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.
Maternal desaturation is common during remifentanil PCA analgesia for labour.
In women receiving a remifentanil PCA for labour analgesia, detectable hypoxia occurs in 25% of women and neonatal CPR potentially related to remifentanil in 1 in 300 babies.
Opioid anti-tussive pholcodine is a potent IgE stimulator, and may increase the risk of perioperative anaphylaxis, and contribute to observed regional variations in rocuronium anaphylaxis.
Pholcodine is an opioid anti-tussive (ie. cough suppressant). It is a common component of over-the-counter cough medications. However it has a special significant to anesthesiologists in relation to anaphylaxis risk, particularly related to neuromuscular agents.
Florvaag et al's 2009 review covers this issue very comprehensively. Earlier 2006 research from Florvaag et al attempting to explain some of the regional variability in anaphylaxis rates showed that exposure to pholcodine causes an 60-105 times increase in IgE levels!
Countries where pholcodine use is common (eg Norway) seem to have experienced higher levels of anaphylaxis to neuromuscular blocking agents than countries where it is not common (eg Sweden). In fact, in Norway rocuronium anaphylaxis was such a problem that its use was restricted to modified rapid sequence inductions. A pholcodine containing cough syrup has been withdrawn from the market in Norway because of this (and levels of sensitisation seem to be dropping although it is still too early to draw conclusions). It will be interesting to see if there are other compounds that have a similar effect on IgE sensitisation and whether other countries will consider withdrawing pholcodine products.
In addition to the two articles from Florvaag that specifically look at Pholcodine and it's effects, there is also an interesting review looking at recent insights into anaphylaxis in the anaesthetic setting from Dewachter and team.
High STOP-Bang score ≥ 3 continues to be a useful predictor of post-operative complications and length of hospital stay.
Obstructive sleep apnoea patients receiving opioids should have post-operative continuous monitoring.
It’s notable how poor the evidence base is for many drugs for use in children. This is indicative of the lack of studies rather than efficacy, though is always worth remembering. Even from Germany, the Land of Tramadol, this Cochrane review could not unearth significant evidence for using tramadol for pediatric post-operative pain.
Continuous femoral nerve block is better than single-shot femoral nerve block for providing analgesia after total knee replacement.