Anaesthesia
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The use of cell salvage during caesarean section has been increasing steadily, although there are concerns relating to cost, a perceived risk of amniotic fluid embolism, and fetal red cell sensitisation. We present observational data from almost a decade of use of intra-operative cell salvage in obstetrics. By the end of this period, we set up cell salvage collection for > 98% of all caesarean sections. ⋯ In total, 647 (55%) women have had alloimmunisation testing, with two positive cases. Quality control data indicate that the quality of blood processed from partial first bowls is no worse than that from full bowls. We discuss the costs of providing this service with regard to: staffing costs; single suction; leucodepletion filters; selectivity in the processing of collected blood; and the use of partial first bowls.
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We report four years of observational data from a large UK hospital and tertiary referral unit, following the introduction of a rotational thromboelastometry-guided algorithm for treatment of coagulopathy in major obstetric haemorrhage. Fibrinogen concentrate was used to treat acquired hypofibrinogenaemia as defined by a FibTEM A5 value of < 7 mm, or 7-12 mm with ongoing or high risk of haemorrhage. Of 32,647 deliveries over 4 years, 893 (2.7%) women had an estimated blood loss ≥ 1500 ml. ⋯ When coagulopathy does occur, it appears to be multifactorial and can be severe. Point-of-care testing allows early identification and individualised treatment of coagulopathy. This is supported by the improved outcomes reported.
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Comparative Study
Comparison of portable blood-warming devices under simulated pre-hospital conditions: a randomised in-vitro blood circuit study.
Pre-hospital transfusion of blood products is a vital component of many advanced pre-hospital systems. Portable fluid warmers may be utilised to help prevent hypothermia, but the limits defined by manufacturers often do not reflect their clinical use. The primary aim of this randomised in-vitro study was to assess the warming performance of four portable blood warming devices (Thermal Angel, Hypotherm X LG, °M Warmer, Buddy Lite) against control at different clinically-relevant flow rates. ⋯ There was no association between warming and haemolysis with any device (p = 0.949) or flow rate (p = 0.169). Practical issues, which may be relevant to clinical use, also emerged during testing. Our results suggest that there were significant differences in the performance of portable blood warming devices used at flow rates encountered in clinical practice.
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This study investigated displacement of the tracheal tube caused by different methods of intubating stylet removal, using in-vitro experiments and mathematical analysis. In the first in-vitro experiment, we measured the distance travelled by the tube tip during stylet extraction. Then, we investigated the ideal technique for stylet extraction using mathematical analysis, which would cause minimal tube displacement. ⋯ In simulated tracheal intubation, extraction force and force applied to the vocal cords both significantly increased as the bending angle increased. Compared with the 'hockey stick'-shaped stylet, the arcuate-shaped stylet resulted in reduced force. Our results indicate the potential risk for vocal cord injury when using hockey stick-shaped stylets with large bending angles.
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Phase lag entropy, an electro-encephalography-based hypnotic depth indicator, calculates diversity in temporal patterns of phase relationship. We compared the performance of phase lag entropy with the bispectral index™ in 30 patients scheduled for elective surgery. We initiated a target-controlled infusion of propofol using the Schnider model, and assessed sedation levels using the Modified Observer's Assessment of Alertness/Sedation scale every 30 s with each stepwise increase in the effect-site propofol concentration. ⋯ Baseline variability in phase lag entropy and bispectral index was 3.3 and 5.7, respectively. The predicted propofol concentrations, using the Schnider pharmacokinetic model, producing a 50% probability of moderate and deep sedation were 1.96 and 3.01 μg.ml-1 , respectively. Phase lag entropy was found to be useful as a hypnotic depth indicator in patients receiving propofol sedation.