Median effective dose of intranasal dexmedetomidine for satisfactory mask induction in children undergoing examination under anaesthesia for retinoblastoma - A prospective up and down sequential allocation study.

Background and Aims: Inhalational technique is used to induce anaesthesia in children without intravenous access. We aimed to determine the median effective dose (ED50) of intranasal dexmedetomidine to ensure satisfactory mask acceptance during inhalation induction in children with retinoblastoma undergoing examination under anaesthesia. Methods: A prospective sequential allocation study was conducted in children aged 1-60 months divided into Group A (1-18 months) and Group B (18-60 months). Children were administered dexmedetomidine intranasally as premedication. Sedation was assessed using the modified Observer Assessment of Alertness and Sedation Scale until induction. Successful mask acceptance was defined as a cooperative or asleep child during inhalational induction. The starting dose of dexmedetomidine was 1 µg/kg. The next dose varied by 0.2 µg/kg depending on the outcome of this case. According to the Dixon up-and-down method, the mean of midpoints of the failure-success sequence was calculated to obtain the ED50 values. Results: The ED50 of intranasal dexmedetomidine for satisfactory mask acceptance was 0.7 µg/kg (95% confidence interval [CI]: 0.54-0.86) in Group A (n = 23) and 0.96 µg/kg (95% CI: 0.83-1.08) in Group B (n = 25) (P = 0.020). The mean (standard deviation) duration of anaesthesia was 33.5 (14.9) minutes in group A versus 23.5 (8.48) minutes in Group B (P = 0.007). Conclusion: ED50 was lower in children younger than 18 months than in older children. There was no difference in the time to discharge from the post-anaesthesia care unit despite the procedure being longer in smaller children.

Sevoflurane Consumption During Inhalational Induction in Children: A Randomized Comparison of Minute Ventilation-Based Techniques With Standard Fixed Fresh Gas Flow Technique.

This study was done to ascertain the optimum fresh gas flow (FGF) offering the best balance between rapid induction and minimal waste in pediatric patients. Forty-five children (weighing 10-20 kg) undergoing elective procedures under general anesthesia were randomly assigned into 3 groups: 0.5 minute ventilation (MV), MV, and S (FGF = 6 L/min). After priming the pediatric closed circuit, anesthesia was induced using a face mask with 8% sevoflurane in 100% oxygen (Draeger Primus Vista 120 anesthesia machine) at FGF-determined MV per group allocation. After loss of eyelash reflex (time 1 [T1]), intravenous cannulation (T2) and laryngeal mask airway (LMA) placement (T3) were done. Total sevoflurane consumed during induction (measured using logbook function) was the primary outcome. The cost of sevoflurane, any reflex movement, tachycardia (heart rate change > 20%), or additional propofol boluses required were also recorded. Sevoflurane consumption (3.8 vs 5.8 vs 9.2 mL) and cost of sevoflurane (104.2 vs 199.4 vs 312.8 rupees) were lowest in group 0.5 MV (P < .001). There was no difference in hemodynamic parameters, movement on cannulation/LMA insertion, and rescue propofol boluses required. For pediatric sevoflurane induction, half the MV-based FGF provided similar anesthetic conditions for LMA insertion with minimum sevoflurane consumption.

Induction techniques that reduce redistribution hypothermia: a prospective, randomized, controlled, single blind effectiveness study.

