Mary Ellen McCann

Neurodevelopmental outcome at 2 years of age after general anaesthesia and awake-regional anaesthesia in infancy (GAS): an international multicentre, randomised controlled 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-totreat 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.Summary Background There is pre-clinical evidence that general anaesthetics affect brain development. There is mixed evidence from cohort studies that young children exposed to anaesthesia may have an increased risk of poorer neurodevelopmental outcome. This trial aims to determine if GA in infancy has any impact on neurodevelopmental outcome. The primary outcome for the trial is neurodevelopmental outcome at 5 years of age. The secondary outcome is neurodevelopmental outcome at two years of age and is reported here. Methods We performed an international assessor-masked randomised controlled equivalence trial in infants less than 60 weeks post-menstrual age, born at greater than 26 weeks gestational age having inguinal herniorrhaphy. Infants were excluded if they had existing risk factors for neurologic injury. Infants were randomly assigned to awake-regional (RA) or sevoflurane-based general anaesthesia (GA). Web-based randomisation was performed in blocks of two or four and stratified by site and gestational age at birth. The outcome for analysis was the composite cognitive score of the Bayley Scales of Infant and Toddler Development, Third Edition. 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. The trial was registered at ANZCTR, ACTRN12606000441516 and ClinicalTrials.gov, NCT00756600. Findings Between February 2007, and January 2013, 363 infants were randomised to RA and 359 to GA. Outcome data were available for 238 in the RA and 294 in the GA arms. The median duration of anaesthesia in the GA arm was 54 minutes. For the cognitive composite score there was equivalence in means between arms (RA-GA: +0·169, 95% CI −2·30 to +2·64). Interpretation For this secondary outcome we found no evidence that just under an hour of sevoflurane anaesthesia in infancy increases the risk of adverse neurodevelopmental outcome at two years of age compared to RA.

The management of preoperative anxiety in children: An update

Anxiety in children undergoing surgery is characterized by subjective feelings of tension, apprehension, nervousness, and worry that may be expressed in various forms (1). Postoperative maladaptive behaviors, such as new onset enuresis, feeding difficulties, apathy and withdrawal, and sleep disturbances, may also result from anxiety before surgery. In fact, studies have indicated that up to 60% of all children undergoing surgery may present with negative behavioral changes at 2 wk postoperatively (1,2). Variables such as age, temperament, and anxiety of the child and parent in the preoperative holding area have been identified as predictors for these behavioral changes (1). Extreme anxiety during induction of anesthesia is also associated with an increase of these postoperative negative behavioral changes (3). In addition to behavioral manifestations, preoperative anxiety activates the human stress response, leading to increased serum cortisol, epinephrine, and natural killer cell activity (4,5). This stress response can be activated by many different noxious stimuli including fear, anxiety, pain, cold, major surgery, and infection. The main components of the stress system are the corticotropin-releasing hormone and the locus ceruleus-norepinephrine/autonomic systems and their peripheral effectors, the hypothalamic pituitary-adrenal axis and the limbs of the autonomic system (5). There is also evidence for a bidirectional communication between the neuroendocrine system and the immune system. Stress activates the hypothalamic pituitary-adrenal axis, increases circulating glucocorticoids, and is associated with alterations of immune function and susceptibility to infection and neoplastic disease (6). The human response to surgical stress is characterized by a series of hormonal, immunological, and metabolic changes that together constitute the global surgical stress response (7,8). This perioperative response is considered a homeostatic mechanism for adapting to the perioperative injury. The effects of the surgical stress response, however, may be detrimental: neuroendocrine hormones (e.g., cortisol, catecholamines) and cytokines (e.g., interleukin-6) provoke a negative nitrogen balance and catabolism, delay wound healing, and cause postoperative immunosuppression (7,8). Children are particularly vulnerable to the global surgical stress response because of limited energy reserves, larger brain masses, and obligatory glucose requirements (9). Because acute psychological stress, such as preoperative anxiety, is associated with immediate stress hormone release, the contribution of perioperative psychological factors to the global perioperative stress response cannot be ignored. In adults, increased preoperative anxiety is associated with poor postoperative behavioral and clinical recovery (10,11). As an indicator of the importance of preoperative anxiety, a panel of 72 anesthesiologists recently ranked various anesthesia low-morbidity clinical outcomes based on importance and frequency. The five clinical outcomes with the highest combined score were incisional pain, nausea, vomiting, preoperative anxiety, and discomfort from IV insertion (12). Thus, consensus is evident among anesthesiologists about the need to treat anxiety before surgery. In a modern epidemiological framework, diseases can be characterized in terms of risk factors, interventions, and outcomes. In this update, we will review preoperative anxiety in children using this conceptual framework (Fig. 1).

The differences in the bispectral index between infants and children during emergence from anesthesia after circumcision surgery.

