The dose-response of caudal ropivacaine in children

Comparison of caudal tramadol versus caudal fentanyl with bupivacaine for prolongation of postoperative analgesia in pediatric patients

Background and Aims:

Caudal block is a common technique for pediatric analgesia for infraumblical surgeries. Because of the short duration of analgesia with bupivacaine alone various additive have been used to prolong the action of bupivacaine. The present study was aimed to evaluate the analgesic effect of tramadol or fentanyl added to bupivacaine for infraumblical surgeries in pediatric patients.

Materials and Methods:

We conducted a prospective, randomized, single-blind controlled trial. After written informed consent from parents, 100 patients belonging to American Society of Anesthesiologist physical status I-II, in the age group of 1-12 years, of either sex undergoing infraumblical surgery under general anesthesia were divided into two groups. Group BT received 1 ml/kg of 0.25% bupivacaine with tramadol 2 mg/kg in normal saline and Group BF received 1 ml/kg of 0.25% bupivacaine with fentanyl 2 μg/kg in normal saline with maximum volume of 12 ml in both groups. All patients were assessed intraoperatively for hemodynamic changes, the requirement of sevoflurane concentration, as well as postoperatively for pain by using FLACC (F = Face, L = Leg, A = Activity, C = Cry, C = Consolability), pain score and for sedation by using four point sedation score.

Results:

The mean duration of analgesia was 10–18 h in Group BT while in Group BF it was 7-11 h. The postoperatively period up to 1½ h, Group BF had higher sedation score up to two as compared to that below one on Group BT.

Conclusion:

Caudal tramadol significantly prolongs the duration of analgesia as compared to caudal fentanyl without any side effects.

Comparison of ropivacaine and bupivacaine with fentanyl for caudal epidural in pediatric surgery

CONTEXT

Ropivacaine, s-enantiomer of amide local anaesthetic produces differential neural blockade with less motor blockade, cardiovascular and neurological toxicity makes it suitable for day case surgery in children.

AIMS

To compare the effectiveness of Inj. Ropivacaine (0.2 or 0.25%) or Inj. Bupivacaine (0.25%) with fentanyl in caudal block for intra and postoperative analgesia.

SETTINGS AND DESIGN

Double blind retrospective randomized study.

MATERIALS AND METHODS

All the patients (n=112) varying from age group 3.02 ± 3.29 years belonging to ASA I-IV were randomly allocated to receive caudal analgesia Group BF inj. Bupivacaine (0.25%, 2 mg/kg) + Inj. Fentany1 μg/kg (n=70) and group RF: Inj. Ropivacaine (0.25% or 0.2%, 2 mg/kg) + inj. Fentanyl 1 μg/kg (n=42). We monitored vitals and requirement of inhalational gases inraoperatively and also observed pain by pain score (Visual Analogue Score in verbal group and Objective Pain Scale in nonverbal group) and vitals postoperatively. We used rescue analgesics (inj. Paracetamol 5 mg/kg iv) when VAS score ≥4.

STATISTICAL ANALYSIS

Student's t-test.

RESULTS

Duration of analgesia was prolonged in both group RF and BF. Time for first rescue analgesic for group RF (6.1 ± 1.1 hr) compared to group BF (5.6 ± 0.9 hr). Haemodynamic stability and less requirement of inhalation agent intraoperatively with group RF than others.

CONCLUSIONS

Ropivacaine with Fentanyl found to be better combination for pediatric surgeries for below umbilical surgeries as an adjuvant to general anaesthesia or sole technique with chances of less complication with high success rate.

Prospective randomized controlled comparison of caudal bupivacaine and ropivacaine in pediatric patients

Background:

Bupivacaine and ropivacaine are commonly used agents for caudal anesthesia in pediatric patients. Several studies have shown different motor and cardiovascular effects of two drugs.

Aim:

The primary objective of this study was to evaluate the efficacy of both drugs and secondary objective was to compare motor blockade and hemodynamic effects caused by them.

Subjects and Methods:

This was a prospective randomized controlled study including 50 consecutive patients in the age group of 1-10 years, who underwent urogenital surgeries under general anesthesia. Caudal block was given with either bupivacaine (0.25%) 1 ml/kg (Group I) or ropivacaine (0.25%) 1 ml/kg (Group II). Heart rate (HR) and systolic blood pressure (SBP) were recorded as a baseline, before the anesthesia induction and then at 30, 60 and 90 min after incision. Pain scores were assessed post-operatively by a single observer at 30 min and then at 2, 4, 8 and 12 h with a 5-point observer pain score (OPS). Patients and observer were blinded to the medication given. The duration of absolute analgesia was defined as the time from caudal injection until the pain score was >2. Motor block was assessed by modified Bromage scale. Statistical analysis was performed with Chi-square test, Student's t-test and log-rank test. P < 0.05 were considered as significant.

Results:

HR and SBP measured at a specific time intervals showed no significant difference. All the patients had adequate intraoperative analgesia. Mean OPS were comparable between two groups. Duration of absolute analgesia was 276.8 (11) min in Group I and 284.8 (12) min for Group II. The only significant difference was the motor-block score at 2, 3 and 4 h after surgery, although the score was same 1 h post-operatively.

Conclusion:

The efficacy of both ropivacaine and bupivacaine is almost same in terms of onset and duration of analgesia. Therefore, the motor blockade caused by ropivacaine is less; there is no significant difference in cardiovascular events.

Comparing caudal and intravenous ketamine for supplementation of analgesia after Salter innominate osteotomy

PURPOSE

Previous studies claim that caudal administration of ketamine causes effective analgesia. The aim of this study was to assess the clinical effectiveness of ketamine after caudal or intravascular administration in pediatric patients that underwent orthopedic surgery to distinguish between local and systemic analgesia.

METHODS

After the induction of general anesthesia, 36 patients, aged 18 months to 10 years, assigned to undergo orthopedic surgery, received a caudal injection of bupivacaine and were randomly blinded into two groups: one group received 1 mg/kg S(+)-ketamine as the caudal group and the other group received 1 mg/kg S(+)-ketamine as the intravascular group. Postsurgical measurements included the effectiveness of postsurgical analgesia, which was assessed by using the observational pain scale (OPS), duration of analgesia, sedation score, and hemodynamic and respiratory monitoring.

RESULTS

The mean time to first analgesia was clearly longer in the caudal ketamine group (13.35 h) than in the intravenous ketamine (9.93 h) group (P < 0.01). During the 24-h observation time, fewer children asked for additional analgesic drugs in the caudal group (8 of 18, 44.4 %) than in the intravenous group (12 of 18, 66.6 %; P = 0.01). The times to first micturation and spontaneous leg movements and the incidence of nausea and vomiting were similar in the two groups. The OPS and sedation scores after operation showed no obvious differences between the groups at any time.

CONCLUSION

Although caudal ketamine provides good postsurgical analgesia due to its potential neurotoxicity and only small clinical differences with intravenous ketamine, the administration of intravenous ketamine might be a reasonable option to potentially extend the postsurgical analgesic effect of the caudal administration of local anesthetics in children undergoing Salter osteotomy.

