Ultrasound-Measured Hyomental Distance Ratio Combined With the Upper Lip Bite Test as a Predictor of Difficult Laryngoscopy in Obese Patients: A Prospective Observational Study
试验速览
- 阶段
- 不适用
- 状态
- 尚未招募
- 入组人数
- 134
- 试验地点
- 1
研究概览
简要总结
The aim of this observational study is to evaluate the accuracy of the HMDR combined with the ULBT as a predictor of difficult laryngoscopy in obese patients undergoing elective surgery under general anesthesia, regarding:
- Correlation of HMDR-ULBT values with Cormack-Lehane grades during laryngoscopy.
- Comparison of HMDR-ULBT with standard HMDR in predicting difficult laryngoscopy.
详细描述
Airway management is a cornerstone of safe anesthesia practice. Difficult laryngoscopy and intubation remain a critical challenge for anesthesiologists. The ability to predict difficult airway situations preoperatively remains crucial, particularly in high-risk populations such as obese patients. These patients have significantly higher rates of difficult mask ventilation and tracheal intubation.
Numerous bedside screening tests have been established to predict difficult laryngoscopy, including the Mallampati classification, thyromental distance, the upper lip bite test (ULBT), and hyomental distance (HMD) measurements. However, none of these tests alone possesses sufficient sensitivity or specificity, and their predictive performance in obese individuals remains variable .
The Hyomental Distance Ratio (HMDR), defined as the ratio of the hyomental distance in maximal head extension to that in the neutral position , is a dynamic parameter reflecting upper airway compliance and anatomical displacement. An HMDR value <1.2 has been associated with increased risk of difficult laryngoscopy in several studies . Traditionally, the HMDR is measured either manually with a ruler or more objectively using ultrasound.
The Upper Lip Bite Test (ULBT) is a simple, validated bedside test assessing mandibular protrusion and temporomandibular joint mobility, two key factors influencing the success of glottic visualization . The ULBT is performed in a conscious state, making it a practical tool in airway assessment.
Given that the ULBT involves active mandibular protrusion, it may mimic the anterior displacement of airway structures achieved during head extension or jaw thrust. Therefore, measuring the hyomental distance while the patient performs the ULBT could serve as a novel dynamic modification of the traditional HMDR-potentially offering a more functional and patient-cooperative measure.
研究设计
- 研究类型
- Interventional
- 分配方式
- Na
- 干预模型
- Single Group
- 主要目的
- Other
- 盲法
- None
入排标准
- 年龄范围
- 18 Years 至 65 Years（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •Adult obese patients aged 18 to 65 years.
- •Both sexes.
- •American Society of Anesthesiologists (ASA) physical status II- III.
- •Body Mass Index (BMI) ≥ 30 kg/m² (classified as obese).
- •Scheduled for elective surgical procedures requiring general anesthesia with endotracheal intubation.
- •Ability to understand and provide informed written consent.
- •Cooperative and able to perform the ULBT on command.
- •Normal dentition (presence of upper and lower incisors to perform ULBT accurately).
排除标准
- •History of maxillofacial trauma, surgery, or congenital facial anomalies affecting mandibular movement or neck anatomy.
- •Known or suspected difficult airway requiring awake intubation.
- •Patients with limited neck mobility (e.g., cervical spine disease or immobilization).
- •Temporomandibular joint disorders or restricted mandibular mobility.
- •Pregnancy.
研究者
Makarious Morris Aboelkheir Shenouda
Assistant Lecturer of Anesthesiology
Cairo University