Anaesthesia
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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
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.