Caudal epidural block: a review of test dosing and recognition of systemic injection in children

Advantages of ketamine in pediatric anesthesia

Although ketamine is primarily used for induction and maintenance of general anesthesia, it also presents sedative, amnestic, anesthetics, analgesic, antihyperalgesia, neuroprotective, anti-inflammatory, immunomodulant, and antidepressant effects. Its unique pharmacodynamics and pharmacokinetic properties allow the use of ketamine in various clinical settings including sedation, ambulatory anesthesia, and intensive care practices. It has also adopted to manage acute and chronic pain management. Clinically, ketamine produces dissociative sedation, analgesia, and amnesia while maintaining laryngeal reflexes, with respiratory and cardiovascular stability. Notably, it does not cause respiratory depression, maintaining both the hypercapnic reflex and the residual functional capacity with a moderate bronchodilation effect. In the pediatric population, ketamine can be administered through practically all routes, making it an advantageous drug for the sedation required setting such as placement of difficult vascular access and in uncooperative and oppositional children. Consequently, ketamine is indicated in prehospital induction of anesthesia, induction of anesthesia in potentially hemodynamic unstable patients, and in patients at risk of bronchospasm. Even more, ketamine does not increase intracranial pressure, and it can be safely used also in patients with traumatic brain injuries. This article is aimed to provide a brief and practical summary of the role of ketamine in the pediatric field.

Update on Local Anesthetic Toxicity, Prevention and Treatment During Regional Anesthesia in Infants and Children

Local anesthetic agents play a key role in the treatment and prevention of pain in children. Although generally safe and effective, as with any pharmacologic agent, adverse effects may occur with the administration of these medications. Systemic absorption or inadvertent systemic injection during bolus dosing or continuous infusion can result in local anesthetic systemic toxicity with life-threatening neurological and cardiac complications. The following article reviews the pharmacology of local anesthetic agents, outlines previous reports of systemic toxicity during regional anesthesia, and discusses prevention and treatment algorithms.

Caudal Anesthesia for Pediatric Subumbilical Surgery, Less Load on the Postoperative Recovery Unit

Introduction

Caudal epidural anesthesia, when used as a sole method for surgical anesthesia, has favorable effects on the recovery duration and the time spent in the recovery unit. In this study we made a retrospective analysis of pediatric surgery operations under local, regional and general anesthesia. We aimed to find shorter postoperative recovery times with local and regional anesthesia.

Materials and methods

Data of the pediatric patients undergone subumbilical surgery during the two-year period in Pediatric Surgery clinic were collected. The patients’ age, sex, surgery type, anesthesia and airway control routes, as well as duration of anesthesia, operation and recovery were obtained.

Results

Data of 937 patients were analyzed, of whom 811 (86.6%) were males. Caudal anesthesia was performed in 240 patients (25.6%) and the mean age of these patients was 3.83 ± 3.00 years. The patients with caudal and local anesthesia spent significantly less time in the postoperative recovery unit, compared with general anesthesia groups (P < 0.001).

Conclusion

Caudal anesthesia as a sole method for pediatric subumbilical surgery is a relatively safe method. Patients having operation under caudal anesthesia have faster discharge times from postoperative recovery units, compared with general anesthesia. This probably reduces recovery unit expenditures.

A Comparative Study of 0.25% Levobupivacaine, 0.25% Ropivacaine, and 0.25% Bupivacaine in Paediatric Single Shot Caudal Block

Aim

There are limited data comparing levobupivacaine, ropivacaine, and bupivacaine in paediatric patients. So, this study was performed to evaluate the caudal effectiveness of all the three drugs in paediatric patients undergoing infraumbilical surgeries and associated complications with these drugs.

Material and Methods

90 patients of ASA grade I and II posted for elective infraumbilical surgeries were randomly divided into three groups of 30 each. A standardized anaesthetic protocol was used. Patients received 0.25% levobupivacaine in group 1, 0.25% ropivacaine in group 2, and 0.25% bupivacaine in group 3. The effectiveness of block was assessed using caudal effectiveness score. Postoperative pain relief was assessed with modified Hannallah pain score. Haemodynamic parameter monitoring was done. The duration of analgesia and associated complications were studied. Statistical analysis was done using the chi-square test for nonparametric data. Parametric data were analysed using ANOVA for intergroup comparison and Tukey's HSD for intragroup comparison.

Results

Demographic data were comparable. Haemodynamic parameters remained within normal range. Mean caudal effectiveness score in all the three groups was statistically insignificant (p > 0.05). The duration of analgesia provided by bupivacaine (145.31 ± 26.17 min) was longer than levobupivacaine (126.15 ± 15.15 min) and ropivacaine (114.68 ± 11.32 min) (p < 0.01). Mean postoperative pain scores were lower in group 3 as compared to group 1 and group 2.

Conclusion

We conclude that levobupivacaine and ropivacaine provide similar intraoperative quality with minimal haemodynamic variability and shorter duration of postoperative analgesia without any significant complications when compared with racemic bupivacaine. This trial is registered with CTRI/2018/03/012402.

