Effect of Intravenous Propofol Anesthesia Induction on Cardiac Function

Study population After approval by the institutional ethics committee and written informed consent, we prospectively enrolled adult patients who were scheduled for elective non-cardiac surgery. During the preoperative anesthesia visit, we selected patients with low-risk as indicated by the revised cardiac risk index of 0 and normal LV function (ejection fraction ≥ 60% and septal e' ≥ 8 cm/s). We excluded patients with an arrhythmia, poor lateral axis in supine position, regional wall motion abnormality, or other structural heart diseases. Patients with any of the following conditions were also excluded: unfavorable airway or facemask fit, intractable coughing, hiccups, or hypotension (mean BP < 60 mmHg) requiring IV positive inotropes or vasoconstrictors during the study period.

Anesthesia induction Upon each patient's arrival at the holding area, we placed an 18-gauge IV line in the right forearm vein and administered 10 mL/kg/hour of lactated Ringer's solution, 0.2 mg of glycopyrrolate, and 0.03 mg/kg of midazolam, as a premedication. Once in the operation room, we started to monitor electrocardiography, non-invasive BP, HR, pulse oximeter oxygen saturation, and the bispectral index (BIS). Anaesthesia induction was started in the following manner. Patients took a spontaneous respiration with inspired oxygen (8 L/min) through a transparent facemask and a circulation system with a reservoir bag. Bolus propofol (2.0 mg/kg) was administered intravenously for 10 seconds, after which assisted ventilation followed. After 5 minutes, complete induction was confirmed via a lack of train-of-four response and followed by tracheal intubation for maintenance anesthesia.

Intraoperative transthoracic echocardiography: Imaging After positioning the patient supine on the operation table, serial transthoracic echocardiography was performed with a portable GE Vivid Q platform (General Electric, Milwaukee, WI), before (T0) and 1, 3, and 5 minutes after the propofol bolus injection (T1, T2 and T3, respectively) along with hemodynamic recordings at the same time (BP, HR, and BIS). Two-dimensional imaging of parasternal and apical views and pulsed wave (PW) Doppler imaging of mitral inflow & LV outflow were performed. DTI was recorded at both septal and lateral mitral annulus from the apical 4-chamber view to determine longitudinal endocardial velocities with a sweep of 66.7 mm/s. Each set of images required less than 30 seconds.