Lancet
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Randomized Controlled Trial Multicenter Study
Anaesthetic depth and complications after major surgery: an international, randomised controlled trial.
What’s all the fuss?
Significant observational evidence suggested an association between mortality and deep anaesthesia, in particular a 2017 meta-analysis. However it has been suspected that anaesthetic depth may merely be a surrogate marker for intraoperative hypotension, a well-established risk factor for post-operative mortality and morbidity.
With this large RCT, the Balanced Anaesthesia Study Group has shown that deep general anaesthesia is not associated with an increase 1-year mortality.
What did they do?
The researchers conducted an ambitious, large (6,644 patients), multi-center, randomised controlled trial. Patients aged ≥60 years undergoing major surgery (expected ≥2h surgery and ≥2d hospital stay) were randomised to receive volatile general anaesthesia targeting BIS 50 or BIS 35.
To minimise intra-operative blood pressure as a confounder, anaesthetists were required to specify a target MAP before BIS-group allocation.
They found...
Not only was there no mortality difference between the BIS 50 and BIS 35 groups, there were also no major or moderate morbidity differences, or difference in recovery or length of stay. BIS targets were adequately achieved, though not perfect, and MAP was clinically similar for both groups.
Context is everything
This is about as high-quality as a large, modern study looking at longer-term outcomes can get. It is widely applicable to most populations and common general anaesthetic scenarios, except for a few important caveats:
- Very few ASA 4 (5%) patients were enrolled.
- Only volatile-maintenance anaesthesia was studied not propofol/TIVA.
- We can draw no conclusion regarding the consequences of extreme-depth (ie. BIS << 35).
- The actual depth difference between the BIS-35 and BIS-50 groups was not as much as perhaps ideal: mean BIS 39 vs 47 respectively...
Final thought
...there was (only) one case of awareness in the light-depth BIS 50 group, despite 39% of patients receiving volatile < 0.7 MAC.
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Randomized Controlled Trial Multicenter Study
Recurrence of breast cancer after regional or general anaesthesia: a randomised controlled trial.
What makes this a landmark study?
Since Exadaktylos’ (2006) extraordinary retrospective study showing a 30% reduction in breast cancer recurrence with a regional analgesia technique, we have been anxious to learn whether anaesthetic choice my impact cancer outcome.
Various in vitro studies suggested plausible explanations for how opioids and volatiles could promote cancer recurrence, although quality evidence remainded missing.
The Breast Cancer Recurrence Collaboration has filled this gap, setting out to answer this question with an international, multicenter, randomised controlled trial.
What did they do?
Over 12 years 2,132 women were enrolled and ranomised to either paravertebral block & propofol, or sevoflurane. Some in the paravertebral group were exposed to sevoflurane when required (17%), and did receive intraoperative fentanyl, although roughly half as much on average as the volatile group.
And they found?
There was no difference in cancer recurrence rate or persistent wound pain between groups. Even when analysing only patients who received no sevoflurane (83% of regional group) no difference was identified.
This does not mean that a paravertebral technique offers no benefit: it almost eliminated the need for volatile anaesthesia, reduced opioid demand and reduced post-operative nausea & vomiting – all positive outcomes. But it did not reduce cancer recurrence.
Be smart
This result cannot be generalised beyond breast cancer to more invasive, stress-inducing cancer surgery (eg. prostatectomy, pneumonectomy). Our knowledge of perioperative factors that depress host defences (surgical stress, volatiles and opioids) are still relevant when we consider how anaesthetic choices may contribute to improving patient outcomes.
Explore further...
Dig deeper with other articles collected in Anesthesia technique and cancer recurrence.
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Systematic reviews have consistently shown that individuals with mental disorders have an increased risk of premature mortality. Traditionally, this evidence has been based on relative risks or crude estimates of reduced life expectancy. The aim of this study was to compile a comprehensive analysis of mortality-related health metrics associated with mental disorders, including sex-specific and age-specific mortality rate ratios (MRRs) and life-years lost (LYLs), a measure that takes into account age of onset of the disorder. ⋯ Danish National Research Foundation.