Liposomal Bupivacaine for Peripheral Nerve Blockade: A Randomized, Controlled, Crossover, Triple-blinded Pharmacodynamic Study in Volunteers.

BACKGROUND: Little is known about the pharmacodynamic characteristics of liposomal bupivacaine. Hypothesizing that they would not identify pharmacodynamic differences from plain bupivacaine during the initial period after administration, but would find better long-term pharmacodynamic characteristics, the authors designed a randomized, controlled, triple-blinded, single-center study in volunteers. METHODS: Volunteers aged 18 to 55 yr (body mass index, 18 to 35 kg/m2) received two ulnar nerve blocks under ultrasound guidance. Using a crossover design with a washout phase of 36 days or more, one block was performed with liposomal and one with plain bupivacaine. Which came first was determined by randomization. Sensory data were collected by pinprick testing and motor data by thumb adduction, either way in comparison with the contralateral arm. Endpoints included success, time to onset, and duration of blockade. Residual efficacy was assessed by the volunteers keeping a diary. Statistical analysis included Wilcoxon signed-rank and exact McNemar's tests, as well as a generalized estimation equation model. RESULTS: Successful sensory blockade was noted in 8 of 25 volunteers (32%) after liposomal and in 25 of 25 (100%) after plain bupivacaine (P < 0.0001). Significant differences emerged for time to onset, defined as 0% response to pinpricking in four of five hypothenar supply areas (P < 0.0001), and for time from onset to 80% or 20% in one of five areas (P < 0.001; P < 0.001). Carryover effects due to the randomized sequencing were unlikely (estimate, -0.6286; sequence effect, 0.8772; P = 0.474). Self-assessment greater than 3.5 days did reveal, for liposomal bupivacaine only, intermittent but unpredictable episodes of residual sensory blockade. CONCLUSIONS: The results show that liposomal bupivacaine is not a suitable "sole" drug for intraoperative regional anesthesia. Findings of its limited long-term efficacy add to existing evidence that a moderate effect, at best, should be expected on postoperative pain therapy.

Peripheral regional anaesthesia and outcomes: a narrative review of the literature from 2013 to 2023.

The use of peripheral regional anaesthesia continues to increase, yet the evidence supporting its use and impact on relevant outcomes often lacks scientific rigour, especially when considering the use of specific blocks for a particular surgical indication. In this narrative review, we consider the relevant literature in a 10-yr period from 2013. We performed a literature search (MEDLINE and EMBASE) for articles reporting randomised controlled trials and other comparative trials of peripheral regional anaesthetic blocks vs systemic analgesia in adult patients undergoing surgery. We evaluated measures of effective treatment and complications. A total of 128 studies met our inclusion criteria. There remains variability in the technical conduct of blocks and the outcomes used to evaluate them. There is a considerable body of evidence to support the use of interscalene blocks for shoulder surgery. Saphenous nerve (motor-sparing) blocks provide satisfactory analgesia after knee surgery and are preferred to femoral nerve blocks which are associated with falls when patients are mobilised early as part of enhanced recovery programmes. There are additional surgical indications where the efficacy of cervical plexus, intercostal nerve, and ilioinguinal/iliohypogastric nerve blocks have been demonstrated. In the past 10 yr, there has been a consolidation of the evidence indicating benefit of peripheral nerve blocks for specific indications. There remains great scope for rigorous, multicentre, randomised controlled trials of many peripheral nerve blocks. These would benefit from an agreed set of patient-centred outcomes.

Augmented reality in ultrasound-guided regional anaesthesia: useful tool or expensive toy?

Use of augmented reality is increasingly applied in medical education and practice. The main advantage of this technology is the display of relevant information in the visual field of multiple operators. Here we provide a critical analysis of the potential application of augmented reality in regional anaesthesia.

A prospective observational study on the feasibility of subumbilical laparoscopic procedures under epidural anesthesia in sedated spontaneously breathing infants with a natural airway.

