Evaluation of the effect of perioperative administration of S(+)-ketamine hydrochloride injection for postoperative acute pain in children: study protocol for a prospective, multicenter, randomized, open-label, parallel-group, pragmatic clinical trial

Abstract Background Inadequate postoperative pain management increases the risk of adverse events after the surgery and aggressive perioperative pain prevention has both short-term and long-term benefits. S(+)-ketamine is an N-methyl-D-aspartic acid (NMDA) receptor antagonist with a strong analgesic effect and can significantly relieve postoperative acute pain and reduce opioid consumption. However, for children, it still needs to be confirmed by large sample clinical studies. Methods This is a pragmatic, randomized controlled trial which will evaluate the effect of perioperative administration of S(+)-ketamine hydrochloride injection for postoperative acute pain in children in a pragmatic clinical setting. A total of 3000 children (≤17 years old) undergoing surgery will be included in this protocol. Subjects will be randomized 2:1 to either receive S(+)-ketamine hydrochloride injection or conventional therapy without S(+)-ketamine during the entire perioperative period. The primary endpoints are the area under the receiver operating characteristic (ROC) curve of Face Legs Activity Cry and Consolability (FLACC, 0–7 years old) scale score or Numerical Rating Scale (NRS, 8–17 years old) score within 48 h after surgery, and the consumption of opioids within 48 h after surgery. The secondary endpoints include the time of first use of rescue analgesics after surgery, rescue analgesia rate within 48 h after surgery, anesthesia recovery time, incidence of emergency delirium (for 0-7 years old), changes of anxiety and depression scale scores at 48 h after surgery (for 8-17 years old), incidence of intraoperative adverse events (AEs), and incidence of postoperative AEs and pharmacoeconomic indicators. AEs and serious AEs were recorded to evaluate safety. Discussion This trial will be the first pragmatic clinical trial to prospectively assess the effect of perioperative administration of S(+)-ketamine hydrochloride injection for postoperative acute pain in children, which is of great significance to the continuous optimization of clinical anesthesia and analgesia programs for children. Trial registration This trial was registered in the U.S. National Institutes of Health ClinicalTrials.gov database ( http://clinicaltrials.gov ; Registration number: NCT04834427). Registered on 8 April 2021

Structure of an integrin with an αI domain, complement receptor type 4

We report the structure of an integrin with an αI domain, αXβ2, the complement receptor type 4. It was earlier expected that a fixed orientation between the αI domain and the β-propeller domain in which it is inserted would be required for allosteric signal transmission. However, the αI domain is highly flexible, enabling two βI domain conformational states to couple to three αI domain states, and greater accessibility for ligand recognition. Although αXβ2 is bent similarly to integrins that lack αI domains, the terminal domains of the α- and β-legs, calf-2 and β-tail, are oriented differently than in αI-less integrins. Linkers extending to the transmembrane domains are unstructured. Previous mutations in the β2-tail domain support the importance of extension, rather than a deadbolt, in integrin activation. The locations of further activating mutations and antibody epitopes show the critical role of extension, and conversion from the closed to the open headpiece conformation, in integrin activation. Differences among 10 molecules in crystal lattices provide unprecedented information on interdomain flexibility important for modelling integrin extension and activation