Remifentanil requirement for acceptable intubation conditions with two different doses of ketamine without a neuromuscular blocking agent in pediatric patients.

OBJECTIVE: The optimal remifentanil concentration for improving intubation conditions when intubation is performed without neuromuscular blocking agents (NMBAs) but with ketamine as an induction agent remains unknown. Here, we aimed to identify the effective bolus doses of remifentanil required to achieve acceptable intubation conditions upon anesthesia induction with 1 or 2 mg/kg ketamine without NMBAs. PATIENTS AND METHODS: In this prospective, double-blinded, randomized up-down sequential allocation study, we enrolled pediatric patients aged 3-12 years undergoing general anesthesia for inguinal hernia surgery. The patients were randomly allocated to one of two groups to receive either ketamine 1.0 mg/kg (K1 group) or 2.0 mg/kg (K2 group) intravenously until seven success-failure pairs were achieved. The remifentanil dose for each patient was determined using the modified Dixon's up-and-down method with an initial dose of 2.5 µg/kg and a step size of 0.5 µg/kg. RESULTS: In total, 51 patients (22 in the K1 group and 29 in the K2 group) were enrolled. The effective dose (ED)50s of remifentanil for obtaining clinically acceptable intubation conditions under anesthesia induction with ketamine but without NMBAs was 3.2 µg/kg in the K1 group and 1.6 µg/kg in the K2 group. High-dose remifentanil with 1 mg/kg ketamine was associated with more severe chest wall rigidity and lower mean blood pressure and heart rate than was low-dose remifentanil with 2 mg/kg ketamine. CONCLUSIONS: The ED50 of remifentanil required for clinically acceptable intubation conditions with anesthesia induction using 1 mg/kg ketamine without NMBAs in pediatric patients was twice that when using 2 mg/kg ketamine. The combination of 2 mg/kg ketamine and remifentanil was better at preventing chest wall rigidity.

Ulnar nerve morphology on magnetic resonance imaging predicts nerve recovery after surgery for cubital tunnel syndrome.

Magnetic resonance imaging (MRI) can evaluate nerve morphology in cubital tunnel syndrome (CuTS), but its value in predicting surgical outcome is unclear. The purpose of this study was to determine whether ulnar nerve morphology on MRI correlated with outcome after CuTS surgery. We reviewed 40 patients who had preoperative MRI and electrodiagnostic (EDX) examinations for CuTS and outcome evaluation 6 months and 2 years postoperatively. Using MRI, ulnar nerve cross-sectional area (UNCSA), changes in signal intensity, and any space-occupying lesion were evaluated. Other factors assessed were age, symptom duration and severity, type-2 diabetes and EDX parameters. Factors associated with unfavorable surgical outcome were identified. At 6 months postoperatively, 12 patients (30%) had excellent, 19 (47.5%) good, 8 (20%) fair and 1 (2.5%) poor results on modified Wilson-Krout criteria. On univariate analysis, unfavorable outcomes were associated with increased UNCSA, space-occupying lesion, and decreased motor nerve conduction velocity (mNCV), and on multivariate analysis with increased UNCSA 1 cm distal from the epicondyle only (model 1) or increased UNCSA 1 cm proximal from the epicondyle and decreased mNCV (model 2). At 2 years, 15 patients (37.5%) had excellent, 21 (52.5%) good, 3 (7.5%) fair and 1 (2.5%) poor results, and no factors correlated with unfavorable outcome. Increased UNCSA on MRI was associated with unfavorable outcome at 6 months but not at 2 years. This study suggests that morphologic ulnar nerve changes can predict delayed nerve recovery after surgery for CuTS.

Effect of different doses of ketamine with low-dose rocuronium on intubation conditions in children: prospective randomized double blind trial.

OBJECTIVE: The effect of ketamine on intubation condition, when used as an induction agent with low-dose rocuronium, is unknown. This study aimed to compare the effects of three doses of ketamine used with 0.3 mg/kg rocuronium and 1 µg/kg fentanyl on intubation conditions in children undergoing short elective surgery. PATIENTS AND METHODS: The study was performed as a prospective, randomized double-blind clinical trial. A total of 60 children aged 2 to 12 years, who were scheduled for inguinal herniorrhaphy under general anesthesia, were randomly allocated into three groups on the basis of ketamine dose: 1 mg/kg (Group K1, n = 20), 1.5 mg/kg (Group K1.5, n = 20), and 2 mg/kg (Group K2, n = 20). The primary outcome was the intubation condition. Other assessments included hemodynamic data, recovery profile, adverse events in the postanesthetic care unit (PACU) and use of fentanyl as a rescue analgesic in the PACU were also assessed. RESULTS: The occurrence of a clinically acceptable intubation condition increased with the use of an increased dose (≥ 1.5 mg/kg) (K1/K1.5/K2: 30%/65%/65%; p=0.038, for trends p=0.028). Hemodynamic data, recovery profile and adverse events in PACU showed no difference among groups. Fentanyl dose used in the PACU was higher in K1 than K2 and the number of patients requiring rescue analgesics in the PACU decreased in accordance with the dose of ketamine (K1/K1.5/K2: 30%/15%/0%; p=.031, for trends p=0.013). CONCLUSIONS: Different intubation conditions were observed on the basis of ketamine dose used in conjunction with 0.3 mg/kg rocuronium and fentanyl 1 µg/kg. Ketamine dose ≥ 1.5 mg/kg with low-dose rocuronium should be used to improve intubation conditions in pediatrics.