UNLABELLED The bispectral index (BIS) correlates with consciousness during adult anesthesia. In this prospective, blinded study of children (n = 24) and infants (n = 25) undergoing elective circumcision, we evaluated BIS and consciousness level during emergence from anesthesia. Anesthesia was maintained with sevoflurane, and a penile nerve block was performed in each patient before surgical stimulation. At the completion of surgery, the sevoflurane was decreased stepwise from 0.9% in increments of 0.2%, and arousal was tested with a uniform auditory stimulus given after a steady state of end-tidal sevoflurane concentration was achieved at each step. The BIS increased significantly as the sevoflurane concentrations decreased in children (0.9%, 62.5 +/- 8.1; 0.7%, 70.8 +/- 7.4; and 0.5%, 74.1 +/- 7.1; P < 0.001 for 0.7% and 0.5% compared with 0.9%), but a similar relationship was not demonstrated in infants. The BIS values at 0.7% and 0.5% sevoflurane were significantly higher in children than infants (P < 0.02 and P < 0.002, respectively). In both children and infants, the BIS increased significantly from pre- to postarousal (children, 73.5 +/- 7 to 83.1 +/- 12, P = 0.01; infants, 67.8 +/- 10 to 85.6 +/- 13.6, P < 0.001). The BIS at which arousal was possible with the stimulus tended to be higher in children than in infants (P = 0.06). IMPLICATIONS In this study comparing the Bispectral index (BIS) in infants and children undergoing circumcision surgery by use of a standardized surgical and anesthetic technique, a significant decrease in BIS was detected in children during a stepwise decrease in end-tidal sevoflurane concentration. A similar relationship was not demonstrated in infants less than 1 yr old. In both children and infants, BIS increased significantly from pre- to postarousal. Additional studies are necessary to determine changes in BIS with maturational changes in the electroencephalogram.

The bispectral index and explicit recall during the intraoperative wake-up test for scoliosis surgery

In this prospective study, we evaluated the bispectral index (BIS) and postoperative recall during the intraoperative wake-up examination in 34 children and adolescents undergoing scoliosis surgery. Each anesthesiologist was blinded to BIS values throughout surgery and the wake-up test. The BIS, mean arterial blood pressure, and heart rate were compared at: before starting the wake-up test, patient movement to command, and after the patient was reanesthetized. The anesthetic technique for Group 1 was small-dose isoflurane, nitrous oxide, fentanyl, and midazolam and for Group 2 was nitrous oxide, fentanyl, and midazolam. Controlled hypotension was used for all cases. At patient movement to command, the patients were told a specific color to remember (teal) and on the second postoperative day were interviewed for explicit recall of the color and other intraoperative events. A total of 37 wake-up tests were performed in 34 patients. There was a significant increase in both groups of BIS (P < 0.001), mean arterial blood pressure (P < 0.001), and heart rate (P < 0.01) at the time of purposeful patient movement followed by a significant decline in BIS after reintroduction of anesthesia (P < 0.01). No patient recalled intraoperative pain, one patient recalled the wake-up test but not the color, and five patients recalled the specified color. We conclude that BIS may be a useful clinical monitor for predicting patient movement to command during the intraoperative wake-up test, particularly when controlled hypotension is used and hemodynamic responses to emergence of anesthesia are blunted.

The correlation of bispectral index with endtidal sevoflurane concentration and haemodynamic parameters in preschoolers

Background: Bispectral index (BIS) is a signal processing device that potentially is a pharmacodynamic measure of the effects of anaesthesia on the central nervous system.

Anesthesia and outcome after neonatal surgery: The role for randomized trials

Editor’s Note: This is the second in a three-part series of Editorial Views regarding design of clinical trials to address the effect of anesthesia on the developing brain. Animal studies have suggested that anesthetic exposure could affect neurocognitive development, and there is an urgent need for clinical trials to determine whether this effect occurs in humans. This series presents the opinions of three world thought leaders in the possible designs of such clinical trials.

Infantile Postoperative Encephalopathy: Perioperative Factors as a Cause for Concern

We report on 6 infants who underwent elective surgery and developed postoperative encephalopathy, which had features most consistent with intraoperative cerebral hypoperfusion. All infants were <48 weeks’ postmenstrual age and underwent procedures lasting 120 to 185 minutes. Intraoperative records revealed that most of the measured systolic blood pressure (SBP) values were <60 mm Hg (the threshold for hypotension in awake infants according to the Pediatric Advanced Life Support guidelines) but that only 11% of the measured SBP values were <1 SD of the mean definition of hypotension (<45 mm Hg) as reported in a survey of members of the Society for Pediatric Anesthesia in 2009. Four infants also exhibited prolonged periods of mild hypocapnia (<35 mm Hg). One infant did not receive intraoperative dextrose. All infants developed new-onset seizures within 25 hours of administration of the anesthetic, with a predominant cerebral pathology of supratentorial watershed infarction in the border zone between the anterior, middle, and posterior cerebral arteries. Follow-up of these infants found that 1 died, 1 had profound developmental delays, 1 had minor motor delays, 2 were normal, and 1 was lost to follow-up. Although the precise cause of encephalopathy cannot be determined, it is important to consider the role that SBP hypotension (as well as hypoglycemia, hyperthermia, hyperoxia, and hypocapnia) plays during general anesthesia in young infants in the development of infantile postoperative encephalopathy. Our observations highlight the lack of evidence-based recommendations for the lower limits of adequate SBP and end-tidal carbon dioxide in anesthetized infants.

