Effect of needle type on plane block spread in a cadaveric porcine model.

INTRODUCTION: Plane blocks are an increasingly common type of regional anaesthesia technique in the perioperative period. Increased spread of local anaesthesia during plane blocks is thought to be related to an increased area of pain coverage. This study sought to assess differences in injectate spread comparing Tuohy needles with standard insulated stimulating block needles. METHODS: 10 Yorkshire-Cross porcine cadavers were used in this study. Immediately following euthanasia, the cadavers underwent bilateral ultrasound-guided transversus abdominis plane (TAP) block injection with radiopaque contrast dye, with one side placed with a 20 g Tuohy needle, and the other side with a 20 g insulated stimulating block needle. Injectate spread was assessed using plain film X-ray and area of spread was measured to compare differences. RESULTS: All 10 animals underwent successful ultrasound-guided TAP block placement. In all 10 animals, the area of contrast spread was greater with the Tuohy than stimulating needle. Wilcoxon signed-rank test was used to analyse the difference between the groups. The average difference between the two sides was 33.02% (p=0.002). CONCLUSIONS: This is the first study to demonstrate differences in injectate spread with different needle types. This suggests enhanced spread with Tuohy needle compared with standard block needle, and may encourage its use during plane blocks.

Why are US military personnel prescribed transdermal fentanyl patches?

INTRODUCTION: Transdermal fentanyl is a continuous release opioid delivery system intended for use in opioid-tolerant patients requiring around-the-clock opioid therapy. The purpose of this study is to identify the most common indications for transdermal fentanyl prescriptions in active duty US military personnel, and determine whether these prescriptions meet US Food and Drug Administration (FDA) labelling. METHODS: Active duty US military personnel initiating transdermal fentanyl therapy with prescriptions filled at Military Health System pharmacies between 2015 and 2019 were identified in the Military Data Repository. Electronic health records were searched for patient demographic information, clinical information and prescription data. A total of 225 patients with complete data were identified. RESULTS: The most common reason for transdermal fentanyl initiation was chronic non-cancer musculoskeletal pain. Among patients with non-cancer pain, 36% received their initial prescription from an internal medicine/primary care provider, and 35% did not meet published US FDA criteria for opioid tolerance prior to treatment initiation. There was an 81% decrease in patients initiating therapy between 2015 and 2019. CONCLUSIONS: While a substantial minority of transdermal fentanyl prescriptions to US military personnel did not meet FDA guidelines on appropriate use, the overall number of prescriptions fell dramatically over the study period. This suggests that automated profile review or additional targeted policies to limit transdermal fentanyl prescribing are unnecessary at this time.

Cellular recognition and activation within the lymphoid system.

The present study is concerned with cellular recognition and activation within the lymphoid system. Data presented indicate that in human peripheral blood phagocytes recognize and preferentially bind phagocytes, and thymus-derived (T) lymphocytes recognize and preferentially bind other T lymphocytes rather than thymus-indepedent (B) lymphocytes. Recognition of non-self results in activation of lymphoid cells; recent data using a calcium ionophore, A23 187, suggest that calcium may act as an intracellular messenger by which signals for cellular activation are transmitted from the cell surface to the nucleus.