BACKGROUND: Laparoscopic procedures are usually performed under general anesthesia with a secured airway including endotracheal intubation or supraglottic airways. AIMS: This is a prospective study of the feasibility of subumbilical laparoscopic procedures under epidural anesthesia in sedated, spontaneous breathing infants with a natural airway. METHODS: We consecutively enrolled 20 children <3 years old with nonpalpable testes scheduled for diagnostic laparoscopy with or without an ensuing orchidopexy, inguinal revision, or Fowler-Stephens maneuver. Inhalational induction for venous access was followed by sedation with propofol and ultrasound-guided single-shot epidural anesthesia via the caudal or thoracolumbar approach using 1.0 or 0.5 ml kg-1 ropivacaine 0.38%, respectively. The primary outcome measure was block success, defined as no increase in heart rate by >15% or other indicators of pain upon skin incision. RESULTS: Of the 20 children (median age: 10 months; IQR: 8.3-12), 17 (85%) were anesthetized through a caudal and 3 (15%) through a direct thoracolumbar epidural, 18 (90%) underwent a surgical procedure and 2 (10%) diagnostic laparoscopy only. Five patients (25%) received block augmentation using an intravenous bolus of fentanyl (median dose: 0.9 µg kg-1 ; IQR: 0.8-0.95) after the initial prick test and before skin incision. There was no additional need for systemic pain therapy in the operating theater or recovery room. No events of respiratory failure or aspiration were observed. CONCLUSIONS: In experienced hands, given our success rate of 100%, epidural anesthesia performed in sedated spontaneously breathing infants with a natural airway can be an alternative strategy for subumbilical laparoscopic procedures.

Establishing reference ranges of cord blood: point-of-care hemostatic function assessment in preterm and term neonates.

BACKGROUND: Thrombelastometry, allowing timely assessment of global hemostatic function, is increasingly used to guide hemostatic interventions in bleeding patients. Reference values are available for adults and children, including infants but not neonates immediately after birth. METHODS: Neonates were grouped as preterm (30 + 0 to 36 + 6 weeks/days) and term (37 + 0 to 39 + 6 weeks/days). Blood samples were drawn from the umbilical cord immediately after cesarean section and analyzed by thrombelastometry. Reference ranges were determined for the extrinsic and intrinsic coagulation pathways, fibrin polymerization, and hyperfibrinolysis detection. RESULTS: All extrinsically activated test parameters, but maximum lysis (P = 0.139) differed significantly between both groups (P ≤ 0.001). Maximum clot firmness in the fibrin polymerization test was comparable (P = 0.141). All intrinsically activated test parameters other than coagulation time (P = 0.537) and maximum lysis (P = 0.888) differed significantly (P < 0.001), and so did all aprotinin-related test parameters (P ≤ 0.001) but maximum lysis (P = 0.851). CONCLUSIONS: This is the first study to identify reference ranges for thrombelastometry in preterm and term neonates immediately after birth. We also report differences in clot initiation and clot strength in neonates born <37 versus ≤40 weeks of gestation, mirroring developmental hemostasis. IMPACT: Impact: This prospective observational study is the first to present reference ranges in preterm and term infants for all types of commercially available tests of thrombelastometry, notably also including the fibrin polymerization test. IMPORTANCE: Viscoelastic coagulation assays such as thrombelastometry have become integral to the management of perioperative bleeding by present-day standards. Reference values are available for adults, children, and infants but not for neonates. Key message: Clot initiation and formation was faster and clot strength higher in the term than in the preterm group. Parameters of thrombelastometry obtained from cord blood do not apply interchangeably to preterm and term neonates.

Epidural versus general anesthesia for open pyloromyotomy in infants: A retrospective observational study.

