Level of sedation evaluation with Cerebral State Index and A-Line Arx in children undergoing diagnostic procedures

BACKGROUND: Monitoring of anesthesia depth is difficult clinically, particularly in children. The aim of this study was to assess the correlation existing between CSI (Cerebral State Index), or AAI (A-line ARX) and a clinical sedation scale such as UMSS (University of Michigan Sedation Scale), during deep sedation with propofol in children undergoing diagnostic procedures. METHODS: Twenty ASA I and II children, scheduled to undergo deep sedation for magnetic resonance imaging (MRI) or Esophagogastroduodenoscopy (EGDS), were enrolled. The patients were randomly assigned to receive depth of anesthesia monitoring with CSI or AAI. The anesthetist administered repeated doses of propofol every 10 s to a UMSS score of 3-4. An attending anesthetist, not involved in drug administration, recorded time and doses of sedation medications, vital signs, UMSS score and CSI or AAI score. All the evaluations were recorded at awake state (baseline), every 10 s until an UMSS score of 3-4 and every 3 min until the children were awake. RESULTS: We enrolled 13 males and seven females ranging in age from 8 months to 7 years. After induction of anesthesia CSI and AAI scores decreased and from the end of the procedure to emergence the two scores increased. The CSI data showed a strong correlation with the UMSS scores (r = -0.861; P < 0.0001); we found a similar correlation between the AAI data and the UMSS scores (r = -0.823; P < 0.0001). CONCLUSIONS: Our study suggests that CSI and AAI may be two, real-time and objective tools to assess induction and emergence during propofol sedation in children undergoing EGDS and MRI.     

Midazolam dose for loss of response to verbal stimulation during the unilateral or bilateral spinal anesthesia

Background: We have conducted this study to investigate whether unilateral or bilateral spinal anesthesia with bupivacaine induces different sensitivity to intravenous (i.v.) midazolam for sedation.
Methods: Forty-two patients undergoing various elective unilateral lower extremity surgeries were allocated into two groups: (1) unilateral spinal anesthesia group (Group US, n =21; heavy bupivacaine 5 mg/ml, 9 mg) and (2) bilateral spinal anesthesia group (Group BS, n =21; heavy bupivacaine 5 mg/ml, 9 mg). One milligram of midazolam was injected i.v. at 30-s intervals until the patients did not respond to the hand grasp test beginning 15 min after spinal anesthesia. The concentration of plasma bupivacaine was evaluated every 15 min for the first 75 min after the start of the spinal anesthesia, and the bispectral index was monitored continuously.
Results: The mean venous plasma concentration of bupivacaine was not significantly different between Group US and BS. The dose of midazolam required to abolish responses to verbal commands was significantly lower in Group BS (mean 5.9±1.2 mg) vs. Group US (mean 9.0±1.4 mg).
Conclusions: A higher dosage of midazolam is required for loss of response to verbal stimulation during unilateral spinal anesthesia than during bilateral spinal anesthesia.     

