Double-layered blood vessels over 3 mm in diameter extruded by the inverse-gravity technique.

One of the most promising techniques for treating severe peripheral artery disease is the use of cellular tissue-engineered vascular grafts (TEVGs). This study proposes an inverse-gravity (IG) extrusion technique for creating long double-layered cellular TEVGs with diameters over 3 mm. A three-layered coaxial laminar hydrogel flow in an 8 mm-diameter pipe was realised simply by changing the extrusion direction of the hydrogel from being aligned with the direction of gravity to against it. This technique produced an extruded mixture of human aortic smooth muscle cells (HASMCs) and type-I collagen as a tubular structure with an inner diameter of 3.5 mm. After a 21 day maturation period, the maximal burst pressure, longitudinal breaking force, and circumferential breaking force of the HASMC TEVG were 416 mmHg, 0.69 N, and 0.89 N, respectively. The HASMC TEVG was endothelialised with human umbilical vein endothelial cells to form a tunica intima that simulated human vessels. Besides subcutaneous implantability on mice, the double-layered blood vessels showed a considerably lower adherence of platelets and red blood cells once exposed to heparinised mouse blood and were considered nonhaemolytic. The proposed IG extrusion technique can be applied in various fields requiring multilayered materials with large diameters.

A comparison of ketamine and morphine analgesia in prehospital trauma care: a cluster randomized clinical trial in rural Quang Tri province, Vietnam.

BACKGROUND: The use of opioid analgesics in prehospital trauma care has been reported to have negative side effects on the airway and circulation. Several studies of urban trauma management have recommend ketamine as a safe and efficient analgesic. To date, however, no controlled trials of prehospital opioid analgesics versus ketamine in rural trauma management have been published. OBJECTIVE: This study aimed to compare the analgesic effects and side effects of ketamine and morphine in a prehospital, low-resource setting. METHODS: The study was conducted with a prospective, cluster-randomized design. The Quang Tri province of Vietnam was divided into two sectors that alternated monthly between ketamine and morphine treatments. A total of 169 trauma patients were treated outside hospital settings with ketamine, while 139 patients were treated with morphine. RESULTS: The treatment effects were measured by comparing the Visual Analogue Scale (VAS) ratings in the field to those upon on admission. The analgesic effects were positive and similar for the two drugs. The rate of vomiting was significantly lower in the ketamine group (5%) than in the morphine group (19%, 95% CI for difference 8-22%). The rate of hallucinations and agitation was higher in ketamine-treated patients (11%) than in the morphine-treated patients (1.5%, 95% CI for difference 4-16%). In this study, patients with head trauma (n = 57) showed no adverse effects on consciousness level after being treated with ketamine. CONCLUSION: Ketamine had an analgesic effect similar to morphine and carried a lower risk of airway problems. The risk of hallucinations and agitation was increased in the ketamine group. These findings are of medical significance, particularly in rough and low-resource scenarios.