BACKGROUND: Thoracic epidural anesthesia for open infantile hypertrophic pyloric stenosis surgery is a controversial issue in the presence of little comparative data. AIMS: To compare this approach to general anesthesia for desaturation events (≤90% oxygen saturation) and absolute values of minimal oxygen saturation, minimal heart frequency, operating-room occupancy time, and durations of surgery in a retrospective study design. METHODS: Data were retrieved for patients with infantile hypertrophic pyloric stenosis managed by thoracic epidurals under sedation or general anesthesia with rapid sequence induction between 01/2007 and 12/2017. Oxygen saturation and heart rate were analyzed over eight 5-minutes intervals relative to the start of anesthesia / sedation (four-time intervals) and before discharge of the patient from the operating room (four-time intervals). Fisher's exact tests and mixed model two-way analysis of variance for repeated measures were employed for intergroup comparisons. RESULTS: The epidural and general anesthesia groups included 69 and 32 evaluable infants, respectively. Patients managed under epidural anesthesia had cumulatively higher minimimal mean (SD) oxygen saturation values (98.2 [2.6] % versus 96.6 [5.2] %, p < 0.001) and lower minimal mean (SD) heart rate values (127.9 [15.0] beats per minute versus 140.7 [17.2] beats per minute, p < 0.001) over time. Similarly, the frequency of desaturation events (defined as ≤90% oxygen saturation) was significantly lower for these patients during the period of 5 minutes after induction of sedation or general anesthesia (odds ratio 7.4 [2.1-25.9]; p = 0.001) and during the subsequent period of five minutes (odds ratio 6.2 [1.1-33.9]; p = 0.031). One case of prolonged respiratory weaning was observed in the general anesthesia group. The mean (SD) operating-room occupancy was 61.9 (16.6) minutes for the epidural anesthesia group versus 73.3 (22.2) minutes for the general anesthesia group (p = 0.005) as a result of shorter emergence from sedation. CONCLUSIONS: In our series, maintaining spontaneous breathing with minimal airway manipulation in patients undergoing open repair of hypertrophic pyloric stenosis under single-shot epidural anesthesia resulted in fewer desaturation events ≤90% than general anesthesia. In addition, this approach seems to result in shorter turnover times in the operating room.

Generic versus reference listed ropivacaine for peripheral nerve blockade: A randomised, triple-blinded, crossover, equivalence study in volunteers.

BACKGROUND: Generic drug preparations do not require the same degree of scrutiny as the originally licensed preparation before they can be approved for clinical use. The permitted tolerance limits for bioequivalent preparations might be associated with clinically relevant differences for drugs with a narrow therapeutic index, such as local anaesthetics. OBJECTIVE: We compared pharmacokinetic and pharmacodynamic characteristics of generic and reference listed or original preparations of ropivacaine. DESIGN: The current healthy volunteer study used a randomised, triple-blinded, cross-over equivalence design. SETTING: Tertiary university hospital, Medical University of Vienna. SUBJECTS: Healthy male volunteers (N=18) aged 18 to 60 years. INTERVENTIONS: A series of three ultrasound-guided ulnar nerve blocks separated by at least 6 days were carried out on each volunteer. Reference listed ropivacaine (NaropinTM) was used for two blocks and a generic preparation of ropivacaine was used for the other block. Sensory block onset and duration were evaluated using loss of pinprick sensation. MAIN OUTCOME MEASURES: Duration of sensory block was the primary outcome. Secondary outcomes included time-to-onset of sensory block, ropivacaine pharmacokinetics from venous blood samples and pH of the preparations. Equivalence was evaluated using the ratios of means and 90% confidence intervals (CIs) of log transformed data. RESULTS: Equivalence was demonstrated for the primary outcome measure, the duration of sensory block [original : generic ratio 1.01 (90% CI 0.87 to 1.16); P < 0.007] and all pharmacokinetic variables. Equivalence could not be concluded for time-to-onset of sensory block [reference : generic ratio 0.80 (90% CI 0.63 to 1.03); P = 0.27], although reproducibility of this variable using our experimental model was lower than for other variables. The generic preparation was significantly more alkaline [difference 0.06 pH units (95% CI 0.04 to 0.07); P < 0.0001]. CONCLUSION: Our finding of equivalence for sensory block duration and key pharmacokinetic variables between a generic and original preparation of ropivacaine is reassuring. The significant, but small, difference in pH is not clinically important. TRIAL REGISTRATION: EudraCT 2019-003148-61, German Clinical Trials Register (DRKS 00017750).