Efficacy of clonidine as an adjuvant to ropivacaine for caudal analgesia in children undergoing subumbilical surgery

Context:

The use of clonidine as an adjuvant to ropivacaine in different concentrations through the caudal space has been shown to improve the analgesic efficacy of local anesthetics.

Aims:

The purpose of our study was to compare the efficacy of ropivacaine 0.1% with clonidine 1 mcg/kg to that of plain 0.1% and 0.2% ropivacaine for caudal analgesia in children.

Settings and Design:

Prospective, double blind, randomized controlled trial.

Materials and Methods:

Sixty children in the age group of 1–6 years undergoing subumbilical surgeries were included in the study. Group A received 1 ml/kg of 0.1% ropivacaine, group B received 1 ml/kg of 0.1% ropivacaine with clonidine 1 mcg/kg, and group C received 1 ml/kg of 0.2% ropivacaine.

Results:

The mean duration of analgesia was 243.7 ± 99.29 min in group A, 590.25 ± 83.93 min in group B, and 388.25 ± 82.35 min in group C. The duration of analgesia was significantly prolonged in group B compared to groups A and C with the P value of 0.001. At 8 h, all the 20 children in group A had received the first rescue analgesic compared to 18 children in group C and 3 children in group B. The duration of motor blockade after extubation was 30.6 ± 7.8 min and was noted only in group C. Only 1 child in group B received two rescue medications compared to 15 (75%) children in group A and 8 (40%) children in group C. None of the groups were treated for bradycardia or hypotension and no significant sedation was noted.

Conclusions:

Clonidine 1 mcg/kg with ropivacaine 0.1% prolongs the duration and quality of analgesia compared to plain ropivacaine 0.1% and 0.2% without any significant sedation.

Caudal ropivacaine-clonidine: A better post-operative analgesic approach

The aim was to determine qualitative and quantitative aspects of caudal block, haemodynamic effects, and post-operative pain relief of ropivacaine 0.25% versus ropivacaine 0.25% with clonidine for lower abdominal surgeries in paediatric patients. A double-blind study was conducted among 44 paediatric patients in the Department of Anaesthesiology and Intensive Care of our institute. A total of 44 ASA-I paediatric patients between the ages of 1 and 9 years, scheduled for elective hernia surgery, were enrolled in this randomised double-blind study. The caudal block was administered with ropivacaine 0.25% (Group I) and ropivacaine 0.25% and clonidine 2 µg/kg (Group II) after induction with general anaesthesia. Haemodynamic parameters were observed before, during and after the surgical procedure. Post-operative analgesic duration, total dose of rescue analgesia, pain scores and any side effects were looked for and recorded. All the results were tabulated and analysed statistically. The variables in the two groups were compared using the non-parametric tests. For all statistical analyses, the level of significance was P < 0.05. Forty-four patients were enrolled in this study and their data were subjected to statistical analysis: 22 patients in both the groups were comparable with regard to demographic data, haemodynamic parameters and other vitals and were statistically non-significant (P>0.05). The duration of analgesia was significantly prolonged in Group II (P<0.05). The dose requirement for post-operative pain relief was also significantly lesser in Group II. The incidences of side effects were almost comparable and non-significant. A caudal block with 0.25% of isobaric ropivacaine combined with 2 µg/kg of clonidine provides efficient analgesia intra-operatively and prolonged duration of analgesia post-operatively.

Ultrasound assessment of cranial spread during caudal blockade in children: the effect of different volumes of local anaesthetics

BACKGROUND

Despite the large amount of literature on caudal anaesthesia in children, the issue of volume of local anaesthetics and cranial spread is still not settled. Thus, the aim of the present prospective randomized study was to evaluate the cranial spread of caudally administered local anaesthetics in children by means of real-time ultrasound, with a special focus on the effects of using different volumes of local anaesthetics.

METHODS

Seventy-five children, 1 month to 6 yr, undergoing inguinal hernia repair or more distal surgery were randomized to receive a caudal block with 0.7, 1.0, or 1.3 ml kg(-1) ropivacaine. The cranial spread of the local anaesthetic within the spinal canal was assessed by real-time ultrasound scanning; the absolute cranial segmental level and the cranial level relative to the conus medullaris were determined.

RESULTS

All the blocks were judged to be clinically successful. A significant correlation was found between the injected volume and the cranial level reached by the local anaesthetic both with regards to the absolute cranial segmental level and the cranial level relative to the conus medullaris.

CONCLUSIONS

The main finding of the present study was positive, but numerically small correlation between injected volumes of local anaesthetic and the cranial spread of caudally administered local anaesthetics. Therefore, the prediction of the cranial spread of local anaesthetic, depending on the injected volume of the local anaesthetic, was not possible. EudraCT Number: 2008-007627-40.

Minimum local analgesic concentration of ropivacaine for intra-operative caudal analgesia in pre-school and school age children

We compared the minimum local analgesia concentration of ropivacaine for intra-operative caudal analgesia in pre-school and school age children. Fifty-one boys, undergoing hypospadius repair surgery, were stratified into pre-school or school age groups. After induction of anaesthesia, caudal block was performed with ropivacaine 1 ml.kg⁻¹ of the desired concentration. The first child in each group received ropivacaine 0.125%, and subsequent concentrations were determined by the analgesic response of the previous patient using Dixon's up-and-down method. Under general anaesthesia with 0.7 minimum alveolar concentration of sevoflurane, the minimum local analgesia concentration of ropivacaine for intra-operative caudal block was 34% greater in school age than in pre-school age boys (0.143% (95% CI 0.132-0.157%) vs 0.107% (95% CI 0.089-0.122%), respectively; p < 0.001). This study indicates that a higher concentration of ropivacaine is needed for school age than pre-school age children to provide intra-operative caudal analgesia when combined with general anaesthesia.

Efficacy of bupivacaine-neostigmine and bupivacaine-tramadol in caudal block in pediatric inguinal herniorrhaphy

BACKGROUND

Limited duration of analgesia is among the limitations of single caudal injection with local anesthetics. Therefore, the purpose of this study was to evaluate the effectiveness and safety of bupivacaine in combination with either neostigmine or tramadol for caudal block in children undergoing inguinal herniorrhaphy.

METHODS

In a double-blinded randomized trial, sixty children undergoing inguinal herniorrhaphy were enrolled to receive a caudal block with either 0.25% bupivacaine (1 ml x kg(-1)) with neostigmine (2 microg x kg(-1)) (group BN) or tramadol (1 mg x kg(-1)) (group BT). Hemodynamic variables, pain and sedation scores, additional analgesic requirements, and side effects were compared between two groups.

RESULTS

Duration of analgesia was longer in group BT (17.30 +/- 8.24 h) compared with group BN (13.98 +/- 10.03 h) (P = 0.03). Total consumption of rescue analgesic was significantly lower in group BT compared with group BN (P = 0.04). There were no significant differences in heart rate, mean arterial pressure, and oxygen saturation between groups. Adverse effects excluding the vomiting were not observed in any patients.

CONCLUSION

In conclusion, tramadol (1 mg x kg(-1)) compared with neostigmine (2 microg x kg(-1)) might provide both prolonged duration of analgesia and extended time to first analgesic in caudal block.