The pharmacokinetics of epidural ropivacaine in infants and young children.

The pharmacokinetic variables of ropivacaine were characterized after epidural bolus injection in pediatric patients. The subjects, 7 infants (aged 3–11 mo) and 11 young children (aged 12–48 mo), received 1.7 mg/kg of ropivacaine via a lumbar epidural catheter. Total plasma concentrations of ropivacaine measured over 24 h were assayed by high-pressure liquid chromatography, and pharmacokinetic modeling was performed by Nonlinear Mixed Effects Modeling analysis. The median peak venous plasma concentrations (Cmax) in infants and young children were 610 &mgr;g/L (interquartile range [IQR], 550–725 &mgr;g/L) and 640 &mgr;g/L (IQR, 540–750 &mgr;g/L), respectively. The median times to maximum plasma ropivacaine concentration (Tmax) were 60 min (IQR, 60–120 min) in infants and 60 min (IQR, 30–90 min) in young children. There were no statistical differences between median values of Cmax and Tmax between infants and young children. The calculated clearance (CL) in infants was 4.26 mL · min−1 · kg−1 (9% coefficient of variation), and in young children it was 6.15 mL · min−1 · kg−1 (11% coefficient of variation). The CL for infants was significantly less than the CL for young children (P < 0.01). The volume of distribution was estimated to be 2370 mL/kg (9% coefficient of variation) for both young children and infants. No systemic toxicity was observed in either group.

Apnea after Awake Regional and General Anesthesia in Infants: The General Anesthesia Compared to Spinal Anesthesia Study-Comparing Apnea and Neurodevelopmental Outcomes, a Randomized Controlled Trial

Background:Postoperative apnea is a complication in young infants. Awake regional anesthesia (RA) may reduce the risk; however, the evidence is weak. The General Anesthesia compared to Spinal anesthesia study is a randomized, controlled trial designed to assess the influence of general anesthesia (GA) on neurodevelopment. A secondary aim is to compare rates of apnea after anesthesia. Methods:Infants aged 60 weeks or younger, postmenstrual age scheduled for inguinal herniorrhaphy, were randomized to RA or GA. Exclusion criteria included risk factors for adverse neurodevelopmental outcome and infants born less than 26 weeks gestation. The primary outcome of this analysis was any observed apnea up to 12 h postoperatively. Apnea assessment was unblinded. Results:Three hundred sixty-three patients were assigned to RA and 359 to GA. Overall, the incidence of apnea (0 to 12 h) was similar between arms (3% in RA and 4% in GA arms; odds ratio [OR], 0.63; 95% CI, 0.31 to 1.30, P = 0.2133); however, the incidence of early apnea (0 to 30 min) was lower in the RA arm (1 vs. 3%; OR, 0.20; 95% CI, 0.05 to 0.91; P = 0.0367). The incidence of late apnea (30 min to 12 h) was 2% in both RA and GA arms (OR, 1.17; 95% CI, 0.41 to 3.33; P = 0.7688). The strongest predictor of apnea was prematurity (OR, 21.87; 95% CI, 4.38 to 109.24), and 96% of infants with apnea were premature. Conclusions:RA in infants undergoing inguinal herniorrhaphy reduces apnea in the early postoperative period. Cardiorespiratory monitoring should be used for all ex-premature infants.

General Anesthetics in Pediatric Anesthesia: Influences on the Developing Brain

Millions of newborn and infants receive anesthetic, sedative and analgesic drugs for surgery and painful procedures on a daily basis. However, recent laboratory reports clearly demonstrate that anesthetic and sedative drugs induced both neuroapoptosis and neurocognitive deficits in laboratory models. This issue is of paramount interest to pediatric anesthesiologists and intensivists because it questions the safety of anesthetics used for fetal and neonatal anesthesia. Most clinically utilized anesthetic drugs have been found to induce neuronal cell death in the developing brain and to potentially cause long-term neurological impairment. Conversely, painful stimuli without analgesia and anesthesia have been implicated in triggering neuro-apoptosis in juvenile mammalian models. Published retrospective reviews demonstrate temporary neurological sequelae after prolonged anesthetic exposure in young children and larger studies identify long-term neurodevelopmental impairment after neonatal surgery and anesthesia. This paper examines the evidence for the effects of commonly used anesthetics on neuronal structure and neurocognitive function in laboratory models and reviews the relevant clinical human epidemiologic data.