Article Notes
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This quote is usually attributed to the Greek poet Archilochus, over 2,500 years ago... though today popularised by the US Navy SEALs! (and perhaps a few medical simulation specialists 😉) ↩
- Remifentanil infusions above 0.20-0.25 μg/kg/min are associated with hyperalgesia (OIH = Opioid Induced Hyperalgesia) and tolerance (AOT = Acute Opioid Tolerance) respectively.
- Some of these effects can be mitigated by multimodal analgesia (notably ketamine), and possibly by gradual weaning of a remifentanil infusion.
- The findings have been predominately identified in rats and volunteer human studies. The clinical and longterm significance is still uncertain.
- Although OIH and AOT arise from different physiological mechanisms, they are clinically difficult (if not impossible) to differentiate.
- The clinical priority for management is prevention.
- Preoperative: reduce fasting; provide carbohydrate loading; multimodal preanesthesia medication.
- Intraoperative: standardised intraoperative anesthesia; protective ventilation; goal-directed fluid therapy (minimization); postop nausea and vomiting prophylaxis.
- Postoperative: multimodal analgesia.
A neat little study...
Gurus and team showed improvement in assertiveness and 'speaking up' behaviour among junior anaesthesia trainees, during a simulation workshop after exposure to a didactic session on speaking up behaviour – when compared to a control simulation group who did not receive the didactic session. (n=22)
The take-home message
There is likely benefit to explicitly discussing the issue of, and most importantly techniques for, speaking up when anaesthesia trainees witness management errors or oversights.
The one short-coming
The effects were only observed in a simulation environment, and while probably applicable to the more-consequential real world, as with much simulation research we are often dependent on surrogate markers of performance improvement.
Nonetheless, "we don't rise to the level of our expectations, we fall to the level of our training",1 right?
Daniel Jolley
Why is this important?
Suspicions that anesthetic technique impacts survival after cancer surgery continues to be both unanswered and psychologically weighty: are anesthetic choices undermining patient survival?
What did they do?
This Taiwanese research group conducted a retrospective cohort-study in a single hospital covering 10 years of elective hepatectomy patients, comparing propofol to desflurane anesthesia. Notably, hepatocellular carcinoma is one of the leading causes of cancer death in Taiwan.
And they found...?
TIVA propofol was associated with a dramatically better survival (hazard ratio 0.57 (0.38-0.59)), even in subgroup analysis dependent on staging.
Reality check
Although this finding is consistent with other observational studies across a range of cancers, the apparent size of the benefit (50% mortality reduction!) should give us pause.
Given inconsistent findings from a range of similar observational studies, it is unlikely that there is a real treatment effect of this magnitude.
While we await results from well-powered RCTs, the jury is still out on whether anesthesia choices impact any specific cancer surgery...
Daniel Jolley
Take this one with a large grain of salt. At best it shows cerebral perfusion was safely maintained in this small cohort of patients receiving a rather unique, though not personalized, anesthetic recipe.
It’s very unlikely that this 22 patient observational study is sufficiently powered to reassure concerns that prone positioning does not effect cerebral blood flow, although it does point in that direction.
Daniel Jolley
Daniel Jolley
One of the earliest published case series linking post-operative hepatic necrosis to halothane anaesthesia.
We now know this occurs in about 1 in 10,000-30,000 adult halothane anaesthetics, and 1 in 60,000 in children, with a historical mortality of 30-70%. In 20% of cases the hepatitis is mild and self-limiting.
Daniel Jolley
An infamous article from 1985 that investigated the relationship between perioperative myocardial ischaemia and postoperative myocardial infarction in 1,023 elective CABG patients. The study findings are broadly consistent with our understanding that increasing myocardial oxygen demand in those with coronary artery disease is undesirable.
Although there are unsurprising problems with this 35 year old article, it is best known for the infamous anesthesiologist number 7 who subjected his/her patients to disproportionately more postop infarcts, along with tachycardia and hypertension.
Final word? Don’t be a number 7 anesthesiologist...
Daniel Jolley
What did they do?
Kowark and friends randomised 343 patients across four German hospitals to receive desflurane, sevoflurane or propofol for maintenance anesthesia using a laryngeal airway for surgery expected to be up to 2 hours.
And they found?
There was no difference in airway reactions among the three groups, and the desflurane patients emerged (statistically) significantly faster.
Hang on...
But the difference in emergence times was, i) at most only 2 minutes, and ii) was a surrogate marker for what actually matters – when a patient leaves the PACU or hospital – which wasn't reported.
Additionally, the study protocol very prescriptively defined when volatiles were decreased (50% at 5 min before expected surgical finish) and ceased – the same for both Des and Sevo. Yet it is common practice to begin weaning Sevo earlier than Des if trying to achieve comparable emergence.
Could this even be applied to my patients?
Probably not. Unless you are in the habit of using remifentanil infusions (0.15 mcg/kg/min) for surgery that almost certainly does not justify its use and have access to uniquely European analgesics piritramide and metamizole.
The elephant in the room...
Why do we persist in trying to find new justifications for desflurane, given its expense and high environmental costs? (And for that matter, remifentanil?!).
This study demonstrates the well known faster pharmacokinetics of desflurane during an unnecessarily complex laryngeal mask anesthetic, and yet adds little to meaningful clinical outcomes.
Daniel Jolley
Also see Carbon Footprint from Anaesthetic gas use [pdf] from the UK’s Sustainable Development Unit.
Daniel Jolley
“Inhalational anaesthetic agents are chlorofluorocarbons, ‘greenhouse gases’ that have between 349 (sevoflurane) and 3714 (desflurane) times the global warming potential over a 20 year time horizon of carbon dioxide (isoflurane 1401), equivalent to driving a car 18 (sevoflurane) to ~350 miles (desflurane) per hour of anaesthetic use (isoflurane 30 miles); these figures do not account for the additional carbon cost of heating desflurane vaporisers. Together with nitrous oxide, inhalational anaesthetic agents contribute ~2.5% of the 22.8 million tonnes of carbon dioxide equivalents the NHS produces annually.” - White
Daniel Jolley
Why is this important?
With obesity rates over 40% in many industrialised countries, and accelerating growth in bariatric surgery for more than a decade, there is need for evidence based guidelines to direct perioperative care.
This evidence review was conducted to identify protocols that achieve "superior outcomes, reduced length of hospital stay, and cost savings" for bariatric patients.
Many of the institutional protocols were founded on ERAS principals originating with colorectal surgery.
Ok, what did they identify?
The AHRQ made evidence-based anesthesia recommendations across three areas:
Reality check
These protocols largely reflect 'good quality modern anesthesia', and there is little here that is specific to bariatric patients.
This is not a critcism, but a reminder that it's consistent and holistic application of quality anesthesia across the perioperative period that improves outcomes – especially among higher risk patients. Interventions do not need to be fancy, just quality principles consistently applied.
Daniel Jolley