Epidural ropivacaine versus ropivacaine plus tramadol in postoperative analgesia in children undergoing major abdominal surgery: a comparison

PURPOSE

In this study, we aimed to compare the effects of ropivacaine alone and ropivacaine plus tramadol administered epidurally for postoperative analgesia in children.

METHODS

Following Ethics Committee approval and informed parent consent, 44 children aged between 2 and 12 years, with ASA physical status I or II, who were undergoing major abdominal surgery were included in the study. Following tracheal intubation, patients were placed into lateral decubitus position and an epidural catheter (22-24 G) was inserted by using a Tuohy needle. Patients were randomly divided into two groups to receive either ropivacaine alone (0.2%), 0.7 ml/kg, in group I, or ropivacaine (0.2%) plus tramadol (2 mg/kg), with total volume 0.7 ml/kg, in group II, epidurally in both groups. Hemodynamic variables, pain and sedation scores, duration of analgesia, and side effects were recorded postoperatively.

RESULTS

The duration of analgesia was significantly longer in group RT than in group R (298.6 ± 28 and 867.9 ± 106.8 min in group I and II, respectively) (P < 0.05). CHEOPS scores were significantly lower in group RT at 30 min, 45 min, and 3 h postoperatively than in group R (P < 0.05). However, sedation scores were similar between the two groups. Twenty-two patients (100%) in group R and 13 patients (59%) in group RT needed supplemental analgesia postoperatively. There were no significant differences in side effects between the groups.

CONCLUSION

In children undergoing major abdominal surgery, epidural tramadol, added to epidural ropivacaine, provided lower pain scores, longer duration of analgesia, and lower postoperative analgesic requirement.

Two different doses of caudal neostigmine co-administered with levobupivacaine produces analgesia in children

SUMMARY BACKGROUND

This study was aimed to evaluate the analgesic efficacy duration of analgesia, and side effects of two different doses of caudal neostigmine used with levobupivacaine in children.

METHODS

Sixty boys, between 5 months and 5 years, undergoing genitourinary surgery were allocated randomly to one of three groups (n =20 each). Group I patients received caudal 0.25% levobupivacaine (1 ml.kg(-1)) alone. Groups II and III patients received neostigmine (2 and 4 microg.kg(-1) respectively) together with levobupivacaine used in the same does as Group I. Pain scores were assessed using Children's and Infant's Postoperative Pain Scale (CHIPPS) at 15th (t(1)) min after arrival to postanesthetic care unit, and 1st (t(2)), 2nd (t(3)), 3rd (t(4)), 4th (t(5)), 8th (t(6)), 16th (t(7)), and 24th (t(8)) hour postoperatively. Duration of analgesia, amount of additional analgesic (paracetamol), score of motor blockade and complications were recorded for 24 h postoperatively, and compared between groups.

RESULTS

CHIPPS scores were higher during t(2), t(3), t(6), t(7), and t(8) periods, duration of analgesia was shorter, and total analgesic consumption was higher in Group I compare to neostigmine groups (P < 0.05). Duration of postoperative analgesia and total analgesic consumption were similar in Groups II and III (P > 0.05). Adverse effects were not different between three groups.

CONCLUSIONS

Caudal neostigmine in doses of 2 and 4 microg.kg(-1) with levobupivacaine extends the duration of analgesia without increasing the incidence of adverse effects, and 2 microg.kg(-1) seems to be the optimal dose, as higher dose has no further advantages.

Relative analgesic potencies of levobupivacaine and ropivacaine for caudal anesthesia in children

BACKGROUND

Comparing relative potency of new local anesthetics, such as levobupivacaine and ropivacaine, by the minimum local analgesic concentration model has not been described for caudal anesthesia. Therefore, we performed a prospective, randomized, double-blind study to determine the minimum local analgesic concentrations of a caudal single shot of ropivacaine and levobupivacaine in children and to describe the upper dose-response curve.

METHODS

We performed a two-stage prospective, randomized, double-blind study comparing the dose-response curves of caudal ropivacaine and levobupivacaine in children. In phase 1, 80 boys were randomized to receive either ropivacaine or levobupivacaine. In the second phase a further 32 patients were randomly allocated to receive caudal anesthesia with doses designed to delineate the upper dose-response range (the 50% effective dose [ED(50)]-ED(95) range).

RESULTS

There were no significant differences in ED(50) values for caudal ropivacaine and levobupivacaine. The ED(50) for levobupivacaine estimated from the Dixon Massey method was 0.069% (95% CI 0.056%-0.082%) and for ropivacaine was 0.075% (95% CI 0.058%-0.092%). Estimated by isotonic regression the ED(50) and ED(95) respectively of levobupivacaine were 0.068 (0.04-0.09) and 0.20% (95% CI 0.16%-0.24%). For ropivacaine ED 50 and ED95 were 0.066 (0.033-0.098) and 0.225% (95% CI 0.21%-0.24%).

CONCLUSIONS

In children receiving one minimum alveolar anesthetic concentration of sevoflurane, there were no significant differences in the ED(50) for caudal levobupivacaine and ropivacaine. The potency ratio at ED(50) was 0.92 and 0.89 at ED(95), indicating that caudal levobupivacaine and ropivacaine have a similar potency.

Ultrasonography-guided rectus sheath block in paediatric anaesthesia—a new approach to an old technique †

BACKGROUND

The purpose of this study was an anatomical and clinical evaluation of ultrasonography-guided rectus sheath blocks in children.

METHOD

A total of 30 children were included in the sono-anatomical part of the study. The depth of the anterior and posterior rectus sheath was evaluated with a portable SonSite 180 plus ultrasound machine and a 5-10 MHz linear probe. In total, 20 consecutive children undergoing umbilical hernia repair were included in the clinical part of this study. After induction of general anaesthesia children received a rectus sheath block under real-time ultrasonographic guidance by placing 0.1 ml kg(-1) bilaterally in the space between the posterior aspect of the sheath and the rectus abdominis muscle.

RESULTS

Ultrasonographic visualization of the posterior rectus sheath was possible in all children. The correlation between the depth of the posterior rectus sheath and weight (adjusted r(2)=0.175), height (adjusted r(2)=0.314) and body surface area (adjusted r(2)=0.241) was poor. The ultrasound-guided rectus sheath blockade provided sufficient analgesia in all children with no need for additional analgesia in the perioperative period.

CONCLUSION

The bilateral placement of levobupivacaine 0.25% 0.1 ml kg(-1) in the space between the posterior aspect of the rectus sheath and the rectus abdominis muscle under real-time ultrasonographic guidance provides sufficient analgesia for umbilical hernia repair. The unpredictable depth of the posterior rectus sheath in children is a good argument for the use of ultrasonography in this regional anaesthetic technique in children.

Ultrasonographic-Guided Ilioinguinal/Iliohypogastric Nerve Block in Pediatric Anesthesia: What is the Optimal Volume?