Sedation during spinal anesthesia

BACKGROUND: Central neuraxial anesthesia has been reported to decrease the dose of both intravenous and inhalational anesthetics needed to reach a defined level of sedation. The mechanism behind this phenomenon is speculated to be decreased afferent stimulation of the reticular activating system. The authors performed a two-part study (nonrandomized pilot study and a subsequent randomized, double-blind, placebo-controlled study) using the Bispectral Index (BIS) monitor to quantify the degree of sedation in unmedicated volunteers undergoing spinal anesthesia. METHODS: Twelve volunteers underwent BIS monitoring and observer sedation scoring (Observer's Assessment of Alertness/Sedation Scale [OAA/S]) before and after spinal anesthesia with 50 mg hyperbaric lidocaine, 5%. Subsequently, 16 volunteers blinded to the study were randomized to receive spinal anesthesia with 50 mg hyperbaric lidocaine, 5% (n = 10) or placebo (n = 6) and underwent BIS and OAA/S monitoring. RESULTS: In part I, significant changes in BIS scores of the volunteers occurred progressively (P = 0.003). The greatest variations from baseline BIS measurement occurred at 30 and 70 min. In part II, there were significant decreases in OAA/S and self-sedation scores for patients receiving spinal anesthesia versuscontrol patients (P = 0.04 and 0. 01, respectively). The greatest decrease in OAA/S scores occurred at 60 min. BIS scores were similar between groups (P = 0.4). CONCLUSIONS: Spinal anesthesia is accompanied by significant sedation progressively when compared with controls as measured by OAA/S and self-sedation scores. This effect was not related to block height. The late sedation observed by OAA/S at 60 min may indicate a second mechanism of sedation, such as delayed rostral spread of local anesthetics. BIS was not a sensitive measure of the sedation associated with spinal anesthesia in the randomized, blinded portion of this study.     

The safety and efficacy of spinal anesthesia for surgery in infants: the Vermont Infant Spinal Registry

Studies with modest numbers of patients have suggested that spinal anesthesia in infants is associated with a very infrequent incidence of complications, such as hypoxemia, bradycardia, and postoperative apnea. Although spinal anesthesia would seem to be a logical alternative to general anesthesia for many surgical procedures, it remains an underutilized technique. Since 1978, clinical data concerning all infants undergoing spinal anesthesia at the University of Vermont have been prospectively recorded. In all, 1554 patients have been studied. Anesthesia was performed by anesthesia trainees and attending anesthesiologists. The success rate for LP was 97.4%. An adequate level of spinal anesthesia was achieved in 95.4% of cases. The average time required to induce spinal anesthesia was 10 min. Oxygen hemoglobin desaturation to <90% was observed in 10 patients. Bradycardia (heart rate <100 bpm) occurred in 24 patients (1.6%). This study confirms the infrequent incidence of complications associated with spinal anesthesia in infants. Spinal anesthesia can be performed safely, efficiently, and with the expectation of a high degree of success. Spinal anesthesia should be strongly considered as an alternative to general anesthesia for lower abdominal and lower extremity surgery in infants.     

Sedation during Spinal Anesthesia

Background: Central neuraxial anesthesia has been reported to decrease the dose of both intravenous and inhalational anesthetics needed to reach a defined level of sedation. The mechanism behind this phenomenon is speculated to be decreased afferent stimulation of the reticular activating system. The authors performed a two-part study (nonrandomized pilot study and a subsequent randomized, double-blind, placebo-controlled study) using the Bispectral Index (BIS) monitor to quantify the degree of sedation in unmedicated volunteers undergoing spinal anesthesia.

Methods: Twelve volunteers underwent BIS monitoring and observer sedation scoring (Observer's Assessment of Alertness/Sedation Scale [OAA/S]) before and after spinal anesthesia with 50 mg hyperbaric lidocaine, 5%. Subsequently, 16 volunteers blinded to the study were randomized to receive spinal anesthesia with 50 mg hyperbaric lidocaine, 5% (n = 10) or placebo (n = 6) and underwent BIS and OAA/S monitoring.

Results: In part I, significant changes in BIS scores of the volunteers occurred progressively (P = 0.003). The greatest variations from baseline BIS measurement occurred at 30 and 70 min. In part II, there were significant decreases in OAA/S and self-sedation scores for patients receiving spinal anesthesia versus control patients (P = 0.04 and 0.01, respectively). The greatest decrease in OAA/S scores occurred at 60 min. BIS scores were similar between groups (P = 0.4).     