Adjuvants to local anesthetics: Current understanding and future trends

Although beneficial in acute and chronic pain management, the use of local anaesthetics is limited by its duration of action and the dose dependent adverse effects on the cardiac and central nervous system. Adjuvants or additives are often used with local anaesthetics for its synergistic effect by prolonging the duration of sensory-motor block and limiting the cumulative dose requirement of local anaesthetics. The armamentarium of local anesthetic adjuvants have evolved over time from classical opioids to a wide array of drugs spanning several groups and varying mechanisms of action. A large array of opioids ranging from morphine, fentanyl and sufentanyl to hydromorphone, buprenorphine and tramadol has been used with varying success. However, their use has been limited by their adverse effect like respiratory depression, nausea, vomiting and pruritus, especially with its neuraxial use. Epinephrine potentiates the local anesthetics by its antinociceptive properties mediated by alpha-2 adrenoreceptor activation along with its vasoconstrictive properties limiting the systemic absorption of local anesthetics. Alpha 2 adrenoreceptor antagonists like clonidine and dexmedetomidine are one of the most widely used class of local anesthetic adjuvants. Other drugs like steroids (dexamethasone), anti-inflammatory agents (parecoxib and lornoxicam), midazolam, ketamine, magnesium sulfate and neostigmine have also been used with mixed success. The concern regarding the safety profile of these adjuvants is due to its potential neurotoxicity and neurological complications which necessitate further research in this direction. Current research is directed towards a search for agents and techniques which would prolong local anaesthetic action without its deleterious effects. This includes novel approaches like use of charged molecules to produce local anaesthetic action (tonicaine and n butyl tetracaine), new age delivery mechanisms for prolonged bioavailability (liposomal, microspheres and cyclodextrin systems) and further studies with other drugs (adenosine, neuromuscular blockers, dextrans).

Caudal Epidural Analgesia in Pediatric Patients: Comparison of 0.25% Levobupivacaine and 0.25% Ropivacaine in Terms of Motor Blockade and Postoperative Analgesia

CONTEXT

Ropivacaine and Levo-Bupivacaine have been safely used for caudal anaesthesia in children, but there are limited studies comparing the efficacy of 0.25% Ropivacaine and 0.25% Levo-Bupivacaine for caudal anaesthesia in infraumbilical surgeries.

AIMS

The aim of this study was to compare the incidence of motor blockade and postoperative analgesia with 0.25% ropivacaine and 0.25% levobupivacaine for the caudal block in children receiving infraumbilical surgery.

SETTINGS AND DESIGN

This was a randomized double-blinded study.

SUBJECTS AND METHODS

Sixty patients of either sex, between 1 and 10 years posted for elective infraumbilical surgeries, to receive caudal block with either (Group R) ropivacaine 0.25% or (Group L) levobupivacaine 0.25% of volume 1 ml/kg were included in the study. Motor blockade was assessed using motor power scale, and pain was assessed every 1 h for first 6 h, then 2nd hourly for following 18 h using modified Hannallah objective pain scale. If pain score is ≥4, the patients were given paracetamol suppositories 20 mg/kg as rescue analgesia.

STATISTICAL ANALYSIS USED

All analyses were performed using Chi-square test, Student's independent t-test, Kruskal-Wallis test, Mann-Whitney U-test.

RESULTS

The time for full motor recovery was similar in both groups; in Group R, ropivacaine: 180.50 ± 14.68 min, and in Group L, levobupivacaine: 184.50 ± 18.02 min, with P = 0.163. The duration of postoperative pain relief between the groups was 330.50 ± 9.54 min in Group L (levobupivacaine) and 312.67 ± 5.56 min in Group R (ropivacaine) with P = 0.165 not statistically significant.

CONCLUSIONS

Both ropivacaine 0.25% and levobupivacaine 0.25% have similar recovery from motor blockade and postoperative analgesia.

Changes of epidural blood flow after epidural administration of epinephrine in young rats

PURPOSE

For caudal epidural analgesia, the needle is inserted at a site where vessels are abundant. To avoid complications related to intravascular administration of the local anesthetic, epinephrine is usually added, but there is no evidence about the safety of epidural administration of epinephrine in pediatric patients. The objective of this study was to assess the changes in epidural blood flow after epidural injection of epinephrine in young rats.

METHODS

With approval of the local ethics committee, four young Sprague-Dawley rats weighing 110-120 g were investigated. The rats were anesthetized with isoflurane via a mask. After there was no escape reaction to pain, an arterial catheter, epidural blood flow monitor (Laser Doppler blood flow ALF 21; ADVANCE Corp.), and caudal epidural catheter were inserted while the rats remained under general anesthesia. Exactly, 10 μl of 1 : 1000 epinephrine was then infused, followed by measurement of the blood pressure and epidural blood flow. After the recovery of the blood pressure and epidural blood flow to baseline, 10 μl of saline was infused through the epidural catheter. The blood pressure and epidural blood flow were then measured again.

RESULTS

One rat was excluded because epinephrine was inadvertently injected into the epidural vessels. Therefore, three rats were investigated in this experiment. Blood flow in the epidural space showed no change after the injection of saline. When epinephrine was administered into the epidural space, epidural blood flow decreased immediately and low flow persisted for 6-15 min. The reduction of blood flow was not very great, being only 8-14%, so there was no risk of spinal ischemia which would require 60-80% reduction.