Recurrence of breast cancer after regional or general anaesthesia: a randomised controlled trial.

BACKGROUND: Three perioperative factors impair host defence against recurrence during cancer surgery: the surgical stress response, use of volatile anaesthetic, and opioids for analgesia. All factors are ameliorated by regional anaesthesia-analgesia. We tested the primary hypothesis that breast cancer recurrence after potentially curative surgery is lower with regional anaesthesia-analgesia using paravertebral blocks and the anaesthetic propofol than with general anaesthesia with the volatile anaesthetic sevoflurane and opioid analgesia. A second hypothesis was that regional anaesthesia-analgesia reduces persistent incisional pain. METHODS: We did a randomised controlled trial at 13 hospitals in Argentina, Austria, China, Germany, Ireland, New Zealand, Singapore, and the USA. Women (age <85 years) having potentially curative primary breast cancer resections were randomised by computer to either regional anaesthesia-analgesia (paravertebral blocks and propofol) or general anaesthesia (sevoflurane) and opioid analgesia. The primary outcome was local or metastatic breast cancer recurrence. The secondary outcome was incisional pain at 6 months and 12 months. Primary analyses were done under intention-to-treat principles. This trial is registered with ClinicalTrials.gov, NCT00418457. The study was stopped after a preplanned futility boundary was crossed. FINDINGS: Between Jan 30, 2007, and Jan 18, 2018, 2132 women were enrolled to the study, of whom 24 were excluded before surgery. 1043 were assigned to regional anaesthesia-analgesia and 1065 were allocated to general anaesthesia. Baseline characteristics were well balanced between study groups. Median follow-up was 36 (IQR 24-49) months. Among women assigned regional anaesthesia-analgesia, 102 (10%) recurrences were reported, compared with 111 (10%) recurrences among those allocated general anaesthesia (hazard ratio 0·97, 95% CI 0·74-1·28; p=0·84). Incisional pain was reported by 442 (52%) of 856 patients assigned to regional anaesthesia-analgesia and 456 (52%) of 872 patients allocated to general anaesthesia at 6 months, and by 239 (28%) of 854 patients and 232 (27%) of 852 patients, respectively, at 12 months (overall interim-adjusted odds ratio 1·00, 95% CI 0·85-1·17; p=0·99). Neuropathic breast pain did not differ by anaesthetic technique and was reported by 87 (10%) of 859 patients assigned to regional anaesthesia-analgesia and 89 (10%) of 870 patients allocated to general anaesthesia at 6 months, and by 57 (7%) of 857 patients and 57 (7%) of 854 patients, respectively, at 12 months. INTERPRETATION: In our study population, regional anaesthesia-analgesia (paravertebral block and propofol) did not reduce breast cancer recurrence after potentially curative surgery compared with volatile anaesthesia (sevoflurane) and opioids. The frequency and severity of persistent incisional breast pain was unaffected by anaesthetic technique. Clinicians can use regional or general anaesthesia with respect to breast cancer recurrence and persistent incisional pain. FUNDING: Sisk Healthcare Foundation (Ireland), Eccles Breast Cancer Research Fund, British Journal of Anaesthesia International, College of Anaesthetists of Ireland, Peking Union Medical College Hospital, Science Fund for Junior Faculty 2016, Central Bank of Austria, and National Healthcare Group.

Brachial plexus block with ultrasound guidance for upper-limb trauma surgery in children: a retrospective cohort study of 565 cases.