The effects of mivacurium‐induced neuromuscular block on Bispectral Index and Cerebral State Index in children under propofol anesthesia – a prospective randomized clinical trial

Background: In adults anesthetized with propofol, muscle relaxants may decrease the Bispectral Index (BIS). The aim of this prospective randomized trial was to detect the influence of a muscle relaxant bolus on the BIS and the Cerebral State Index (CSI) in children under propofol anesthesia. Methods: Forty pediatric patients, age 6.6 ± 3.3 years, weight 24 ± 9 kg, scheduled for surgical procedures requiring general anesthesia were enrolled. Two minutes after i.v. injection of 0.3 mcg·kg⁻¹ of sufentanil, general anesthesia was induced by an initial bolus of 3 mg·kg⁻¹ of propofol, followed by a continuous infusion titrated to achieve a stable BIS value of 50 ± 5. Patients received either mivacurium 0.25 mg·kg⁻¹ (Group Miva) or NaCl 0.9% 0.12 ml·kg⁻¹ (Group Control). Mean BIS and CSI values per minute were compared between (Miva vs. Control) and within groups (Baseline vs 5 min. after study drug administration). Results: The observed changes in BIS and CSI values before and after administration of study drugs revealed no differences between the study groups. Mean baseline BIS and CSI values were lower than 5 min after study drug administration. There were no intergroup differences with respect to BIS and CSI values at any time point. Conclusions: These data suggest that in pediatric patients anesthetized with propofol, administration of mivacurium has no impact on BIS and CSI values.     

Adding clonidine to lidocaine for intravenous regional anesthesia prevents tourniquet pain.

Tourniquet pain often complicates the use of the pneumatic tourniquet during surgical procedures performed under IV regional anesthesia. Clonidine-containing local anesthetic solutions have better analgesic properties than plain solutions when used for spinal, epidural, or peripheral blocks. We tested the hypothesis that the addition of clonidine may improve the quality of IV regional anesthesia, especially tourniquet tolerance. Forty patients were allocated randomly in a double-blinded, randomized study to receive 40 mL of 0.5% lidocaine and either 1 mL of isotonic saline or clonidine (150 microg). A double-cuffed tourniquet was kept inflated until patients complained of pain, leading to release of the distal cuff. Pain at the tourniquet site, at the surgical site, and in the distal part of the arm was rated on a visual analog scale (VAS) and a verbal rating scale (VRS) every 15 min during tourniquet placement and every 15 min for 1 h after tourniquet deflation. Motor blockade, sedation, arterial pressure, and heart rate were also recorded. VAS and VRS scores were significantly lower in the clonidine group 30 and 45 min after tourniquet inflation. The tolerance for the distal tourniquet was also significantly longer in the clonidine group (median [range]: 22 [10-40] vs 10 [5-20] min; P < 0.05); motor blockade was comparable between the two groups. Pain was not different in the two groups after tourniquet release. The clonidine group experienced a higher degree of sedation. We conclude that clonidine improves tourniquet tolerance when added to a local anesthetic solution. IMPLICATIONS: A 150-microg dose of clonidine added to lidocaine improved tourniquet tolerance during IV regional anesthesia.     

Spinal anesthesia for arthroscopic knee surgery

BACKGROUND AND OBJECTIVE: The purpose of the study was to compare the effects of adding 50 microg of morphine, 25 microg of fentanyl or saline to 6 mg of hyperbaric bupivacaine on postoperative analgesia and time to urination in patients undergoing arthroscopic knee surgery under spinal anesthesia. METHODS: The study was designed in a prospective, randomized, double-blinded and placebo-controlled manner. Sixty ASA I-II patients were randomized into the following three groups: Group BM: 6 mg of bupivacaine and 50 microg of morphine, Group BF: 6 mg of bupivacaine and 25 microg of fentanyl, and Group BS: 6 mg of bupivacaine and saline. Selective spinal anesthesia was performed in a lateral decubitus position, with the operative knee dependent for 10 min. RESULTS: In all groups satisfactory anesthesia was provided during the operation. There was a statistically significant difference between all the groups in times to voiding [Group BM 422 +/- 161 min; Group BF 244 +/- 163 min; Group BS 183 +/- 54 min (mean +/- SD)]. The incidence of pruritus was significantly greater in Group BM (80%) and BF (65%) in comparison with Group BS (no pruritus) (P < 0.05). The incidence of nausea was significantly increased in Group BM (35%) in comparison with Group BF (10%) and Group BS (P < 0.05). Analgesic consumption was significantly greater in Group BS in comparison with Groups BM and BF (P < 0.01). CONCLUSIONS: We conclude that during spinal anesthesia even mini-dose intrathecal morphine is not acceptable for outpatient surgery due to side-effects, especially severely prolonged time to urination.     

