Article Notes
- 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.
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