EEG-derived pain threshold index for prediction of postoperative pain in patients undergoing laparoscopic urological surgery: a comparison with surgical pleth index.

Recently a novel pain recognition indicator derived from electroencephalogram(EEG) signals, pain threshold index(PTI) has been developed. The aim of this study was to determine whether PTI can be used for prediction of postoperative acute pain while surgical pleth index(SPI) applied as control. Eighty patients undergoing laparoscopic urological surgery under general anesthesia were enrolled. Data of SPI, PTI and a sedative index-wavelet index(WLI) were recorded within last 10 min at the end of surgery. The postoperative pain scores (NRS, numerical rating scale) were obtained. The Bland-Altman analysis was used for evaluation of consistency between PTI and SPI, whereas receiver-operating characteristic (ROC) curves was used for the mean values of PTI, SPI, and WLI to distinguish between mild (NRS 0-3) and moderate-severe (NRS 4-10) pain, and calculate their "best-fit" cut-off values. Data from 76 patients were included for final analysis. There was a good agreement between SPI and PTI values at the end of surgery. The ROC analysis showed a cut-off PTI value of 53 to discriminate between mild and moderate-to-severe pain, while SPI is 44 for this discrimination. Further analysis indicated that PTI had a best predictive accuracy reflected by highest area under curve (AUC)(0.772, 95% CI: 0.661-0.860)with sensitivity(62.50%) and specificity(90.91%) and a best positive predictive value(83.3%,95% CI: 68.4-98.2%). PTI obtained at the end of surgery, which have better predictive accuracy for postoperative pain than SPI, could differentiate the patients with moderate-to-severe pain from those with mild pain after they awaken from anesthesia.Clinical trial registration Chinese Clinical Trials Registry: ChiCTR1900024789.

[Influence of neuromuscular blockade on motor evoked potential of forearm muscles].

OBJECTIVE: To investigate the influence of different degrees of neuromuscular blockade on motor evoked potential (MEP) of forearm muscles under the same condition of anesthesia depth and analgesia. METHODS: Forty ASA I - II patients aged 20 - 60 underwent general anesthesia via intravenous injection of propofol, fentanyl, and vecuronium to achieve the bispectral index (BIS) at the level of (50 + 10) during neurosurgical operation. The patients were all given fentanyl infusion at a rate of 2 microg/kg/h during the operation and continuous vecuronium injection while the value of train of four stimulations (TOF) was monitored under 3 different levels: TOF = 4 (TOF(4)), TOF = 2 (TOF(2)), and TOF = 0 (TOF(0)). The values of amplitude and latency at the 3 forearm muscles, forearm flexors (FF), abductor pollicis brevis (APB), and abductor digiti minimi (ADM) were monitored and compared under stable hemodynamic status. RESULTS: There was no significant differences in the latency of compound muscle action potential (CMAP) between the anesthesia status TOF(4) and anesthesia status TOF(2) in FF, APB, and ADM (all P > 0.05). The amplitude of CMAP deceased gradually as the degree of neuromuscular blockade increased in FF, APB, and ADM (all P < 0.05). CMAP could not be recorded when the value of TOF was 0 (P < 0.01). CONCLUSION: Neuromuscular blocking drugs significantly depress the MEP in a dose-dependent manner. Intra-operatively it may be preferable to maintain the value of TOF not less than 2 during the critical periods of MEP monitoring.

The effects of P6 electrical acustimulation on postoperative nausea and vomiting in patients after infratentorial craniotomy.

BACKGROUND: Postoperative nausea and vomiting (PONV) are frequent and harmful complications after neurosurgery. Current pharmacy-based treatment is the standard of care; it, however, lacks efficiency. Invasive and noninvasive acupuncture at the P6 meridian point has been shown to be effective in the prevention of PONV. We evaluated the effectiveness of transcutaneous electrical acupoint stimulation (TEAS) at P6 for the prophylaxis of PONV in patients undergoing infratentorial craniotomy. METHODS: In this prospective, blind, and randomized study, patients received TEAS at P6 on the dominant side starting 30 minutes before the induction of anesthesia and up to 24 hours after surgery or sham acustimulation at P6. The anesthesia was maintained with sevoflurane/remifentanil and intermittent fentanyl/cisatracurium. Antiemetics with 4 mg ondansetron and 10 mg dexamethasone were administered intraoperatively. Data documenting postoperative episodes of nausea and vomiting and the need for antiemetic rescue (10 mg metoclopramide intramuscularly) were collected. Statistical analysis was performed using the χ test. P<0.05 was considered to be significant. RESULTS: Of the 130 patients enrolled, 119 patients completed the study. The 24-hour cumulative incidence of vomiting was significantly lower in the TEAS group than in the control group (22% vs. 41%, P=0.025). The cumulative incidences of nausea at 6 hours (27% vs. 47%, P=0.019) and 24 hours (33% vs. 58%, P=0.008) after surgery were also significantly lower in the TEAS group compared with the control group. The overall requirements of rescue antiemetics were similar between the groups. CONCLUSION: Perioperative TEAS at P6 may be an effective adjunct to the standard antiemetic drug therapy for the prevention of PONV after infratentorial craniotomy.