Determination of the 50% effective concentration of dexmedetomidine as an adjuvant in combined spinal-epidural anesthesia with Narcotrend / 南方医科大学学报

<p><b>OBJECTIVE</b>To determine the 50% effective concentration (EC(50) ) of dexmedetomidine (DEX) as an adjuvant for achieving the minimal effect in combined spinal-epidural anesthesia (CSEA) with Narcotrend.</p><p><b>METHODS</b>Thirty ASA class I-II patients undergoing CSEA were allocated to receive 0.5% bupivacaine injection (2 ml) in the subarachnoid space, followed by a target-controlled infusion of DEX for at least 60 min. The target concentration of DEX was adjusted according to the response of the previous patient using a double-blind, up-and-down sequential method. The initial DEX concentration of the first patient was 0.5 ng/ml. An Observers Assessment of Alertness/Sedation Scale (OAA/S) score of no more than 3 within 30 min defined an effective sedation. The Narcotrend index (NTI) related to the OAA/S score was recorded as well. The correlation between Narcotrend and OAA/S score was analyzed.</p><p><b>RESULTS</b>The EC(50) of DEX as an adjuvant in CSEA was 0.35∓0.07 ng/ml. The NTI was positively correlated to the OAA/S score (r=0.967, P=0.000). The regression equation was OAA/S =-3.922+0.094NTI (F=401.710, P=0.000).</p><p><b>CONCLUSION</b>We suggest a novel protocol using DEX as a adjunct in CSEA. The EC(50) % of DEX to result in ideal sedation (OAA/S≤3) was 0.35∓0.07 ng/ml. NTI may serve as an objective index for sedation assessment in CSEA.</p>

Effect of the degree of muscle relaxation on motor-evoked potential elicited by transcranial electrical stimulation in spine surgery / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the effect of the degree of muscle relaxation on motor-evoked potential elicited by transcranial electrical stimulation in patients undergoing spine surgery.</p><p><b>METHODS</b>Sixty ASA I or II patients undergoing spine surgery were randomly divided into 5 groups (n=12). After an initial intubation, continuous cisatracurium infusion was administered with continuous monitoring of T1. The infusion dose was adjusted according muscle relaxation monitoring, and different muscle relaxation degrees were maintained in the 5 groups. The band and latency of D1 in motor-evoked potential was observed with also subjective assessment of the muscle relaxation.</p><p><b>RESULTS</b>Significant differences in the band and latency were noted in groups I and II compared with the reference values, but not in groups III, IV and V. Subjective assessment revealed significant differences between groups IV and V and groups I and III in terms of the number of cases with poor muscle relaxation.</p><p><b>CONCLUSION</b>T1 value between 10% and 15% is sufficient for MEP monitoring and allows the maintenance of good muscle relaxation during spine surgery.</p>

Influence of epidural ropivacaine in combination with fentanyl for labor analgesia on the clinical outcome of labor / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effect of epidural ropivacaine in combination with fentanyl for labor analgesia on the clinical outcome of labor.</p><p><b>METHODS</b>A retrospective study was conducted involving 281 healthy primiparas, including 106 undergoing spontaneous labor who received epidural 0.15% ropivacaine in combination with fentany (1microg/ml) and 175 without epidural analgesia. The active phase duration, durations of each labor stages, delivery modes, management of labor, postpartum hemorrhage, incidence of fetal distress and asphyxia neonatorum were recorded in the two groups. The visual analogue scale (VAS) was used to assess the pain of uterine contraction, and modified Bromage scoring system applied to evaluate the lower limb motor block.</p><p><b>RESULTS</b>There were no significant differences in the duration of the first, third or the total labor stages between the two groups, but the second labor stage was prolonged in the labor analgesia group. The ratio of spontaneous labor, assisted vaginal delivery, and incidence of asphyxia neonatorum were higher, whereas the duration of the active stage was shortened in the analgesia group.</p><p><b>CONCLUSION</b>Epidural ropivacaine in combination with fentanyl in labor can decrease the incidence of cesarean section, and the duration of the active stage can be shortened with application of ocytocin.</p>