CONCLUSION

Administration of epinephrine into the epidural space was safe in young rats. While reduction of epidural blood flow was observed, there was no spinal ischemia.

Neonatal pain management

The past 2-3 decades have seen dramatic changes in the approach to pain management in the neonate. These practices started with refuting previously held misconceptions regarding nociception in preterm infants. Although neonates were initially thought to have limited response to painful stimuli, it was demonstrated that the developmental immaturity of the central nervous system makes the neonate more likely to feel pain. It was further demonstrated that untreated pain can have long-lasting physiologic and neurodevelopmental consequences. These concerns have resulted in a significant emphasis on improving and optimizing the techniques of analgesia for neonates and infants. The following article will review techniques for pain assessment, prevention, and treatment in this population with a specific focus on acute pain related to medical and surgical conditions.

Phenylephrine as a simulated intravascular epidural test dose in pediatrics: a pilot study

BACKGROUND

A test dose is used to detect intravascular injection during neuraxial block in pediatrics. Accidental intravascular epidural local anesthetic injection might be unrecognized in anesthetized children leading to potential life-threatening complications. In children, sevoflurane anesthesia blunts the hemodynamic response when intravascular cathecolamines are administered. No studies have explored the hemodynamics and the criteria for a positive test dose result following phenylephrine in sevoflurane anesthetized children.

METHODS

Healthy children undergoing minor procedures were randomly assigned to receive intravenous placebo, or 5 μg∙kg(-1) phenylephrine (n = 11/group) during sevoflurane anesthesia. Hemodynamic response was assessed using electrocardiography, pulse oxymetry and non-invasive blood pressure monitoring for 5 min following drug administration in anesthetized patients.

RESULTS

All patients receiving phenylephrine showed a decreased heart rate (HR) but not all of them met the positive criterion for test dose response. Overall, at 1 min, patients receiving phenylephrine showed a 25% decrease in HR from the baseline while an increase in blood pressure was noticed in 54% of patients receiving phenylephrine.

DISCUSSION

Phenylephrine might be a future indicator of positive intravascular test dose. Further investigation is needed to find out the phenylephrine dose that elicits a reliable hemodynamic response and whether phenylephrine needs to be dose age-adjusted in order to appreciate relevant hemodynamic changes in children receiving neuraxial blocks undergoing general anesthesia.

Caudal epidural blockade in adolescents

BACKGROUND

Various options are available for the provision of analgesia following major surgical procedures including systemic opioids and regional anesthetic techniques. Regional anesthetic techniques offer the advantage of providing analgesia while avoiding the deleterious adverse effects associated with opioids including nausea, vomiting, sedation and respiratory depression. Although used commonly in infants and children, there is a paucity of experience with the use of caudal epidural blockade in adolescents.

METHODS

We retrospectively reviewed the perioperative care of adolescents undergoing major urologic or orthopedic surgical procedures for whom a caudal epidural block was placed for postoperative analgesia.

RESULTS

The cohort for the study included 5 adolescents, ranging in age from 13 to 18 years and in weight from 42 to 71 kilograms. Caudal epidural analgesia was accomplished after the induction of anesthesia and prior to the start of the surgical procedure using 20-25 mL of either 0.25% bupivacaine or 0.2% ropivacaine with clonidine (1 μg/kg). The patients denied pain the recovery room. The time to first request for analgesia varied from 12 to 18 hours with the patients requiring 1-3 doses of analgesic agents during the initial 24 postoperative hours.

CONCLUSIONS

Our preliminary experience demonstrates the efficacy of caudal epidural block in providing analgesia following major urologic and orthopedic surgical procedures. The applications of this technique as a means of providing postoperative analgesia are discussed.

Ketamine: use in anesthesia

The role of ketamine anesthesia in the prehospital, emergency department and operating theater settings is not well defined. A nonsystematic review of ketamine was performed by authors from Australia, Europe, and North America. Results were discussed among authors and the final manuscript accepted. Ketamine is a useful agent for induction of anesthesia, procedural sedation, and analgesia. Its properties are appealing in many awkward clinical scenarios. Practitioners need to be cognizant of its side effects and limitations.

Electrocardiographic and blood pressure alterations caused by intravenous injection of ropivacaine - a study in piglets

OBJECTIVES

Objective signs to detect inadvertent intravascular injection of local anesthetics are essential in the anesthetized pediatric patient. For early detection of intravenous bupivacaine administration, it was shown that an epinephrine containing test dose reliably provoked T-wave alterations, changes in heart rate (HR) and blood pressure, whereas intravenous injection of plain bupivacaine could not be detected until high doses were applied. This study investigates electrocardiographic and hemodynamic alterations caused by intravenous ropivacaine.

METHODS

Twenty-four piglets, anesthetized with sevoflurane, were randomized into two groups: Group R received as test dose plain ropivacaine 0.2% and group RE, ropivacaine 0.2% + epinephrine 5 μg·ml(-1) . Under stable conditions, 0.2 ml kg(-1) of the test solution was intravenously injected. Twenty minutes later, 0.4 ml kg(-1) was applied. A positive effect was defined as HR increase ≥ 10 bpm, increase in mean arterial pressure (MAP) ≥ 15 mmHg, T-wave increase ≥ 25% baseline. In another setting ropivacaine was intravenously infused until cardiac arrest.

