Awake caudal anesthesia in ex-premature infants undergoing lower abdominal surgery: A narrative review.

BACKGROUND AND OBJECTIVES: The aim of this narrative review is to evaluate the literature describing the use of caudal anesthetic-based techniques in premature and ex-premature infants undergoing lower abdominal surgery. METHODS: All available literature from inception to August 2023 was retrieved according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines from Medline, PubMed, Embase, and the Cochrane Library. Two authors reviewed all references for eligibility, abstracted data, and appraised quality. RESULTS: Of the 211 articles identified, 45 met our inclusion criteria yielding 1548 cases with awake caudal anesthesia. The review included 558 (36.0%) cases of awake caudal anesthesia, 837 cases (54.1%) of "awake" caudal anesthesia with sedation, and 153 cases (9.9%) of combined spinal caudal epidural anesthesia without sedation. The overall anesthetic failure rate was 7.2% (71.9:1000 caudals). Failure rates were highest for CSEA (13.7%, 7.7-18.4), intermediate for awake caudal (6.6%, 5.26-9.51), and lowest for sedated caudal anesthesia (5.85%, 4.48-7.82). The incidence (range) of perioperative apnea was highest for sedated caudal anesthesia (8.16, 0%-24%), intermediate for awake caudal (7.62%, 0%-60%), and lowest for CSEA (5.53%, 0%-14.3%). High spinal anesthesia occurred in 0.84%, or 8.35:1000 caudals overall. The incidence was highest in awake caudal anesthesia cases (1.97% or 19.7:1000 caudals), intermediate with caudal with sedation (1.07% or 10.7:1000 caudals), and lowest in CSEA (0.7% or 6.6:1000 caudals). Our review was confounded by incomplete data reporting and small sample sizes as most were case reports. There were no high-quality randomized controlled trials, and the eight single-center retrospective data reviews lacked sufficient data to perform meta-analysis. CONCLUSIONS: There is insufficient evidence to validate or refute the benefits of the use of "awake" caudal anesthesia in premature and ex-premature infants. The high doses of local anesthetics used, the high failure rate, and the increased incidence of high spinal anesthesia would suggest that the techniques offer no real advantages over awake spinal anesthesia or general anesthesia with a regional block.

Second infant spinal anesthetic: Incidence, dose modification, and adverse events after initial failure.

INTRODUCTION: Infant spinal anesthesia is an important technique in premature and ex-premature infants undergoing lower abdominal surgery. Previous studies of infant spinal anesthesia report high failure rates, but fail to adequately identify contributing factors. The aim of this study is to retrospectively review spinal anesthetics from a quaternary anesthetic centre to determine overall spinal failure rate, incidence of second spinal attempts and adverse events associated with a second spinal anesthetic. METHODS: A retrospective review of infant spinal anesthetics performed between May 2016 and June 2023. RESULTS: Five hundred and fifty-one infants (mean postmenstrual age 42.9 weeks and weight 3873 g) were included. The overall success rate on first attempt was 86.5% with a further 5.1% requiring a successful second spinal anesthetic after initial failure. Spinal anesthetic failure requiring conversion to general anesthesia occurred in 9.4% of cases The causes of failed spinal anesthetic were inability to access the subdural space (dry tap 4.2%), inadequate motor blockade (2.9%), and repeated bloody taps (2.2%). Spinal anesthetic failure was significantly increased in cases where the anesthetist was routinely performing less than 5 spinal anesthetics per year [OR 2.21 (95% CI 1.28, 3.83, p = .004)] but only weakly associated with years of pediatric anesthetic experience. Failure rates were 21.4% with styletted spinal needles and 9.2% for non styletted [OR 2.68 (95% CI 1.23-5.86, p = .012)]. The incidence of perioperative apnoea was 6.7% with the highest rate in infants in which failed spinal anesthesia required conversion to general anesthesia (25%). There were 28 cases where initial spinal anesthetic failed to produce adequate anesthesia and a repeat spinal anesthetic was performed. Repeat spinal anesthesia was successful in 92.8% of cases with awake caudal anesthesia successful in 7.2% of cases. In three cases high spinal blockade occurred, one after a single spinal and two after a repeat spinal. Both repeat spinal high block cases required intubation and brief resuscitation. CONCLUSION: Infant spinal anesthesia is associated with high success rates if experienced anesthetists are present or performing the block. Repeat spinal anesthesia may be associated with an increased incidence of high spinal block. Greater awareness of the slow onset of high block should promote techniques aimed at minimizing cephalad spread of local anesthetic including slight head up positioning during surgery.

Prediction of Early Postoperative Pain in Infants Undergoing Primary Cleft Palate Repair.