Comparison of the paediatric blade of the Pentax-AWS and Ovassapian airway in fibreoptic tracheal intubation in patients with limited mouth opening and cervical spine immobilization by a semi-rigid neck collar: a randomized controlled trial.

BACKGROUND: We compared the performances of the paediatric blade of a Pentax Airway Scope and an Ovassapian airway in fibreoptic tracheal intubation in patients whose necks were stabilized by semi-rigid neck collars. METHODS: Ninety patients were enrolled in this prospective, open-label, randomized controlled trial. Patients were randomly allocated to one of two groups (Group OVA-FOB and Group AWS-FOB). The time to tracheal intubation, success rate of tracheal intubation, number of optimization manoeuvres (jaw thrust), and difficulty of manipulation of the fibreoptic bronchoscope were compared between the groups. RESULTS: The time to tracheal intubation was significantly shorter (32 vs 50 s; median difference 19 s; 95% confidence interval 14-25 s; P<0.001) and manipulation of the fibreoptic bronchoscope was significantly easier for Group AWS-FOB. Optimization manoeuvres were rarely required to facilitate fibreoptic tracheal intubation in Group AWS-FOB [jaw thrust, 0 (0%); jaw thrust with anterior neck collar removal, 1 (2%)] compared with that required in Group OVA-FOB [jaw thrust, 39 (87%); jaw thrust with anterior neck collar removal, 2 (4%)]. There was no significant difference in the success rate of tracheal intubation on the first attempt between groups [Group AWS-FOB, 45 (100%); Group OVA-FOB, 44 (98%)]. CONCLUSIONS: Combined use of the paediatric blade of a Pentax Airway Scope and a fibreoptic bronchoscope enabled rapid tracheal intubation, minimizing the use of external manoeuvres of the airway, in patients with limited mouth opening and cervical spine immobilization by semi-rigid neck collars, compared with use of the Ovassapian airway and the fibreoptic bronchoscope. CLINICAL TRIAL REGISTRATION: NCT02827110.

Target-controlled infusion of remifentanil for laryngeal mask airway insertion during sevoflurane induction in adults.

OBJECTIVE: This randomized, double-blind study investigated the suitable target effect-site concentration of remifentanil for laryngeal mask airway (LMA) insertion during inhalation induction with sevoflurane. METHODS: Patients aged 18 - 60 years were randomly assigned to one of three groups receiving infusions of normal saline (control group), or infusions with target effect-site remifentanil concentrations of either 1 ng/ml (R1 group) or 2 ng/ml (R2 group), 1 min after the induction of anaesthesia with sevoflurane. LMA insertion was attempted 2 min after induction. Insertion conditions were graded using a six-variable, three-point scale (excellent, intermediate or poor). RESULTS: A total of 102 patients were included. The proportion of patients ranked as excellent for the LMA insertion was significantly higher in groups R1 and R2 compared with the control group. The incidence of apnoea was significantly more frequent in the R2 group than in the control or R1 groups. CONCLUSIONS: Compared with 1 ng/ml remifentanil or normal saline, target-controlled infusion of 2 ng/ml remifentanil significantly improved the LMA insertion conditions during sevoflurane inhalational induction, although apnoeic episodes were more frequently observed.

Comparison of the optimal effect-site concentrations of remifentanil for preventing cough during emergence from desflurane or sevoflurane anaesthesia.

OBJECTIVE: To compare the effect-site concentrations of remifentanil target-controlled infusion (TCI) that produced 50% and 95% of the maximal effect (EC50 and EC95, respectively) for preventing cough during emergence from desflurane or sevoflurane anaesthesia, in patients undergoing elective thyroidectomy. METHODS: Adults undergoing elective thyroidectomy were randomized to receive anaesthesia with desflurane or sevoflurane. The EC50 and EC95 values for remifentanil TCI were determined using Dixon's up-and-down method and probit analysis with sigmoid curve. RESULTS: In total, 48 patients aged 20-64 years were enrolled in the study. The EC50±SD of remifentanil TCI, determined by Dixon's up-and-down method, were 1.54±0.70 and 1.11±0.24 ng/ml for desflurane and sevoflurane, respectively. The EC95 of remifentanil TCI, analysed by probit analysis, were 2.88 ng/ml and 2.29 ng/ml for desflurane and sevoflurane, respectively. The effect-site concentration of remifentanil TCI for preventing cough during emergence from desflurane anaesthesia was not significantly higher than that observed for sevoflurane. CONCLUSIONS: During emergence from anaesthesia, variations in effect-site concentrations of remifentanil for preventing cough are of limited importance as they do not generate significant differences in results.

