Effective plasma concentration of propofol impacting the myocardial contractility of patients aged 60-69 using echocardiography

Objective To investigate the effective plasma concentration of propofol that impacts the myocardial contractility in patients aged 60-69 by echocardiography combined with target-controlled infusion(TCI) technique. Methods Fifty patients aged 60 to 69, classified as ASA physical statusⅠ,Ⅱ, without cardiovascular diseases, were scheduled for elective surgery under general anesthesia. The patients were randomly allocated into five groups(group Ⅰ-Ⅴ), respectively received propofol via plasma TCI with initial plasma concentration of 3.5, 4.0, 4.5, 5.0, 5.5 mg/L. SBP, DBP and HR were recorded by a non-invasive monitoring, and echocardiography was used to record the left ventricular motions, the left ventricular diastolic diameter(Dd), the end systolic diameter(Ds), the left ventricular ejection fraction(EF), the left ventricular fractional shortening(FS), and the heart cardiac output(CO). The parameters were measured before injection (T0), 1 minute (T1), 3 minutes (T2), 5 minutes (T3), 8 minutes (T4) and 10 minutes (T5) after propofol injection. Probability unit regression analysis was used to calculate the EC50 of which the EF and FS decreased by 10% and 20%. Results Compared to T0, the SBP, DBP and CO at T2-T5 were decreased in all groups(P 0.05). Compared to group Ⅰ, the EF and FS at T3-T5 were decreased in group Ⅱ-Ⅴ (P<0.05). Compared to group Ⅳ, the EF and FS at T3 and T4 were decreased in group Ⅴ(P<0.05). The EC50 for decreasing the EF by 10% and 20% was 4.40 mg/L and 5.20 mg/L, respectively. The EC50 for decreasing the FS by 10% and 20% was 4.01 mg/L and 5.20 mg/L, respectively. Conclusions Propofol at plasma concentrations of 4.0-5.5 mg/L dose-dependently inhibited the myocardial contractility in patients aged 60-69. Key words: Propofol; Dose-response relationship; Myocardial contractility; Echocardiography