[Feasibility analysis of wavelet index for monitoring the depth of anesthesia in patients undergoing general anesthesia].

Objective: To evaluate the value of wavelet index (WLI) in general anesthesia through a comparison of WLI with bispectral index (BIS).

Methods: A total of 53 patients scheduled for elective surgery with ASA (American Society of Anesthesiologists) I-II were selected to undergo general anesthesia. The monitoring probes of BIS, WLI and muscle relaxation were connected in awaking patients. The values of WLI and BIS were recorded at 10 min (T₁) entering OR (operating room), immediate before anesthesia induction (T₂), when the OAA/S (observer's assessment of alertness/sedation) score declined gradually to 5(T₃), 4(T₄), 3(T₅), 2(T₆), 1(T₇) after the infusion of propofol, after vecuronium given when the TOF value decreased to 100 (T₈), 75(T₉), 50 (T₁₀), 25 (T₁₁), 0 (T₁₂) after the injection of vecuronium, tracheal intubation (T₁₃), 1 min (T₁₄), 3 min (T₁₅) and 5 min (T₁₆) after the completion of tracheal intubation, immediate before initiating surgical procedure (T₁₇), beginning the operation (T₁₈), 1 min (T₁₉), 3 min (T₂₀), 5 min (T₂₁) post-operation, skin suturing (T₂₂), end of surgery (T₂₃), tracheal extubation (T₂₄), 1 min (T₂₅) and 5 min (T₂₆)cd post-extubation, immediate before exiting OR (T₂₇).

Results: The value of WLI at T₁₀-T₁₃, T₂₂-T₂₇ was more than BIS (P < 0.05). The Bland-Altman analysis showed that WLI was accepted comparing with BIS during the period of anesthesia. The bias was -2.99, 95% limits of agreement -29.97% to 21.56%. The correlation coefficients of OAA/S score with BIS and WLI were: r(BIS) = 0.884, r(WLI) = 0.757 (P = 0.000).

Conclusion: WLI index is feasible for monitoring the depth of general anesthesia.