BACKGROUND: While much effort has been devoted to correcting intraoperative hypothermia, less attention has been directed to preventing redistribution hypothermia. In this study, we compared three different anesthetic induction techniques to standard IV propofol inductions (control) in their effect on reducing redistribution hypothermia. METHODS: Elective, afebrile patients, age 18 to 55 years, were randomly assigned to one of four groups (n = 50 each). Group "INH/100" was induced with 8% sevoflurane in 100% oxygen, Group "INH/50" with 8% sevoflurane in 50% oxygen and 50% nitrous oxide, Group "PROP" with 2.2 mg/kg propofol, and Group "Phnl/PROP" with 2.2 mg/kg propofol immediately preceded by 160 mcg phenylephrine. Patients were maintained with sevoflurane in 50% nitrous oxide and 50% oxygen in addition to opioid narcotic. Forced air warming was used. Core temperatures were recorded every 15 min after induction for 1 h. RESULTS: Compared to control group PROP, the mean temperatures in groups INH/100, INH/50, and Phnl/PROP were higher 15, 30, 45 and 60 min after induction (p < 0.001 for all comparisons), averaging between 0.39 °C and 0.54 °C higher. In group PROP, 60% of patients had at least one temperature below 36.0 °C in the first hour whereas only 16% did in each of groups INH/100, INH/50, and Phnl/PROP (p < 0.0001 in each group compared to PROP). CONCLUSIONS: In this effectiveness trial, inhalation inductions with sevoflurane or with prophylactic phenylephrine bolus prior to propofol induction reduced the magnitude of redistribution hypothermia by an average of 0.4 to 0.5 °C in patients aged 18 to 55 years. TRIAL REGISTRATION: Retrospectively registered on clinical-trials.gov as NCT02331108 , November 20, 2014.

Pretreatment with nitrous oxide enhances induction of anesthesia with sevoflurane: A randomized controlled trial.

BACKGROUND AND AIMS: Inhalation anesthesia with sevoflurane may be enhanced by several drugs or techniques. The aim of the present study was to investigate the effect of nitrous oxide (N2O) pretreatment on the speed of anesthesia induction with sevoflurane. MATERIAL AND METHODS: Eighty patients scheduled for hysteroscopy under general anesthesia were randomly assigned to inhale for 10 min before induction 50% N2O in oxygen or air via a facemask. Anesthesia was induced with 7-8% sevoflurane in oxygen via a facemask. Bispectral index (BIS), end-tidal carbon dioxide (EtCO2) tidal volume, respiratory rate, oxygen saturation (SpO2), and heart rate were recorded every minute during the 10 min pretreatment periods and every 30 s during the first 300 s of induction with sevoflurane. During induction of anesthesia inspired and end-tidal sevoflurane concentrations were also recorded. RESULTS: During the 10 min of inspired 50% N2O or air BIS, EtCO2, tidal volume, respiratory rate and heart rate values did not differ between the two groups except for the SpO2, which was higher in the N2O group (P < 0.001). During induction of anesthesia the N2O group exhibited lower BIS values (P = 0.001), being significant at 60-150 s (P < 0.001, P < 0.001, P = 0.002, P = 0.014) as well as at 270 s (P = 0.004). EtCO2 and tidal volume were consistently lower in the N2O group (P = 0.001, P = 0.041 respectively) and respiratory rate was higher (P = 0.007). CONCLUSION: Our results show that pretreatment of the patients with 50% N2O for 10 min enhances the speed of induction with sevoflurane as assessed by the BIS monitoring.

[Management of difficult airway with inhalation induction in a patient with Lennox-Gastaut syndrome and neck injury]. / Manejo de vía aérea difícil con inducción inhalatoria en paciente con síndrome de Lennox-Gastaut y traumatismo cervical.

Lennox-Gastaut syndrome is a childhood epileptic encephalopathy, and is characterized by frequent and difficult to treat seizures associated with mental retardation. The case is presented of a 21 year-old male with Lennox-Gastaut syndrome, with bilateral cervical facet joint dislocation fracture at C6-C7 and spinal canal compression as a result of a fall during a seizure. In this case the management of the difficult airway expected in an awake and uncooperative patient, with cervical spinal cord injury is described. An airway management strategy was proposed, that allowed a rapid and safe airway control with the best possible tolerance and maintaining the neck immobilised, so as not to increase neurological injury. Within this strategy, plan A was defined as inhalation induction with sevoflurane to maintain spontaneous breathing and tracheal intubation with Airtraq®. We believe that the Airtraq® video laryngoscope with inhalational induction with sevoflurane is a valid and effective alternative in the management of expected difficult airway.

Comparative evaluation of different values of bispectral index in determination of the appropriate level of anesthesia for tracheal intubation during inhalational induction of anesthesia in pediatrics.

