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Biomedical subjects

Andrew J Davidson

Publications and source records attributed to Andrew J Davidson.

8 recordsLinked to original sources
PubMed2006

The effects of caudal local anesthesia blockade on the Bispectral Index during general anesthesia in children.

BACKGROUND: Peripheral deafferentation induced by epidural or spinal anesthesia reduces the degree of cortical arousal in adults. This study aimed at determining if caudal blockade decreases the level of arousal, as measured by Bispectral Index (BIS) in unstimulated children, and to determine if this effect differed between age groups. METHODS: Hospital ethics committee approval and parental consent was obtained. Children (age between 24 months and 5 years) and infants (between 6 and 24 months of age) were recruited if they were scheduled for below umbilical surgery that would usually require caudal local anesthesia blockade. Before the procedure, subjects within each age group were randomized to either caudal group (1 ml.kg(-1) 0.25% bupivacaine), or control group (no caudal). In all groups, anesthesia was induced with sevoflurane and maintained at a constant endtidal concentration of 1.5% sevoflurane without N(2)O. Five minutes after induction a baseline BIS was recorded (BIS(1)). In the caudal groups, a caudal block was then performed while in the control groups no block was performed. Fifteen minutes later, the BIS was again recorded (BIS(2)). The change in BIS over this time period was the primary outcome (BIS(Delta)). After measurement, subjects in the control groups received a caudal block before the start of surgery. RESULTS: Twenty-nine infants and 18 children completed the study protocol. In children, BIS(Delta) was significantly different between the caudal group and control (-5.7 vs -0.7, P = 0.04). In infants, no significant difference was detected in BIS(Delta) between caudal and control groups. CONCLUSIONS: Caudal blockade decreased the degree of arousal, as measured by BIS, in unstimulated children aged 2-5 years. No change in arousal was detected in infants.

Analysis of Variance↗
PubMed2006

A cohort study of the incidence and risk factors for negative behavior changes in children after general anesthesia.

BACKGROUND: Hospitalization and anesthesia can have a substantial psychological impact on children, which may be manifested by negative behavioral change. The primary aims of this study were to estimate the incidence of negative behavior change postanesthesia in a large cohort of children, and to identify the possible risk factors. METHODS: One thousand two hundred and fifty children aged from 3 to 12 years scheduled for anesthesia for a variety of procedures were enrolled. The absolute version of the Vernon Post Hospitalization Behavior Questionnaire (PHBQ) was used to assess behavior change at 3 and 30 days postanesthesia. Deterioration in seven or more items of behavior was defined to be a significant negative behavior change. Demographic data, anesthesia details, type and extent of preparation, details of procedure and length of hospitalization were recorded. Child temperament, child anxiety and parental anxiety were also measured. RESULTS: Twenty-four percent of children had significant negative behavior change at day 3 and 16% at day 30. After logistic regression, factors associated with significant negative behavior change at 3 days were increased parental state anxiety, younger age, overnight admission, lower birth order and preparation via having a discussion with the anesthetist. At day 30, longer hospitalization, younger age, reading the anesthesia preparation book and a previous difficult anesthesia experience were associated with significant negative behavior change. Also at day 30, reading the anesthesia preparation book was strongly associated with negative behavior change in children having short procedures, but not longer procedures. However, at both 3 and 30 days, the amount of variability explained by factors included in the models was low. CONCLUSIONS: Significant negative behavior change can occur in children after anesthesia. It is difficult to precisely predict in which children this will occur, however, some individual, family and procedural variables are associated with significant negative behavior change. If used, preparation should be considered according to level of surgical complexity.

Age Factors↗
PubMed2006

Measuring anesthesia in children using the EEG.

Advances in electroencephalogram (EEG) processing have produced new interest in measuring anesthesia using the EEG. There are a number of EEG-based anesthesia 'depth' monitors now available and their use in pediatric anesthesia is increasing. Although these monitors have been extensively studied in adults, there are relatively few studies examining their validity or use in children. To some extent we must rely on adult data. However, extrapolation of data from adults to children requires an in depth understanding of the physiology behind the data. The first question is what is being measured. What is anesthesia? A model of anesthesia has several components with arousal as a core component. Arousal can be linked to clinical observations, and correlates with anatomical and physiological studies. The EEG has characteristics that fairly consistently change with arousal during anesthesia, but the relationship between arousal and the EEG is imprecise and drug dependent. This relationship is the basis for using the EEG to measure anesthesia and provides only an indirect measure of consciousness and memory formation. A good understanding of how the EEG is related to anesthesia is essential when interpreting the EEG during anesthesia, and especially when extending the use of the EEG to measure anesthesia in children. Physiological studies in adults and children indicate that EEG-derived anesthesia depth monitors can provide an imprecise and drug-dependent measure of arousal. Although the outputs from these monitors do not closely represent any true physiological entity, they can be used as guides for anesthesia and in so doing have improved outcomes in adults. In older children the physiology, anatomy and clinical observations indicate the performance of the monitors may be similar to that in adults, although the clinical relevance of outcomes may be different. In infants their use cannot yet be supported in theory or in practice.

