ABSTRACT
Objective To assess the changes in the effect compartment concentration (Ce) and bispectral index (BIS) during a step-by-step TCI of propofol in the elderly.Methods Ten ASA Ⅰ -Ⅱ patients (6 male, 4 female) aged 67-77yr and weighing 51-78kg, undergoing elective surgery were studied. Patients with severe cardiovascular disease were excluded. The patients were unpremedicated. Anesthesia was induced with propofol administered by a TCI system (Diprifusor) . The target concentration (Ct) of propofol was increased step-by-step from 1?g?ml-1 to 4?g?ml-1 in 6 steps. At each step Ct increased by 0.5?g?ml-1 and the interval between the two steps was 2min. The changes in Ce (calculated and displayed by Diprifusor) and BIS were recorded. Modified OAA/S sedation score were measured. Blood samples were taken from artery for determination of blood concentration of propofol (Cb) before TCI (T0 ) and when Ct was 1, 2, 3, and 4?g*******ml-1 (T1-4) in 5 randomly selected patients.Results (1) Ce consistently increased with the increase in Ct and there was a delay between Ct and Ce. When Ct was increased to 4?g*******ml-1, it took (14.4 ? 0.5) min to achieve the balance between Ct and Ce. (2) Cb of propofol was higher than Ct of propofol at each step. MDPE and MDAPE was 9.7% and 11.2% respectively. (3) There was a close correlation between BIS and Ct, Ce and OAA/S score( r = - 0.878, - 0.888 and 0.913 respectively , P