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Dixon's Up-and-down Method (dixon + up-and-down_method)

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Medical Sciences	100%

Selected Abstracts

Effects of different doses of remifentanil on the end-tidal concentration of sevoflurane required for tracheal intubation in children

ANAESTHESIA, Issue 8 2009
L. He
Summary We investigated the effects of different doses of remifentanil on the end-tidal concentration of sevoflurane required for tracheal intubation in children without the use of neuromuscular blocking drugs. One hundred and thirty paediatric patients, aged 3,8 years, were randomly allocated to receive no remifentanil (group control) or remifentanil 0.1 ,g.kg,1.min,1 (group remi0.1), 0.2 ,g.kg,1.min,1 (group remi0.2), 0.3 ,g.kg,1.min,1 (group remi0.3). All patients were anaesthetised using 5% sevoflurane. After loss of eyelash reflex, remifentanil 1 ,g.kg,1 was injected over 1 min followed by an appropriate group-dependent infusion and the end-tidal sevoflurane concentration was changed. Predetermined end-tidal sevoflurane concentrations for each group were determined using the Dixon up-and-down method. After the target concentration of sevoflurane was maintained for 5 min, the child's trachea was intubated. Successful intubation was defined as excellent or good intubating conditions. The end-tidal concentration (SD) of sevoflurane for successful tracheal intubation in 50% of children (ED50) were 5.16 (0.22)% in control, 3.27 (0.18)%, 1.81 (0.20)% and 1.01 (0.11)%, in remi0.1, remi0.2, and remi0.3 groups, respectively. Using probit analysis, the 95% effective dose (ED95) of sevoflurane were 5.60% (95% CI 5.35,7.66), 3.77% (95% CI 3.45,7.74), 2.18% (95% CI 1.96,3.86), 1.19% (95% CI 1.06,1.82) in control, remi0.1, remi0.2, and remi0.3 groups, respectively. [source]

The optimal bolus dose of alfentanil for tracheal intubation during sevoflurane induction without neuromuscular blockade in day-case anaesthesia

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 1 2008
J. Y. KIM
Background: The purpose of this study was to determine the optimal bolus dose of alfentanil required to provide successful intubating conditions following inhalation induction of anaesthesia using 5% sevoflurane and 60% nitrous oxide without neuromuscular blockade in adult day-case anaesthesia. Methods: Twenty-four adults, aged 18,60 years, undergoing general anaesthesia for short ambulatory surgery were enroled into the study. After vital capacity induction, with sevoflurane 5% and 60% nitrous oxide in oxygen, pre-determined dose of alfentanil was injected over 30 s. The dose of alfentanil was determined by modified Dixon's up-and-down method (2 ,g/kg as a step size). Ninety seconds after the end of bolus administration of alfentanil, the trachea was intubated. Systolic blood pressure, heart rate and SpO2 were recorded at anaesthetic induction, before, 1 min and 3 min after intubation. Results: The bolus dose of alfentanil for successful tracheal intubation was 10.7±2.1 ,g/kg in 50% of patients during inhalation induction. From probit analysis, 50% effective dose (ED50) and ED95 values (95% confidence limits) of alfentanil were 10.7 ,g/kg (8.0,12.9 ,g/kg) and 14.9 ,g/kg (12.9,31.1 ,g/kg), respectively. Conclusions: Using the modified Dixon's up-and-down method, the bolus dose of alfentanil for successful tracheal intubation was 10.7±2.1 ,g/kg in 50% of adult patients during inhalation induction using 5% sevoflurane and 60% nitrous oxide in oxygen without neuromuscular blocking agent in day-case anaesthesia. [source]

Minimum local analgesic concentration of ropivacaine for intra-operative caudal analgesia in pre-school and school age children

ANAESTHESIA, Issue 10 2010
X. M. Deng
Summary We compared the minimum local analgesia concentration of ropivacaine for intra-operative caudal analgesia in pre-school and school age children. Fifty-one boys, undergoing hypospadius repair surgery, were stratified into pre-school or school age groups. After induction of anaesthesia, caudal block was performed with ropivacaine 1 ml.kg,1 of the desired concentration. The first child in each group received ropivacaine 0.125%, and subsequent concentrations were determined by the analgesic response of the previous patient using Dixon's up-and-down method. Under general anaesthesia with 0.7 minimum alveolar concentration of sevoflurane, the minimum local analgesia concentration of ropivacaine for intra-operative caudal block was 34% greater in school age than in pre-school age boys (0.143% (95% CI 0.132,0.157%) vs 0.107% (95% CI 0.089,0.122%), respectively; p < 0.001). This study indicates that a higher concentration of ropivacaine is needed for school age than pre-school age children to provide intra-operative caudal analgesia when combined with general anaesthesia. [source]

Effect-site concentration of remifentanil for laryngeal mask airway insertion during target-controlled infusion of propofol

ANAESTHESIA, Issue 2 2009
M. K. Kim
Summary The purpose of this study was to determine the effect-site concentration of remifentanil that would provide optimal conditions for successful laryngeal mask airway insertion during a target-controlled infusion (TCI) of propofol at 3.5 ,g.ml,1 without the use of neuromuscular blockade. Five minutes after propofol infusion, remifentanil was infused at a dose determined by a modified Dixon's up-and-down method. Five minutes after remifentanil infusion, the laryngeal mask was inserted. The effect-site concentration of remifentanil for successful laryngeal mask insertion in 50% of adults (EC50) was 3.04 (SD 0.49) ng.ml,1 during a TCI of 3.5 ,g.ml,1 propofol without neuromuscular blockade. From the probit analysis, the EC50 and EC95 of remifentanil were 2.84 ng.ml,1 (95% CI 2.09,3.57 ng.ml,1) and 3.79 ng.ml,1 (95% CI 3.26,9.25 ng.ml,1), respectively. [source]