RESULTS

After injection of 0.2 or 0.4 ml kg(-1) test solution, a positive increase in HR and MAP was found in 0% of group R and in 100% of group RE. An increase in T-wave ≥ 25% was found in 42% of group R and in 100% of group RE. During intoxication, T-elevation was seen in 83%.

CONCLUSIONS

An epinephrine containing test dose ropivacaine reliably provoked T-wave elevations and increases in HR and MAP. A small dose plain ropivacaine caused T-elevations in a remarkable percentage, whereas higher, quite toxic doses provoked T-elevations in most of the pigs.

[Pediatric caudal anesthesia : importance and aspects of safety concerns]

Caudal block is a safe procedure commonly used for pediatric perioperative analgesia. Complications are extremely rare but nevertheless local and systemic contraindications must be excluded. Optimal safety and quality result when strict attention is paid to technical details. These are discussed in detail in this review. A local anesthetic (LA) containing epinephrine allows early detection of inadvertent intravascular LA administration; therefore an epinephrine/LA mixture is recommended at least for the test dose. In terms of safety the choice of LA itself is probably of secondary importance. Clonidine as an adjuvant has an excellent risk/benefit profile with minimal side effects. Inadvertent systemic LA intoxication is a rare but potentially fatal complication of regional anesthesia and measures for prevention and early detection are essential. Should circulatory arrest occur, immediate resuscitation following standard guidelines is to be initiated including the use of epinephrine as the first line drug. Intravenous administration of lipid solutions may be beneficial as a secondary adjunct to stabilize hemodynamics but is not an alternative to epinephrine.

[Pediatric caudal anesthesia: importance and aspects of safety concerns]

Caudal block is a safe procedure commonly used for pediatric perioperative analgesia. Complications are extremely rare but nevertheless local and systemic contraindications must be excluded. Optimal safety and quality result when strict attention is paid to technical details. A local anesthetic (LA) containing epinephrine allows early detection of inadvertent intravascular LA administration; therefore an epinephrine/LA mixture is recommended at least for the test dose. In terms of safety the choice of LA itself is probably of secondary importance. Clonidine as an adjuvant has an excellent risk/benefit profile with minimal side effects. Inadvertent systemic LA intoxication is a rare but potentially fatal complication of regional anesthesia and measures for prevention and early detection are essential. Should circulatory arrest occur, immediate resuscitation following standard guidelines is to be initiated including the use of epinephrine as the first line drug. Intravenous administration of lipid solutions may be beneficial as a secondary adjunct to stabilize hemodynamics but is not an alternative to epinephrine.

Controversial issues in pediatric regional anesthesia

Regional anesthesia in children has reached in the last decades a widespread approval and today is a valid and effective technique used in the daily activity in many pediatric centres. Data from surveys and studies show the very low rate of complications and suggest that the use of regional techniques in children is at least as safe as general anesthesia alone. Despite these evidences there are aspects still creating discussions on the best approach to avoid or prevent risks and on the way to make this techniques more and more reliable and safe. Compartment syndrome, test dose, loss-of-resistance technique and blocks performed under general anesthesia are examples of, sometimes, never-ending stories; this review without the presumption to solve every problem shows the more recent data to offer, if possible, the best updated-answer on these topics.

Caudal epidural block in children and infants: retrospective analysis of 2088 cases

BACKGROUND AND OBJECTIVES

Regional anesthesia is usually preferred as caudal block via the epidural space. However, the number of large-scale studies including pediatric caudal blocks is small. The objective of this study was to evaluate complications and side effects of local anesthetics and adjuvant drugs.

DESIGN AND SETTING

Retrospective, descriptive study of cases occurring during the period December 2007 to October 2009.

METHODS

Of 4815 medical records were screened, 2088 pediatric cases were identified and included in this study.

RESULTS

As a local anesthetic, we preferred mostly levobupivacaine in 1669 (79.9%) patients and bupivacaine in 419 (20.1%) patients. As adjuvant drug, we preferred mostly morphine (41 patients), fentanyl (7 patients) and adrenaline (6 patients) in 54 (2.5%) patients. For general anesthesia induction, we preferred mostly propofol (1996 patients, 94.2%); for maintenance, sevoflurane (1773 patients, 84.9%). For airway control, we preferred mostly the ProSeal laryngeal mask (PLMA), in 1008 (48.2%) patients. One thousand six hundred five (76.9%) patients were from outpatient clinics and 483 (23.1%) patients were from inpatient clinics. No permanent complication was encountered after caudal blocks.

CONCLUSION

We conclude that caudal epidural blocks are a safe and effective method for subumbilical day-case pediatric surgeries when performed by anesthetists.