Recently, our study group demonstrated the usefulness of ultrasonographic guidance in ilioinguinal/iliohypogastric nerve blocks in children. As a consequence, we designed a follow-up study to evaluate the optimal volume of local anesthetic for this regional anesthetic technique. Using a modified step-up-step-down approach, with 10 children in each study group, a starting dose of 0.2 mL/kg of 0.25% levobupivacaine was administered to perform an ilioinguinal/iliohypogastric nerve block under ultrasonographic guidance. After each group of 10 patients, the results were analyzed, and if all blocks were successful, the volume of local anesthetic was decreased by 50%, and a further 10 patients were enrolled into the study. Failure to achieve a 100% success rate within a group subjected patients to an automatic increase of half the previous volume reduction to be used in the subsequent group. Using 0.2 and 0.1 mL/kg of 0.25% levobupivacaine, the success rate was 100%. With a volume of 0.05 mL/kg of 0.25% levobupivacaine, 4 of 10 children received additional analgesia because of an inadequate block. Therefore, according to the protocol, the amount was increased to 0.075 mL/kg of 0.25% levobupivacaine, where the success rate was again 100%. We conclude that ultrasonographic guidance for ilioinguinal/iliohypogastric nerve blocks in children allowed a reduction of the volume of local anesthetic to 0.075 mL/kg.

Anesthetic Efficacy of Different Ropivacaine Concentrations for Inferior Alveolar Nerve Block

This study was conducted on 72 American Society of Anesthesiologists class 1 patients scheduled for extraction of a mandibular third molar after inferior alveolar nerve block. Each patient was randomly administered one of the following ropivacaine concentrations: 0.75%, 0.5%, 0.375%, or 0.25% (18 patients per group). Onset of block (mean +/- SD) was rapid for both 0.75% (1.4 +/- 0.4 minutes) and 0.5% (1.7 +/- 0.5 minutes) ropivacaine but significantly slower for the 0.375% (4.2 +/- 2.5 minutes) and 0.25% (10.7 +/- 3.0 minutes) concentrations. Tooth extraction was performed successfully with the 0.5% and 0.75% concentrations, and supplemental injections were not required. Second injections, however, were required with 0.375% ropivacaine. Anesthesia was unsuccessful in 13 patients given 0.25% ropivacaine even after 3 injections. The mean durations of soft tissue anesthesia were 3.3 +/- 0.3 hours and 3.0 +/- 0.3 hours for the 0.75% and 0.5% concentrations, but significantly shorter with more dilute concentrations. The duration of analgesia showed a similar pattern, with the 0.75% and 0.5% concentrations producing prolonged analgesia of 6.0 +/- 0.4 hours and 5.6 +/- 0.4 hours. These results indicate that 0.5% and 0.75% concentrations were effective for intraoral nerve blockade, with both a rapid onset and prolonged duration of pain control.

A comparison of epidural bupivacaine, levobupivacaine, and ropivacaine on postoperative analgesia and motor blockade

In this prospective, randomized, observer-blinded clinical trial, we compared the incidence of unwanted lower extremity motor blockade and the analgesic efficacy between small-dose (0.125%; 0.2 mg x kg(-1) x h(-1)) postoperative epidural infusions of bupivacaine (Group B; n = 28), levobupivacaine (Group L; n = 27), and ropivacaine (Group R; n = 26) in children after hypospadias repair. Motor blockade and pain were assessed at predetermined time points during 48 h by using a modified Bromage scale and the Children's and Infant's Postoperative Pain Scale (CHIPPS). Postoperative analgesia was almost identical in all three study groups (CHIPPS range, 0-3), with no need for the administration of supplemental analgesia in any patient. However, significantly more patients in Group B (n = 6; P = 0.03) displayed signs of unwanted motor blockade during the observation period compared with Group L (n = 0) and Group R (n = 0). In conclusion, significantly less unwanted motor blockade was associated with postoperative epidural infusions of 0.125% levobupivacaine or ropivacaine in children after hypospadias repair as compared with a similar infusion of bupivacaine. However, no difference with regard to postoperative analgesia could be detected among the three different local anesthetics studied.

DOSE-RESPONSE OF ROPIVACAINE ADMINISTERED CAUDALLY TO CHILDREN UNDERGOING SURGICAL PROCEDURES UNDER SEDATION WITH MIDAZOLAM

1. In a double-blind randomized controlled design, 50 children were allocated to receive bupivacaine 0.25% or ropivacaine 0.25%, 0.32%, 0.40% or 0.50% by caudal block. 2. Caudal block was performed after induction of anaesthesia with 2-5% sevoflurane, atropine 10 microg/kg and midazolam 100-300 microg/kg. During the surgical procedure, patients were maintained under spontaneous ventilation and no intravenous or inhalatory anaesthetic agent was administered. For transoperative sedation, midazolam 100-300 microg/kg was administered every 0.5-1.0 h. Transoperative cardiovascular response, postoperative analgesia and local and systemic complications were evaluated. 3. Groups were similar (P > 0.05) in sex, age, weight and in the time elapsed from caudal block to the beginning of the surgical procedure. The surgical time was significantly lower in the ropivacaine 0.25% group. The duration of analgesia was 24 h with ropivacaine 0.25% and approximately 10 h in the other four groups (P < 0.001). Linear regression analysis revealed a significant relationship between the postoperative analgesic period produced by ropivacaine and the surgical time (r = -0.48, two-sided P = 0.002). Systolic and diastolic blood pressures remained in the physiologically normal range for the duration of the transoperative period. Vomiting was present in only one patient receiving ropivacaine 0.50%. 4. In children, the duration of analgesia produced by caudal block with ropivacaine may be affected by surgical time. At surgical times of 0.5-1 h, ropivacaine 0.25% produced at least 24 h postoperative analgesia. At similar surgical times, ropivacaine 0.32%, 0.40% and 0.50% produced similar analgesic times to bupivacaine 0.25%.

Comparison of caudal ropivacaine, ropivacaine plus ketamine and ropivacaine plus tramadol administration for postoperative analgesia in children

BACKGROUND

The aim of this study was to compare the effect of single-dose caudal ropivacaine, ropivacaine plus ketamine and ropivacaine plus tramadol in children for postoperative pain management.

METHODS

Following ethics committee approval and informed parental consent, 99 ASA PS I or II children, between 1 and 10 years of age, scheduled for elective inguinal hernia repair with general anaesthesia, were recruited. After induction of anaesthesia and placement of a laryngeal mask airway (LMATM), the patients were randomly divided into three groups to receive either caudal ropivacaine alone (0.4%, 2 mg x kg(-1)) in group R (n = 32) or ropivacaine (0.2%, 1 mg x kg(-1)) plus ketamine (0.25 mg x kg(-1)) in group RK (n = 33) or ropivacaine (0.2%, 1 mg x kg(-1)) plus tramadol (1 mg x kg(-1)) in group RT (n = 34) with a total volume of 0.5 ml x kg(-1). Systemic blood pressure (SBP and DBP), heart rate (HR), peripheral O2 saturation (SpO2), respiratory rate (RR), sedation and pain scores were recorded at 5, 10, 15 and 30 min, 1, 3, 4 and 6 h following recovery from anaesthesia. Pain was evaluated by Children's Hospital of Eastern Ontario Pain Scale, and sedation with a five-point sedation test.

