Anaesthesia
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Randomized Controlled Trial
Combined spinal epidural vs epidural labour analgesia: does initial intrathecal analgesia reduce the subsequent minimum local analgesic concentration of epidural bupivacaine?
Labour analgesia initiated using a combined spinal-epidural (CSE) technique may reduce subsequent epidural bupivacaine requirements compared with an epidural-only technique. We compared the minimum local analgesic concentrations (MLAC) of epidural bupivacaine following initial intrathecal or epidural injection. In a prospective, double-blind study, 115 women requesting epidural analgesia were randomly assigned to receive either an epidural with bupivacaine 20 mg and fentanyl 40 μg or a CSE with intrathecal bupivacaine 2.5 mg and fentanyl 5 μg. ⋯ When further analgesia was requested, bupivacaine 20 ml was given, and the concentration was determined using the technique of up-down sequential allocation. The MLAC of bupivacaine in the epidural group was 0.032% wt/vol (95% CI 0.020-0.044) compared with 0.047% wt/vol (95% CI 0.042-0.052) in the CSE group. Bupivacaine requirements for the second injection were increased following intrathecal analgesia by a factor of 1.45 (p = 0.026) compared with epidural analgesia.
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Randomized Controlled Trial Comparative Study
Measurement of forces applied during Macintosh direct laryngoscopy compared with GlideScope® videolaryngoscopy.
Laryngoscopy can induce stress responses that may be harmful in susceptible patients. We directly measured the force applied to the base of the tongue as a surrogate for the stress response. Force measurements were obtained using three FlexiForce Sensors(®) (Tekscan Inc, Boston, MA, USA) attached along the concave surface of each laryngoscope blade. ⋯ Complete data were available for 23 patients. Compared with the Macintosh, we observed lower median (IQR [range]) peak force (9 (5-13 [3-25]) N vs 20 (14-28 [4-41]) N; p = 0.0001), average force (5 (3-7 [2-19]) N vs 11 (6-16 [1-24]) N; p = 0.0003) and impulse force (98 (42-151 [26-444]) Ns vs 150 (93-207 [17-509]) Ns; p = 0.017) with the GlideScope. Our study shows that the peak lifting force on the base of the tongue during laryngoscopy is less with the GlideScope videolaryngoscope compared with the Macintosh laryngoscope.
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Randomized Controlled Trial Comparative Study
A randomised trial comparing the i-gel (TM) with the LMA Classic (TM) in children.
We performed a prospective, randomised trial comparing the i-gel(TM) with the LMA Classic(TM) in children undergoing general anaesthesia. Ninety-nine healthy patients were randomly assigned to either the i-gel or the LMA Classic. The outcomes measured were airway leak pressure, ease of insertion, time taken for insertion, fibreoptic examination and complications. ⋯ A good fibreoptic view of the glottis was obtained in 74% of the i-gel group and in 43% of the LMA Classic group (p < 0.001). There were no significant complications. In conclusion, the i-gel provided a similar leak pressure, but a shorter insertion time and improved glottic view compared with the LMA Classic in children.
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Randomized Controlled Trial
Effect of intravenous lipid emulsion on bupivacaine plasma concentration in humans.
Intravenous lipid emulsion is the recommended treatment for severe local anaesthetic intoxication. Lipid emulsion may entrap lipid soluble drugs by functioning as a 'lipid sink', but its effect on bupivacaine pharmacokinetics remains unknown. In this randomised, double-blind, crossover study, eight healthy male volunteers were infused bupivacaine 0.5mg.kg(-1) intravenously over 20 min, followed by an infusion of either intravenous lipid emulsion or Hartmann's solution for 30 min. ⋯ We observed no significant adverse effects of lipid emulsion. In conclusion, lipid emulsion may slightly increase the rate of bupivacaine tissue distribution. No 'lipid sink' effect was observed with the non-toxic dose of bupivacaine used.
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Randomized Controlled Trial Comparative Study
A randomised comparison of the LMA SupremeTM and LMAProSealTM in children.
We conducted a randomised trial comparing the size-2 LMA Supreme™ with the LMA ProSeal™ in 60 children undergoing surgery. The outcomes measured were airway leak pressure, ease and time for insertion, fibreoptic examination, incidence of gastric insufflation, ease of gastric tube placement, quality of the airway during anaesthetic maintenance and complications. ⋯ Both devices provided effective ventilation requiring minimal airway manipulation. The LMA Supreme can be a useful alternative to the LMA ProSeal when single-use supraglottic devices with gastric access capabilities are required.