British journal of anaesthesia
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Randomized Controlled Trial
Renin-angiotensin-aldosterone system dynamics after targeted blood pressure control using angiotensin II or norepinephrine in cardiac surgery: mechanistic randomised controlled trial.
The role of the renin-angiotensin-aldosterone axis in vasoplegia after cardiac surgery remains unclear. We tested the hypothesis that, compared with norepinephrine, infusion of angiotensin II titrated to achieve similar mean arterial pressure (MAP) would suppress plasma renin concentration (PRC) while maintaining aldosterone levels. ⋯ Australian and New Zealand Clinical Trials Registry-ACTRN12621000195853 23/02/2021.
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Variability is high in predicted propofol concentrations during clinical anaesthesia titrated by target-controlled infusion (TCI) to maintain a processed EEG parameter (bispectral index [BIS]) within a specified range. We have shown that the potential for improving the pharmacokinetic model is minimal. The drug titration paradox revealed that titration challenges the classical relationship between drug dose and effect in both individuals and the population. We hypothesised that dynamic factors during surgery beyond the static genetic, epigenetic, and other factors such as age, height, and weight affect the necessary dose. We compared the variability of measured end-tidal sevoflurane concentrations with predicted effect-site propofol concentrations when titrated to a BIS range of 40-60, with the hypothesis that the variability in measured sevoflurane concentrations would not be less than the variability in estimated propofol concentrations. ⋯ Improvements in prediction accuracy of pharmacokinetic models beyond that of those already in clinical use are unlikely to reduce variability in target anaesthetic concentrations across patients in clinical practice.
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Editorial Comment
Improving pulse oximetry accuracy in dark-skinned patients: technical aspects and current regulations.
Recent concerns regarding the clinical accuracy of pulse oximetry in dark-skinned patients, specifically in detecting occult hypoxaemia, have motivated research on this topic and recently reported in this journal. We provide an overview of the technical aspects of the issue, the sources of inaccuracy, and the current regulations and limitations. These insights offer perspectives on how pulse oximetry can be improved to address these potential limitations.
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A recent systematic review and meta-analysis by Wang and colleagues in the British Journal of Anaesthesia calls into question the concept that perioperative benzodiazepine administration is associated with development of postoperative delirium in older individuals after anaesthesia and surgery. This editorial focuses on potential bias within the systematic review and addresses major concerns surrounding benzodiazepine use in the older perioperative population.
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Editorial Comment
Achieving a preoperative haemoglobin above 130 g L-1 may be more important in female than in male patients before cardiac surgery.
Sex-specific preoperative haemoglobin levels and the need for perioperative red cell transfusion in men and women are still debated. Cavalli and colleagues examined the appropriateness of World Health Organization (WHO) anaemia thresholds (haemoglobin <130 g L-1 for males and <120 g L-1 for females) in a retrospective cohort analysis of >6000 adult patients undergoing cardiac surgery with cardiopulmonary bypass. The authors concluded that the WHO anaemia threshold disproportionately disadvantages female cardiac surgery patients, and a preoperative haemoglobin level of at least 130 g L-1 should be targeted in all cardiac surgical patients regardless of sex.