Bupivacaine caudal epidural anesthesia: assessing the effect of general anesthetic technique on block onset

Anaesthetic interventions for prevention of awareness during surgery

BACKGROUND

General anaesthesia is usually associated with unconsciousness. 'Awareness' is when patients have postoperative recall of events or experiences during surgery. 'Wakefulness' is when patients become conscious during surgery, but have no postoperative recollection of the period of consciousness.

OBJECTIVES

To evaluate the efficacy of two types of anaesthetic interventions in reducing clinically significant awareness:- anaesthetic drug regimens; and- intraoperative anaesthetic depth monitors.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL, ISSUE 4 2016); PubMed from 1950 to April 2016; MEDLINE from 1950 to April 2016; and Embase from 1980 to April 2016. We contacted experts to identify additional studies. We performed a handsearch of the citations in the review. We did not search trial registries.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) of either anaesthetic regimens or anaesthetic depth monitors. We excluded volunteer studies, studies of patients prior to skin incision, intensive care unit studies, and studies that only randomized different word presentations for memory tests (not anaesthetic interventions).Anaesthetic drug regimens included studies of induction or maintenance, or both. Anaesthetic depth monitors included the Bispectral Index monitor, M-Entropy, Narcotrend monitor, cerebral function monitor, cerebral state monitor, patient state index, and lower oesophageal contractility monitor. The use of anaesthetic depth monitors allows the titration of anaesthetic drugs to maintain unconsciousness.

DATA COLLECTION AND ANALYSIS

At least two authors independently scanned abstracts, extracted data from the studies, and evaluated studies for risk of bias. We made attempts to contact all authors for additional clarification. We performed meta-analysis statistics in packages of the R language.

MAIN RESULTS

We included 160 studies with 54,109 enrolled participants; 53,713 participants started the studies and 50,034 completed the studies or data analysis (or both). We could not use 115 RCTs in meta-analytic comparisons because they had zero awareness events. We did not merge 27 of the remaining 45 studies because they had excessive clinical and methodological heterogeneity. We pooled the remaining 18 eligible RCTs in meta-analysis. There are 10 studies awaiting classification which we will process when we update the review.The meta-analyses included 18 trials with 36,034 participants. In the analysis of anaesthetic depth monitoring (either Bispectral Index or M-entropy) versus standard clinical and electronic monitoring, there were nine trials with 34,744 participants. The overall event rate was 0.5%. The effect favoured neither anaesthetic depth monitoring nor standard clinical and electronic monitoring, with little precision in the odds ratio (OR) estimate (OR 0.98, 95% confidence interval (CI) 0.59 to 1.62).In a five-study subset of Bispectral Index monitoring versus standard clinical and electronic monitoring, with 34,181 participants, 503 participants gave awareness reports to a blinded, expert panel who adjudicated or judged the outcome for each patient after reviewing the questionnaires: no awareness, possible awareness, or definite awareness. Experts judged 351 patient awareness reports to have no awareness, 87 to have possible awareness, and 65 to have definite awareness. The effect size favoured neither Bispectral Index monitoring nor standard clinical and electronic monitoring, with little precision in the OR estimate for the combination of definite and possible awareness (OR 0.96, 95% CI 0.35 to 2.65). The effect size favoured Bispectral Index monitoring for definite awareness, but with little precision in the OR estimate (OR 0.60, 95% CI 0.13 to 2.75).We performed three smaller meta-analyses of anaesthetic drugs. There were nine studies with 1290 participants. Wakefulness was reduced by ketamine and etomidate compared to thiopental. Wakefulness was more frequent than awareness. Benzodiazepines reduces awareness compared to thiopental, ketamine, and placebo., Also, higher doses of inhaled anaesthetics versus lower doses reduced the risk of awareness.We graded the quality of the evidence as low or very low in the 'Summary of findings' tables for the five comparisons.Most of the secondary outcomes in this review were not reported in the included RCTs.

AUTHORS' CONCLUSIONS

Anaesthetic depth monitors may have similar effects to standard clinical and electrical monitoring on the risk of awareness during surgery. In older studies comparing anaesthetics in a smaller portion of the patient sample, wakefulness occurred more frequently than awareness. Use of etomidate and ketamine lowered the risk of wakefulness compared to thiopental. Benzodiazepines compared to thiopental and ketamine, or higher doses of inhaled anaesthetics versus lower doses, reduced the risk of awareness.