Cerebral state monitor, a new small handheld EEG monitor for determining depth of anaesthesia: a clinical comparison with the bispectral index during day-surgery

BACKGROUND AND OBJECTIVE: The cerebral state index (CSI) derived from a new small handheld electroencephalogram monitor was studied during routine day surgical anaesthesia titrated according to the bispectral index (BIS). The objective was to determine the degree of agreement between the two monitors. METHODS: Anaesthesia was induced with propofol and fentanyl (0.1 mg) in 38 patients undergoing general anaesthesia for routine day-surgery. Maintenance anaesthesia (sevoflurane (20/38), desflurane (10/38) or propofol (8/38)) titrated by BIS XP (Aspect Medical, Natwick, MA, USA) and BIS and CSI (cerebral State Monitor, Danmeter; Odense, Denmark) index values were recorded every minute. No patient received muscle relaxation. Observer's Assessment of Alertness/Sedation rating scale was used to assess level of sedation. RESULTS: Pair-wise recordings (914) of CSI and BIS were collected. The indices showed similar pattern and decreased with increasing level of sedation, however with large ranges for each level of sedation. Median indices were similar during surgery (BIS: 50 (14-89); CSI: 51 (7-88)) and both indices increased (P 20% from BIS-index in 24% of readings, and on rare occasions CSI indices deviated >100% from the BIS reading. When BIS < 40, CSI decreased slower than BIS and with wider spreading. CONCLUSIONS: When used for day-surgery anaesthesia without muscle relaxation, CSI and BIS show similar patterns and numerical values but with the incidence of occasionally large discrepancies between pair-wise readings. Which monitor is the more dependable remains to be established and cannot be implied from this initial explorative study.     

Spinal anaesthesia in full-term infants of 0-6 months: are there any differences regarding age?

BACKGROUND AND OBJECTIVE: The aim of the study was to report our experience concerning the effectiveness, complications and safety of spinal anaesthesia, and to determine whether spinal anaesthesia was effective in full-term infants undergoing elective inguinal hernia repair. METHODS: Sixty-eight full-term infants aged < 6 months were included in the study. Infants were divided into three groups; Group I (< 1 month, n = 20), Group II (> 1 and < 3 months, n = 26), and Group III (3-6 months, n = 22). All spinal blocks were performed under mask inhalation anaesthesia. A dose of bupivacaine 0.5% 0.5 mg kg(-1) was used for infants under 5kg and 0.4 mg kg(-1) for those over 5 kg. Heart rate, mean arterial pressure, respiratory rate and SPO2 were recorded before and after spinal anaesthesia at 5 min intervals. Time to onset of analgesia, time to start of operation, duration of operation, anaesthesia and hospitalization, postoperative analgesic requirement and complications were recorded. RESULTS: Adequate spinal anaesthesia without sedation was better, time to obtain maximum cutaneous analgesia was shorter and need for sedation and postoperative analgesic requirement were significantly lower in Group I. Although heart rate, mean arterial pressure and respiratory rate decreased < 20% in all groups following spinal analgesia, the decrease in Group I was lower than the others. CONCLUSIONS: Spinal anaesthesia is an effective choice in inguinal hernia repair for full-term infants aged < 1 month, providing excellent and reliable surgical conditions. However, this technique is not as useful for infants aged between 1 and 6 months.     