RESULTS

No difference was found regarding age, weight and duration of operation between the groups (P > 0.05). No patient experienced hypotension, bradycardia or respiratory depression. Duration of analgesia was longer in group RT (1377 +/- 204 min) than group R (1006 +/- 506 min) (P = 0.001). In the tramadol group, fewer patients required supplementary analgesics in the first 24 h (P = 0.005). Sedation scores were below 2 in all groups. Incidence of postoperative nausea and vomiting was higher in group RT (eight patients) and group RK (seven patients) than group R (one patient, P = 0.032).

CONCLUSIONS

Ropivacaine (0.4%), ropivacaine (0.2%) plus ketamine (0.25 mg x kg(-1)) and ropivacaine (0.2%) plus tramadol (0.5 mg x kg(-1)) provided sufficient analgesia in children, but the duration of analgesia was longer in the RT group.

Regional anaesthetic techniques for neonatal surgery: indications and selection of techniques

The goal of neonatal care is to optimise the outcome of term and preterm infants with minimal suffering. Neonates are rare patients for the anaesthetist, therefore personal and even global experiences are limited. This chapter focuses on strategies for dealing with common clinical situations, e.g. heel lancing, obtaining vascular access, circumcision, hernia repair and pyloric stenosis, as well as major neonatal surgery. With the exception of heel lancing, regional techniques are useful in all cases. However, a careful risk-benefit analysis is mandatory, especially when considering more invasive techniques such as epidural catheters.

Pharmacokinetics of levobupivacaine 0.25% following caudal administration in children under 2 years of age † †Declaration of interest. This work was funded by Chiroscience Limited, Cambridge, UK

BACKGROUND

Levobupivacaine, the S(-)enantiomer of racemic bupivacaine is less cardiotoxic than racemic bupivacaine and the R(+)enantiomer dexbupivacaine, while retaining similar local anaesthetic properties and potency to racemic bupivacaine. The pharmacokinetic profiles of the two bupivacaine enantiomers differs and that of racemic bupivacaine may be age dependent. We examined the pharmacokinetics of levobupivacaine after its single shot caudal epidural administration in children.

METHODS

An open-label phase 2 study was undertaken to examine the pharmacokinetics of levobupivacaine 0.25% 2 mg kg(-1) in 49 children aged less than 2 yr, after single shot caudal epidural administration. Plasma concentrations were determined at intervals up to 60 min after caudal injection.

RESULTS

Time to peak plasma concentration (T(max)) ranged between 5 and 60 min (median 30 min) and was reached later in children aged less than 3 months (P<0.005). Peak plasma concentration (C(max)) ranged between 0.41 and 2.12 micro g ml(-1) (median 0.80, mean (SD) 0.91 (0.40) micro g ml(-1)).

CONCLUSION

After the caudal epidural administration of levobupivacaine 2 mg kg(-1) in children less than 2 yr of age, C(max) was within the accepted safe range for racemic bupivacaine. T(max) varied and occurred later in some children, particularly those aged less than 3 months. Sampling in future pharmacokinetic studies in this age group should extend beyond 60 min.

Benefit-Risk Assessment of Ropivacaine in the Management of Postoperative Pain

Ropivacaine is a long-acting amide-type local anaesthetic, released for clinical use in 1996. In comparison with bupivacaine, ropivacaine is equally effective for subcutaneous infiltration, epidural and peripheral nerve block for surgery, obstetric procedures and postoperative analgesia. Nevertheless, ropivacaine differs from bupivacaine in several aspects: firstly, it is marketed as a pure S(-)-enantiomer and not as a racemate, and secondly, its lipid solubility is markedly lower. These features have been suggested to significantly improve the safety profile of ropivacaine, and indeed, numerous studies have shown that ropivacaine has less cardiovascular and CNS toxicity than racemic bupivacaine in healthy volunteers. Extensive clinical data have demonstrated that epidural 0.2% ropivacaine is nearly identical to 0.2% bupivacaine with regard to onset, quality and duration of sensory blockade for initiation and maintenance of labour analgesia. Ropivacaine also provides effective pain relief after abdominal or orthopaedic surgery, especially when given in conjunction with opioids or other adjuvants. Nevertheless, epidurally administered ropivacaine causes significantly less motor blockade at low concentrations. Whether the greater degree of blockade of nerve fibres involved in pain transmission (Adelta- and C-fibres) than of those controlling motor function (Aalpha- and Abeta-fibres) is due to a lower relative potency compared with bupivacaine or whether other physicochemical properties or stereoselectivity are involved, is still a matter of intense debate. Recommended epidural doses for postoperative or labour pain are 20-40 mg as bolus with 20-30 mg as top-up dose, with an interval of >or=30 minutes. Alternatively, 0.2% ropivacaine can be given as continuous epidural infusion at a rate of 6-14 mL/h (lumbar route) or 4-10 mL/h (thoracic route). Preoperative or postoperative subcutaneous wound infiltration, during cholecystectomy or inguinal hernia repair, with ropivacaine 100-175 mg has been shown to be more effective than placebo and as effective as bupivacaine in reducing wound pain, whereby the vasoconstrictive potency of ropivacaine may be involved. Similar results were found in peripheral blockades on upper and lower limbs. Ropivacaine shows an identical efficacy and potency to that of bupivacaine, with similar analgesic duration over hours using single shot or continuous catheter techniques. In summary, ropivacaine, a newer long-acting local anaesthetic, has an efficacy generally similar to that of the same dose of bupivacaine with regard to postoperative pain relief, but causes less motor blockade and stronger vasoconstriction at low concentrations. Despite a significantly better safety profile of the pure S(-)-isomer of ropivacaine, the increased cost of ropivacaine may presently limit its clinical utility in postoperative pain therapy.

Caudal neostigmine for postoperative analgesia in paediatric surgery

BACKGROUND

This study was conducted to evaluate analgesia and side-effects of caudal neostigmine coadministered with bupivacaine in paediatric surgery.

METHODS

We studied children, aged 1-5 years, undergoing elective surgery (inguinal hernia and hypospadias). After standard induction of anaesthesia, caudal anaesthesia was performed. Group 1 received 0.25% bupivacaine 0.5 ml.kg-1 and Group 2 received 0.25% bupivacaine 0.5 ml x kg-1 with 1 microg x kg-1 neostigmine via the caudal route. Heart rate, mean arterial pressure, peripheral oxygen saturation were recorded before induction, after induction but before caudal anaesthesia, and then every 5 min after caudal anaesthesia. Haemodynamic, Toddler, Preschooler, Postoperative Pain Scale (TPPPS) pain score and sedation score values were recorded 30 min after extubation and at hours 2, 4, 6, 12 and 24. A pain score >3/10 resulted in administration of rectal paracetamol. The duration of postoperative analgesia was defined as the time between caudal drug injection and the first rectal paracetamol administration.

RESULTS

There were no differences between the groups in demographic and haemodynamic date, duration of surgery and anaesthesia, time to extubation or sedation scores. The duration of postoperative pain relief did not differ between the two groups; 15.40 +/- 10.97 h for group 1 vs. 15.45 +/- 10.99 h for group 2 (P > 0.05). The incidence of nausea (three patients in group 2 and one patient in group 1) was not statistically significant. No other side-effects were seen.