Effects of sevoflurane versus other general anaesthesia on emergence agitation in children

BACKGROUND

Sevoflurane is an inhaled volatile anaesthetic that is widely used in paediatric anaesthetic practice. Since its introduction, postoperative behavioural disturbance known as emergence agitation (EA) or emergence delirium (ED) has been recognized as a problem that may occur during recovery from sevoflurane anaesthesia. For the purpose of this systematic review, EA has been used to describe this clinical entity. A child with EA may be restless, may cause self-injury or may disrupt the dressing, surgical site or indwelling devices, leading to the potential for parents to be dissatisfied with their child's anaesthetic. To prevent such outcomes, the child may require pharmacological or physical restraint. Sevoflurane may be a major contributing factor in the development of EA. Therefore, an evidence-based understanding of the risk/benefit profile regarding sevoflurane compared with other general anaesthetic agents and adjuncts would facilitate its rational and optimal use.

OBJECTIVES

To compare sevoflurane with other general anaesthetic (GA) agents, with or without pharmacological or non-pharmacological adjuncts, with regard to risk of EA in children during emergence from anaesthesia. The primary outcome was risk of EA; secondary outcome was agitation score.

SEARCH METHODS

We searched the following databases from the date of inception to 19 January 2013: CENTRAL, Ovid MEDLINE, Ovid EMBASE, the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (EBSCOhost), Evidence-Based Medicine Reviews (EBMR) and the Web of Science, as well as the reference lists of other relevant articles and online trial registers.

SELECTION CRITERIA

We included all randomized (or quasi-randomized) controlled trials investigating children < 18 years of age presenting for general anaesthesia with or without surgical intervention. We included any study in which a sevoflurane anaesthetic was compared with any other GA, and any study in which researchers investigated adjuncts (pharmacological or non-pharmacological) to sevoflurane anaesthesia compared with no adjunct or placebo.

DATA COLLECTION AND ANALYSIS

Two review authors independently searched the databases, decided on inclusion eligibility of publications, ascertained study quality and extracted data. They then resolved differences between their results by discussion. Data were entered into RevMan 5.2 for analyses and presentation. Comparisons of the risk of EA were presented as risk ratios (RRs) with 95% confidence intervals (CIs). Sevoflurane is treated as the control anaesthesia in this review. Sensitivity analyses were performed as appropriate, to exclude studies with a high risk of bias and to investigate heterogeneity.

MAIN RESULTS

We included 158 studies involving 14,045 children. Interventions to prevent EA fell into two broad groups. First, alternative GA compared with sevoflurane anaesthesia (69 studies), and second, use of an adjunct with sevoflurane anaesthesia versus sevoflurane without an adjunct (100 studies). The overall risk of bias in included studies was low. The overall Grades of Recommendation, Assessment, Development and Evaluation Working Group (GRADE) assessment of the quality of the evidence was moderate to high. A wide range of EA scales were used, as were different levels of cutoff, to determine the presence or absence of EA. Some studies involved children receiving potentially inadequate or no analgesia intraoperatively during painful procedures.Halothane (RR 0.51, 95% CI 0.41 to 0.63, 3534 participants, high quality of evidence) and propofol anaesthesia were associated with a lower risk of EA than sevoflurane anaesthesia. Propofol was effective when used throughout anaesthesia (RR 0.35, 95% CI 0.25 to 0.51, 1098 participants, high quality of evidence) and when used only during the maintenance phase of anaesthesia after sevoflurane induction (RR 0.59, 95% CI 0.46 to 0.76, 738 participants, high quality of evidence). No clear evidence was found of an effect on risk of EA of desflurane (RR 1.46, 95% CI 0.92 to 2.31, 408 participants, moderate quality of evidence) or isoflurane (RR 0.76, 95% CI 0.46 to 1.23, 379 participants, moderate quality of evidence) versus sevoflurane.Compared with no adjunct, effective adjuncts for reducing the risk of EA during sevoflurane anaesthesia included dexmedetomidine (RR 0.37, 95% CI 0.29 to 0.47, 851 participants, high quality of evidence), clonidine (RR 0.45, 95% CI 0.31 to 0.66, 739 participants, high quality of evidence), opioids, in particular fentanyl (RR 0.37, 95% CI 0.27 to 0.50, 1247 participants, high quality of evidence) and a bolus of propofol (RR 0.58, 95% CI 0.38 to 0.89, 394 participants, moderate quality of evidence), ketamine (RR 0.30, 95% CI 0.13 to 0.69, 231 participants, moderate quality of evidence) or midazolam (RR 0.57, 95% CI 0.41 to 0.81, 116 participants, moderate quality of evidence) at the end of anaesthesia. Midazolam oral premedication (RR 0.81, 95% CI 0.59 to 1.12, 370 participants, moderate quality of evidence) and parental presence at emergence (RR 0.91, 95% CI 0.51 to 1.60, 180 participants, moderate quality of evidence) did not reduce the risk of EA.One or more factors designated as high risk of bias were noted in less than 10% of the included studies. Sensitivity analyses of these studies showed no clinically relevant changes in the risk of EA. Heterogeneity was significant with respect to these comparisons: halothane; clonidine; fentanyl; midazolam premedication; propofol 1 mg/kg bolus at end; and ketamine 0.25 mg/kg bolus at end of anaesthesia. With investigation of heterogeneity, the only clinically relevant changes to findings were seen in the context of potential pain, namely, the setting of adenoidectomy/adenotonsillectomy (propofol bolus; midazolam premedication) and the absence of a regional block (clonidine).

