Clinic of Anaesthesia and Intensive Care Unit, Ospedali Riuniti Ancona (SF, SC, VG), Università Politecnica delle Marche, Ancona (PP, AD), Anaesthesia and Intensive Care, AOU Policlinico Vittorio Emanuele, Catania, Italy (MS) and Clinical Center Zvezdara, Belgrade, Serbia (IZ).
Eur J Anaesthesiol. 2018 Aug;35(8):605-612. doi: 10.1097/EJA.0000000000000832.
Unpredictable difficult laryngoscopy remains a challenge for anaesthesiologists, especially if difficult ventilation occurs during standard laryngoscopy. Accurate airway assessment should always be performed, but the common clinical screening tests have shown low sensitivity and specificity with a limited predictive value. Ultrasound-based airway assessment has been proposed recently as a useful, simple, noninvasive bedside tool as an adjunct to clinical methods, but to date, few studies are available about the potential role of ultrasound in difficult airway evaluation, and these are mostly limited to specific groups of patients.
The aim of this study was to determine the correlation between the sonographic measurements of anterior cervical soft tissues thickness and Cormack-Lehane grade view at direct laryngoscopy in patients with normal clinical screening tests.
Prospective, single blinded, observational study.
Operating theatre of a teaching hospital from May 2017 to September 2017.
A total of 301 patients at least 18 years of age undergoing elective surgery under general anaesthesia with tracheal intubation were included in the study.
Pre-operative evaluation was performed before surgery, demographic variables were collected and clinical screening tests to predict a difficult airway were performed. Patients with predicted difficult intubation were excluded. A 10 to 13-MHz linear ultrasound transducer was placed in the transverse plane and the thickness of the anterior cervical soft tissues was measured at two levels [thyrohyoid membrane (pre-epiglottic space) and vocal cords (laryngeal inlet)] with the patient's head in a neutral position. At each level, the distance from the skin in the median axis and the surrounding area was measured. The laryngoscopic view was graded by a different anaesthetist with more than 5 years of experience with direct laryngoscopy, blinded to the ultrasound assessments.
The 'pre-epiglottic space thickness' at the level of thyrohyoid membrane was measured as the median distance from skin to epiglottis (mDSE) and the pre-epiglottic area was calculated; the mDSE cut-off value of 2.54 cm (sensitivity 82%, specificity 91%) and the pre-epiglottic area cut-off value of 5.04 cm (sensitivity 85%, specificity 88%) were the best predictors of a Cormack-Lehane grade at least 2b at direct laryngoscopy and of difficult intubation. The cut-off value of mDSE showed greater sensitivity in female patients (94 vs. 86%) and greater specificity in male patients (92 vs. 83%). No correlation was found between difficult laryngoscopy and ultrasound assessments at the level of the vocal cords.
Airways ultrasounds might be considered as a predictor of restricted/difficult laryngoscopy and unpredicted difficult intubation.
ClinicalTrials.gov: NCT03547193.
对于麻醉师来说，预测困难的喉镜检查仍然是一个挑战，尤其是在标准喉镜检查过程中出现困难通气时。应始终进行准确的气道评估，但常见的临床筛查测试显示出较低的敏感性和特异性，预测价值有限。基于超声的气道评估最近已被提议作为一种有用、简单、非侵入性的床边工具，作为临床方法的辅助手段，但迄今为止，关于超声在困难气道评估中的潜在作用的研究很少，而且这些研究大多仅限于特定的患者群体。
本研究旨在确定在接受过正常临床筛查测试的患者中，前颈软组织厚度的超声测量值与直接喉镜检查时的 Cormack-Lehane 分级视图之间的相关性。
前瞻性、单盲、观察性研究。
2017 年 5 月至 2017 年 9 月在一所教学医院的手术室进行。
共纳入 301 例年龄至少 18 岁、拟行全身麻醉下气管插管的择期手术患者。
在手术前进行术前评估，收集人口统计学变量，并进行预测困难气道的临床筛查测试。排除预测插管困难的患者。使用 10 至 13MHz 线性超声换能器在横切面上放置，并在患者头部处于中立位置时测量前颈软组织的两个水平（甲状舌骨膜（会厌前间隙）和声带（声门入口））的厚度。在每个水平上，从皮肤中线和周围区域测量到的距离。由一位具有超过 5 年直接喉镜检查经验的麻醉师进行不同的喉镜检查，并对超声评估进行盲法。
在甲状舌骨膜水平测量的“会厌前间隙厚度”被定义为皮肤到会厌的中位数距离（mDSE），并计算出会厌前区域；mDSE 的截断值为 2.54cm（敏感性 82%，特异性 91%）和会厌前区域的截断值为 5.04cm（敏感性 85%，特异性 88%）是直接喉镜检查时 Cormack-Lehane 分级至少 2b 和插管困难的最佳预测指标。mDSE 的截断值在女性患者中的敏感性更高（94%比 86%），在男性患者中的特异性更高（92%比 83%）。在声带水平，喉镜检查困难与超声评估之间未发现相关性。
气道超声检查可作为限制/困难喉镜检查和预测困难插管的预测指标。
ClinicalTrials.gov：NCT03547193。
