IntroductionDifficult airway management is closely related to the safety and quality of medical care. However, the low incidence of correct prediction of difficult airway in clinical screening tests presents physicians with a dilemma. Depressed airway neuromuscular tension during sleep and anaesthesia tends to cause collapse of fragile parts of the upper airway. Although previous studies have confirmed that anterior cervical tissue thickness is associated with difficult airways, there is no evidence to support a correlation between a difficult airway and specific patterns or findings of anaesthesia-induced airway collapse. Thus, this study aims to examine changes in airway dimensions before and after induction of general anaesthesia to explore whether it could provide useful information regarding the specific anatomic changes occurring which may cause difficult airways.Methods and analysisThis will be a single-centre prospective observational single-blinded study, conducted in a tertiary teaching hospital in Guangzhou, China. Subjects will be recruited from patients (aged 18–65 years) scheduled for elective surgery under general anaesthesia. Sonographic measurement will be performed to detect changes in the thickness of the anterior cervical soft tissue before and after anaesthetic induction. Based on the resulting data distribution, analyses will initially compare these changes using a paired t-test or the Wilcoxon signed-rank test. The correlation of sonographic changes and Cormack–Lehane grade will be evaluated by using receiver-operating characteristic curves to detect the sensitivity and specificity of a measurement for detecting difficulties. Linear stepwise regression analysis will be used to assess the correlation between airway changes and demographic variables as well as clinical tests.Ethics and disseminationEthical approval has been obtained from the Ethics Committee of the First Affiliated Hospital of Guangzhou University of Chinese Medicine (ZYYECK (2018) 041). The results will be disseminated through conference presentations, professional journals and peer-reviewed publications.Trial registration numberChiCTR1900021123; Pre-results.

The ETView tracheoscopic ventilation tube (TVT) is a tracheal tube (TT) incorporating a video camera and a light source in its tip. The view from the tip appears continuously on a portable monitor in the anesthesia area. We evaluated the effectiveness and usefulness of the single/double ETView TVT in monitoring the tracheal tube position during general anesthesia undergoing video-assisted thoracoscopic lobectomy.Eighty-three patients with pulmonary bullae (American Society of Anesthesiologists (ASA) I-III) undergoing lobectomy, with general anaesthesia, were included. Patients were randomly assigned to 3 groups, based on the tube ETView double-lumen tube (VDT), ETView single-lumen tube (VST), or traditional double lumen tube (DT).All 83 patients’ intubations were successful to achieve 1-lung ventilation: 74 patients at the first attempt (22/26 in VDT, 26/28 in VST, 26/29 in DT group) and 9 patients at the second attempt. The time to achieve 1-lung ventilation with the VDT was 58.5 ± 21.5 (mean ± SD) seconds, the VST was 38.2 ± 10.1 (mean ± SD) seconds, and the DT group was 195.5 ± 40.3 (mean ± SD) seconds. During operations, the ETView tubes provided continuous airway visualization in all patients; a good view was obtained in 24/25 patients in VDT/VST, moderate in 4/12 patients in VDT/VST, and poor in 1/1 patients in VDT/VST. When the patient left the postanesthesia care unit, all had sore throat and 26/15/25 patients in VDT/VST/DT group had hoarseness. All had good outcomes of the surgical operations.We found the ETView tube to be helpful in the endotracheal intubation and continuous surveillance of tube position in patients with video-assisted thoracoscopic lobectomy. The ETView single lumen endotracheal tube had fewer associated complications and is superior to the 2 double-lumen tubes.

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