AUTHORS' CONCLUSIONS

Propofol, halothane, alpha-2 agonists (dexmedetomidine, clonidine), opioids (e.g. fentanyl) and ketamine reduce the risk of EA compared with sevoflurane anaesthesia, whereas no clear evidence shows an effect for desflurane, isoflurane, midazolam premedication and parental presence at emergence. Therefore anaesthetists can consider several effective strategies to reduce the risk of EA in their clinical practice. Future studies should ensure adequate analgesia in the control group, for which pain may be a contributing or confounding factor in the diagnosis of EA. Regardless of the EA scale used, it would be helpful for study authors to report the risk of EA, so that this might be included in future meta-analyses. Researchers should also consider combining effective interventions as a multi-modal approach to further reduce the risk of EA.

Caudal dexmedetomidine decreases the required concentration of levobupivacaine for caudal block in pediatric patients: a randomized trial

BACKGROUND AND OBJECTIVES

Dexmedetomidine (D) can prolong the duration of local anesthetics, but the effect of caudal dexmedetomidine on the potency of levobupivacaine (L) for caudal block has not been investigated. This study was designed to determine the effect of caudal dexmedetomidine on levobupivacaine for caudal block in pediatric patients.

METHODS

Eighty-nine children scheduled for elective inguinal hernia repair or hydrocele were randomly assigned to one of the three groups: Group L (caudal levobupivacaine), Group LD1 (levobupivacaine plus 1 μg·kg(-1) dexmedetomidine), or Group LD2 (levobupivacaine plus 2 μg·kg(-1) dexmedetomidine). The primary endpoint was the minimum local anesthetic concentration (MLAC), which was determined using the Dixon up-and-down method. The secondary endpoints were the duration of analgesia and sedation.

RESULTS

The MLAC values (sd) of caudal levobupivacaine were 0.103 (0.01)%, 0.068 (0.02)%, and 0.055 (0.03)% in Groups L, LD1, and LD2, respectively. The values of EC50 and EC95 (95% CI) of caudal levobupivacaine from logistic regression analysis were 0.094 (0.083-0.105)% and 0.129 (0.1-0.159)%, 0.058 (0.044-0.072)% and 0.106 (0.067-0.144)%, and 0.046 (0.033-0.059)% and 0.091 (0.055-0.127)% in Groups L, LD1, and LD2, respectively. The mean durations of analgesia in the postoperative period were 141, 378, and 412 min in Groups L, LD1, and LD2, respectively (L vs LD1 or LD2, P < 0.001). The mean durations of sedation in both Groups LD1 and LD2 also were significantly prolonged, compared with Group L (P < 0.01).

CONCLUSIONS

Caudal dexmedetomidine reduces the MLAC values of levobupivacaine and improves postoperative analgesia in children without any neurological side effects.

Empirical evaluation of age groups and age-subgroup analyses in pediatric randomized trials and pediatric meta-analyses

BACKGROUND

An important step toward improvement of the conduct of pediatric clinical research is the standardization of the ages of children to be included in pediatric trials and the optimal age-subgroups to be analyzed.

METHODS

We set out to evaluate empirically the age ranges of children, and age-subgroup analyses thereof, reported in recent pediatric randomized clinical trials (RCTs) and meta-analyses. First, we screened 24 RCTs published in Pediatrics during the first 6 months of 2011; second, we screened 188 pediatric RCTs published in 2007 in the Cochrane Central Register of Controlled Trials; third, we screened 48 pediatric meta-analyses published in the Cochrane Database of Systematic Reviews in 2011. We extracted information on age ranges and age-subgroups considered and age-subgroup differences reported.