[Bupivacaine toxicity and propofol anesthesia : animal study on intravascular bupivacaine injection]

BACKGROUND

Several reports have confirmed the efficacy of Intralipid® (containing soya bean oil, egg phospholipids, glycerin and water) in the therapy of systemic local anesthetic intoxication. Pretreatment with Intralipid® shifted the dose-response to bupivacaine-induced asystole in rats. Whether intravenous anesthesia with propofol in the widely used medium chain triglyceride lipid emulsion increases the therapeutic range of systemically administered bupivacaine or not is unknown and was investigated in this study.

METHODS

A total of 30 piglets aged 2-6 weeks and weighing 4.5-6.5 kg were randomized into 2 groups and anesthetized with sevoflurane (group S) alone or with propofol 10 mg/kg body weight (BW)/h plus sevoflurane (group PS). After 60 min of steady state anesthesia arterial blood was sampled for assessment of blood gases, acid-base state and triglyceride plasma concentrations. Thereafter bupivacaine 0.125% was continuously infused by an infusion syringe pump through a central venous line at a rate of 4 mg/kg BW/min until invasively measured mean arterial pressure (MAP) was reduced by 50% of initial value. The bupivacaine infusion was stopped, blood for assessment of bupivacaine plasma concentration was drawn and the spontaneous hemodynamic course was observed. Resuscitation was not attempted. Results are presented as median and range. The Mann-Whitney U-test was used to assess differences between the two groups for triglyceride as well as for bupivacaine plasma concentrations measured at MAP 50%. A p-value≤0.05 was considered to be significant.

RESULTS

Baseline conditions (arterial blood pH, plasma protein and triglyceride plasma concentrations) did not differ significantly between the two groups. After 1 h of anesthesia, triglyceride plasma concentrations were significantly increased in group PS (median 0.69 mmol/l) compared to the corresponding baseline values (median 0.14 mmol/l; p<0.001) and to the 1 h values of group S (median 0.16 mmol/l; p<0.001). The total amount of bupivacaine administered was 9 mg/kg BW in both groups (6-13 mg/kg BW in group S, 5-13 mg/kg BW in group PS). Resulting bupivacaine plasma concentrations were 180 μmol/l (83-686 μmol/l) in group S and 185 μmol/l (130-465 μmol/l) in group PS. However, the total amount of bupivacaine administered and bupivacaine plasma concentrations at MAP 50% did not reveal statistically significant differences between the two groups but a huge variability of both parameters within each group was observed. None of the 30 piglets spontaneously recovered and they died from pulseless electrical activity or from asystolic cardiac arrest. The time from MAP 50% until cardiac arrest demonstrated a large variability but did not reveal significant differences between the two groups. The time to cardiac arrest was similar in both groups.

CONCLUSION

Medium/long chain triglyceride lipid emulsion (50:50) as widely used in propofol solutions did not increase therapeutic safety in cases of intravascular bupivacaine administration in this piglet model.

Impact of propofol on electrocardiographic alterations during intravascular application of bupivacaine--a study in piglets

BACKGROUND

Intravascular application of a small dose of local anesthetics (LA) with epinephrine as well as larger doses of LA under sevoflurane anesthesia results in increase in T-wave amplitude in the electrocardiogram (ECG). The aim of this study was to elucidate whether propofol anesthesia affects these ECG alterations or not.

METHODS

Thirty neonatal pigs were randomized into two groups. Group 1 was anesthetized with sevoflurane, group 2 with sevoflurane plus continuous propofol infusion (10 mg·kg(-1)·h(-1)). A test dose of 0.2 ml·kg(-1) bupivacaine 0.125% + epinephrine 1 : 200,000 was injected intravenously. Arterial pressure was monitored. ECG was analyzed for changes in T-wave amplitude (positive if ≥25% baseline) and heart rate. In another setting, bupivacaine 0.125% was intravenous infused at a rate of 4 mg·kg(-1)·min(-1). ECG was analyzed for alteration in T-wave amplitude and heart rate at 1.25, 2.5, and 5 mg·kg(-1) bupivacaine infused.

RESULTS

T-wave elevation after the administration of an epinephrine containing LA test dose was similar between the two groups. Increase in heart rate caused by the test dose were significantly higher in group 2 (P = 0.008). During continuous bupivacaine administration, T-wave elevation occurred in 40% and 71% (group 1 and 2) at 1.25 mg·kg(-1), in 80% and 100% at 2.5 mg·kg(-1), and in 93% and 86% at 5 mg·kg(-1) bupivacaine infused.

CONCLUSION

Continuous propofol infusion does not suppress the ECG signs of a systemically administered epinephrine containing LA test dose nor does it suppress the ECG signs caused by high doses of intravenous applied bupivacaine.

Successful resuscitation of bupivacaine-induced cardiotoxicity in a neonate

We report a case of bupivacaine-induced cardiotoxicity in a neonate following caudal epidural block under general anesthesia for urologic surgery. Prompt recognition of the complication allowed early intervention with both standard resuscitative measures and administration of 20% Intralipid(®) , resulting in a good outcome.

Plethysmographic pulse wave amplitude is an effective indicator for intravascular injection of epinephrine-containing epidural test dose in sevoflurane-anesthetized pediatric patients

BACKGROUND

Plethysmographic pulse wave amplitude (PPWA) was effective in detecting intravascular injection of epidural test dose with 100% sensitivity and specificity in adults. We evaluated the efficacy of PPWA in detecting intravascular injection of a simulated epidural test dose during sevoflurane anesthesia in pediatric patients.