CONCLUSIONS

We found that a single caudal injection of 1 microg x kg-1 neostigmine mixed with bupivacaine offers no significant advantage over bupivacaine alone for postoperative pain relief in children undergoing genitourinary surgery.

Benefit and risks of local anesthetics in infants and children

Regional anesthesia has become a routine part of the practice of anesthesiology in infants and children. Local anesthetic toxicity is extremely rare in infants and children; however, seizures, dysrhythmias, cardiovascular collapse, and transient neuropathic symptoms have been reported. Infants and children may be at increased risk from local anesthetics compared with adults. Larger volumes of local anesthetics are used for epidural anesthesia in infants and children than in adults. Metabolism and elimination of local anesthetics can be delayed in neonates, who also have decreased plasma concentrations of alpha(1)-acid glycoprotein, leading to increased concentrations of unbound bupivacaine. Most regional anesthetic procedures in infants and children are performed with the patient heavily sedated or anesthetized; because of this, and because a test dose is not a particularly sensitive marker of intravenous injection in the anesthetized patient, detection of intravascular local anesthetic injection is extremely difficult. The same local anesthetics used in adult anesthetic practice are also used in infants and children. Because of its extremely short duration of action, chloroprocaine has been used primarily for continuous epidural techniques in infants and children. The use of tetracaine has generally been limited to spinal and topical anesthesia. Lidocaine (lignocaine) has been used extensively in infants and children for topical, regional, plexus, epidural and spinal anesthesia. The association between prilocaine and methemoglobinemia has generally restricted prilocaine use in infants and children to the eutectic mixture of local anesthetics (EMLA). Because of its greater degree of motor block compared with other long-acting local anesthetics, etidocaine has generally been limited to plexus blocks in infants and children. Mepivacaine has been used for both plexus and epidural anesthesia in infants and children. Because postoperative analgesia is often the primary justification for regional anesthesia in infants and children, bupivacaine, a long-acting local anesthetic, is the most commonly reported local anesthetic for pediatric regional anesthesia. Given the lower toxic threshold of bupivacaine compared with other local anesthetics, the risk-benefit ratio of bupivacaine may be greater than that of other local anesthetics. Two new enantiomerically pure local anesthetics, ropivacaine and levobupivacaine, offer clinical profiles comparable to that of bupivacaine but without its lower toxic threshold. The extreme rarity of major toxicity from local anesthetics suggests that widespread replacement of bupivacaine with ropivacaine or levobupivacaine is probably not necessary. However, there are clinical situations, including prolonged local anesthetic infusions, use in neonates, impaired hepatic metabolic function, and anesthetic techniques requiring a large mass of local anesthetic, where replacement of bupivacaine with ropivacaine, levobupivacaine or (for continuous techniques) chloroprocaine appears prudent.

[Use of ropivacaine for peridural postoperative analgesia]

OBJECTIVES

To describe pharmacology and toxicology of ropivacaine. To assess the clinical efficacy of ropivacaine when used for postoperative epidural analgesia and to provide recommendations for clinical practice.

DATA SOURCES

Search in the Medline data base of original articles in French and English published since 1995, using the following key words: ropivacaine, postoperative analgesia, epidural, caudal block.

STUDY SELECTION

Prospective randomised studies in adults and children were selected. Letters to editors and editorials were excluded.

DATA EXTRACTION

Articles have been analyzed: to determine the dose of ropivacaine required for postoperative epidural analgesia, to assess the benefits of combination of epidural ropivacaine and additives (opioids or other), to compare epidural ropivacaine and bupivacaine and to assess the use of ropivacaine via caudal route for paediatric postoperative analgesia.

DATA SYNTHESIS

20 mg h-1 of ropivacaine is required to provide effective analgesia. This dose produces a motor block in a significant number of patients. Combination with an opioid allows for a reduction in ropivacaine requirement and subsequently in the incidence of motor blockade. In adults, equipotency ratio of ropivacaine and bupivacaine varies between 1.5/1 and 1/1 depending upon the concentration used. At equipotent doses, early postoperative mobilisation is facilitated with ropivacaine. In case of paediatric caudal analgesia, this ratio is close to 1.

CONCLUSIONS

Epidural ropivacaine combined with opioid provide good postoperative pain relief. Reduction in the incidence of motor blockade and safe toxicological profile make this local anaesthetic a suitable alternative of bupivacaine for postoperative epidural analgesia.

Paediatric regional anaesthesia--what makes a difference?

Regional anaesthetic techniques are useful for providing post-operative pain control for ambulatory surgery in children. This chapter focuses on unique features of paediatric anatomy and physiology that allow successful performance of these techniques. An overview of the effective use of long-acting local anaesthetics in children is presented. Combinations of local anaesthetics and adjunct medications that prolong caudal blockade, the most commonly performed paediatric block, are reviewed, with a goal of providing prolonged analgesia with minimal side-effects. An overview of the use of peripheral nerve blockade and specific recommendations for the use of these blocks in children is also presented.

The minimum local anesthetic concentration of ropivacaine for caudal analgesia in children

Ropivacaine is a new long-acting amino-amide local anesthetic. The concentrations of ropivacaine used in caudal analgesia range from 0.1% to 0.5%. The purpose of this study was to determine the minimum local analgesic concentration of ropivacaine to provide caudal analgesia in children. In a prospective, randomized, double-blinded clinical study, we studied 26 ASA grade I patients aged 1 to 5 yr who were scheduled for hypospadias operation under general anesthesia with caudal ropivacaine analgesia. General anesthesia was maintained with an end-tidal enflurane concentration of 0.8% in 100% oxygen (0.5 minimum alveolar anesthetic concentration [MAC]). Each child received 1 mL/kg of ropivacaine solution through a caudal catheter. The first child received ropivacaine 0.2%, and subsequent concentrations were determined by the analgesic response of the previous patient to the initial skin incision by use of Dixon's up-and-down sequential allocation. The testing interval was set at 0.025%. The minimum local analgesic concentration of ropivacaine for caudal analgesia under general anesthesia with 0.5 MAC enflurane was 0.11% (95% confidence interval [CI], 0.09%-0.12%), and the 95% effective concentration was 0.13% (95% CI, 0.12%-0.21%). In conclusion, the minimum local analgesic concentration of ropivacaine to provide effective caudal analgesia in children under general anesthesia with 0.5 MAC enflurane was found to be 0.11% (95% CI, 0.09%-0.12%).

IMPLICATIONS

Ropivacaine is a new long-acting amino-amide local anesthetic. The concentrations of ropivacaine used in caudal analgesia ranged from 0.1% to 0.5%. This study determined the minimum local analgesic concentration of ropivacaine to establish effective caudal analgesia under general anesthesia with 0.5 minimum alveolar anesthetic concentration enflurane in children.