RESULTS

The age range of children in RCTs published in Pediatrics varied from 0.1 to 17.5 years (median age: 5; interquartile range: 1.8-10.2) and only 25% of those presented age-subgroup analyses. Large variability was also detected for age ranges in 188 RCTs from the Cochrane Central Register of Controlled Trials, and only 28 of those analyzed age-subgroups. Moreover, only 11 of 48 meta-analyses had age-subgroup analyses, and in 6 of those, only different studies were included. Furthermore, most of these observed differences were not beyond chance.

CONCLUSIONS

We observed large variability in the age ranges and age-subgroups of children included in recent pediatric trials and meta-analyses. Despite the limited available data, some age-subgroup differences were noted. The rationale for the selection of particular age-subgroups deserves further study.

Effect of caudal block on sevoflurane requirement for lower limb surgery in children with cerebral palsy

BACKGROUND

Caudal block is a widely used technique for providing perioperative pain management in children. In this randomized double-blinded study, we evaluated the effects of preoperative caudal block on sevoflurane requirements in children with cerebral palsy (CP) undergoing lower limb surgery while bispectral index (BIS) values were maintained between 45 and 55.

METHODS

52 children undergoing Achilles-tendon lengthening were randomized to receive combined general-caudal anesthesia (caudal group, n = 27) or general anesthesia alone (control group, n = 25). Caudal block was performed with a single dose of 0.7 ml·kg(-1) of 1.0% lidocaine containing epinephrine at 5 μg·ml(-1). The control group received no preoperative caudal block. The endtidal sevoflurane concentrations (ET(sev)) were adjusted every minute to maintain the BIS values between 45 and 55.

RESULTS

The ET(sev) required to maintain the BIS values were not significantly different between the control and caudal groups after induction of anesthesia [2.1 (0.2) vs 2.2 (0.4); P = 0.773]. However, significantly higher ET(sev) was observed in the control group before surgical incision [2.0 (0.2) vs 1.8 (0.3); P = 0.013] and during the first 20 min after surgical incision [2.2 (0.3) vs 1.4 (0.3); P < 0.001]. There was no significant difference in BIS values between the control and caudal groups throughout the study period (P > 0.05). In the caudal group, the caudal block was successful in 25 of 27 (92.6%) patients.

CONCLUSIONS

Caudal block effectively reduced sevoflurane requirements by 36% compared to general anesthesia alone in children with CP undergoing lower limb surgery while BIS values were maintained between 45 and 55.

Hemodynamic effects of levobupivacaine after pediatric caudal anesthesia evaluated by transesophageal doppler

BACKGROUND

The aim of this study is to determine if there are significant differences in hemodynamic effects between combined general-regional anesthesia using levobupivacaine 0.25% 2 ml x kg(-1) via the caudal route in comparison with balanced general anesthesia using continuous infusion of remifentanil in young children undergoing genitourinary surgery.

PATIENTS AND METHODS

62 ASA I-II pediatric patients (12 female, 50 male) aged 6 months to 7 years undergoing genitourinary surgery were included in the study. Patients were randomly allocated into one of two groups of 31 patients each. Group Caud received caudal blockade with levobupivacaine 0.25% 2 mg x kg(-1) in combined general-regional anesthesia and Group Gen received balanced general anesthesia with remifentanil. The noninvasive hemodynamic parameters were measured in each group 5 min after induction of general anesthesia or caudal block (Tcaud), after further 5 min coincident with skin incision (Tsi), 10 min after skin incision (T10i), at the end of surgical procedure (Tend). The time between Tcaud and Tsi was 10 min and the measurements during the interval time T10i-Tend were performed every 15 min according to the duration of surgical procedures.

RESULTS

There was a decrease in all measured hemodynamic parameters at skin incision. The decreases occurred in both groups with those in the caudal group occurring at skin incision and those in the balanced anesthesia group occurring at 10 min after skin incision. These variations showed no significant differences for any of the stated outcomes; neither between the groups at each time point nor in the caudal in comparison with baseline measurements.

CONCLUSIONS

Using transesophageal Doppler no differences in hemodynamic parameters could be detected between balanced general anesthesia with either caudal levobupivacaine or remifentanil infusion. Both techniques showed good hemodynamic stability with only minor changes from baseline over time which are unlikely to be of clinical significance except possibly in patients with preexisting cardiovascular compromise. Other studies with noninvasive monitoring in a larger population are required to better understand the consequences of caudal blockade on CO and on regional blood flow in infants.