BACKGROUND: Upper-limb trauma is a common indication for surgery in children, and general anaesthesia remains the method of choice for these procedures, even though suitable techniques of brachial plexus block are available and fast provision of regional anaesthesia offers a number of distinct advantages. METHODS: A retrospective analysis was performed of the data of a large cohort of children undergoing ultrasound-guided brachial plexus blocks during a 4-yr period at a major trauma centre with a catchment area of 3.5 million. A total of 565 cases were sourced from two independently operating patient documentation systems. Patient data were stratified into age groups with block success as the primary outcome parameter. The influence of age on the incidence of block failure was assessed with logistic regression. RESULTS: The block failure rate was 5.1%, starting at 1.2% in the youngest (0-3 yr), then continuously increasing up to 12.5% in the oldest (15-18 yr) but also smallest group. Age emerged as an independent predictor of block failure with an odds ratio of 1.115 and a 95% confidence interval of 1.014-1.226 (P=0.025). No complications were observed. CONCLUSIONS: In a cohort of children receiving real-world care, with regional blocks performed by a range of anaesthetists with different skill levels, a success rate of 94.9% for upper-limb blocks in children under various levels of sedation was observed. Upper-limb blocks can be performed with high probability of success and an excellent margin of safety; this particularly applies to small children. CLINICAL TRIAL REGISTRATION: NCT03842423.

Brainwave entrainment to minimise sedative drug doses in paediatric surgery: a randomised controlled trial.

BACKGROUND: Anaesthetic drugs may cause neuroapoptosis in children and are routinely used off-label in specific age groups. Techniques that reduce anaesthetic drug dose requirements in children may thus enhance the safety of paediatric sedation or anaesthesia. Brainwave entrainment, notably in the form of auditory binaural beats, has been shown to have sedative effects in adults. We evaluated the influence of brainwave entrainment on propofol dose requirements for sedation in children. METHODS: We randomised 49 boys scheduled for sub-umbilical surgery under caudal blockade to an entrainment or a control group. Small differences in pitch were applied to each ear to create binaural beats, supplemented by synchronous visual stimuli, within the electroencephalographic frequency bands seen during relaxation and (rapid eye movement/non-rapid eye movement) sleep. After establishment of caudal block, propofol infusion was started at 5 mg kg-1 h-1. Intraoperatively, the infusion rate was adjusted every 5 min depending on the sedation state judged by the bispectral index (BIS). The infusion rate was decreased by 1 mg kg-1 h-1 if BIS was <70, and was increased if BIS was >70, heart rate increased by 20%, or if there were other signs of inadequate sedation. RESULTS: Mean propofol infusion rates were 3.0 (95% confidence interval [CI]: 2.4-3.6) mg kg-1 h-1vs 4.2 (95% CI: 3.6-4.8) mg kg-1 h-1 in the entrainment and control groups, respectively (P<0.01). BIS values were similar in the two groups. CONCLUSIONS: Brainwave entrainment effectively reduced the propofol infusion rates required for sedation in children undergoing surgery with regional anaesthesia. Further studies are needed to investigate the possibility of phasing out propofol infusions completely during longer surgical procedures and optimising the settings of brainwave stimulation. CLINICAL TRIAL REGISTRATION: DRKS00005064.

Caudal epidural blocks in paediatric patients: a review and practical considerations.

Caudal epidural blockade in children is one of the most widely administered techniques of regional anaesthesia. Recent clinical studies have answered major pharmacodynamic and pharmacokinetic questions, thus providing the scientific background for safe and effective blocks in daily clinical practice and demonstrating that patient selection can be expanded to range from extreme preterm births up to 50 kg of body weight. This narrative review discusses the main findings in the current literature with regard to patient selection (sub-umbilical vs mid-abdominal indications, contraindications, low-risk patients with spinal anomalies); anatomical considerations (access problems, age and body positioning, palpation for needle insertion); technical considerations (verification of needle position by ultrasound vs landmarks vs 'whoosh' or 'swoosh' testing); training and equipment requirements (learning curve, needle types, risk of tissue spreading); complications and safety (paediatric regional anaesthesia, caudal blocks); local anaesthetics (bupivacaine vs ropivacaine, risk of toxicity in children, management of toxic events); adjuvant drugs (clonidine, dexmedetomidine, opioids, ketamine); volume dosing (dermatomal reach, cranial rebound); caudally accessed lumbar or thoracic anaesthesia (contamination risk, verifying catheter placement); and postoperative pain. Caudal blocks are an efficient way to offer perioperative analgesia for painful sub-umbilical interventions. Performed on sedated children, they enable not only early ambulation, but also periprocedural haemodynamic stability and spontaneous breathing in patient groups at maximum risk of a difficult airway. These are important advantages over general anaesthesia, notably in preterm babies and in children with cardiopulmonary co-morbidities. Compared with other techniques of regional anaesthesia, a case for caudal blocks can still be made.

