A collection of landmark research articles relevant to obstetric anesthesia. Some, such as Hawkins' audits of U.S. maternal deaths, are significant because of their historical impact. Others hold direct clinical relevance for practice today.summary
Articles of interest relevant to labor epidural analgesia, both specifically focusing on obstetric epidurals and more peripherally relevant to obstetric labor analgesia.summary
Why the excitement?
Since the landmark 2017 WOMAN trial (collected below) showed that tranexamic acid (TXA) may reduce mortality in post-partum haemorrhage, TXA has increasingly been found in close proximity to where obstetric spinal anaesthetics are commonly performed.
TXA's operating theatre ubiquity has also been enhanced by it's replacement of aprotonin in cardiac surgery (Myles 2017, Koster 2015), after the former's associated mortality bump, along with the increasingly routine use of TXA in major joint surgery to reduce bleeding and transfusion (Ho 2003, Poeran 2014).
Recent reviews have identified 21 case reports of mistaken intrathecal administration of TXA over 60 years of anaesthetic publications – although it is likely many cases have been unreported.
Seems rare - why should I be concerned?
- Intrathecal TXA has a 50% mortality, and frequently leaves survivors with permanent neurological injury.
- Once recognised, immediate, aggressive management may improve outcome (particularly, CSF lavage).
- Although rarely published, the increased use of intra-operative TXA may bring it into close proximity with common intrathecal drug ampoules, increasing the risk of this devastating error. Case report publication dates support the increasing incidence.
- Knowing the potential for this error is the first step to avoiding it both personally and systemically.
- Almost all cases involve drug swap errors with major human factor contributions.
...and 1 more note
Although there remains much conflicting evidence, largely of a low-quality observational nature, the highest quality evidence to date refutes assertions that epidural fentanyl reduces breastfeeding rates.
Notably Lee et al.’s 2017 RCT of over 300 women showed no effect of epidural fentanyl up to 2 mcg/mL and successful maternal breastfeeding up to 6 weeks.summary
First described in 1909, and then used for treatment of various types of headache and facial pain, the sphenopalatine ganglion block may offer a novel, simple and less-invasive treatment for post-dural puncture headache.
Very little has been published, primarily case studies, case series and retrospective audits. This limited data does however suggest that the technique may be as effective as the traditional epidural blood patch, though with significantly fewer risks.
Larger studies are however needed to properly define the block's role in treating PDPH.
Publications describe a trans-nasal approach, either sitting or supine. First topicalising with co-phenylcaine spray, then placing 2%-4% viscous lignocaine-soaked cotton-tipped applicators for 10 minutes, and finally repeated for a further 20 minutes. Success appears to range from 30-70%.
The mechanism of action may result from parasympathetic blockade at the SPG, resulting in reversal of the cerebral vasodilation thought to be associated with post dural puncture headache.
Several videos showing how simple SPG techniques:
- Roger Browning demonstrating one method for performing a topical SPG block.
- SPG Block for chronic migraine.
- SPG demonstration in the ED setting.
- SPG demonstration for family member to perform later at home.