Article Notes
- Paravertebral – OR 3.62 [95% CI, 1.33–7.86]
- Upper limb — OR 1.75 [95% CI, 0.93–2.99]
- Lower limb — OR 0.24 [95% CI, 0.05–0.71]
- Trunk — 0.00 [95% CI, 0–0.94]
Interesting to note that not only did the pudendal nerve block group experience better analgesia than the caudal block group, they were also exposed to a much smaller absolute dose of bupivacaine (0.75 mg/kg vs 2.5 mg/kg). This is important not only because of the safety implications, but also because allows extra LA for top-up if the block is inadequate or fails.
Real-time ultrasound guidance of central line insertion dramatically reduces the incidence of procedural failure (RR 0.18), arterial puncture (RR 0.25), haematoma (RR 0.30), pneumothorax (RR 0.21), and haemothorax (RR 0.10). Studies specifically investigating children and infants were however too small to make significant conclusions.
Although this Cochrane review supports the belief that epidural and paravertebral blocks may reduce persistent-surgical pain after thoracotomy or breast cancer surgery respectively, the authors highlight the low total number of subjects (only 339 patients) in the five trials analysed. This is enough evidence to consider the PSP-benefits of regional anesthesia, but far from enough to be conclusive or change practice.
To explore the future contradiction of highly-cited research Ioannidis investigated just under 50 of the most significant and highly regarded medical research findings from 1990 to 2003. Of 45 that concluded their interventions were effective, 34 had had their hypothesis retested. Of these 34, over 40% (14) were subsequently shown to be incorrect or exaggerated. Forty percent of some of the most highly regarded, practice-changing medical evidence from the 20th century subsequently disproven!
Ioannidis demonstrated that 80% of non-randomized studies were wrong, and among randomized controlled studies 25% were incorrect. Even large, multicenter, randomized clinical trials were predictably wrong in 10% of studies.
Note that this was firstly a retrospective trial, and secondly that it was a re-analysis of data from an earlier study, the 'Vitamins In Nitrous Oxide trial', and as such not designed with assessment of this article's end point in mind.
Nonetheless an interesting and relevant finding that calls in to question the idea that intra-operative N2O has post-operative analgesia benefit via it's known NMDA antagonism. As with many things, *further studies are required"...
The incidence of systemic local anesthetic toxicity showed different risk profiles at different injection sites. In order of decreasing incidence of systemic toxicity events:
Of the 25,336 peripheral nerve blocks in the study, there were only 22 episodes of local anesthetic toxicity. 12 events occurred in the 20,401 PNBs performed with ultrasound guidance and 10 events in the 4,745 blocks performed without ultrasound.
Important to note that the 9 studies included for meta-analysis (524 patients in total) were quite heterogenous: 7 performed under spinal anaesthesia and 2 under general; TAP performed using anatomical landmarks in 3 and ultrasound in 6; spinals used various doses of fentanyl and/or morphine; and the TAP blocks used ropivacaine (4), bupivacaine (4) or levobupivacaine (1). Post-operative analgesic regimes also varied.
Thus these findings should be cautiously applied to your local setting.