OBJECTIVE: Identification of at risk patients before surgery could facilitate improved clinical communication, care pathways and postoperative pain management. DESIGN: A retrospective cohort study was performed in all infants who had undergone cleft palate repair. SETTING: Tertiary Institutional. PARTICIPANTS: Infants < 36 months of age who underwent primary repair of cleft palate between March 2016 and July 2022. INTERVENTION: Requirement for analgesic intervention in the post operative care unit. MAIN OUTCOME MEASURE: Adverse perioperative event defined as pain or distress. Secondary outcomes were the incidence of airway obstruction, hypoxemia or unplanned intensive care admission. RESULTS: Two hundred and ninety one patients (14.6 months,10.1 kg weight) were included. Cleft distribution included submucous (5.2%), Veau I (23.4%), Veau 2 (38.1%), Veau 3 (24.4%), and Veau 4 (8.9%). Overall 35% of 291 infants undergoing cleft palate repair experienced pain or distress requiring opiate intervention in the first hour after surgery. Infants with a Veau 4 cleft palate had 1.8 times and Veau 2 cleft palate had 1.5 times the risk of postoperative pain compared to infants with Veau 1 cleft palate (relative risk 1.82, 95%CI 1.04-3.18 and 1.49, 95%CI 0.96-2.32 respectively). The use of bilateral above elbow arm splints was significantly associated with postoperative pain or distress (odds ratio 2.23, 95%CI 1.01-5.16). CONCLUSIONS: Post operative pain requiring intervention in PACU is common despite adequate intraoperative multimodal analgesia, local anaesthesia infiltration and postoperative opiate infusions. Infants undergoing soft palate alone or submucous palate repair may require less perioperative opiates.

Levobupivacaine plasma concentrations following repeat caudal anesthetics.

AIM: A single caudal anesthetic at the start of lower abdominal surgery is unlikely to provide prolonged analgesia. A second caudal at the end of the procedure extends the analgesia duration but total plasma concentrations may be associated with toxicity. Our aim was to measure total plasma levobupivacaine concentrations after repeat caudal anesthesia in infants and to generate a pharmacokinetic model for prediction of plasma concentrations after repeat caudal anesthesia in neonates, infants and children. METHODS: Infants undergoing definitive repair of anorectal malformations or Hirschsprung's disease received a second caudal anesthesia at the end of the procedure. Total levobupivacaine concentrations were assayed 3-4 times in the first 6 h after the initial caudal. These data were pooled with data from four studies describing plasma concentrations after levobupivacaine caudal or spinal anesthesia. Population pharmacokinetic parameters were estimated using nonlinear mixed-effects models. Covariates included postmenstrual age and body weight. Parameter estimates were used to simulate concentrations after a repeat levobupivacaine 2.5 mg kg-1 caudal at 3 or 4 h following an initial levobupivacaine 2.5 mg kg-1 caudal. RESULTS: Twenty-one infants (postnatal age 11-32 weeks, gestation 37-39 weeks, weight 5.2-8.6 kg) were included. The measured peak plasma concentration after repeat caudal levobupivacaine 2.5 mg kg-1 4 h after initial caudal was 1.38 mg L-1 (95% prediction interval 0.60-2.6 mg L-1 ) and 3 h after initial caudal was 1.46 mg L-1 (0.60-2.80) mg L-1 . Simulation of total plasma concentrations in neonates (7 kg, 57 weeks postmenstrual age) given caudal levobupivacaine 4 h after the initial caudal were 1.76 mg L-1 (0.68-3.50) mg L-1 if 2.5 mg kg-1 levobupivacaine was used and 0.88 mg L-1 (0.34-1.73) mg L-1 if 1.25 mg kg-1 of 0.125% levobupivacaine was used. In simulated older children (20 kg, 6 years), the mean maximum concentration was 1.43 mg L-1 (0.60-2.70) mg L-1 if 2.5 mg kg-1 levobupivacaine was repeated at 3 h. CONCLUSION: Repeat caudal levobupivacaine 2.5 mg kg-1 at 3 h after an initial 2.5 mg kg-1 dose does not exceed the concentration associated with systemic local anesthetic toxicity. In 2.5% of simulated neonates (weight 3.8 kg, PMA 40 weeks), repeat caudal anesthesia demonstrates broaching of the lower concentration limit associated with toxicity at both 3 and 4 h after initial caudal.

Pediatric lower limb peripheral nerve blocks: Indications, effectiveness, and the incidence of adverse events.

