Anaesthesia
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Randomized Controlled Trial
Quantitative analysis of changes in blood concentrations and 'presumed effect-site concentration' of sevoflurane during one-lung ventilation.
During one-lung ventilation, ventilation-perfusion mismatch decreases the arterial concentration of inhaled anaesthetics due to the arterial-to-venous concentration difference. This study tested the hypothesis that in humans, the 'presumed effect-site concentration' (taken as the mid-point between the arterial and superior jugular venous concentrations) of inhaled anaesthetic falls during one-lung (vs two-lung) ventilation. ⋯ During one-lung ventilation, the end-expiratory sevoflurane concentration was stable at ∼1.3% but the mean (SD) presumed effect-site concentration declined initially from 58 (6.7) to 43 (4.7) μg.ml(-1) (p=0.011) before slowly recovering. A period of insufficient depth of anaesthesia is thus a risk during one-lung ventilation.
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Randomized Controlled Trial Comparative Study
A randomised, controlled trial comparing the Airtraq™ optical laryngoscope with conventional laryngoscopy in infants and children.
The Airtraq(™) optical laryngoscope became available in paediatric sizes in the UK in May 2008. We conducted a randomised, controlled trial comparing the Airtraq with conventional laryngoscopy during routine anaesthesia in children. We hypothesised that the Airtraq laryngoscope would perform as well as conventional laryngoscopy. ⋯ The mean (SD) intubation time using the Airtraq was longer than conventional laryngoscopy overall (47.3 (32.6) vs 26.3 (11.5) s; p=0.002), though the difference was only significant for children (p=0.003) and not for infants (p=0.29). The Airtraq provided a better view of the larynx compared with conventional laryngoscopy (in infants (percentage of glottic opening scores 100 (95-100 [90-100]) vs 77 (50-90 [40-100]), respectively; p=0.001; visual analogue scores for field of view 9.2 (9.2-9.5 [8.2-10.0]) vs 6.8 (5.1-8.0 [4.7-10.0]), respectively; p=0.001). In children, the Airtraq provided a similar view of the larynx (percentage of glottic opening scores 100 (100-100 [40-100]) vs 100 (90-100 [50-100]), respectively; visual analogue scores for field of view 9.2 (8.6-10.0 [7.0-10.0]) vs 9.2 (8.6-10.0 [5.6-10.0]), respectively; both p>0.05), compared with conventional laryngoscopy.
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Randomized Controlled Trial Comparative Study
Comparison of the antitussive effect of remifentanil during recovery from propofol and sevoflurane anaesthesia.
This prospective randomised study compared the antitussive effect of remifentanil during recovery from either propofol or sevoflurane anaesthesia. Seventy-four female patients undergoing thyroidectomy were anaesthetised with either propofol and remifentanil or sevoflurane and remifentanil. ⋯ Time to awakening and time to extubation were significantly shorter in the propofol group (4.7 min, 6.1 min min, respectively) compared with the sevoflurane group (7.9 min and 8.9 min respectively) (p < 0.001 and p = 0.002, respectively). An effect-site concentration of 2 ng.ml(-1) of remifentanil was associated with smooth emergence from both propofol and sevoflurane anaesthesia.
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Randomized Controlled Trial Comparative Study
A randomised controlled trial comparing two insertion techniques for the Laryngeal Mask Airway Flexible™ in patients undergoing dental surgery.
The Laryngeal Mask Airway Flexible™ (LMA Flexible) has been widely utilised for dental, ophthalmology and otorhinolaryngology-related procedures. Our study evaluates two different techniques of inserting the LMA Flexible for patients undergoing day-case dental surgery. One hundred and eight patients were randomly assigned into two groups based on the LMA Flexible insertion technique--either laryngoscopy-guided (n=54) or digital manipulation (standard technique; n=54). ⋯ There were no significant differences between the two groups for haemodynamic changes. Sore throat was more common in the group with the standard technique (35.2% vs 16.7%, p<0.05). Our study suggests the use of the laryngoscope to guide insertion of the LMA Flexible for dental surgery is a better option compared with the standard technique of digital manipulation.
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Randomized Controlled Trial
Evaluation of radial and ulnar blood flow after radial artery cannulation with 20- and 22-gauge cannulae using duplex Doppler ultrasound.
This study evaluated ulnar and radial artery blood flow after radial artery cannulation during general anaesthesia using Doppler ultrasound. A total of 80 patients were randomly assigned to receive radial artery cannulation with either a 20-G or 22-G cannula. Arterial diameter, peak systolic velocity, end-diastolic velocity, resistance index and mean volume flow were measured at four time points in both arteries: before anaesthesia; 5 min after intubation; immediately after cannulation; and 5 min after cannulation. ⋯ Radial blood flow was decreased immediately after cannulation and recovered to pre-cannulation values 5 min after cannulation. There were no statistical differences between groups at each time point. Radial artery cannulation causes compensatory increase in ulnar artery blood flow, and the difference in cannula size has minimal effect on this change.