Dexamethasone as an adjuvant for peripheral nerve blockade: a randomised, triple-blinded crossover study in volunteers.

BACKGROUND: The efficacy of dexamethasone in extending the duration of local anaesthetic block is uncertain. In a randomised controlled triple blind crossover study in volunteers, we tested the hypothesis that neither i.v. nor perineurally administered dexamethasone prolongs the sensory block achieved with ropivacaine. METHODS: Ultrasound-guided ulnar nerve blocks (ropivacaine 0.75% wt/vol, 3 ml, with saline 1 ml with or without dexamethasone 4 mg) were performed on three occasions in 24 male volunteers along with an i.v. injection of saline 1 ml with or without dexamethasone 4 mg. The combinations of saline and dexamethasone were as follows: control group, perineural and i.v. saline; perineural group, perineural dexamethasone and i.v. saline; i.v. group, perineural saline and i.v. dexamethasone. Sensory block was measured using a VAS in response to pinprick testing. The duration of sensory block was the primary outcome and time to onset of sensory block the secondary outcome. RESULTS: All 24 subjects completed the trial. The median [inter-quartile range (IQR)] duration of sensory block was 6.87 (5.85-7.62) h in the control group, 7.37 (5.78-7.93) h in the perineural group and 7.37 (6.10-7.97) h in the i.v. group (P=0.61). There was also no significant difference in block onset time between the three groups. CONCLUSION: Dexamethasone 4 mg has no clinically relevant effect on the duration of sensory block provided by ropivacaine applied to the ulnar nerve. CLINICAL TRIAL REGISTRATION: DRKS, 00014604; EudraCT, 2018-001221-98.

Regional blocks carried out during general anesthesia or deep sedation: myths and facts.

PURPOSE OF REVIEW: More patients will accept regional blocks if these are performed during sedation or general anesthesia. This review discusses regional anesthesia in sedated or anesthetized patients. RECENT FINDINGS: As complications of regional blocks are rare, regional anesthesia can be considered aswell-tolerated. Awake patients will notice only a minority of needle-to-nerve contacts, that renders the notion of a 'live monitor' obsolete. Using high-resolution ultrasound, the needle can be advanced to an extraepineural position for injection, thus strictly avoiding needle-to-nerve contact or intraepineural injection of local anesthetic. Rare cases of intoxication manifest more immediately when the patient is awake but some general anesthesia drugs reduce the seizure-inducing potency of local anesthetics, and hemodynamic signs of intoxication are also detectable under general anesthesia, allowing for faster cardiopulmonary resuscitation as the patient is anesthetized already. SUMMARY: With the use of ultrasound guidance in skilled hands, it is a reasonable option to perform neuraxial and peripheral regional blocks in sedated or anesthetized patients. Performing the procedure safely and effectively requires an adequate level of experience with the specific block technique in question.

Forced-Air Warming During Pediatric Surgery: A Randomized Comparison of a Compressible with a Noncompressible Warming System.

