Anaesthesia
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Randomized Controlled Trial
The effect of short time periods of pre-operative warming in the prevention of peri-operative hypothermia.
The aim of our study was to evaluate the performance of different durations of active pre-operative skin-surface warming (pre-warming) to prevent peri-operative hypothermia and postoperative shivering. We randomly assigned 200 patients, scheduled for surgery of 30-90 min under general anaesthesia, to receive passive insulation or forced-air skin surface warming for 10, 20 or 30 min. Body temperature was measured at the tympanic membrane. ⋯ Without pre-warming, 38/55 (69%) patients became hypothermic (< 36 °C) at the end of anaesthesia, whereas only 7/52 (13%), 3/43 (7%) and 3/50 (6%) patients following 10, 20 or 30 min pre-warming, respectively, became hypothermic (p < 0.001 vs no pre-warming). Shivering was observed in 10 patients without, and in three, three and one patients with pre-warming in the respective groups (p = 0.02). Pre-warming of patients for only 10 or 20 min before general anaesthesia mostly prevents hypothermia and reduces shivering.
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Randomized Controlled Trial
The effect of posture and anaesthetic technique on the surgical pleth index.
The surgical pleth index has been shown to correlate with surrogate variables of nociception during general anaesthesia, and it has been suggested to be of use as a depth of anaesthesia monitor. However, little is known about confounding factors. As the main determining variables are based on both central and peripheral autonomic regulatory mechanisms, we hypothesised that changing a patient`s posture may produce a marked effect. ⋯ Mean (SD) values of the surgical pleth index after adoption of the lithotomy position were reduced from 57 (22) to 21 (6) under general anaesthesia, 63 (15) to 31 (9) under spinal anaesthesia alone, and 52 (14) to 22 (8) under spinal anaesthesia with sedation (all p < 0.01). In healthy volunteers, the surgical pleth index increased from 37 (13) to 57 (11) (p < 0.01) after 30° head-up tilt and was reduced from 35 (11) to 25 (11) after head-down tilt (p < 0.05). Change in posture has a marked effect on the surgical pleth index which lasts for at least 45 min, and this must be considered when interpreting the displayed values.
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Randomized Controlled Trial
Development and validation of a novel tool to estimate peri-operative blood loss.
Surgical blood loss predicts peri-operative outcomes. We have developed and validated Blood Loss Scores to estimate peri-operative blood loss during major abdominal surgery. ⋯ The score, taking into account suction fluid volume and haemoglobin concentration, explained more of the variance in the measured blood loss than the experts' assessment (77% vs 54%, p = 0.05) or the change in haemoglobin concentration (77% vs 11%, p < 0.0001). Addition of the change in haemoglobin concentration improved the estimate for the 24- and 48-h postoperative Blood Loss Scores to explain 78% and 80% of the variance of measured blood loss.
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Randomized Controlled Trial Comparative Study
LMA Supreme™ vs i-gel™--a comparison of insertion success in novices.
Two new supraglottic airway devices, the LMA Supreme™ (LMA) and the i-gel™, offer potential benefits when inserted by inexperienced operators. This study compared the insertion success rate and ventilation profile between the LMA Supreme and the i-gel when inserted by operators without previous airway management expertise. Following a short lecture and manikin training, airway novices were randomly allocated to insert either the LMA Supreme or the i-gel into 80 patients undergoing breast surgery. ⋯ Mean (SD) leak pressure (29 (8) vs 23 (11) cmH(2)O, p = 0.007) and expired tidal volume (PCV 17 cmH(2)O) (785 (198) vs 654 (91), p = 0.001) were significantly greater with the LMA Supreme than with the i-gel, respectively. More patients complained of pharyngolaryngeal pain with the LMA Supreme than with the i-gel (17/39 (44%) vs 8/41 (20%); p = 0.053). We found better first time success rate, fewer failures, and a better seal with the LMA Supreme compared with the i-gel, indicating that the LMA Supreme may be preferable for emergency airway use by novices.
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Randomized Controlled Trial Comparative Study
A comparison of Rapydan® patch and Ametop® gel for venous cannulation.
Ametop(®) gel (4% tetracaine) is used to provide topical anaesthesia for venous cannulation. Rapydan(®) patch (7% lidocaine and 7% tetracaine) has been developed to provide topical anaesthesia by a different mechanism, that of heat assisted delivery. We compared the topical anaesthetic effect of these agents for venous cannulation. ⋯ Median(IQR[range]) pain scores were not different between groups with 11 (5-20 [0-72]) for Rapydan and 10 (5-24 [0-95]) for Ametop (p = 0.63). Adequate topical anaesthesia was achieved in over 90% of patients in both groups. Rapydan produces topical anaesthesia comparable with Ametop for venous cannulation.