[Effect comparison of ultrasound-guided lower extremity nerve block and spinal anesthesia in ankle surgery].

Objective: To compare the anesthesia effect between ultrasound-guided lower extremity nerve block and spinal anesthesia in ankle surgery. Methods: Upon the approval of institutional Ethics Committee and informed consent, 80 patients American Society of Anesthesiology (ASA)Ⅰ-Ⅱaged 18-70 yr, undergoing ankle surgery from December 2014 to May 2015 in the Fifth Affiliated Hospital of Wen Zhou Medical College, were randomly divided by random numbers into two groups (n=40): nerve block group (group N) and spinal anesthesia (group S). The group N was combined with ultrasound-guided femoral nerve, obturator nerve, lateral femoral cutaneous nerve and sacral plexus block; group S was selected spinal anesthesia in the gap of L3-L4. Times of anesthesia procedure (Tr), sensory block (Tfb), motor block (Tmb), duration of sensory block (Tfr) and duration of motor block (Tmr) were recorded. The incidence of hypotension within 30 min after anesthesia and 24 hours postoperatively analgesic were also recorded. The effect of anesthesia was evaluated. Results: The Tr, Tfb, Tmb, Tfr and Tmr in group N and group S were (15.0±1.5), (11.2±1.2), (13.4±1.4), (816.0±112.9), (432.0±138.9)min and (8.7±1.2), (2.3±0.6), (3.8±1.1), (436.7±130.5), (320.0±34.6)min, respectively. Tr, Tfb, Tmb, Tfr and Tmr in group N were significantly longer than that in group S (t=20.742, 41.945, 34.101, 13.901, 4.948, all P<0.05). There was no significant difference in the incidences of hypotension within 30 min after anesthesia (0 vs 7.5%, P>0.05). The incidence of 24 hours postoperatively analgesic in group N were significantly lower than that in group S (45.0% vs 77.5%, P<0.05). Compared with group S, there was no significant difference in the percentage of anesthetic effect reached gradeⅠ(95% vs 100%, P>0.05) in group N. Conclusion: Ultrasound-guided nerve block could be safe and effective in patients undergoing ankle surgery, and postoperative analgesia time of nerve block is longer than that of spinal anesthesia.

Experimental observations of soliton wave trains in electron beams.

The first experimental observation of a Korteweg-de Vries-type soliton wave train in intense electron beams is reported. A narrow, large-amplitude perturbation on a long-pulse beam is observed to steepen and spawn a soliton wave train. The pulse width and amplitude of each peak remain unchanged over a long propagation distance, and the amplitude is inversely proportional to the square of the width. Two such pulses are seen to pass through each other, emerging from the collision unchanged. The experimental results are reproduced by particle-in-cell simulations.