BACKGROUND: Induction of anesthesia is the most crucial period of general anesthesia. Inhalational induction is the most commonly used technique in pediatric anesthesia. Tracheal intubation can be done after reaching the deep levels of anesthesia. The depth of anesthesia is often difficult to be judged. Bispectral index is a measure of the effects of anesthesia on brain. This study was designed to evaluate the efficacy of bispectral index (BIS) in clarifying suitable depth of anesthesia for tracheal intubation during inhalational induction of anesthesia. METHODS: In a clinical trial, ninety patients, ASA I & II, 1 to 6 years old, scheduled for elective surgery were enrolled into the study. After starting BIS monitoring, patients randomly were divided into three groups. Then, anesthesia was induced by gradual increase of halothane in 50% mixture of oxygen (O(2)) and N(2)O and continued until target BIS (60 ± 2, 50 ± 2 and 40 ± 2) achieved. After tracheal intubation, the duration of laryngoscopy and the presence of laryngospasm, bronchospasm, laryngoscopy failure, the movement of extremities and the changes in SpO2 and BIS were recorded. The data were analyzed by chi-square and ANOVA at 0.05 level of significance. RESULTS: BIS could not determine the appropriate level of anesthesia for tracheal intubation in this setting. There were no differences in laryngoscopy duration and the occurrence of laryngospasm, bronchospasm, laryngoscopy failure, extremity movement and awakening time among three groups. CONCLUSIONS: These results confirmed that there was no significant difference in the incidence of complications related to intubation at different BIS values (from 60 to 40) during inhalation induction, and probably to achieve an adequate or more reliable depth of anesthesia, the lower values of BIS is required.

A portable inhalational induction device provides co-operative induction of anaesthesia in preanaesthetic area for children.

BACKGROUND: We introduce a new, simple portable inhalational induction device (PD) that provides co-operative inhalational induction of anaesthesia using N(2)O and subsequent sevoflurane in the preanaesthetic induction area in children. METHODS: Forty-five children (30 to 94 months old age, <35 kg) who were scheduled to undergo simple operations were assigned randomly to one of three regimens. Patients were encouraged by their parents to inhale N(2)O followed by sevoflurane (PD N(2)O-sevo group) or sevoflurane (PD sevo group) using a portable inhalational induction device in the preanaesthetic induction area until they were unable to respond to their names. They were then transferred to the operating room while maintaining inhalation of sevoflurane via the device. The control group underwent conventional inhalational induction in the operating room with the parents in attendance. RESULTS: Patients in the PD N(2)O-sevo group had a higher co-operative inhalation frequency than the patients in the PD sevo or the control group. Anaesthesia induction in the PD N(2)O-sevo and the PD sevo groups were faster than in the control group. Parent satisfaction score (0-100) was higher for the PD N(2)O-sevo group than for the control group. CONCLUSIONS: A new portable inhalational induction device allows faster induction in co-operation with parents present in the preanaesthetic induction area compared to conventional inhalational induction in the unfamiliar operating room with the parents in attendance.

Adequate sevoflurane concentrations in inhalation induction of sevoflurane following administration of remifentanil.

BACKGROUND: Currently, sevoflurane and remifentanil are utilized frequently for the inhalation induction of anesthesia. However, there is currently an insufficient amount of clinical data regarding the inhalation induction of sevoflurane after the administration of remifentanil. METHODS: 80 patients undergoing elective surgery were allocated randomly to four groups. Group A inhaled only sevoflurane at 8 vol%. Other groups were administered 3 ng/ml of remifentanil and inhaled sevoflurane at 8 vol% (group B) or 6 vol% (group C) or 4 vol% (group D). All groups also received 0.6 mg/kg of rocuronium. The blood pressure and heart rate were measured at pre-induction, and before and after tracheal intubation. After operation, the patients??levels of satisfaction with the inhalation induction were evaluated. RESULTS: The time to loss of consciousness was substantially longer in group D than in the other groups, but no significant differences were noted among the groups in terms of satisfaction scores. The HR in groups B, C and D increased significantly after pre-intubation as compared to baseline in group A. The HR decreased significantly during induction as compared to group A. The MAP in groups B, C and D decreased significantly at 1 and 2 minutes after tracheal intubation as compared to group A. In group D only, we noted no significant differences in the MAP as compared to baseline at 1, 2 minutes after tracheal intubation. CONCLUSIONS: 4 vol% sevoflurane was a more appropriate concentration for the inhalation induction of anesthesia when coupled with 3 ng/ml of remifentanil.