AIM: While the proportion of pediatric anesthetics with regional anesthesia in pediatric patients has steadily increased, there are only a few series that describe the use of lower limb peripheral nerve blocks in children. Our aim was to describe the indications, anesthetic approach, and complications associated with lower limb blocks in children undergoing orthopedic surgery in a center with a large caseload of complex patients. METHODS: In a retrospective analysis of prospectively collected data, we reviewed children who had a peripheral nerve block for orthopedic surgery placed between January 2016 and January 2021 at the Royal Children's Hospital Melbourne. Block data were sourced from the electronic medical record and departmental regional anesthesia database. Data collected included demographics, the site of catheter placement and technique of nerve block, presence of sensory/motor blockade, the use of perioperative opioids, and any complications related to peripheral nerve block. RESULTS: A total of 1438 blocks were performed in 1058 patients. Four patients had clinical features of perioperative neurological injury giving an incidence of 3 per 1000 blocks (95% CI 1.1-8:1000). Only one patient had a sensory deficit persisting longer than 6 months for an incidence of 0.8 per 1000 blocks (95% CI 0.1-5:1000). All four peripheral nerve injury followed tibial osteotomy for lengthening procedures or correction of tibial torsion. The etiology of the injury could not be determined despite imaging and surgical exploration and the contribution of popliteal sciatic nerve block to the subsequent PNI could not be confirmed. There were no cases of local anesthetic systemic toxicity. CONCLUSION: An increased risk of perioperative peripheral nerve injury is associated with pediatric tibial osteotomy for congenital deformity. While popliteal sciatic nerve block was not directly implicated in the nerve injury the presence of a prolonged sensory block can delay early recognition and treatment of peripheral nerve injury.

Prediction of levobupivacaine concentrations in neonates and infants following neuraxial rescue blocks.

AIM: Pharmacokinetic simulation was used to characterize levobupivacaine disposition after regional anesthetic rescue for failed spinal anesthesia in neonates and infants. METHODS: Population pharmacokinetics of levobupivacaine were estimated after spinal blockade in a cohort of neonates and infants (n = 25, postnatal age 5-18 weeks, gestation 21-41 weeks, weight 2.4-6 kg). Total levobupivacaine concentrations were assayed 3-4 times in the first hour after spinal levobupivacaine 1 mg kg-1 administration. Parameters were estimated using nonlinear mixed-effects models and supported by priors. Covariates included postnatal age and total body weight. Parameter estimates were used to simulate total levobupivacaine concentrations after a primary spinal levobupivacaine 1 mg kg-1 with rescue caudal levobupivacaine 1.5-2.5 mg kg-1 . RESULTS: A one-compartment model with a mature clearance 21.5 L h-1  70 kg-1 (CV 47.3%) and central volume 189 L 70 kg-1 (CV 37%) adequately described time-concentration profiles. Clearance maturation was described using a maturation half-time of 11.5 weeks postnatal age. The absorption half-time for spinal levobupivacaine was 2.6 min (CV 56.8%). The upper (97.5% prediction) for peak concentrations after rescue caudal levobupivacaine were 1.5 mg kg-1 , 2 mg kg-1 , and 2.5 mg kg-1 was 2.05 mg L-1 , 2.5 mg L-1 , and 2.9 mg L-1 respectively. CONCLUSION: Total bupivacaine concentrations greater than 2.5 mg L-1 are associated with neurotoxicity in adults. Predicted concentrations after either a repeat spinal or a caudal rescue dose of levobupivacaine 1.5 mg kg-1 1 h after spinal levobupivacaine administration are below the neurotoxic concentration threshold.

Anesthesia management of laser photocoagulation for retinopathy of prematurity. A retrospective review of perioperative adverse events.

AIMS: The aim of this study was to report the incidence of perioperative adverse events occurring in infants undergoing diode laser photocoagulation of retinopathy of prematurity and to identify clinical risk factors that may affect the incidence. METHODS: This was a retrospective study of anesthetic and medical records of premature infants who were treated in the neonatal intensive care unit or an operating theater with laser photocoagulation in our institution between January 2014 and December 2019. Infants less than 38 weeks post-menstrual age or less than 2000 grams were considered high risk for complications. Electronic medical records were evaluated for clinical and demographic characteristics, comorbidities, and perioperative complications of anesthesia. RESULTS: Sixty-one infants (39 males, 22 females) underwent 72 laser treatments. The mean gestational age was 25.3 weeks (SD 1.6), and mean birth weight was 730 grams (SD 202). At treatment, the mean postmenstrual age was 37.5 weeks (SD 2.7) and weight was 2320 g (SD 610). Laser therapy was performed in an operating theater in 66 procedures (91.7%) and in the neonatal unit in 6 cases (8.3%). Twenty-nine (40.3%) laser surgeries occurred outside normal week-day daytime operating hours. Intraoperative hypotension occurred in 12 procedures (16.7%) but was not significantly different in high-risk infants (16.1% vs 16.7% OR 0.94 P = .94) or in procedures performed in-hours (16.3% vs 17.2% OR 0.93 P = .91). Post-extubation apnea occurred in 21 procedures (29%) but was not significantly different in high-risk infants (29.0% vs 27.3% OR 0.98 P = .34) or in procedures performed in-hours (27.9% vs 31.1% OR 0.86 P = .77). Infants remained intubated at the end of the procedure in 58 (80.5%) cases and 29 (40.3%) remained ventilated more than 24 hours after the procedure. CONCLUSION: The incidence of perioperative adverse events was not associated with patient's age, current weight, timing, or location of the procedure. Extubating infants at the end of the procedure is however associated with a high rate of apneas and bradycardia, and consideration should be given to keeping low weight infants undergoing prolonged procedures out-of-hours intubated.