The effect of intrathecal fentanyl on Cerebral State Index‐guided sedation during spinal anaesthesia*

This study investigated the effect of intrathecal fentanyl on the dose of propofol during sedation guided by Cerebral State Index monitoring. Seventy patients were randomly assigned to receive either fentanyl 25 μg (n = 35) or normal saline (n = 35) with hyperbaric bupivacaine 12.5 mg for spinal anaesthesia. Propofol was infused to maintain a Cerebral State Index value of 65–75 for 30 min. The propofol infusion time and dose required to reach a Cerebral State Index value of 75 were recorded together with the time required to reach a Cerebral State Index value higher than 90 after cessation of sedation. The onset time for sedation was faster and the recovery time was slower in the fentanyl group compared to those in the saline group (p = 0.018 and 0.027, respectively). The propofol doses required for onset and maintenance of sedation were significantly lower in the fentanyl group compared to those in the control group (p = 0.018 and < 0.001, respectively). In conclusion, adding intrathecal fentanyl 25 μg during spinal anaesthesia significantly reduced the dose of propofol required for sedation and prolonged the subsequent recovery time.     

眼科手术患儿瑞芬太尼复合异丙酚麻醉的效果

目的 探讨眼科手术患儿瑞芬太尼复合异丙酚麻醉的效果.方法 择期行眼科短小手术患儿48例,年龄4～12岁,按年龄和麻醉药物分为4组(n=12):ⅠPK组4～7岁,氯胺酮复合异丙酚麻醉;ⅠPR组4～7岁,瑞芬太尼复合异丙酚麻醉;ⅡPK组8～12岁,氯胺酮复合异丙酚麻醉;ⅡPR组8～12岁,瑞芬太尼复合异丙酚麻醉.ⅠPK组和ⅡPK组静脉注射氯胺酮2 mg/kg和异丙酚2 mg/kg麻醉诱导,静脉输注异丙酚6 mg·kg-1·h-1及间断静脉注射氯胺酮1～2 mg/kg维持麻醉.ⅠPR组和ⅡPR组静脉注射瑞芬太尼1 μg/kg和异丙酚2 mg/kg麻醉诱导;麻醉维持:静脉输注异丙酚6 mg·kg-1·h-1和瑞芬太尼0.1 μg·kg-1·min-1,瑞芬太尼每2分钟增加0.025 μg·kg-1·min-1,直至0.2 μg·kg-1·min-1.于麻醉诱导前、麻醉诱导后冲洗眼球时、手术开始后即刻、手术开始后15 min和出手术室时,记录收缩压(SP)、舒张压(DP)、心率(HR)、呼吸频率(RR)、脉搏血氧饱和度和麻醉深度指数(CSI).记录术中和术后不良反应的发生情况.记录麻醉诱导时间、苏醒时间、意识恢复时间和总镇静时间.计算瑞芬太尼平均输注速率.结果 与麻醉诱导前比较,4组SP、DP、HR、RR和CSI均降低(P＜0.05);与ⅠPK组和ⅡPK组比较,ⅠPR组和ⅡPR组RR和CSI降低,术中体动和术后躁动发生率降低,麻醉诱导时间延长,苏醒时间和意识恢复时间缩短(P＜0.05);与ⅠPR组比较,ⅡPR组麻醉诱导时间和意识恢复时间缩短(P＜0.05).ⅡPR组瑞芬太尼平均输注速率小于ⅠPR组(P＜0.05).结论 瑞芬太尼复合异丙酚用于眼科短小手术患儿麻醉可产生良好的麻醉效果,且血液动力学平稳,不良反应少,术后苏醒迅速,而不同年龄患儿瑞芬太尼用量不同.     

