Anaesthesia
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Randomized Controlled Trial
Carbetocin at elective caesarean section: a sequential allocation trial to determine the minimum effective dose in obese women.
Postpartum haemorrhage is a leading cause of maternal death during childbirth. There is an increasing incidence of atonic postpartum haemorrhage in developed countries, and maternal obesity has been proposed as a contributing factor. The dose-response relationship of carbetocin in obese women has not yet been determined. ⋯ The estimated blood loss was 880 (621-1178 [75-2442]) ml. The overall rates of hypotension and hypertension after delivery were 40% and 6.7%, respectively, while nausea occurred in 26.7% of women. The ED90 for carbetocin in obese women at elective caesarean section is lower than the dose of 100 μg currently recommended by the Society of Obstetricians and Gynaecologists of Canada, but is approximately four times higher than the previously demonstrated ED90 of 14.8 μg in women with body mass index < 40 kg.m-2 .
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Randomized Controlled Trial Comparative Study
Differential frontal alpha oscillations and mechanisms underlying loss of consciousness: a comparison between slow and fast propofol infusion rates.
Mechanisms underlying loss of consciousness following propofol administration remain incompletely understood. The objective of this study was to compare frontal lobe electroencephalography activity and brainstem reflexes during intravenous induction of general anaesthesia, in patients receiving a typical bolus dose (fast infusion) of propofol compared with a slower infusion rate. We sought to determine whether brainstem suppression ('bottom-up') predominates over loss of cortical function ('top-down'). ⋯ Alpha band power emerged several minutes after the loss of consciousness in participants allocated to the fast infusion group. Our results show a predominance of 'bottom-up' mechanisms during fast infusion rates and 'top-down' mechanisms during slow infusion rates. The underlying mechanisms by which propofol induces loss of consciousness are potentially influenced by the speed of infusion.
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Randomized Controlled Trial
The effect of cricoid and paralaryngeal force on upper oesophageal occlusion during induction of anaesthesia: a randomised, crossover study.
The aim of this study was to evaluate the effectiveness of cricoid and paralaryngeal force for oesophageal entrance occlusion during induction of anaesthesia. Seventy-four patients were included in this randomised, crossover study. The relative position of the glottis and outer anteroposterior diameter of the upper oesophageal entrance were assessed at baseline, after the application of 30 N cricoid and paralaryngeal force, and after induction of anaesthesia. ⋯ The relative position of the upper oesophageal entrance to the glottis may change after induction of anaesthesia and during direct laryngoscopy. Cricoid and paralaryngeal force both decrease the diameter of the upper oesophageal entrance in awake and anaesthetised states. Occlusion of the oesophageal entrance is achieved more frequently with cricoid force compared with paralaryngeal force during direct laryngoscopy.
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Randomized Controlled Trial
Smoking cessation in elective surgical patients offered free nicotine patches at listing: a pilot study.
Free nicotine patches may promote pre-operative smoking cessation. Smokers (≥ 10 cigarettes.day-1 ) awaiting non-urgent surgery were randomly assigned (3:1) to an offer of free nicotine patches or a control group who were not offered free nicotine patches. The suggested regimen lasted 5 weeks, with patch strength decreasing incrementally after 3 and 4 weeks. ⋯ Participants offered nicotine patches were more likely to engage in a cessation attempt lasting more than 24 h, 46 (11.6%) vs. 5 (3.7%), OR 3.4 [95%CI 1.8-8.8], p = 0.010. Out of 78 participants who quit smoking by the day of surgery and were followed up at 6 months, 46 (59%) had relapsed. Offering free nicotine patches stimulated interest in quitting compared with controls, but our protocol had limited effectiveness.
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Randomized Controlled Trial
The effect of needle tip tracking on procedural time of ultrasound-guided lumbar plexus block: a randomised controlled trial.
Technology that facilitates performance of deep peripheral nerve blocks is of clinical interest. The Onvision™ is a new device for ultrasonographic needle tip tracking that incorporates an ultrasound sensor on the needle tip that is then represented by a green circle on the ultrasound screen. The primary aim of this study was to investigate the effect of needle tip tracking on procedural time in the first human volunteer study. ⋯ No differences were found for any other secondary outcomes. The use of Onvision needle tip tracking did not reduce procedural time for out-of-plane ultrasound-guided lumbar plexus block but did reduce the number of hand movements and path lengths. This may indicate improved needle control but further studies are needed to confirm this finding.