Anaesthesia
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The aim of this prospective clinical study was to evaluate the location of paravertebral catheters that were placed using the classical landmark puncture technique and to correlate the distribution of contrast dye injected through the catheters with the extent of somatic block. Paravertebral catheter placement was attempted in 31 patients after video-assisted thoracic surgery. In one patient, an ultrasound-guided approach was chosen after failed catheter placement using the landmark method. ⋯ There was also a discrepancy between the radiological findings and the observed distribution of loss of sensation. We have demonstrated an unacceptably high misplacement rate of paravertebral catheters using the landmark method. Additional research is required to compare the efficacy and safety of continuous paravertebral block using ultrasound-guided techniques or surgical inserted catheters.
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Randomized Controlled Trial Comparative Study
A randomised crossover trial comparing a single-use polyvinyl chloride laryngeal mask airway with a single-use silicone laryngeal mask airway.
We compared insertion rates of single-use polyvinyl chloride laryngeal mask airways (LMAs) vs single-use silicone LMAs in 72 anaesthetised patients. Both airways were produced by Flexicare Medical. Laryngeal mask airway insertion was successful on the first attempt in 68/72 (94%) polyvinyl chloride LMAs vs 64/72 (89%) silicone LMAs (p = 0.39). ⋯ Laryngeal mask airway position, as assessed using a fibrescope, was not different (p = 0.077). The median (IQR [range]) leak pressure was 16 (12-20 [6-30]) cmH(2) O for the polyvinyl LMA and 18 (13-22 [6-30]) cmH(2) O or the silicone LMA (p = 0.037). In conclusion, we did not find any important differences between polyvinyl chloride and silicone laryngeal mask airways.
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Randomized Controlled Trial
Changes in the photoplethysmogram with tracheal intubation and remifentanil concentration.
Autonomic sympathetic activation, for instance following noxious stimuli, decreases the size and flattens the shape of the photoplethysmographic peripheral pulse waveform. We report a simple measure of the waveform shape, the ratio of mean-to-peak wave amplitude, for measuring nociception level during general anaesthesia. Fifty participants, anaesthetised with propofol and remifentanil, were randomly allocated to one of three different remifentanil effect-site concentrations (1, 3 and 5 ng.ml(-1) ). ⋯ The mean (SD) ratios following intubation at remifentanil effect-site concentrations of 1 ng.ml(-1) , 3 ng.ml(-1) and 5 ng.ml(-1) , were 0.49 (0.03), 0.48 (0.03) and 0.45 (0.04), respectively. Remifentanil therefore suppressed changes in the mean-to-peak ratio caused by tracheal intubation (p = 0.006). The ratio of the mean-to-peak plethysmographic amplitude may represent a simple measure of the balance of autonomic sympathetic and parasympathetic activity under general anaesthesia, and its performance following intubation was significantly different from peak amplitude (p = 0.046).
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Our aim was to compare peri-operative core temperatures and the incidence of hypothermia in obese and non-obese women with active forced-air warming. Twenty female patients scheduled for abdominal surgery were allocated to two groups according to body mass index. Ten obese (30.0-34.9 kg.m(-2) ) and 10 non-obese (18.5-24.9 kg.m(-2) ) women received forced-air warming on their lower limbs. ⋯ The incidences of intra-operative hypothermia were lower in the obese group (10%) compared with non-obese group (60%; p = 0.019). In the postoperative recovery phase, the mean (SD) core temperature data were higher in the obese group than in the non-obese group (36.2 (0.4) vs 35.6 (0.5) °C, respectively (p < 0.001)). In conclusion, obese female patients have higher peri-operative core temperature and a lower incidence of hypothermia compared with non-obese female patients during abdominal surgery with active forced-air warming.