Spinal Anesthesia Speeds Active Postoperative Rewarming

Background: Redistribution of body heat decreases core temperature more during general than regional anesthesia. However, the combination of anesthetic- and sedative-induced inhibition may prevent effective upper-body thermoregulatory responses even during regional anesthesia. The extent to which each type of anesthesia promotes hypothermia thus remains controversial. Accordingly, the authors evaluated intraoperative core hypothermia in patients assigned to receive spinal or general anesthesia. They also tested the hypothesis that the efficacy of active postoperative warming is augmented when spinal anesthesia maintains vasodilation.

Methods: Patients undergoing lower abdominal and leg surgery were randomly assigned to receive general anesthesia (isoflurane and nitrous oxide; n = 20) or spinal anesthesia (bupivacaine; n = 20). Fluids were warmed to 37 [degree sign] Celsius and patients were covered with surgical drapes. However, no other active warming was applied during operation. Ambient temperatures were maintained near 20 [degree sign] Celsius. After operation, patients were warmed with a full-length, forced-air cover set to 43 [degree sign] Celsius. Shivering, when observed, was treated with intravenous meperidine.

Results: The mean spinal analgesia level, which was at the sixth thoracic level during surgery, remained at the T12 dermatome after 90 min after operation. Core temperatures did not differ significantly during surgery and decreased to 34.4 +/- 0.5 [degree sign] Celsius and 34.1 +/- 0.4 [degree sign] Celsius, respectively, in patients given spinal and general anesthesia. After operation, however, core temperatures increased significantly faster (1.2 +/- 0.1 [degree sign] Celsius/h vs. 0.7 +/- 0.2 [degree sign] Celsius/h, mean +/- SD; P <0.001) in patients given spinal anesthesia. Consequently, patients given spinal anesthesia required less time to rewarm to 36.5 [degree sign] Celsius (122 +/- 28 min vs. 199 +/- 28 min; P < 0.001).     

Spinal anesthesia for diagnostic cardiac catheterization in high-risk infants

BACKGROUND: The main goals of diagnostic cardiac catheterization (DCC) in infants are to evaluate the anatomy and physiology of congenital and acquired cardiac defects while maintaining normal respiratory and hemodynamic variables. The aims of anesthesia for infants undergoing DCC are to prevent pain and movement during the procedure. General anesthesia (GA) or deep sedation could have undesirable respiratory and hemodynamic effects for conducting such studies. Furthermore, GA is associated with increased risks, especially in high-risk infants. Spinal anesthesia (SA) is a successful alternative to GA in surgery on infants with a history of prematurity and respiratory problems, with minimal respiratory and hemodynamic changes. METHODS: We studied whether those advantages were applicable to DCC, and used a predetermined SA protocol in a cohort of 12 infants with compromised respiratory status. Success rate, study completion, complications, hemodynamic and respiratory effects and recovery profile were recorded. RESULTS: Failure rate was significantly higher in infants older than 6 months. There was no significant difference between baseline and intraprocedure hemodynamic and respiratory parameters. The time to discharge was relatively short (33 +/- 12 min). CONCLUSIONS: Spinal anesthesia apparently provides stable hemodynamics and respiratory variables, rapid recovery and discharge time, and may be a viable alternative to GA or deep sedation in high-risk infants <6 months old undergoing DCC.     

Central effects of epidural and intravenous clonidine in patients anesthetized with enflurane/nitrous oxide. An electroencephalographic analysis.

Epidural clonidine produces regional anesthesia as well as sedation and a decrease in anesthetic requirements. To assess these effects, the electroencephalogram (EEG) was recorded after epidural or intravenous (iv) injection of clonidine during enflurane/N2O anesthesia. Eighteen ASA physical status 1 women undergoing vaginal hysterectomy were allocated randomly to receive epidural clonidine (8 micrograms.kg-1 in 4 ml over 2 min) and iv saline (10 ml over 14 min); or epidural saline (4 ml over 2 min) and iv clonidine (8 micrograms.kg-1 in 10 ml over 14 min); or epidural saline (4 ml over 2 min) and iv saline (10 ml over 14 min). The level of anesthesia was kept constant beginning 10 min before and until 44 min after epidural injection. EEG power spectral analysis was performed throughout the study period using a 2-min average of 8-9-s epochs. Clonidine significantly reduced EEG total power only after epidural administration (P less than 0.05). Relative power increased in the delta band in both the epidural and iv clonidine groups (P less than 0.001). The depression of the total EEG power after epidural injection could be explained neither by systemic absorption alone nor by hemodynamic variations. It may represent the contribution of the direct spinal action of this alpha 2-adrenergic agonist to general anesthesia.     

