Regional anesthesia and pain medicine 07/2012; 37(4):460-1. · 4.16 Impact Factor
ABSTRACT: Epidural catheters are routinely used in regional and obstetric anesthesia. The flexible catheter is advanced without imaging control into the epidural space, and coiling or kinking of the catheter may occur, compromising the effectiveness of epidural anesthesia. Potentially near-infrared (NER) light detection may help, tracking advancement of the catheter in the epidural space.
Nonembalmed human cadavers donated to the University of Washington Willed Body program were placed prone. Catheters containing NER-emitting wire were introduced into the lumbar and thoracic epidural space. The progress of the emitting wire was tracked using the LumenVu NER guidance system, and the final location of the catheter was confirmed with fluoroscopy.
Total 12 attempts were made to place the catheter. In 7 cases (4 lumbar and 3 thoracic), good progression of the catheter in the epidural space was achieved with excellent visibility at low NER power levels. Maximum light intensity was registered when the catheter tip was found in the midline dorsal interlaminar position, as confirmed by fluoroscopy. The light intensity decreased while the catheter tip was traversing under the lamina. Poor progression of the catheter with negligible visibility of the tip at the highest NER level occurred in obese specimen (n = 2) or when the tip was in extraforaminal (n = 1), paramedian or paravertebral positions (n = 2).
Many variables such as obesity, paravertebral and extraforaminal catheter locations, and intervening bony structures can impede the application of NER technology for epidural catheter placements. Further optimization of the technology for clinical use is necessary.
Regional anesthesia and pain medicine 04/2012; 37(3):354-6. · 4.16 Impact Factor
ABSTRACT: Diagnostic and therapeutic injections of the zygapophyseal joint (z-joint) are routinely performed under radiologic guidance (eg, fluoroscopy, computed tomography). Technically, these procedures could also be completed using ultrasound guidance, but existing evidence insufficiently supports this alternative imaging method, and it cannot therefore be recommended as a standard practice. There has also been no published proof-of-concept study using a routine fluoroscopy control for ultrasound-guided z-joint injections.
A cadaver study was performed to validate ultrasound as an imaging modality for z-joint injections. Fifty z-joint injections were performed on 5 nonembalmed specimens. In-plane ultrasound approach was implemented. Zygapophyseal joints were accessed through a needle placement under the joint capsule into the posterior synovial recess. Iohexol was thereby injected, and fluoroscopy was subsequently performed.
In 44 (88%) of 50 performed injections, the intra-articular spread of the contrast agent was clearly observed on the fluoroscopy image. In 6 (12%) of 50 cases, the contrast flow appeared in the soft tissues. In 4 of the 6 failed injections, the z-joint gap was not evident on an ultrasound image. No intravascular, nerve root, or epidural injections were observed.
Ultrasound may be a viable alternative to fluoroscopy or computed tomography as a guidance method for lumbar z-joint injections.
Regional anesthesia and pain medicine 03/2012; 37(2):228-31. · 4.16 Impact Factor