The incidence of postoperative nausea and vomiting after thyroidectomy using three anaesthetic techniques.

The choice of anaesthetics can affect the incidence of postoperative nausea and vomiting (PONV). This study compared the incidence of PONV in 177 female patients who underwent thyroidectomy, with anaesthesia induced and maintained using one of three regimens: (i) sevoflurane (thiopental sodium 4 - 5 mg/kg and sevoflurane 2.0 - 2.5 vol% in 50% air); (ii) total intravenous anaesthesia (TIVA; propofol-remifentanil [target blood concentrations 2.5 - 3.5 µg/ml and 3.5 - 4.5 ng/ml, respectively]); or (iii) combined inhalation and intravenous anaesthesia (sevoflurane 1.0 vol% in 50% air plus propofol-remifentanil [target blood concentrations 1.5 - 2.5 µg/ml and 2.5 - 3.5 ng/ml, respectively]). The incidence and severity of PONV and the need for rescue antiemetics were assessed at 0 - 24 h postoperatively. Overall, the incidence of PONV was significantly lower in the TIVA and combined groups compared with the sevoflurane group (33.9%, 39.0% and 64.4%, respectively). In conclusion, the maintenance of anaesthesia with propofol-remifentanil or sevoflurane-propofol-remifentanil decreased the incidence of PONV compared with sevoflurane alone.

Bolus effective dose of ketamine for preventing withdrawal movement on injection of rocuronium in paediatric patients.

The bolus effective dose of ketamine required to prevent withdrawal movement on injection of rocuronium was determined in 27 paediatric patients undergoing elective surgery. A predetermined dose of ketamine was given intravenously on arrival in the operating room and anaesthesia (2.5% thiopental, 5 mg/kg) was administered 1 min later. After loss of consciousness, 1% rocuronium at 0.6 mg/kg was injected over 5 s and the presence or absence of withdrawal movement recorded. The effective dose of ketamine was determined using a modified Dixon up-and-down method with a step size of 0.1 mg/kg, successful prevention of withdrawal movement being defined as no response or movement at the wrist only. The bolus effective dose of ketamine for preventing withdrawal movement after injection of rocuronium following thiopental anaesthesia in 50% of paediatric patients (ED(50)) was 0.21 mg/kg according to the modified Dixon up-and-down method. Probit analysis indicated an ED(50) of 0.18 mg/kg and an ED(95) of 0.33 mg/kg. The latter was the most satisfactory dose in the clinical setting.

Reduction of microemulsion propofol-induced injection pain via target-controlled remifentanil infusion.

The intravenous injection of microemulsion propofol to induce anaesthesia causes more intense and frequent pain than lipid emulsion propofol. This study investigated whether different target effect-site concentrations of remifentanil could prevent pain due to microemulsion propofol injection. In total, 96 patients were randomly assigned to one of three groups receiving target effect-site concentrations of remifentanil 0 (control group), 4 or 6 ng/ml, followed by injection with microemulsion propofol. Remifentanil pretreatment significantly reduced the incidence and severity of injection pain compared with the control group. Although no difference in pain reduction between the two remifentanil-treated groups was observed, those receiving a target effect-site concentration of 6 ng/ml exhibited an increased rate of complications, compared with those receiving 4 ng/ml. In conclusion, prior administration of remifentanil at a target effect-site concentration of 4 ng/ml is a useful strategy to decrease the injection pain of microemulsion propofol.

Effect of remifentanil on tracheal intubation conditions and haemodynamics in children anaesthetised with sevoflurane and nitrous oxide.

This study examined the effect of remifentanil added to inhalation agents on intubating conditions in children (aged one to seven years). As is our routine, all patients were premedicated with 0.004 mg/kg glycopyrrolate intramuscularly 30 minutes before anaesthesia to prevent bradycardia and salivary secretion, and received intravenous 1 mg/kg ketamine prior to transfer into the operating room to facilitate separation of the child from the parents. Laryngoscopy was attempted after ventilation with 8% sevoflurane in 50% nitrous oxide and 50% oxygen for two minutes, and intravenous administration of either a placebo bolus of saline (Group S) or one of two doses of remifentanil, 1 microg/kg (Group R1) or 2 microg/kg (Group R2) given over 30 seconds, commenced at the beginning of the sevoflurane administration. Only 18 of 32 patients (56.3%) in Group S had acceptable intubating conditions compared with 31 of 32 patients (96.9%) in Group R1 and 32 of 32 patients (100%) in Group R2 (P < 0.001). Mean blood pressure was lower in Group R1 and R2 compared with Group S (P < 0.005). Our routine use of ketamine and glycopyrrolate may have influenced the relative lack of significant hypotension and bradycardia. Sevoflurane, nitrous oxide and remifentanil provided acceptable conditions for tracheal intubation in children and could be an acceptable alternative to intravenous induction and neuromuscular blocking agents.