Anesthesia↗
PubMed2006

Risk factors for anxiety at induction of anesthesia in children: a prospective cohort study.

BACKGROUND: In children anxiety at induction of anesthesia is a common and important aspect of the psychological impact of anesthesia and surgery. Previous studies examining risk factors for increased anxiety have found contradictory results. This may be due to using small, or highly selective population samples, or failure to adjust for confounding variables. Results may also be culturally or institutionally specific. The aim of this study was to identify possible risk factors in a large representative cohort of children. METHODS: One thousand two hundred fifty children aged 3-12 years were recruited. Anxiety at induction of anesthesia was assessed using the modified Yale preoperative anxiety scale. Children with an anxiety score of greater than 30 were classified as having high anxiety. Anesthetists were blinded to the assessment. Data recorded included age, gender, past healthcare history, family details, use of sedative premedication, anesthesia details, admission details, parental anxiety and child temperament. An unadjusted analysis was performed to identify possible risk factors for high anxiety. An adjusted regression analysis was then performed including the potential risk factors identified in the unadjusted analysis. RESULTS: The incidence of high anxiety at induction was 50.2%. In the adjusted analysis, younger age, behavioral problems with previous healthcare attendances, longer duration of procedure, having more than five previous hospital admissions and anxious parents at induction were all associated with high anxiety at induction. Hospital admission via the day stay ward was associated with less anxiety. Sedative premedication was associated with less anxiety in children with ASA status greater than one. However, the variability explained by factors included in the model was low (5.3%). CONCLUSIONS: Some simple preoperative questions can help identify children at risk of heightened anxiety at induction of anesthesia; however, it remains difficult to precisely predict which child will experience high anxiety.

Anesthesia↗
PubMed2005

Awareness during anesthesia in children: a prospective cohort study.

During routine adult anesthesia, the risk of awareness is 0.1%-0.2%. No recent studies have reported the incidence in children. Altered pharmacology and differing anesthesia techniques suggest that the incidence may differ in children. In this prospective cohort study, we determined the incidence of awareness during anesthesia in children. Eight-hundred-sixty-four children aged 5-12 yr who had undergone general anesthesia at The Royal Children's Hospital were interviewed on 3 occasions to determine the incidence of awareness. The awareness assessment was nested within a larger study of behavior change after anesthesia. Reports of suspected awareness were sent to four independent adjudicators. If they all agreed, a case was classified as true awareness. Twenty-eight reports were generated. There were 7 cases of true awareness, for an incidence of 0.8% (95% confidence interval, 0.3%-1.7%). Only one aware child received neuromuscular blockers, compared with 12% in the nonaware group. No aware child reported distress, and no substantial difference was detected in behavior disturbance between aware (20%) and nonaware (16%) children. The data provide some evidence that, like adults, children are also at risk of intraoperative awareness. Although the cause remains unclear, anesthesiologists should be alerted to the possibility of awareness in children.

Anesthesia↗
PubMed2002

A comparison of prilocaine and lidocaine for intravenous regional anaesthesia for forearm fracture reduction in children.

BACKGROUND: In this prospective blinded randomized study, we compared prilocaine and lidocaine for intravenous regional anaesthesia for forearm fracture reduction in children. METHODS: Two hundred and seventy-nine children, aged 316 years, were enrolled and randomly assigned to receive 3 mg.kg-1 of either prilocaine or lidocaine. The severity of fracture was classified according to the displacement of the radius (i.e., no radial fracture, angulated, partly displaced or completely displaced). Pain during the procedure was assessed as none, minimal, moderate or severe. RESULTS: There was no significant difference between agents in the proportion of patients with a successful reduction (prilocaine 94%, lidocaine 92%). Compared with less severe fractures, successful reduction was less common in the completely displaced fractures (P < 0.001) but there was no significant difference in this category between anaesthetic agents (successful reduction: prilocaine, 84%; lidocaine, 78%). Analgesia was superior in the lidocaine group with more patients having no or minimal pain (prilocaine, 78%; lidocaine, 90%, P < 0.05). CONCLUSIONS: Both agents are effective for forearm fracture reduction in children with a high incidence of successful reductions, particularly in the minimally or nondisplaced fractures. Lidocaine provided superior analgesia.

Adolescent↗