necessary for gastroscopy and showed that increasing age reduces it. Propofol concentration that suppresses somatic response induces loss of consciousness in almost all young patients.

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