Conjoined twins in 2020 - state of the art and future directions.

PURPOSE OF REVIEW: A number of high profile conjoined twin separations have been extensively covered by the world media. Anaesthesia for conjoined twins is a procedure rarely experienced by paediatric anaesthetists. The increased survival of the twins has prompted discussion as to the most appropriate selection of patients, teams and hospitals to provide exceptional anaesthetic care. RECENT FINDINGS: The number of conjoined twins presenting for surgery remains low with many infants not surviving foetal or early neonatal life. Anaesthetic management of less common conjoined infants such as craniopagus twins has highlighted the benefit of careful patient selection, extensive preoperative investigations and meticulous multidisciplinary team planning. The role of simulation of possible adverse perioperative events has been highlighted. Three dimensional anatomical models and virtual reality systems have permitted surgical planning in advance of actual intervention. A number of legal and ethical concerns have been reported especially in the setting of emergency separation where surgery is likely to contribute to death of one of the twins. SUMMARY: There appears to be an expanding role for international teams with extensive separation experience becoming involved in international teleconferencing to improve patient management in low-resource countries. Whether the perioperative outcome is better when the conjoined twins are transferred to major centres for surgery or teams operate in the twin's country of origin remains to be seen.

Neurodevelopmental outcome at 5 years of age after general anaesthesia or awake-regional anaesthesia in infancy (GAS): an international, multicentre, randomised, controlled equivalence trial.

BACKGROUND: In laboratory animals, exposure to most general anaesthetics leads to neurotoxicity manifested by neuronal cell death and abnormal behaviour and cognition. Some large human cohort studies have shown an association between general anaesthesia at a young age and subsequent neurodevelopmental deficits, but these studies are prone to bias. Others have found no evidence for an association. We aimed to establish whether general anaesthesia in early infancy affects neurodevelopmental outcomes. METHODS: In this international, assessor-masked, equivalence, randomised, controlled trial conducted at 28 hospitals in Australia, Italy, the USA, the UK, Canada, the Netherlands, and New Zealand, we recruited infants of less than 60 weeks' postmenstrual age who were born at more than 26 weeks' gestation and were undergoing inguinal herniorrhaphy, without previous exposure to general anaesthesia or risk factors for neurological injury. Patients were randomly assigned (1:1) by use of a web-based randomisation service to receive either awake-regional anaesthetic or sevoflurane-based general anaesthetic. Anaesthetists were aware of group allocation, but individuals administering the neurodevelopmental assessments were not. Parents were informed of their infants group allocation upon request, but were told to mask this information from assessors. The primary outcome measure was full-scale intelligence quotient (FSIQ) on the Wechsler Preschool and Primary Scale of Intelligence, third edition (WPPSI-III), at 5 years of age. The primary analysis was done on a per-protocol basis, adjusted for gestational age at birth and country, with multiple imputation used to account for missing data. An intention-to-treat analysis was also done. A difference in means of 5 points was predefined as the clinical equivalence margin. This completed trial is registered with ANZCTR, number ACTRN12606000441516, and ClinicalTrials.gov, number NCT00756600. FINDINGS: Between Feb 9, 2007, and Jan 31, 2013, 4023 infants were screened and 722 were randomly allocated: 363 (50%) to the awake-regional anaesthesia group and 359 (50%) to the general anaesthesia group. There were 74 protocol violations in the awake-regional anaesthesia group and two in the general anaesthesia group. Primary outcome data for the per-protocol analysis were obtained from 205 children in the awake-regional anaesthesia group and 242 in the general anaesthesia group. The median duration of general anaesthesia was 54 min (IQR 41-70). The mean FSIQ score was 99·08 (SD 18·35) in the awake-regional anaesthesia group and 98·97 (19·66) in the general anaesthesia group, with a difference in means (awake-regional anaesthesia minus general anaesthesia) of 0·23 (95% CI -2·59 to 3·06), providing strong evidence of equivalence. The results of the intention-to-treat analysis were similar to those of the per-protocol analysis. INTERPRETATION: Slightly less than 1 h of general anaesthesia in early infancy does not alter neurodevelopmental outcome at age 5 years compared with awake-regional anaesthesia in a predominantly male study population. FUNDING: US National Institutes of Health, US Food and Drug Administration, Thrasher Research Fund, Australian National Health and Medical Research Council, Health Technologies Assessment-National Institute for Health Research (UK), Australian and New Zealand College of Anaesthetists, Murdoch Children's Research Institute, Canadian Institutes of Health Research, Canadian Anesthesiologists Society, Pfizer Canada, Italian Ministry of Health, Fonds NutsOhra, UK Clinical Research Network, Perth Children's Hospital Foundation, the Stan Perron Charitable Trust, and the Callahan Estate.

