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Background Ultrasonography (US) is recently used frequently as a tool for airway assessment prior to intubation (endotracheal tube (ETT) placement), and several indicators have been proposed in studies with different reported performances in this regard. This systematic review and meta-analysis reviewed the performance of US in difficult airway assessment. Methods This systematic review and meta-analysis was conducted according to the guideline of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and the Cochrane book. All the studies that had carried out difficult airway assessments using US, had compared the indicators in difficult and easy groups, and had published the results in English by the time we conducted our search in April 28, 2020, were included. Results In the initial search, 17,156 articles were retrieved. After deleting the duplicate articles retrieved from multiple databases, 7578 articles remained for screening based on the abstracts and titles. Finally, the full text of 371 articles were assessed and the data from 26 articles were extracted, which had examined a total of 45 US indicators for predicting difficult intubation. The most common US index was the “thickness of anterior neck soft tissue at the vocal cords level”. Also, “skin to epiglottis” and “anterior neck soft tissue at the hyoid bone level” were among the most common indicators examined in this area. Conclusion This systematic review showed that US can be used for predicting difficult airway. Of note, “skin thickness at the epiglottis and hyoid levels”, “the hyomental distance”, and “the hyomental distance ratio” were correlated with difficult laryngoscopy in the meta-analysis. Many other indicators, including some ratios, have also been proposed for accurately predicting difficult intubation, although there have been no external validation studies on them.

Background This study was conducted to compare the effectiveness of low-dose ketamine versus ketorolac in pain control in patients with acute renal colic presenting to the emergency department (ED). Methods This is a double-blind randomized clinical trial. The initial pain severity was assessed using the numerical rating scale (NRS). Then, ketamine or ketorolac was administered intravenously at a dose of 0.6 mg/kg and 30 mg respectively. The pain severity and adverse drug reactions were recorded 5, 15, 30, 60, and 120 min thereafter. Results The data of 62 subjects in the ketamine group and 64 patients in the ketorolac group were analyzed. The mean age of the patients was 34.2 ± 9.9 and 37.9 ± 10.6 years in the ketamine and ketorolac group, respectively. There was no significant difference in the mean NRS scores at each time point, except for the 5 min, between the two groups. Despite a marked decrease in pain severity in the ketamine group from drug administration at the 5 min, a slight increase in pain was observed from the 5 min to the 15 min. The rate of adverse drug reactions, including dizziness ( P = 0.001), agitation ( P = 0.002), increased systolic blood pressure (> 140 mmHg), and diastolic blood pressure (> 90 mmHg) was higher in the ketamine group. Conclusions Low dose ketamine is as effective as ketorolac in pain management in patients with renal colic presenting to the ED. However, it is associated with a higher rate of adverse drug reactions.