Preoperative X-ray C2C6AR is applicable for prediction of difficult laryngoscopy in patients with cervical spondylosis

Abstract

Background Airway management is one of the most important techniques in anesthesia practice and inappropriate airway management is related with airway injury, brain hypoxia, and even death. The patients with cervical spondylosis are often confronted with difficult laryngoscopy who are more prone to appear difficult airway, so it is important to figure out valuable predictors of difficult laryngoscopy in these patients. Methods We randomly enrolled 270 patients undergoing elective cervical spine surgery and analyzed the cervical mobility data in predicting difficult laryngoscopy. The preoperative X-ray radiological indicators were measured by an attending radiologist. Cormack-Lehane scales were assessed during intubation, and patients with a class III or IV view were assigned to the difficult laryngoscopy group. Results Univariate analysis showed that the hyomental distance (HMD, the distance between the hyoid bone and the tip of the chin) and the hyomental distance ratio (HMDR, the ratio between HMD in the extension position and the one in the neutral position) might not be suitable indicators in patients with cervical spondylosis. Binary multivariate logistic regression (backward-Wald) analyses identified two independent correlative factors from the cervical mobility indicators that correlated best as a predictor of difficult laryngoscopy: modified Mallampati test (MMT) and C2C6AR (the ratio of the angle between a line passing through the bottom of the second cervical vertebra and a line passing through the bottom of the sixth cervical vertebra in the extension position and the one in the neutral position). The odds ratio (OR) and 95 % CI were 2.292(1.093–4.803) and 0.493 (0.306–0.793), respectively. C2C6AR exhibited the largest area under the curve (0.714; 95 % CI 0.633–0.794). Conclusions C2C6AR based on preoperative X-ray images may be the most accurate predictor of cervical mobility indicators for difficult laryngoscopy in patients with cervical spondylosis. Trial registration The study was registered at the Chinese Clinical Trial Registry (http://www.chictr.org.cn; identifier: ChiCTR-ROC-16,008,598) on June 6, 2016.

Comparative analysis of popular predictors for difficult laryngoscopy using hybrid intelligent detection methods

“…The incidence of airway difficulties in patients with occipito-atlanto complex lesions was higher than that in patients with disease below the complex [ 48 ]. Label-3 achieved the best performance, and might represent the best indicator of challenging laryngoscopy reflecting cervicale movability, consistent with previous result [ 5 ]. The results demonstrated that label-3 was slightly better than label-2, and both were slightly better than label-1.…”

“… Label-2: Atlanto-occipital distance [ 6 ]. Label-3: The corner between the lower margin of the second vertebrae cervicale and the lower margin of the sixth vertebrae cervicale in neutral position [ 5 ].

Figure 5 Labelled laryngoscope X-ray.

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“…Label-2: Atlanto-occipital gap [ 6 ]. Label-3: The ratio of the angle between a line passing through the bottom of the second cervical vertebra and a line passing through the bottom of the sixth cervical vertebra in the neutral position [ 5 ]. All Three labels were based on indicators previously reported in the literature, as well as indicators that might be meaningful considering the clinical experience of professional anesthesiologists.…”

“…Label-3: The corner between the lower margin of the second vertebrae cervicale and the lower margin of the sixth vertebrae cervicale in neutral position [ 5 ].…”

“…The vertical distance between the hyoid’s highest point and the mandibulae has been identified as an accurate individual indicator for challenging laryngoscopy in patients suffering from cervical spondylopathy [ 4 ]. Another predictor, the corner between the second vertebrae cervicale’s inferior edge and the sixth vertebrae cervicale’s bottom edge in neutral position has been shown to have the potential to be an accurate indicator for cervical spondylopathy patients' difficult laryngoscopy prediction [ 5 ]. The atlanto-occipital gap may reflect reduced range of motion and mild atlanto-occipital fusion, and has proven to have the potential ability to detect difficult laryngoscopy [ 6 ].…”