Surgical practice and outcome in 711 neonates and infants undergoing hernia repair in a large multicenter RCT: Secondary results from the GAS Study.

BACKGROUND: The GAS study is an international RCT to evaluate neurodevelopmental outcome comparing general plus regional anesthesia versus regional anesthesia alone in 722 neonates and infants who had inguinal hernia repair up to 60 weeks of postmenstrual age. This paper comprises a secondary descriptive analysis of hernias, aspects of surgery and outcomes. METHODS: The incidence of unilateral and bilateral hernias, side preponderance, predictive factors for bilateral hernias and surgical approaches were collated. Follow-up outcome data were examined at 2 years. RESULTS: Of 711 eligible patients, there were 679 with hernia data showing that 321 hernias were right-sided, 190 left and 168 bilateral. Male to female ratio was 5:1. Of those with unilateral hernias, 25.8% underwent contralateral exploration and in these cases a patent processus vaginalis was found in 68.9%. Bilateral hernias were more common in younger and female patients. At 2 years there was a recurrence rate of 0.99% and in 2.7% of patients a hernia was evident on the contralateral side (metachrony), and this was unrelated to the anesthesia technique. CONCLUSIONS: Bilateral hernias are associated with lower gestational age at birth and female gender. There was a low incidence of complications and the anesthesia technique did not affect surgical outcome. LEVEL OF EVIDENCE: Level 1 evidence from prospective treatment study.

Oesophageal atresia: Are "long gap" patients at greater anesthetic risk?

BACKGROUND: Long gap oesophageal atresia occurs in approximately 10% of all oesophageal atresia infants and surgical repair is often difficult with significant postoperative complications. Our aim was to describe the perioperative course, morbidity, and early results following repair of long gap oesophageal atresia and to identify factors which may be associated with complications. METHODS: This is a single center retrospective cohort study of consecutive patients with oesophageal atresia undergoing surgical repair at The Royal Children's Hospital Melbourne from January 2006 to June 2017. RESULTS: Two hundred and thirty-nine consecutive oesophageal atresia infants included 44 long gap oesophageal atresia infants and 195 non-long gap infants. A high rate of prematurity (24.7%), major cardiac (17%), and other surgically relevant malformations (12.6%) was found in both groups. The median age at oesophageal anastomosis surgery was 65.5 days for the long gap group vs 1 day for the oesophageal atresia group (mean difference 56.8 days, 95% CI 48.1-65.5 days, P < .01). Surgery for long gap oesophageal atresia included immediate primary anastomosis (n = 10), delayed primary anastomosis (n = 11), oesophageal lengthening techniques (n = 12) and primary oesophageal replacement (n = 6). Long gap oesophageal atresia was not associated with an increased incidence of difficult intubation (OR 2.8, 95% CI 0.6-22.1, P = .17), intraoperative hypoxemia (OR 1.6, 95% CI 0.6-4.5, P = .32), or hypotension (OR 0.9, 95% CI 0.5-1.8, P = .81). The surgical duration (177.7 vs 202.1 minute, mean difference [95% CI], 28 [5.5-50.4 minutes], P = .04) and mean duration of postoperative mechanical ventilation (107 vs 199.8 hours, mean difference [95% CI], 91.8 [34.5-149.1 hours], P < .01) were shorter for the non-long gap group. Overall in-hospital mortality was 7.5% (15.9% long gap vs 5.6% non-long gap oesophageal atresia OR 1.1, 95% CI 0.4-3.4, P = .85). CONCLUSION: Long gap oesophageal atresia infants have a similar incidence of perioperative complications to other infants with oesophageal atresia. Current surgical approaches to long gap repair, however, are associated with longer anesthetic exposures and require multiple procedures in infancy to achieve oesophageal continuity.

