Regional anesthesia and pain medicine
-
Reg Anesth Pain Med · May 2011
Randomized Controlled Trial Comparative Study Clinical TrialUltrasound-guided (needle-in-plane) perineural catheter insertion: the effect of catheter-insertion distance on postoperative analgesia.
When using ultrasound guidance to place a perineural catheter for a continuous peripheral nerve block, keeping the needle in plane and nerve in short axis results in a perpendicular needle-to-nerve orientation. Many have opined that when placing a perineural catheter via the needle, the acute angle may result in the catheter bypassing the target nerve when advanced beyond the needle tip. Theoretically, greater catheter tip-to-nerve distances result in less local anesthetic-to-nerve contact during the subsequent perineural infusion, leading to inferior analgesia. Although a potential solution may appear obvious-advancing the catheter tip only to the tip of the needle, leaving the catheter tip at the target nerve-this technique has not been prospectively evaluated. We therefore hypothesized that during needle in-plane ultrasound-guided perineural catheter placement, inserting the catheter a minimum distance (0-1 cm) past the needle tip is associated with improved postoperative analgesia compared with inserting the catheter a more traditional 5 to 6 cm past the needle tip. ⋯ This study did not find evidence to support the hypothesis that, for popliteal-sciatic perineural catheters placed using ultrasound guidance and a needle-in-plane technique, inserting the catheter a minimum distance (0-1 cm) past the needle tip improves (or worsens) postoperative analgesia compared with inserting the catheter a more traditional distance (5-6 cm). Caution is warranted if extrapolating these results to other catheter designs, ultrasound approaches, or anatomic insertion sites.
-
Reg Anesth Pain Med · May 2011
Randomized Controlled Trial Comparative StudyIs circumferential injection advantageous for ultrasound-guided popliteal sciatic nerve block?: A proof-of-concept study.
Ultrasound (US) guidance, in some instances, can increase the success rate and reduce the onset and procedure times for peripheral nerve blockade compared with traditional nerve localization techniques. The presumptive mechanism for these benefits is the ability to accurately inject local anesthetic circumferentially around the target nerve. We aimed to determine whether ensuring circumferential spread of local anesthetic is advantageous for US-guided popliteal sciatic nerve block. ⋯ Ultrasound-guided circumferential injection of local anesthetic around the sciatic nerve at the popliteal fossa can improve the rate of sensory block without an increase in block procedure time or block-related complications compared with a single-location injection technique.
-
Reg Anesth Pain Med · May 2011
Comparative StudyUncomplicated removal of epidural catheters in 4365 patients with international normalized ratio greater than 1.4 during initiation of warfarin therapy.
Current guidelines from the American Society of Regional Anesthesia state that an international normalized ratio (INR) of 1.4 is the upper limit of warfarin anticoagulation for safe removal of an epidural catheter. However, these guidelines are based primarily on expert consensus, and there is controversy regarding this recommendation as being "too conservative." ⋯ Our series of 4365 patients had uncomplicated removal of epidural catheters despite INRs ranging from 1.5 to 5.9. Removal was only during initiation of warfarin therapy (up to approximately 50 hrs after warfarin intake) when several vitamin K factors are likely to still be adequate for hemostasis.
-
Reg Anesth Pain Med · May 2011
ReviewNeedle to nerve proximity: what do the animal studies tell us?
Recent animal studies have provided insight and understanding, as well as promising clinical tools, to help identify needle-to-nerve contact and potentially hazardous intraneural injection. This narrative review describes and summarizes the contemporary animal studies primarily relating to indicators of needle-to-nerve contact and intraneural injection. Resultant nerve injury, whenever sought, is discussed.