Caudal clonidine prolongs analgesia from caudal S(+)-ketamine in children

We performed a prospective randomized double-blinded study to test preservative-free S(+)-ketamine alone or in combination with clonidine for intra- and postoperative caudal blockade in pediatric surgery over a 24-h period. Fifty-three children (1-72 mo) scheduled for inguinal hernia repair were caudally injected with either S(+)-ketamine 1 mg/kg alone (Group K) or with additional clonidine (Group C1 = 1 microg/kg; Group C2 = 2 microg/kg) during sevoflurane anesthesia via a laryngeal mask. Intraoperative monitoring included heart rate, blood pressure, and pulse oximetry; postoperative monitoring included a pain discomfort scale and a sedation score. No additional analgesic drugs were required during surgery. The mean duration of postoperative analgesia was 13.3 +/- 9.2 h in Group K, 22.7 +/- 3.5 h in Group C1, and 21.8 +/- 5.2 h in Group C2 (P < 0.0001, Group K versus other groups). Groups C1 and C2 received significantly fewer analgesics in the postoperative period than Group K (15% and 18% vs 63%; P < 0.01). The three groups had similar postoperative sedation scores. We conclude that the combination of S(+)-ketamine 1 mg/kg with clonidine 1 or 2 microg/kg for caudal blockade in children provides excellent analgesia without side effects over a 24-h period.

IMPLICATIONS

Caudally administered preservative-free S(+)-ketamine combined with 1 or 2 microg/kg clonidine provides excellent perioperative analgesia in children and has minimal side effects.

Ropivacaine undergoes slower systemic absorption from the caudal epidural space in children than bupivacaine

We compared the systemic absorption of ropivacaine and bupivacaine after caudal epidural administration in children. Twenty ASA physical status I or II children aged 1-7 yr undergoing elective hypospadias repair were randomized after the induction of general anesthesia to receive a single caudal epidural injection of 2 mg/kg of either ropivacaine 0.2% (R) or bupivacaine 0.2% (B) in a double-blinded fashion. Peripheral venous blood samples (1 mL) were obtained before and 1, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, and 120 min after the caudal injection. The total R and B concentration was measured in plasma by using high-performance liquid chromatography. All blocks were successful, and there were no complications. The peak plasma concentration (mean +/- SD) (R = 0.67 +/- 0.16 and B = 0.73 +/- 0.23 microg/mL) and the area under the plasma concentration curve (R = 61.9 +/- 20.6 and B = 62.7 +/- 18.2 microg x mL(-1) x min(-1)) were comparable between the two study groups. The median (range) time to attain peak plasma concentration was significantly slower in children who received ropivacaine (R = 65 [10-120] min and B = 20 [15-50] min, P < 0.05). We conclude that ropivacaine undergoes slower systemic absorption from the caudal epidural space in children than does bupivacaine.

IMPLICATIONS

We compared the systemic absorption of ropivacaine (0.2%) and bupivacaine (0.2%) after caudal epidural injection of 2 mg/kg in children aged 1-7 yr. Our results show that ropivacaine undergoes slower systemic absorption from the caudal epidural space in children than does bupivacaine.

The efficacy of caudal ropivacaine 1, 2 and 3 mg x l(-1) for postoperative analgesia in children

BACKGROUND

The aim of this double blind, randomized, comparative study was to assess the analgesic efficacy and incidence of motor block after caudal block using three different concentrations of ropivacaine, 1, 2 and 3 mg x l(-1), in children 4-12-year-old.

METHODS

One hundred and ten children ASA I-II, scheduled for inguinal surgery, were included in the study. After induction of a standardized general anaesthetic technique, all patients received 1 ml x kg(-1) of the ropivacaine solution for a caudal block and were assessed for 8 h after the injection.

RESULTS

The ropivacaine was well tolerated in all patients. Median time to treatment with analgesics was 3.3, 4.5 and 4.2 h in the 1, 2 and 3 mg x ml(-1) groups, respectively. During the first 4 h, the pain scores for both a 6-graded faces scale and a 4-graded observer scale were higher in the 1 mg x ml(-1) group than the 3 mg x ml(-1) group. The median sensory block reached T12 in all groups 1 h after the caudal block. Thereafter, the speed of regression was correlated with the ropivacaine concentration. In the patients with a sensory block from T12 and above, the median time to treatment with analgesics was longer than in the children with a sensory block below T12. The incidence of motor block was 28% in the 3 mg x ml(-1) group in comparison with 0 and 13% in the 1 and 2 mg x ml(-1) groups.

CONCLUSIONS

It was concluded that 1 ml x kg(-1) of ropivacaine 2 mg x ml(-1) for caudal block provided satisfactory postoperative pain relief after inguinal surgery in 4-12-year-old children. Ropivacaine 1 mg x ml(-1) showed less efficacy while the use of ropivacaine 3 mg x ml(-1) was associated with a higher incidence of motor block with minimal improvement in postoperative pain relief.

Plasma concentrations of ropivacaine following a single-shot caudal block of 1, 2 or 3 mg/kg in children

BACKGROUND

For documenting the properties of ropivacaine used for regional anaesthesia in children, the relationship between dose and resulting systemic exposure is essential. The aim of this pharmacokinetic part of a randomised, multicentre, double-blind study was to determine the free and total plasma levels of ropivacaine in children aged between 4 and 12 years following a single-shot caudal dose of 1, 2 or 3 mg/kg of ropivacaine for postoperative pain management.

METHOD

Following induction of a standardised general anaesthetic (halothane; nitrous oxide: oxygen 60:40), a caudal block using 1 ml/kg ropivacaine in concentrations of 1, 2 or 3 mg/ml was performed in 43 ASA I children (body weight 12-25 kg) scheduled for elective inguinal surgery. Blood samples were collected prior to and 15, 30, 45, 60 and 240 min after placement of the caudal block for determination of total and free ropivacaine plasma concentrations.

RESULTS

The peak plasma concentration of total ropivacaine, reached within 15-241 min after the block, increased in proportion to dose, with mean values at 0.27, 0.64 and 0.90 mg/l following 1, 2 and 3 mg/kg respectively. The peak plasma level of free ropivacaine also increased in a dose-proportional manner, with mean levels at 0.014, 0.030 and 0.042 mg/l. The highest individual peak plasma level of free ropivacaine was 0.070 mg/l, well below the threshold levels of CNS toxicity described in adults. No clinical signs of systemic toxicity were observed.

CONCLUSION

Following single-shot caudal doses of 1-3 mg/kg in children up to 25 kg and aged between 4 and 12 years, plasma levels of free ropivacaine increase in proportion to dose and all were shown to be within safe limits.

How to prolong postoperative analgesia after caudal anaesthesia with ropivacaine in children: S-ketamine versus clonidine

BACKGROUND

The aim of the study was to determine whether caudal S-ketamine or clonidine prolonged analgesia together with ropivacaine.

METHODS

Sixty-three boys, aged 1-5 years, who were undergoing minor surgery, were allocated in order to receive one of three solutions for caudal anaesthesia. Group R received 2 mg x kg(-1) 0.2% ropivacaine; group C, 2 mg x kg(-1) 0.2% ropivacaine + clonidine 2 microg x kg(-1); and group K, 2 mg x kg(-1) 0.2% ropivacaine + S-ketamine 0.5 mg x kg(-1).