The effect of thoracoscopy upon the repair of pectus excavatum.

BACKGROUND/AIMS: The Nuss procedure is the most commonly performed operation to correct pectus excavatum (PE). Thoracoscopic assistance has been anecdotally noted to improve the safety of this operative approach. This study aimed to compare complications and clinical outcomes before and after the introduction of thoracoscopy in a single-center. METHODS: A retrospective review was performed of all patients who underwent the Nuss procedure at The Royal Children's Hospital over an 11-year period (2005-2015), collecting data on all intra-operative and post-operative outcomes. RESULTS: A total of 217 Nuss procedures were performed (122 non-thoracoscopic pectus repairs, 95 thoracoscopic pectus repairs). Median patient age was 14.9years, with the majority male (185/217, 84.3%). Patient demographics (age, gender, defect severity) and postoperative recovery were comparable between the two groups. Major complications included cardiac arrest requiring internal cardiac massage, hemothorax, pneumothorax, empyema, bar displacement and infection. The overall major complication rate was low (19/217, 8.8%); however, there was a significant reduction in major complications in the thoracoscopic pectus repair group (13.1% versus 3.2%, p=0.02). CONCLUSIONS: Thoracoscopic vision during the Nuss procedure reduces the risk of major complications. LEVEL OF EVIDENCE: Treatment study - Level III (Retrospective comparative study).

Infant spinal anesthesia: Do girls need a larger dose of local anesthetic?

BACKGROUND: Gender differences in absorption, distribution, and metabolism of a number of anesthetic agents have been identified in adults. Clinically, adult studies suggest women demonstrate slower onset of opioid analgesic effects, lower spinal and epidural dose requirements, and greater sensitivity to neuromuscular blocking agents. Sex-related differences in the pharmacokinetics and pharmacodynamics of local anesthetics in neonates and infants, however, have not been well documented. As a result, it is not known whether modification of the dose of local anesthetic for awake spinal anesthesia in infants is required. AIMS: Our aim was to determine whether the ED50 and ED95 of local anesthetics used for infant spinal anesthesia are different between sexes. METHODS: This was a retrospective analysis of data previously collected during dose-response studies of levobupivacaine and ropivacaine spinal anesthetics. The doses were reanalyzed using generalized linear regression analysis to determine whether there is a discernible difference in dose requirements between male and female infants. RESULTS: One hundred and twenty infant spinal anesthetics were reviewed. For levobupivacaine, the ED50 (95% CI) was 0.69 (0.49-0.88) mg vs 0.49 (0.33-0.65), whereas the ED95(95% CI) was 1.07 (0.73-1.41) vs 0.93 (0.64-1.22) for girls and boys, respectively. For ropivacaine spinal anesthesia, the ED50 (95% CI) was 0.64 (0.35-0.92) mg vs 0.30 (-0.32-0.92), whereas the ED95 (95% CI) was 1.30 (0.73-1.87) vs 1.66 (0.55-2.76) for girls and boys, respectively. CONCLUSION: There is no evidence that sex differences occur at the ED50 dose range or at the clinically relevant ED95 dose. Modification of spinal anesthetic dose is not required for infant girls.

Performance of the BBraun perfusor space syringe driver under hyperbaric conditions.

BACKGROUND: The BBraun Perfusor Space™ syringe driver is already in use by ambulance services and retrieval teams but has not previously been assessed for hyperbaric chamber use. METHODS: Pump flow accuracy was tested at rates between 1 and 40 ml· h⁻¹ using three different brands of 50 ml syringe. Function of the occlusion alarms was assessed using the same syringes. The hyperbaric profile involved pressurisation to 284 kPa at 30 kPa· min⁻¹, 30 min at 284 kPa and decompression at 30 kPa· min⁻¹. Output was recorded from differences in weight of collection containers. A single device was tested. RESULTS: Performance was highly dependent on the syringe type used, with two of the three 50 ml syringes used demonstrating 'stiction' at both low and high occlusion pressure alarm settings, most marked during pressurisation. On decompression from 284 kPa all syringes alarmed at significantly lower pressures. Because of the stiction problems only the flow measurements for the BBrown Omni¬ x 50 ml syringes are reported. At a pressure of 284 kPa, the difference between programmed and delivered rates was within the manufacturer's specification of 10%: at 40 ml· h⁻¹ (median variation 1.25%, IQR 0.5-1.7%), 10 ml· h⁻¹ (8.6%, IQR 8-9.2%), 5 ml· h⁻¹ (-8.8%, IQR - 1.6-8.8%) and 1 ml· h⁻¹ (-4%, IQR 4-12%). Pressurisation was associated with significantly lower flow rates whilst decompression was associated with significantly increased rates. Limited testing at 405 kPa was also within the manufacturer's specifications. CONCLUSION: A BBraun Infusor Space syringe driver performed within acceptable performance criteria but is highly dependent on syringe type and flow rates. The potential for the device to under deliver on pressurisation and over deliver on depressurisation, however, suggests vigilance and appropriate rate adjustments may be necessary during these phases.