METHODS

Eighty infants and children were randomized to receive either 0.5 minimal alveolar concentration (MAC) or 1 MAC sevoflurane and nitrous oxide in oxygen. Patients in each anesthesia group were further randomized to receive either 0.1 mL/kg of 1% lidocaine with 1:200,000 epinephrine (0.5 mug/kg of epinephrine) IV to simulate the intravascular injection of epidural test dose or saline. Heart rate (HR), systolic blood pressure (SBP), and PPWA were monitored for 5 min after injection. A positive test response was defined as HR increase > or =10 bpm, SBP increase > or =15 mm Hg, and PPWA decrease > or =10%.

RESULTS

Injecting the test dose resulted in an average maximum PPWA decrease by 69% +/- 18% and 58% +/- 14% at 79 +/- 22 and 80 +/- 19 s in the 0.5 MAC and 1 MAC sevoflurane groups, respectively. The sensitivity, specificity, positive predictive, and negative predictive values for PPWA were 100% in both sevoflurane groups, whereas by using HR and SBP criteria, the sensitivity was 90% and 95% respectively during 0.5 MAC sevoflurane anesthesia and 85% for both during 1 MAC sevoflurane anesthesia.

CONCLUSION

PPWA is effective for detection of an intravascular injection of a simulated epidural epinephrine-containing test dose in pediatric patients.

Determining the accuracy of caudal needle placement in children: a comparison of the swoosh test and ultrasonography

BACKGROUND

The aim of the present study was to compare two confirmatory tests - the 'swoosh' test (auscultation during caudal injection) and real time ultrasound imaging (both transverse 2D imaging and color flow Doppler imaging) in pediatric patients receiving a caudal epidural block.

METHODS/MATERIALS

This was a retrospective observational study of caudal injections administered to 83 pediatric patients (0-11 years) presenting for elective surgery over a 4 month time period. While injecting small aliquots of local anesthetic, a standard stethoscope was placed over the lower lumbar spine to auscultate for the 'swoosh' test. An ultrasound machine (Sonosite Titan, Sonosite Inc., Bothell, WA, USA) was then utilized for real-time visualization of caudal injectate. Each test performed during the caudal injection (swoosh, turbulence on 2D imaging, or color flow on Doppler imaging) was recorded as positive, negative or equivocal.

RESULTS

Eighty out of 83 patients (96.4%) had a successful caudal block based on minimal or no perioperative narcotic use, minimal or no response to surgical stimulation, the presence of motor blockade and patient comfort in the PACU. Ultrasound was significantly superior to 'swoosh' for sensitivity (96.3% vs 57.5%), negative predictive (40% vs 5.6 value) % and likelihood ratio (2.89 vs 1.73). Specificity and positive predictive value were not different between 'swoosh' and ultrasound. Of the ultrasound tests, turbulence was more sensitive than color flow Doppler (95.0% vs 78.8%).

CONCLUSION

Ultrasonography is superior to the 'swoosh' test as an objective confirmatory technique during caudal block placement in children. We found the presence or absence of turbulence during injection within the caudal space to be the best single indicator of caudal success. We think ultrasonography should be used, if available, when teaching this technique.

Is a fall in baseline heart rate a reliable predictor of a successful single shot caudal epidural in children?

BACKGROUND

This study was designed to investigate whether a fall in heart rate (HR) with injection of local anesthetic into the caudal space can be used as a predictor of correct needle placement.

METHODS

Two hundred and twenty pediatric patients undergoing infraumbilical surgery were recruited to the study. After induction of general anesthesia, baseline HR was recorded and caudal block was performed using 0.75-1 ml x kg(-1) 0.25% bupivacaine, which was injected at a rate of 1 ml x 3 s(-1). The change in HR while injecting an initial 0.2 ml x kg(-1) of drug and during total drug injection was recorded. HR reduction of > or = 3 b x min(-1) was considered a positive test for correct needle placement. The success of block was judged by HR response to skin incision, endtidal halothane concentration required for maintenance of anesthesia and postoperative pain scores.

RESULTS

Caudal block was successful in 209/220 (95%) patients. Mean HR following the initial drug injection (111 +/- 17.7, P < 0.01) and entire drug injection (108.8 +/- 17.2, P < 0.01) was significantly lower than baseline (116.2 +/- 17.5). HR reduction of > or = 3 b x min(-1) was present in 190/209 and 199/209 successful block following initial drug injection and total drug injection respectively. The analysis of study data showed that a fall in HR is a predictor of successful caudal block, with a sensitivity of 90.9%, specificity of 100% and a positive predictive value of 100% after initial injection of local anesthetic.

CONCLUSIONS

We conclude that decrease in HR with drug injection is a simple, objective and reliable test to predict success of caudal block.