The optimum bolus dose of remifentanil to facilitate laryngeal mask airway insertion with a single standard dose of propofol at induction in children.

The purpose of this study was to determine the optimal bolus dose of remifentanil required for the successful insertion of the laryngeal mask airway during propofol induction in children without a neuromuscular blocking agent. Twenty-six paediatric patients, aged 3-10 years, requiring anaesthesia for short ambulatory surgery were recruited. A predetermined bolus dose of remifentanil was injected over 30 s, followed by propofol 2.5 mg.kg(-1) over 10 s. The bolus dose of remifentanil was determined by a modified Dixon's up-and-down method, starting from 0.5 microg.kg(-1) (0.1 microg.kg(-1) as a step size). Laryngeal mask insertion was attempted 90 s after the end of remifentanil injection and the response of patients was classified as either 'movement' or 'no movement'. The bolus dose of remifentanil at which there was a 50% probability of successful laryngeal mask insertion (ED(50)) during induction with 2.5 mg.kg(-1) propofol was 0.56 (0.07) microg.kg(-1) in children without a neuromuscular blocking agent. From probit analysis, the ED(50) and ED(95) of remifentanil were 0.52 microg.kg(-1) (95% confidence limits, 0.42-0.62 microg.kg(-1)) and 0.71 microg.kg(-1) (95% confidence limits, 0.61-1.40 microg.kg(-1)), respectively.

Efficacy and safety of high concentration lidocaine for trigeminal nerve block in patients with trigeminal neuralgia.

AIMS: Local anaesthetics, which act as neurolytics and Na(+) channel blockers, have been used for disrupting the neural firings in certain neuropathic pain conditions. This study was undertaken to investigate the clinical outcome of trigeminal nerve block with 10% lidocaine in the management of trigeminal neuralgia (TN). METHODS: Thirty-five patients with primary TN received trigeminal nerve blocks with 10% lidocaine. Success was defined as complete pain relief or mild pain without medication 1 day after the treatment. We followed the patients up every 2 months assessing for pain recurrence, sensory changes and other complications for a total of 37-45 months (median 43 months). RESULTS: Twelve of the 35 patients (34.3%) responded favourably to the treatment and were considered as success. Eleven patients experienced complete pain relief and one could tolerate pain without medication 1 day after the blocks, which lasted for 3-172 weeks. Four patients experienced mildly decreased sensation in the region of the face supplied by the nerve 1 day after the blocks; however, all recovered normal skin sensation in 6 months. There was neither allodynia nor other sensory discomfort. The pain intensity and current pain duration before treatment were significantly different between the two groups. CONCLUSION: Trigeminal nerve block with high concentration lidocaine (10%) is capable of achieving an intermediate period of pain relief, particularly in patients with lower pain intensity and shorter pain duration prior to the procedure.

Anaesthesia in patients with Brugada syndrome.

Brugada syndrome is characterized by right bundle branch block, ST segment elevation in the precordial leads and sudden death caused by ventricular fibrillation. We present two successful anaesthetic management cases in patients with Brugada syndrome.

Creatine synthesis and transport systems in the male rat reproductive tract.

Previous studies from this laboratory showed that high levels of guanidinoacetate methyltransferase are present in mouse testis and epididymis, whereas guanidinoacetate methyltransferase mRNA and protein are not detected in seminal vesicles where large amounts of creatine (Cr) and phosphocreatine are found (Lee et al., Biol Reprod 1994; 50:152-162). To further investigate the origin(s) of Cr in the male reproductive tract, the expression patterns of the three enzymes and a transporter involved in Cr metabolism were examined with rat reproductive tissues. Western blot analysis showed that expression of L-arginine:glycine amidinotransferase was limited to the kidney. On the other hand, high levels of the mRNAs for both guanidinoacetate methyltransferase and Sadenosylhomocysteine hydrolase were expressed in the testis and epididymis as well as the liver and kidney. Cr transporter mRNA was highly expressed in the seminal vesicle and vas deferens. These results suggest that the source of Cr in the male reproductive tract varies depending on the tissue; in the testes and epididymides, Cr is synthesized from guanidinoacetate, while in the seminal vesicles, Cr is transported from blood. Previous and present findings suggest the importance of Cr metabolism and/or transport for reproductive functions.