A review of anesthetic techniques and outcomes following minimally invasive repair of pectus excavatum (Nuss procedure).

BACKGROUND: Pectus excavatum (PE) is the most common congenital chest wall deformity, occurring in 1 : 1000 children with a male to female ratio of 4 : 1. Several procedures have been described to manage this deformity, including cartilage resection with sternal osteotomy (the Ravitch procedure) and a minimally invasive repair technique (the Nuss procedure). While initially described as a nonthoracoscopic technique, the current surgical approach of the Royal Childrens Hospital involves thoracoscopic assistance. Postoperative pain is significant in patients undergoing the pectus repair and multiple analgesic regimens have been advocated with continuous thoracic epidural infusions and opioid infusions the most common. Some authors have advocated patient-controlled analgesia (PCA), paravertebral nerve blocks (PVNB), and wound infusion catheters as alternatives. AIMS: The primary aim of this study was to assess our experience with postoperative pain and analgesia requirements associated with the minimally invasive repair of pectus excavatum in children. METHODS: This is a retrospective cohort study with a contemporaneous comparison group examining patients treated between January 2005 and December 2015 for minimally invasive repair of pectus excavatum by the Nuss procedure. RESULTS: Two hundred and seventeen patients [mean age 14.9 (sd 1.9) years] with pectus excavatum treated at the Royal Childrens Hospital between 2005 and 2015 were identified. All patients were managed with thoracic epidural analgesia and intravenous morphine infusions. The epidural was effective in the postanesthesia care unit in 97.3% (failure to place an epidural rate was 4 (1.9%); no block on awakening 0.9%). A further 4 (1.8%) were removed within 24 h. The mean morphine equivalent dose in the first 24 h was 0.8 mg·kg-1 ·day-1 . PCA was continued for a mean of 3.8 days and the total mean morphine equivalent dose was 2.2 mg·kg-1 ·day-1 . Minor complications occurred in 67 (30.9%) with postoperative nausea and vomiting in 36 patients (16.6%) and urinary retention requiring an indwelling catheter in 40 patients (18.4%). CONCLUSION: An epidural-based analgesic regime is associated with low pain scores and few acute complications. The continuation of morphine analgesia after the first postoperative day is common but associated with an increased incidence of urinary retention and nausea and vomiting.

Iatrogenic cerebral gas embolism: analysis of the presentation, management and outcomes of patients referred to The Alfred Hospital Hyperbaric Unit.

INTRODUCTION: The aim of this study was to review patients with iatrogenic cerebral gas embolism (CGE) referred to The Alfred Hospital hyperbaric unit to determine whether hyperbaric oxygen treatment (HBOT) reduced morbidity and mortality. METHODS: This is a retrospective cohort study with a contemporaneous comparison group of patients referred between January 1998 and December 2014. The primary end point was good neurological outcome at the time of discharge from hospital or rehabilitation facility as assessed by the Glasgow Outcome Scale (GOS-E). RESULTS: Thirty-six patients were treated with HBOT for CGE and nine patients were diagnosed with CGE but did not receive HBOT. Thirty-two patients developed CGE from an arterial source and 13 from a venous source. The mean time from recognition of the event to institution of HBOT was 15 hours. Four of 45 patients (8.9%) died. Good neurological outcomes (defined as GOS-E 7 or 8) occurred in 27 patients and moderate disability in 13. The only independent factor that was associated with good neurological outcome was time to first HBOT (OR 0.94, 0.89-0.99; P = 0.05). Hemiplegia as the first presenting sign, however, was associated with poor outcome (OR 0.27, 0.06-1.08; P = 0.05). The source of embolus (arterial versus venous), hyperbaric treatment table used and patient age did not affect outcome. CONCLUSION: Appropriate treatment of CGE with hyperbaric oxygen was found to be impeded by delays in diagnosis and subsequent transfer of patients. Better neurological outcome was associated with HBOT within eight hours of CGE.

Pharmacokinetics of levobupivacaine following infant spinal anesthesia.

