NONINVASIVE DETECTION OF BRAIN ACTIVITY VARIATION UNDER DIFFERENT DEPTH OF ANESTHESIA BY EEG COMPLEXITY

Objective To detect the change of brain activity under different depth of anesthesia (DOA) noninvasively. Methods The Lempel-Ziv complexity C(n) was used to analyze EEG and its four components (delta, theta, alpha, beta), which was recorded from SD rats under different DOA. The relationship between C(n) and DOA was studied. Results The C(n) of EEG will decrease while the depth of anesthesia increasing and vice versa. It can be used to detect the change of DOA sensitively. Compared with power spectrum, the change of C(n) is opposite to that of power spectrum. Only the C(n) of delta rhythm has obvious variations induced by the change of DOA, and the variations of delta is as similar as the EEG's. Conclusion The study shows that the desynchronized EEG is replaced by the synchronized EEG when rat goes into anesthesia state from awake, that is just the reason why complexity and power spectrum appear corresponding changes under different DOA. C(n) of delta rhythm dynamic change leads to the change of EEG, and the delta rhythm is the dominant rhythm during anesthesia for rats.

Relationship between depth of anesthesia and effect-site concentration of propofol during induction with the target-controlled infusion technique in elderly patients

Background There are few studies to assess whether the effect-site concentration of propofol can predict anesthetic depth during the target-controlled infusion （TCI） induction in elderly patients. This study aimed to evaluate the relationship between effect-site concentration of propofol and depth of anesthesia during the TCI induction in elderly patients. Methods Ninety patients （60-80 years） with an American Society of Anesthesiologists （ASA） physical status of 1-3, undergoing scheduled abdominal and thoracic surgery under general anesthesia were randomly allocated into one of three groups, Group S1, S2 and S3 （30 patients in each group）. The patients in Group S1 received propofol with a target plasma concentration of 4.0 pg/ml; patients in Group S2 received propofol with an initial target plasma concentrations of 2.0 IJg/ml that was raised to 4.0 pg/ml 3 minutes later; patients in Group S3 received an infused scheme of 3 steps; starting from a target plasma concentration of 2.0 pg/ml that was increased stepwised by 1 pg/ml until a target plasma concentration of 4.0 pg/ml was achieved, the interval between the two steps was 3 minutes. When an Observer＇s Assessment of Alertness/Sedation （OANS） score of 1 was achieved, remifentanil （effect-site concentration （Ce） of 4.0 ng/ml） and rocuronium 0.9 mg/kg were administered. Tracheal intubation was started 2 minutes after rocuronium injection. Changes of propofol Ce, blood pressure （BP）, heart rate （HR）, and bispectral index （BIS） were recorded. Results When an OAA/S score of 1 was achieved, Ce of propofol were （1.7±0.4） pg/ml, （1.9±0.3） pg/ml, （1.9±0.4） pg/ml and the BIS values were 64±5, 65±8, and 62±8 in Groups S1, S2 and S3. Before intubation, Ce of propofol was （2.8±0.2） pg/ml, （2.8±0.3） pg/ml, （2.7±0.3） pg/ml, and the BIS values were 48±7, 51±7, and 47±5 in Groups S1, S2 and S3. By linear regression analysis, a significant correlation between Ce of propofol and BIS values was found （r=-0.580, P 〈0.01）. Systolic blood pressure （SBP） before intubation was significantly lower in Group S1 than in Groups S2 and S3. SBP and HR after intubation in the three groups were significantly increased when compared with pre-intubation values, but they did not exceed baseline values Conclusions During the TCI induction, Ce of propofol with （1.9±0.3） pg/ml may make the elderly patients unconscious. When remifentanil with a Ce of 4.0 ng/ml is added a Ce of propofol with （2.8±0.3） pg/ml is suitable for intubation. The Ce of propofol has a close correlation with the BIS values. Also, a two-step TCI technique seems to be a more suitable method of anesthesia induction in elderly patients compared with the no-stepwise TCI technique and three-step TCI technique.

Wavelet and pain rating index for inhalation anesthesia: A randomized controlled trial

BACKGROUND Wavelet index(WLi)and pain rating index(PRi)are new parameters for regulating general anesthesia depth based on wavelet analysis.AIM To investigate the safety and efficacy of using WLi or PRi in sevoflurane anesthesia.METHODS This randomized controlled trial enrolled 66 patients scheduled for elective posterior lumbar interbody fusion surgery under sevoflurane anesthesia between September 2017 and February 2018.A random number generator was used to assign the eligible patients to three groups:Systolic blood pressure(SBP)monitoring group,WLi monitoring group,and PRi monitoring group.The main anesthesiologist was aware of the patient grouping and intervention used.The primary endpoint was anesthesia recovery time.Secondary endpoints included extubation time,sevoflurane consumption,number of unwanted events/interventions,number of adverse events and postoperative visual analogue scale for pain.RESULTS A total of 62 patients were included in the final analysis(SBP group,n=21;WLi group,n=21;and PRi group,n=20).There were no significant differences among the three groups in patient age,gender distribution,body mass index,American Society of Anesthesiologists class,duration of surgery,or duration of anesthesia.Anesthesia recovery time was shorter in the WLi and PRi groups than in the SBP group with no significant difference between the WLi and PRi groups.Extubation time was shorter in the WLi and PRi groups than in the SBP group.Sevoflurane consumption was lower in the WLi and PRi groups than in the SBP group.Nicardipine was more commonly needed to treat hypertension in the WLi and PRi groups than in the SBP group.CONCLUSION Regulation of sevoflurane anesthesia depth with WLi or PRi reduced anesthesia recovery time,extubation time and sevoflurane consumption without intraoperative unwanted events.