不同速度输注异丙酚对低温体外循环期间患者麻醉深度的影响

目的 探讨不同速度输注异丙酚静脉麻醉下低温体外循环期间大脑状态指数(cerebral state index,CSI)及爆发抑制比(burst supression ratio,BS%)的变化.方法 择期行低温体外循环下心脏瓣膜置换手术患者44例,年龄(18～60)岁.随机分为两组,每组22例.麻醉诱导采用静脉注射异丙酚1mg/ks～1.5 mg/kg,芬太尼10μg/kg,维库溴铵0.1 mg/kg.麻醉维持采用持续静脉输注异丙酚4 mg·kg-1·h-1(P4组)或6 rag·kg-1·h-1(P6组),芬太尼5gμ·kg-·1h-1.记录体外循环(cardio pulmonany bypass,CPB)前5 min(T0)、CPB后2 min(T1)、CP8开始后30 min(T2)、CPB开始后60 min(T3)、停CPB后15 min(T4)时的CSI、BS%、鼻咽温度、平均动脉压(MAP)、心率(HR).结果 CPB期间两组的CSI均下降,与体外循环前比较差异有统计学意义(P<0.05或0.01),P6组CPB 30 min、60 min的CSI与P4组比较为差异有统计学意义(P<0.01).P6组在CPB 30 rain、60 min时出现爆发抑制比,与CPB前比较为差异有统计学意义(P<0.01),与P4组比较为差异有统计学意义(P<0.01).结论 低温CPB期间持续输注异丙酚6 mg·kg-1·h-1时,CSI处于较低水平,BS%明显增多,应适当减少异丙酚的输注速度,以维持合适的麻醉深度.     

Postoperative apnea in former preterm infants: prospective comparison of spinal and general anesthesia

Thirty-six former preterm infants undergoing inguinal hernia repair were studied. All were less than or equal to 51 weeks postconceptual age at the time of operation. Patients were randomly assigned to receive general or spinal anesthesia. Group 1 patients received general inhalational anesthesia with neuromuscular blockade. Group 2 patients received spinal anesthesia using 1% tetracaine 0.4-0.6 mg/kg in conjunction with an equal volume of 10% dextrose and 0.02 ml epinephrine 1:1000. In the first part of the study, infants randomized to receive spinal anesthesia also received sedation with im ketamine 1-2 mg/kg prior to placement of the spinal anesthetic (group 2 A). The remainder of group 2 patients did not receive sedation (group 2 B). Respiratory pattern and heart rate were monitored using an impedance pneumograph for at least 12 h postoperatively. Tracings were analyzed for evidence of apnea, periodic breathing and/or bradycardia by a pulmonologist unaware of the anesthetic technique utilized. None of the patients who received spinal anesthesia without ketamine sedation developed postoperative bradycardia, prolonged apnea, or periodic breathing. Eight of nine infants (89%) who received spinal anesthesia and adjunct intraoperative sedation with ketamine developed prolonged apnea with bradycardia. Two of the eight infants had no prior history of apnea. Five of the 16 patients (31%) who received general anesthesia developed prolonged apnea with bradycardia. Two of these five infants had no prior history of apnea. When infants with no prior history of apnea were analyzed separately, there was no statistically significant increased incidence of apnea in children receiving general versus spinal anesthesia with or without ketamine sedation. Because of the small numbers of patients studied, and the multiple factors that may influence the incidence of postoperative apnea (e.g., prior history of neonatal apnea), standard postoperative respiratory monitoring of these high-risk infants is still recommended following all anesthetic techniques.     

