This is a well known, but fairly novel use of ultrasound. Certainly not standard in any place I’ve worked. But ultrasound for epidurals and spinals seems to be in vogue. Here’s a meta-analysis on ultrasound for spinal and epidural access. Several smaller studies have looked at this combo, but most of them have been underpowered. This recent meta-analysis from BMJ comes to the conclusion that ultrasound eases access and lowers risk of complications:
“Ultrasound imaging can reduce the risk of failed or traumatic lumbar punctures and epidural catheterisations, as well as the number of needle insertions and redirections. Ultrasound may be a useful adjunct for these procedures”
This is all good, but the case against ultrasound is that these procedures already have a low frequency of complications and are usually easy to perform. So, the authors discuss how ultrasound might primarily have a place in patients were access is predicted to be difficult, or readily available for the cases when access proves difficult after starting the procedure.
This sounds exactly like the discussion for and against ultrasound for central lines, which makes me think thoracic/lumbar ultrasound will come sneaking into standard clinical practice sooner rather than later.
The quick look is the way to go?
I think a quick look with ultrasound will be a good thing, much as I use it for central lines: Quick look to confirm ease of access as well as confirming target position and angle. This can be used on most patients – both to train yourself to do lumbar/thoracic ultrasound as well as identifying possible problems ahead of the procedure. I must admit I haven’t used lumbar/thoracic ultrasound in clinical pratice yet, but it sounds enticing. At least for the quick look.
To use ultrasound ‘real time’ requires more resources, more sterile covers and more dexterity and a wish for more hands. It will be hard to push and control the needle, hold the ultrasound and, for epidurals, control the syringe for loss of resistance. One way to overcome that, is to use the hanging drop technique, or maybe even the epidrum if it works as well as in this test dummy video clip with real time ultrasound:
For now, a quick look before the procedure sounds good for anticipated problematic patients, or as a training quick look in standard patients. And a great tool to help placing high epidurals in anaesthetised patients, especially kids.
As a letter to the editor from 2005 in J Clinic Anesth says: “It is foreseeable that [ultrasound] technology can also assist in epidural placement, not only as a prepuncture diagnostic tool but also to guide epidural placement in real time. As technology improves and our acceptance of it increases, ultrasound-guided epidural placement could become a valuable tool both for resident and experienced physician”.
In time, ultrasound will probably work its way into standard spinal/lumbar access protocols as well. Who knows. All I know is that anyone in emergency medicine, anaesthesia or intensive care who’s not familiar with ultrasound is going to lose out.
References and guides
For a good primer on lumbar ultrasound, check out this article.
An interesting look at pediatric techniques, including ultrasound:
New advances in technique for pediatric caudal and epidural placement, Ped Anesth, 2007.
The free, full text of the BMJ meta-analysis is also well worth a read:
Ultrasound imaging for lumbar punctures and epidural catheterisations: systematic review and meta-analysis, BMJ, 2013.