Some studies have compared the clinical profile during propofol induction anesthesia with Target-controlled infusion (TCI) and manually bolus showed similar control of anesthesia, such as depth of anaesthesia and hemodynamic stability, but did not use an objective measure of instantaneous autonomic activity during the brief time of induction anesthesia. In this study, TCI and manually bolus of propofol injection techniques during induction were studied with wavelet-based spectral analysis and the amplitudes of the pulse plethysmographic. The investigators hypothesized that during propofol induction anesthesia, the instantaneous ANS activities was more stable with TCI than traditional manually bolus

Propofol induction anesthesia has been reported to be associated with cardiovascular depression and autonomic nervous system (ANS), which is an important neural control system for maintaining cardiovascular stability and plays a major role in regulating cardiovascular homeostasis. There are many methods for the administration induction of propofol, such as a manually bolus or target-controlled infusion (TCI) techniques. TCI devices could rapidly achieve and maintain the desired predicted concentration and is a more satisfactory technique to reduce the incidence of side effects and with the advantage of better hemodynamic control. More precise knowledge of how anesthetic agents modify ANS activity is important for understanding subsequent cardiovascular responses. However, there was no study using validated measurement of ANS index comparing propofol induction anaesthesia with TCI or manually bolus would have different effects on ANS.

Inclusion Criteria:

• patients scheduled for surgery under general anesthesia

Exclusion Criteria:

• recent administration of sedative or opioid drugs
• emergency surgery
• impairment of renal, hepatic, cardiac or respiratory function

The subjects were selected from patients scheduled for surgery under general anesthesia. Exclusion criteria were recent administration of sedative or opioid drugs, emergency surgery and impairment of renal, hepatic, cardiac or respiratory function. No sedative or opioid drugs were administered before induction of anaesthesia.