Clin Exp Otorhinolaryngol.  2024 May;17(2):177-187. 10.21053/ceo.2023.00023.

Predictors of Difficult Laryngeal Exposure in Suspension Laryngoscopy: A Systematic Review and Meta-Analysis

• Wang M
• Liu Y
• Qiu Y
• Chen H
• Liwen W
• Huang D
• Zhang X
• Li G

• KMID: 2556008
• DOI: http://doi.org/10.21053/ceo.2023.00023

Abstract

Objectives
. Considerable research has been focused on independent predictors of difficult laryngeal exposure (DLE) during suspension laryngoscopy. However, previous studies have yielded inconsistent results and conclusions. Consequently, we performed a meta-analysis of the existing literature with the aim of identifying significant parameters for a standardized preoperative DLE prediction system.
Methods
. We systematically retrieved articles from the PubMed, Embase, Web of Science, China National Knowledge Infrastructure, and Wanfang databases up to October 2022. Data from eligible studies were extracted and analyzed using the R programming language. The effect measures included odds ratios (ORs) with 95% confidence intervals (CIs) for dichotomous variables and mean differences (MDs) with 95% CIs for continuous variables.
Results
. The search yielded 1,574 studies, of which 18 (involving a total of 2,263 patients) were included. Pooled analysis demonstrated that patients with DLE during microsurgery tended to be male (OR, 1.73; 95% CI, 1.16–2.57); were older (MD, 5.47 years, 95% CI, 2.44–8.51 years); had a higher body mass index (BMI; MD, 1.19 kg/m²; 95% CI, 0.33–2.05 kg/m²); had a greater neck circumference (MD, 2.50 cm; 95% CI, 1.56–3.44 cm); exhibited limited mouth opening (MD, −0.52 cm; 95% CI, −0.88 to −0.15 cm); had limited neck flexibility (MD, −10.05 cm; 95% CI, −14.10 to −6.00 cm); displayed various other anatomical characteristics; and had a high modified Mallampati index (MMI) or test score (OR, 3.37; 95% CI, 2.07–5.48).
Conclusion
. We conducted a comprehensive and systematic analysis of the factors relevant to DLE. Ultimately, we identified sex, age, BMI, neck circumference, MMI, inter-incisor gap, hyomental distance, thyromental distance, sternomental distance, and flexion-extension angle as factors highly correlated with DLE.

Keyword

Difficult Laryngeal Exposure; Suspension Laryngoscopy; Anterior Commission; Microlaryngoscopy

Figure

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  Fig. 1. Flow diagram of article screening for systematic review. CNKI, China National Knowledge Infrastructure.

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  Fig. 2. Forest plots illustrating the differences in general parameters, including sex (A), age (B), and body mass index (BMI; C) between the difficult laryngeal exposure (DLE) and non-DLE groups. M-H, Mantel–Haenszel; CI, confidence interval; SD, standard deviation; IV, inverse variance.

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  Fig. 3. Forest plots illustrating the differences in anatomical characteristics including inter-incisor gap (A), neck circumference (B), and flexion-extension angle (C) between the difficult laryngeal exposure (DLE) and non-DLE groups. SD, standard deviation; IV, inverse variance; CI, confidence interval.

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  Fig. 4. Forest plots illustrating the differences in anatomical characteristics including hyomental distance (HMD; A, B), thyromental distance (TMD; C, D), and sternomental distance (SMD; E) between the difficult laryngeal exposure (DLE) and non-DLE groups. SD, standard deviation; IV, inverse variance; CI, confidence interval.

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  Fig. 5. Forest plot illustrating the difference in modified Mallampati index (MMI) between the difficult laryngeal exposure (DLE) and non-DLE groups. M-H, Mantel-Haenszel; CI, confidence interval.

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