RESULTS

Postoperative analgesia assessed by CHEOPS lasted 701 min in group K (P < 0.05) compared with 492 min in group C and 291 min in group R. There were no significant differences between the groups for incidence of haemodynamic and respiratory alterations, motor block or sedation.

CONCLUSIONS

This study demonstrates that S-ketamine 0.5 mg x kg(-1) when added to 0.2% caudal ropivacaine provides better postoperative analgesia than clonidine without any clinically significant side-effect.

Pharmacokinetics and analgesic effect of ropivacaine following ilioinguinal/iliohypogastric nerve block in children

BACKGROUND

The aim was to investigate the efficacy, tolerance and pharmacokinetics of ropivavcaine when administered for ilioinguinal/iliohypogastric block in children.

METHODS

We examined the pharmacokinetics and analgesic efficacy after ilioinguinal/iliohypogastric nerve block with 3 mg.kg-1 ropivacaine 5 mg.ml-1 in 22 children, aged 1-12 years, who were scheduled for inguinal surgery. Sixteen of 22 patients had a postoperative pain score < 4 (Objective Pain Scale). Nine children were given supplementary analgesics during the first six postoperative hours.

RESULTS

The peak plasma concentration of total ropivacaine was 1.50 +/- 0.93 mg.l-1 (mean +/- SD) (range 0.64-4.77 mg.l-1) 15-64 min after the injection. The peak plasma concentration of free ropivacaine was 0.05 +/- 0.03 mg.l-1 (0.02-0.14 mg.l-1), which is well below the threshold for toxicity in adults. The terminal half-life was 2.0 +/- 0.7 h. No safety concerns or symptoms suggestive of systemic toxicity were observed.

CONCLUSION

A dose of 3 mg.kg-1 of ropivacaine given as a single ilioinguinal/iliohypogastric nerve block in 1-12-year-old children provides satisfactory postoperative pain relief, and is well tolerated.

New insights into paediatric regional anaesthesia: new drugs

Over the years paediatric regional anaesthesia has gained a worldwide consensus, and it can now be considered a significant part of perioperative pain control in children. As in many fields, with the use of drugs administered epidurally there is a fundamental need for safety and efficacy. Two new local anaesthetic agents have recently entered the market, ropivacaine and levobupivacaine, which seem to offer a wider safety margin in comparison with the old drugs as well as valid pain control. To prolong their analgesic duration, many adjuvants can be used, and clonidine and ketamine are probably the best solution. This review summarizes the most recent data on these drugs and their use in children.

Ropivacaine: an update of its use in regional anaesthesia

Ropivacaine is a long-acting, enantiomerically pure (S-enantiomer) amide local anaesthetic with a high pKa and low lipid solubility which blocks nerve fibres involved in pain transmission (Adelta and C fibres) to a greater degree than those controlling motor function (Abeta fibres). The drug was less cardiotoxic than equal concentrations of racemic bupivacaine but more so than lidocaine (lignocaine) in vitro and had a significantly higher threshold for CNS toxicity than racemic bupivacaine in healthy volunteers (mean maximum tolerated unbound arterial plasma concentrations were 0.56 and 0.3 mg/L, respectively). Extensive clinical data have shown that epidural ropivacaine 0.2% is effective for the initiation and maintenance of labour analgesia, and provides pain relief after abdominal or orthopaedic surgery especially when given in conjunction with opioids (coadministration with opioids may also allow for lower concentrations of ropivacaine to be used). The drug had efficacy generally similar to that of the same dose of bupivacaine with regard to pain relief but caused less motor blockade at low concentrations. Lumbar epidural administration of 20 to 30ml ropivacaine 0.5% provided anaesthesia of a similar quality to that achieved with bupivacaine 0.5% in women undergoing caesarean section, but the duration of motor blockade was shorter with ropivacaine. For lumbar epidural anaesthesia for lower limb or genitourinary surgery, comparative data suggest that higher concentrations of ropivacaine (0.75 or 1.0%) may be needed to provide the same sensory and motor blockade as bupivacaine 0.5 and 0.75%. In patients about to undergo upper limb surgery, 30 to 40ml ropivacaine 0.5% produced brachial plexus anaesthesia broadly similar to that achieved with equivalent volumes of bupivacaine 0.5%, although the time to onset of sensory block tended to be faster and the duration of motor block shorter with ropivacaine. Ropivacaine had an adverse event profile similar to that of bupivacaine in clinical trials. Several cases of CNS toxicity have been reported after inadvertent intravascular administration of ropivacaine, but only 1 case of cardiovascular toxicity has been reported to date. The outcome of these inadvertent intravascular administrations was favourable.

CONCLUSION

Ropivacaine is a well tolerated regional anaesthetic with an efficacy broadly similar to that of bupivacaine. However, it may be a preferred option because of its reduced CNS and cardiotoxic potential and its lower propensity for motor block.

Comparison of ropivacaine 0.1% and 0.2% with bupivacaine 0.2% for single-shot caudal anaesthesia in children

We compared analgesic efficacy and degree of motor block induced by ropivacaine 0.1% (R 0.1) and 0.2% (R 0.2) vs. bupivacaine 0.2% (B 0. 2) after caudal anaesthesia in children. Total and free plasma concentrations were measured after caudal injection. Duration of caudal analgesia (median/range) was significantly shorter in group R 0.1 (1.7 h/0.2-6 h) than in group R 0.2 (4.5 h/1.7-6 h) or group B 0. 2 (4 h/1-6 h) (P<0.05). Motor block in the first 2 h postoperatively was significantly less for both ropivacaine groups compared with bupivacaine (P<0.05). Peak plasma concentrations after ropivacaine 0.2% were higher and protein binding lower than after bupivacaine 0.2% (P<0.05). We conclude that caudal analgesia with ropivacaine 0.1% is less effective and of shorter duration than that of ropivacaine 0.2%, whereas ropivacaine 0.2% provides pain relief similar to bupivacaine 0.2%. Motor block in the early postoperative period is less with ropivacaine than with bupivacaine.

Pharmacokinetics of 0.2% ropivacaine and 0.2% bupivacaine following caudal blocks in children

BACKGROUND

Ropivacaine is the first S-enantiomer aminoamide local anaesthetic in clinical use, and has been found to be less toxic than bupivacaine. Caudal ropivacine has been shown to cause less motor blockade and longer duration of analgesia in the postoperative period than bupivacaine in children. Plasma levels of ropivacaine and bupivacaine have not been previously compared in children. This study was undertaken to compare the total venous plasma concentrations of similar doses of ropivacaine and bupivacaine following caudal administration.

METHODS

Blood samples were obtained to determine the total venous plasma levels of the used local anaesthetic in 30 children, aged 2.3-8.7 years, ASA I, given 1 ml x kg of either 0.2% ropivacaine or 0.2% bupivacaine in a prospective, randomised manner.

RESULTS

There were no differences in the individual peak plasma concentrations achieved. Time to the measured peak plasma concentration was significantly shorter in the bupivacaine group. The plasma concentrations of bupivacaine were significantly lower than for ropivacaine at 60, 90 and 120 min after the block.

CONCLUSION

Absorption and tissue distribution of ropivacaine is slower than for bupivacaine following caudal administration in children.