BACKGROUND: Perioperative hypothermia is a common problem, challenging the anesthesiologist and influencing patient outcome. Efficient and safe perioperative active warming is therefore paramount; yet, it can be particularly challenging in pediatric patients. Forced-air warming technology is the most widespread patient-warming option, with most forced-air warming systems consisting of a forced-air blower connected to a compressible, double layer plastic and/or a paper blanket with air holes on the patient side. We compared an alternative, forced-air, noncompressible, under-body patient-warming mattress (Baby/Kleinkinddecke of MoeckWarmingSystems, Moeck und Moeck GmbH; group MM) with a standard, compressible warming mattress system (Pediatric Underbody, Bair Hugger, 3M; group BH). METHODS: The study included 80 patients aged <2 years, scheduled for elective surgery. After a preoperative core temperature measurement, the patients were placed on the randomized mattress in the operation theater and 4 temperature probes were applied rectally and to the patients' skin. The warming devices were turned on as soon as possible to the level for pediatric patients as recommended by the manufacturer (MM = 40°C, BH = 43°C). RESULTS: There was a distinct difference of temperature slope between the 2 groups: core temperatures of patients in the group MM remained stable and mean of the core temperature of patients in the group BH increased significantly (difference: +1.48°C/h; 95% confidence interval, 0.82-2.15°C/h; P = 0.0001). The need for temperature downregulation occurred more often in the BH group, with 22 vs 7 incidences (RR, 3.14; 95% confidence interval, 1.52-6.52; P = 0.0006). Skin temperatures were all lower in the MM group. Perioperatively, no side effects related to a warming device were observed in any group. CONCLUSIONS: Both devices are feasible choices for active pediatric patient warming, with the compressible mattress system being better suited to increase core temperature. The use of lower pediatric forced-air temperature settings, as recommended by the manufacturer, in the noncompressible mattress group resulted in more stable core temperature conditions, with fewer forced-air temperature adjustments necessary to avoid hyperthermia.

Feasibility and pharmacokinetics of caudal blockade in children and adolescents with 30-50 kg of body weight.

BACKGROUND: Caudal blockade, although an important technique of pediatric regional anesthesia, is rarely used in children heavier than 30 kg. This reservation is due to anatomical concerns and lack of pharmacokinetic data. We therefore set out to evaluate, in pediatric patients weighing 30-50 kg, the feasibility of ultrasound-guided caudal blockade and the pharmacokinetics of caudally administered ropivacaine. METHODS: Twenty consecutive children were included. General anesthesia was used to ensure a secured airway. For the caudal punctures, we applied the same clinical standards as in smaller children, administering ropivacaine 3.1 mg·ml-1 for a volume of 1 ml·kg-1 via ultrasound guidance. Pharmacokinetic analysis was based on total plasma ropivacaine levels and included maximum concentration (Cmax ), time to Cmax (tmax ), terminal elimination half-life, area under the concentration-time curve for the 4-h sampling period, apparent total body clearance, and apparent volume of distribution. RESULTS: In all 19 cases of successful puncture, we identified the relevant anatomical structures (sacral cornua, sacral hiatus, dura mater) and verified correct administration of the local anesthetic by visualizing its cranial spread. Surgical blockade was successful in 18 of 20 cases (90%; one puncture was technically not possible and one child received intraoperatively 50 µg fentanyl). The pharmacokinetic profile of the administered ropivacaine 3.1 mg·ml-1 indicated plasma levels within safe ranges in pediatric patients weighing 30-50 kg. CONCLUSIONS: Based on our pharmacodynamic and pharmacokinetic results, we suggest that the body weight of 50 kg it is feasible to perform effective and safe caudal blockade in children up to 50 kg body weight.

Safety and efficiency of dexmedetomidine as adjuvant to local anesthetics.

PURPOSE OF REVIEW: To review the current knowledge of dexmedetomidine as an additive drug to local anesthetics in peripheral and neuraxial regional anesthesia. RECENT FINDINGS: Recent studies show a perineural mode of action of dexmedetomidine. Pharmacodynamic characteristics of peripheral and neuraxial regional anesthetic techniques are optimized by the addition of dexmedetomidine to long-acting local anesthetics. Bradycardia and sedation are the main systemic side-effects of dexmedetomidine for regional anesthesia purposes. A dose of approximately 100 µg dexmedetomidine for peripheral techniques may represent the optimal balance between optimization of block characteristics and side-effects. Doses between 3 and 10 µg are described to be sufficient for spinal administration. SUMMARY: Dexmedetomidine has a potency to ameliorate pharmacodynamic characteristics of peripheral and neuraxial regional anesthetic techniques and is therefore currently the most promising additive drug in regional anesthesia. Future scientific efforts should focus on dose finding studies for particular regional anesthetic techniques. Approval of dexmedetomidine for regional anesthetic indications should be the final target.