Periduralanästhesie

In epidural anaesthesia, the anaesthetist injects one or more drugs into the epidural space bordering on the spinal dura mater to achieve a "central" and/or "neuraxial" block. It is one of the earliest techniques in anaesthesia, originally performed exclusively with local anaesthetic agents. Adding other drugs and combining epidural with general anaesthesia or adapting the technique to the needs of children has extended the list of indications. Continuous epidural analgesia is an important tool in postoperative pain management. More and more often, the increasing proportion of patients who have comorbidities or are permanently taking medication that modulates the clotting system demands that the anaesthesiologist balance the individual risks and benefits before inducing epidural anaesthesia.

Innovative approaches to neuraxial blockade in children: the introduction of epidural nerve root stimulation and ultrasound guidance for epidural catheter placement

Continuous epidural blockade remains the cornerstone of pediatric regional anesthesia. However, the risk of catastrophic trauma to the spinal cord when inserting direct thoracic and high lumbar epidural needles in anesthetized or heavily sedated pediatric patients is a concern. To reduce this risk, research has focused on low lumbar or caudal blocks (ie, avoiding the spinal cord) and threading catheters from distal puncture sites in a cephalad direction. However, with conventional epidural techniques, including loss-of-resistance for localization of the needle, optimal catheter tip placement is difficult to assess because considerable distances are required during threading. Novel approaches include electrical epidural stimulation for physiological confirmation and segmental localization of epidural catheters, and ultrasound guidance for assessing related neuroanatomy and real-time observation of the needle puncture and, potentially, catheter advancement. The present article provides a brief and focused review of these two advances, and outlines recent clinical experiences relevant to pediatric epidural anesthesia.

Caudal analgesia and anesthesia techniques in children

PURPOSE OF REVIEW

Caudal epidural blockade remains the cornerstone of pediatric regional anesthesia. In this article we provide a comprehensive review of the recent developments in caudal anesthesia in infants and children.

RECENT FINDINGS

Research has focused on prolonging the duration of single-shot caudal blocks and accurately positioning continuous caudal catheters. New local anesthetics with similar potencies but less toxicity have been introduced. Opioids prolong the duration of analgesia of local anesthetic, but have also been associated with unacceptable side effects, particularly in pediatric outpatients. Various non-opioid adjuncts with more favorable side-effect profiles may increase the duration of analgesia. New ultrasound and nerve-stimulation techniques have been developed to accurately guide epidural catheters to a specific spinal level.

SUMMARY

The addition of ketamine or clonidine to a caudal local anesthetic prolong the duration of the block. However, a preservative-free preparation of ketamine that is suitable for neuraxial use is not widely available. Ultrasound imaging and electrical stimulation are promising options to accurately position a caudal needle. However, because ultrasound imaging is more difficult in older children, nerve stimulation is a more-suitable technique to accurately guide caudal catheters in this patient population. Although complications associated with caudal block are rare, the risks and benefits must be carefully considered on an individual basis.

Confirmation of Direct Epidural Catheter Placement Using Nerve Stimulation in Pediatric Anesthesia

We evaluated the success rate of using low current electrical stimulation (the Tsui test) to identify and confirm direct epidural catheter placement in a pediatric population. Thirty subjects received a standard anesthetic and administration of the Tsui test on epidural placement. The distribution of myotomal activity was recorded. The intended and actual level of the epidural catheter was compared. Myotomal activity was seen in all patients but one. The median current resulting in myotomal activity was 5.3 mA. The median difference between the intended and actual level as confirmed on radiograph was 1.8 levels. The clinical success rate was 93.9%. The positive predictive value of the Tsui test was 82%; i.e., in 23 of 28 cases, the Tsui test correctly identified the position of the epidural catheter tip within 2 vertebral levels. The test did not offer any added advantage when used in the setting of directly placed epidural catheters in our institution over "blind" methods already used to confirm catheter position when using cutaneous landmarks and test dosing.

IMPLICATIONS

A new technique to confirm epidural catheter position uses low current electrical stimulation in pediatric patients. This study evaluated the use of electrical stimulation in 30 pediatric patients for directly placed catheters. Electrical stimulation did not provide any advantage over conventional methods (e.g., cutaneous landmarks) for confirmation of catheter position.

Choice of electrocardiography lead does not affect the usefulness of the T-wave criterion for detecting intravascular injection of an epinephrine test dose in anesthetized children

Accidental intravascular injection of an epinephrine-containing test dose increases T-wave amplitude of lead II electrocardiogram (EKG) in anesthetized children. We designed this study to test whether the choice of EKG lead would affect the usefulness of simulated intravascular test dose. We studied 32 ASA physical status I infants and children (aged 6-49 mo) undergoing elective surgeries during 1.0 minimum alveolar anesthetic concentration sevoflurane and 67% nitrous oxide in oxygen. When hemodynamic stability was obtained, all subjects received IV saline 0.1 mL/kg, followed 4 min later by an IV test dose (0.1 mL/kg) consisting of 1% lidocaine with 1:200,000 epinephrine (epinephrine 0.5 microg/kg) via a peripheral vein to simulate the intravascular injection of the test dose. Heart rate and systolic blood pressure were recorded every 20 and 60 s, respectively, and leads II (n = 32), V(5) (n = 32) and either lead I (n = 15) or III (n = 17), choosing the one with greater preinjection T-wave amplitude, were continuously recorded for 4 min after the saline and the test dose injections. An IV test dose produced significant increases in heart rate, systolic blood pressure, and T-wave amplitude of all EKG leads studied in all subjects, whereas IV saline elicited no changes in these variables. Maximal increases in T-wave amplitude of leads II, I, III, and V(5) were 158% +/- 69%, 175% +/- 78%, 147% +/- 89%, and 170% +/- 72%, respectively (mean +/- SD, P > 0.05). There was no significant difference in temporal changes in T-wave amplitude among the 4 leads, and sensitivity and specificity were 100% on the basis of the T-wave criterion irrespective of the lead examined. Our results indicate that leads II, I, III, and V(5) of EKG are equally effective for detecting intravascular injection of the epinephrine-containing test dose in sevoflurane-anesthetized children.

