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The remifentanil PCA for labour analgesia controversy continues...
Those advocating its first-line use point to reassuring evidence of maternal satisfaction and acceptability, reduced epidural rates, and some suggestion of reduced instrumental delivery rates.
For the negative, the ongoing safety concerns created by routine use of remifentanil PCAs are foremost, particularly given how uneven hospitals can be at implementing best safety practices. Observed rates of significant desaturation range from 25-70%, in addition to potential neonatal effects.
The greatest challenge facing the remiPCA advocates, is that the labour epidural is still the most effective form of labour analgesia, and has only improved over the decades as safety has been both maintained and increased.
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There has been some observational evidence that a greater depth of anesthesia, as measured by BIS, may be associated with an increase in post-operative mortality. In particular the association of the "triple low state" (low BIS, low volatile-ET, low MAP) with post-operative mortality is worrying.
Completion of the Balanced Anaesthesia Study Group’s large RCT looking at this issue however brings us as close to a final word as we may expect. Short et al. (2019) showed no difference in 1-year mortality for older patients undergoing major surgery, whether they received a deep (BIS target 35) or light (BIS target 50) general anaesthetic.
It is likely that earlier observational studies were showing the consequences of intraoperative hypotension resulting from anaesthetic depth, rather than anaesthetic depth itself.
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Hydroxyethyl starches, such as Hespan, Voluven, Volulyte, Tetrahes and Hestar, have been shown in several large trials to increase the risk of acute kidney injury (AKI) and/or the need for renal replacement therapies among critically ill patients, particulalry those suffering sepsis.
Evidence demonstrating harm among fit & healthy surgical patients is however lacking, notably Giles et al could find no increased risk of adverse event among surgical patients in their 2014 meta-analysis. Nonetheless, given the similar lack of demonstrable benefit of HES fluids for this group, avoidance of use in both the ICU and surgical population is prudent.
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