Midazolam premedication reduces propofol requirements for sedation during regional anesthesia

PURPOSE: Propofol is often used for sedation during spinal anesthesia. We investigated the effects of midazolam premedication on the propofol requirements and incidence of complications during sedation. METHODS: In a prospective randomized, controlled, and single-blinded study, 50 patients undergoing elective gynecological surgery were randomly divided into control and midazolam groups. Patients in the midazolam group received 2 mg midazolam im 30 min before arrival at the operation room. After spinal anesthesia was instituted with intrathecal injection of hyperbaric tetracaine, we provided sedation using continuous infusion of propofol. The level of sedation was controlled at a level between "eyes closed but rousable to command" and "eyes closed but rousable to mild physical stimulation" by adjusting the infusion rate. During sedation, the propofol requirements and complications were recorded and patients were asked, two hours after the end of operation, whether they remembered intraoperative events. RESULTS: In the midazolam group, the loading dose, steady state infusion rate, and overall infusion rate of propofol were 0.74 mg x kg(-1), 2.86 mg x kg(-1) x hr(-1), and 3.32 mg x kg(-1) x hr(-1), respectively, which were about 17% lower than those in the control group (P<0.05). Moreover, midazolam premedication reduced the incidence of intraoperative memory (P < 0.05), but had no effects on other complications. CONCLUSION: Midazolam premedication reduced propofol requirements and the incidence of intraoperative memory during sedation. These effects on sedation using propofol during spinal anesthesia are considered beneficial for patients.     

Dexmedetomidine and ketamine for sedation during spinal anesthesia in children

Study ObjectiveTo evaluate the combination of dexmedetomidine and ketamine for sedation during lumbar puncture and sedation for spinal anesthesia in children.DesignRetrospective analysis of quality assurance data sheets and anesthetic records.SettingDeveloping countries with the humanitarian group, Kids First.Patients12 infants and children, ranging in age from two to 9 years.InterventionsA bolus dose of ketamine (two mg/kg) and dexmedetomidine (one μg/kg) was given over three minutes followed by a continuous infusion of dexmedetomidine (two μg/kg/hr for the first 30 min, followed by one μg/kg/hr for the duration of the case). Supplemental analgesia/sedation was provided by ketamine (0.5 mg/kg) as needed.MeasurementsThe need for supplemental ketamine, the ability to complete the procedure, and heart rate (HR), blood pressure, end-tidal carbon dioxide (ETCO₂), and oxygen saturation values were recorded.Main ResultsEffective sedation for lumbar puncture and performance of spinal anesthesia were achieved in all patients. One patient required a supplemental dose of ketamine (0.5 mg/kg). Following the bolus dose of ketamine and dexmedetomidine, HR increased by 11 ± 4 bpm. The greatest HR increase was 20 bpm. No patient had a HR increase ≥ 20% from baseline. The HR decrease was ≤ 30 bpm in 10 of the 12 patients, and the greatest HR decrease was 58 bpm. Systolic blood pressure (SBP) increased from baseline by 10 ± 3 mmHg after administration of the bolus dose of ketamine and dexmedetomidine. During the subsequent dexmedetomidine infusion, SBP decreased by 11 ± 9 mmHg. No patient's respiratory rate decreased to less than 10 breaths/min or increased above 24 breaths/min during the procedural sedation. The highest ETCO₂ was 45 ± 2 mmHg (P < 0.0001). Oxygen saturation remained ≥ 95% during the procedure in all patients.ConclusionA combination of ketamine and dexmedetomidine provides effective sedation during spinal anesthesia in infants and children, with limited effects on cardiovascular and ventilatory function.