IMPLICATIONS

To determine whether an epidurally administered local anesthetic has been accidentally injected into a blood vessel, a small dose of epinephrine is often added to a local anesthetic. We found that increases in T-wave amplitude in leads I, II, III, and V(5) of the electrocardiogram are equally sensitive and specific for detecting intravascular injection of the epinephrine-containing test dose in sevoflurane-anesthetized infants and children.

Simulated epidural test doses using adrenaline and adrenaline/clonidine in sevoflurane-anaesthetized children

A pilot study was conducted using a simulated epidural test dose to ascertain the effects adrenaline, adrenaline/clonidine mixture, and clonidine alone on the accepted criteria for determining the occurrence of an epidural intravascular injection. Seventy-five ASA 1 or 2 children aged from six months to twelve years were sequentially allocated to one of three groups: group A: adrenaline 0.5 microgram/kg, group AC: adrenaline 0.5 microgram/kg and clonidine 0.3 microgram/kg, and group C: clonidine 0.3 microgram/kg. Effects on heart rate, T-wave amplitude and systolic blood pressure were determined after induction of anaesthesia and stabilization using sevoflurane in nitrous oxide and oxygen. Heart rate varied from baseline in a biphasic manner. The maximal increase in mean heart rate for all groups was < 10 beats per minute (bpm). A heart rate rise of > 10 bpm was not seen at any time in 54% of groups A and AC and 92% of group C (Chi-square 11.4, P = 0.003). T-wave changes were also biphasic. 50% of groups A and AC had no increase in T-wave size of > 25% at any sample point, compared with 96% in group C (Chi square = 49.4, P < 0.0001). 34% of groups A and AC did not have a change in systolic blood pressure of > 15 mmHg during the study compared with 100% of group C (Chi-square = 30.2, P < 0.0001). There were no significant differences between groups A and AC for any parameter. Negative predictive value estimates for the current criteria for intravascular injection were low. Clonidine 0.3 microgram/kg produced no effects on the study variables.

Postoperative analgesia in infants and children

PURPOSE OF REVIEW

Although postoperative analgesia in infants and children should be an integral part of the perioperative management, undertreatment of pain is not rare in clinical practice and may influence outcome and long term behaviour. Therefore, this review summarizes results of recent papers and discusses actual trends and future perspectives concerning postoperative pharmacologic pain therapy in infants and children.

RECENT FINDINGS

A multimodal approach using locoregional anesthesia and systemic analgesics is a widely accepted technique. New developments include new local anesthetics with a wider margin of safety and more experience with adjuvants, catheter techniques and systemic analgesics. Replacement of bupivacaine with ropivacaine may be prudent especially for prolonged epidural infusion, use in neonates, impaired hepatic metabolic function, and anesthetic techniques requiring large dosage of local anesthetic. The limited duration of analgesia after single blocks can be prolonged by use of adjuvants (clonidine, ketamine), catheter techniques or early use of systemic analgesics. Non-opioids (acetaminophen, non-steroidal anti-inflammatory drugs) are appropriate for patients with mild to moderate pain or as a component of multimodal pain therapy. Patient- and nurse-controlled analgesia are convenient ways for opioid administration in infants and children.

SUMMARY

The reviewed studies suggest that there are many reliable agents and techniques available to provide a safe and effective postoperative analgesia even in neonates and small infants.

Unusual presentation of long QT syndrome

We describe the case of a 9-yr-old child with undiagnosed long QT syndrome who experienced an intraoperative cardiac arrest after accidental intravascular injection of bupivacaine with epinephrine via a misplaced epidural catheter.

Pain management for pediatric ambulatory anesthesia

PURPOSE OF REVIEW

New developments in analgesic drugs and techniques are being applied to the pediatric population. Appropriate pain management for ambulatory surgery patients helps to facilitate early discharge and minimize postoperative morbidity.

RECENT FINDINGS

A variety of opioid-related drugs, as well as novel delivery routes for opioids, have been reported in the pediatric population. New pharmacokinetic information for acetaminophen has resulted in revised dosage recommendations; applications of the nonsteroidal antiinflammatory agents are also discussed. Furthermore, regional anesthesia and adjuncts are useful in the pediatric ambulatory surgery patient.

SUMMARY

Recent data on techniques for pain management after pediatric ambulatory surgery will help the anesthetist develop a comprehensive plan for the postoperative period.

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.