BACKGROUND: Infant spinal anesthesia with levobupivacaine has been promoted as a technique to reduce both the risk of postoperative apnea and exposure to volatile anesthesia. There is, however, no pharmacokinetic data to support the currently recommended doses. AIMS: Our aim was to determine whether infant levobupivacaine spinal anesthesia is associated with plasma concentrations consistent with a low risk of local anesthetic systemic toxicity. METHODS: This was an open-label pharmacokinetic safety and tolerability study of levobupivacaine spinal anesthesia in infants <55 weeks Post Menstrual Age undergoing lower abdominal surgery. Infants received a spinal anesthetic with levobupivacaine 1 mg·kg(-1) in the left lateral position. RESULTS: Spinal anesthesia was successful in 25 (86.2%) of 29 infants (postmenstrual age 36-52 weeks; weight 2.2-4.7 kg). The median (IQR) total venous levobupivacaine plasma concentrations was 0.33 (0.25-0.42) µg·ml(-1) and unbound venous levobupivacaine was 19.5 (14.5-38) ng·ml(-1) . Median protein binding was 93.5 (91.4-96%). Alpha-1 acid glycoprotein concentrations were 0.25 (0.17-0.37) g·l(-1) and albumin concentrations were 29 (24-32) g·l(-1) . CONCLUSION: Total plasma concentrations and unbound (free) concentration of levobupivacaine were consistently lower than concentrations reported in cases of pediatric local anesthetic toxicity. In a small number of infants requiring a repeat spinal of 1 mg·kg(-1) was also associated with acceptable total and free concentrations. We conclude that levobupivacaine at 1 mg·kg(-1) is associated with no systemic side effects in infants receiving awake spinal anesthesia.

Neurodevelopmental outcome at 2 years of age after general anaesthesia and awake-regional anaesthesia in infancy (GAS): an international multicentre, randomised controlled trial.

BACKGROUND: Preclinical data suggest that general anaesthetics affect brain development. There is mixed evidence from cohort studies that young children exposed to anaesthesia can have an increased risk of poor neurodevelopmental outcome. We aimed to establish whether general anaesthesia in infancy has any effect on neurodevelopmental outcome. Here we report the secondary outcome of neurodevelopmental outcome at 2 years of age in the General Anaesthesia compared to Spinal anaesthesia (GAS) trial. METHODS: In this international assessor-masked randomised controlled equivalence trial, we recruited infants younger than 60 weeks postmenstrual age, born at greater than 26 weeks' gestation, and who had inguinal herniorrhaphy, from 28 hospitals in Australia, Italy, the USA, the UK, Canada, the Netherlands, and New Zealand. Infants were randomly assigned (1:1) to receive either awake-regional anaesthesia or sevoflurane-based general anaesthesia. Web-based randomisation was done in blocks of two or four and stratified by site and gestational age at birth. Infants were excluded if they had existing risk factors for neurological injury. The primary outcome of the trial will be the Wechsler Preschool and Primary Scale of Intelligence Third Edition (WPPSI-III) Full Scale Intelligence Quotient score at age 5 years. The secondary outcome, reported here, is the composite cognitive score of the Bayley Scales of Infant and Toddler Development III, assessed at 2 years. The analysis was as per protocol adjusted for gestational age at birth. A difference in means of five points (1/3 SD) was predefined as the clinical equivalence margin. This trial is registered with ANZCTR, number ACTRN12606000441516 and ClinicalTrials.gov, number NCT00756600. FINDINGS: Between Feb 9, 2007, and Jan 31, 2013, 363 infants were randomly assigned to receive awake-regional anaesthesia and 359 to general anaesthesia. Outcome data were available for 238 children in the awake-regional group and 294 in the general anaesthesia group. In the as-per-protocol analysis, the cognitive composite score (mean [SD]) was 98.6 (14.2) in the awake-regional group and 98.2 (14.7) in the general anaesthesia group. There was equivalence in mean between groups (awake-regional minus general anaesthesia 0.169, 95% CI -2.30 to 2.64). The median duration of anaesthesia in the general anaesthesia group was 54 min. INTERPRETATION: For this secondary outcome, we found no evidence that just less than 1 h of sevoflurane anaesthesia in infancy increases the risk of adverse neurodevelopmental outcome at 2 years of age compared with awake-regional anaesthesia. FUNDING: Australia National Health and Medical Research Council (NHMRC), Health Technologies Assessment-National Institute for Health Research UK, National Institutes of Health, Food and Drug Administration, Australian and New Zealand College of Anaesthetists, Murdoch Childrens Research Institute, Canadian Institute of Health Research, Canadian Anesthesiologists' Society, Pfizer Canada, Italian Ministry of Heath, Fonds NutsOhra, and UK Clinical Research Network (UKCRN).