Double-sided asymmetric metasurfaces achieving sub-microscale focusing from a GaN green laser diode.

We proposed and demonstrated a highly efficient sub-microscale focusing from a GaN green laser diode (LD) integrated with double-sided asymmetric metasurfaces. The metasurfaces consist of two nanostructures in a GaN substrate: nanogratings on one side and a geometric phase based metalens on the other side. When it was integrated on the edge emission facet of a GaN green LD, linearly polarized emission was firstly converted to the circularly polarized state by the nanogratings functioning as a quarter-wave plate, the phase gradient was then controlled by the metalens on the exit side. In the end, the double-sided asymmetric metasurfaces achieve a sub micro-focusing from linearly polarized states. Experimental results show the full width at half maximum of the focused spot size is about 738 nm at the wavelength 520 nm and the focusing efficiency is about 72.8%. Our results lay a foundation for the multi-functional applications in optical tweezers, laser direct writing, visible light communication, and biological chip.

Analgesia and patient comfort after enhanced recovery after surgery in uvulopalatopharyngoplasty: a randomised controlled pilot study.

BACKGROUND: Uvulopalatopharyngoplasty(UPPP) is the most prevalent surgical treatment of obstructive sleep apnea, but postoperative pharyngeal pain may affect patient comfort. The enhanced recovery after surgery pathway has been proved beneficial to many types of surgery but not to UPPP yet. The aim of this pilot study was to preliminarily standrize an enhanced recovery after surgery protocol for UPPP, to assess whether it has positive effects on reducing postoperative pharyngeal pain and improving patient comfort, and to test its feasibility for an international multicentre study. METHODS: This randomised controlled study analysed 116 patients with obstructive sleep apnoea (OSA) who were undergoing UPPP in a single tertiary care hospital. They were randomly divided according to treatment: the ERAS group (those who received ERAS treatment) and the control group (those who received traditional treatment). Ninety-five patients completed the assessment (ERAS group, 59 patients; control group, 36 patients). Pharyngeal pain and patient comfort were evaluated using a visual analogue scale (VAS) at 30 min and at 6, 12, 24 and 48 h after UPPP. Complications, hospitalisation duration, and hospital cost were recorded. RESULTS: The VAS scores for resting pain and swallowing pain were significantly lower in the ERAS group than those in the control group at 30 min and at 6, 12, 24 and 48 h after surgery. Patient comfort was improved in the ERAS group. The hospitalisation duration and cost were comparable between the groups. The incidence of complications showed an increasing trend in the ERAS group. CONCLUSION: The ERAS protocol significantly relieved pharyngeal pain after UPPP and improved comfort in patients with OSA, which showed the prospect for an larger study. Meanwhile a potential increase of post-operative complications in the ERAS group should be noticed. TRIAL REGISTRATION: Chinese Clinical Trial Registry (23/09/2018, ChiCTR1800018537 ).

Supine versus semi-Fowler's positions for tracheal extubation in abdominal surgery-a randomized clinical trial.

BACKGROUND: Tracheal extubation is commonly performed in the supine position. However, in patients undergoing abdominal surgery, the supine position increases abdominal wall tension, especially during coughing and deep breathing, which may aggravate pain and lead to abdominal wound dehiscence. The semi-Fowler's position may reduce abdominal wall tension, but its safety and comfort in tracheal extubation have not been reported. We aimed to evaluate the safety and comfort of different extubation positions in patients undergoing abdominal surgery. METHODS: We enrolled 141 patients with an American Society of Anesthesiologists grade of I-III who underwent abdominal surgery. All patients were anesthetized with propofol, fentanyl, cisatracurium, and sevoflurane. After surgery, all patients were transferred to the post-anesthesia care unit (PACU). Patients were then randomly put into the semi-Fowler's (n = 70) or supine (n = 71) position while 100% oxygen was administered. The endotracheal tube was removed after the patients opened their eyes and regained consciousness. Vital signs, coughing, and pain and comfort scores before and/or after extubation were recorded until the patients left the PACU. RESULTS: In comparison with the supine position, the semi-Fowler's position significantly decreased the wound pain scores at all intervals after extubation (3.51 ± 2.50 vs. 4.58 ± 2.26, 2.23 ± 1.68 vs. 3.11 ± 2.00, 1.81 ± 1.32 vs. 2.59 ± 1.88, P = 0.009, 0.005 and 0.005, respectively), reduced severe coughing (8[11.43%] vs. 21[29.58%], P = 0.008) and bucking after extubation (3[4.29%] vs. 18[25.35%], P < 0.001), and improved the comfort scores 5 min after extubation (6.11 ± 2.30 vs. 5.17 ± 1.78, P = 0.007) and when leaving from post-anesthesia care unit (7.17 ± 2.27 vs. 6.44 ± 1.79, P = 0.034). The incidences of vomiting, emergence agitation, and respiratory complications were of no significant difference. CONCLUSION: Tracheal extubation in the semi-Fowler's position is associated with less coughing, sputum suction, and pain, and more comfort, without specific adverse effects when compared to the conventional supine position. TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR1900025566 . Registered on 1st September 2019.