Ultrasonographic Parameters in Prediction of Difficult Laryngoscopy in Non-suspected Difficult Airway Patients

Study Overview
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Brief Summary
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This study aims to evaluate the ultrasonographic parameters (distance from skin to epiglottis (DSE) and distance from skin to vocal cords (DSVC)) as preoperative predictors of difficult laryngoscopy in non-suspected difficult airway patients undergoing elective surgery.

Detailed Description
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Airway management is an integral part of general anesthesia. It simply aims to secure the patient's airway and achieve adequate ventilation and oxygenation for the patient undergoing surgery under general anesthesia. Unsuccessful airway management due to the unexpected difficulty in laryngoscopy is a life-threatening situation and may lead to morbidity and mortality. Many conventional clinical tests are used in preoperative airway assessment such as modified Mallampati classification, Thyro-mental distance, inter-incisor distance, cervical mobility, and neck circumference, which are used to predict difficulty in the airway, but they have limited value and low sensitivity and specificity. Difficult laryngoscopy cannot be always predicted based on the preoperative assessment by conventional clinical tests. Some patients are thought to have an easy airway by clinical tests, but they show an unexpected difficulty in the laryngoscopy. The laryngeal view of the patient can be assessed and graded during direct laryngoscopy using the Cormack and Lehane grading scale and its modification that describes the laryngoscopy as easy or difficult. Ultrasonography is a valuable promising tool for preoperative airway evaluation through identifying important sonoanatomy of the upper airway such as epiglottis, thyroid cartilage, and vocal cords.

Official Title
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Use of Ultrasonographic Parameters in Preoperative Prediction of Difficult Laryngoscopy in Non-suspected Difficult Airway Patients Undergoing Elective Surgery; a Prospective Observational Study

Conditions
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Ultrasound, Difficult Laryngoscopy, Prediction

Intervention / Treatment
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* Procedure: Ultrasound


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Aged 18 - 65 years. Both sexes. Patients who aren't suspected to have a difficult airway after preoperative airway assessment by conventional clinical tests such as modified Mallampati classification (MMC), thyromental distance (TMD), inter-incisor distance (IID), cervical mobility (CM), And neck circumference (NC). American society of anesthesia (ASA) I, II, and III physical status. Scheduled for elective surgery under general anaethesia. Exclusion Criteria: Patients with maxillofacial injury and airway trauma. Patients with a history of previous difficult intubation. Patients with anatomical abnormalities. Neck scarring, swelling, or burn. Pregnancy. Obesity.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Easy laryngoscopy<br>Laryngeal view grading according to the modified Cormack and Lehane grading scale where grades 1 and 2a are considered easy laryngoscopy and grades 2b, 3, and 4 are considered difficult laryngoscopy. | Procedure: Ultrasound<br>* Ultrasonographic parameters: in the parasagittal plane (1cm from midline) with the patient lying supine, without a pillow, head, and neck in the neutral position, looking straight ahead with mouth closed and the tongue on the floor of the mouth without any movement.<br>|
| Difficult laryngoscopy<br>Laryngeal view grading according to the modified Cormack and Lehane grading scale where grades 1 and 2a are considered easy laryngoscopy and grades 2b, 3, and 4 are considered difficult laryngoscopy. | Procedure: Ultrasound<br>* Ultrasonographic parameters: in the parasagittal plane (1cm from midline) with the patient lying supine, without a pillow, head, and neck in the neutral position, looking straight ahead with mouth closed and the tongue on the floor of the mouth without any movement.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Correlation between the ultrasonographic parameters and the modified Cormack and Lehane grading scale | Correlation between the ultrasonographic parameters (distance from skin to epiglottis ( DSE) and distance from skin to vocal cords (DSVC)) and the modified Cormack and Lehane grading scale of laryngoscopy as easy or difficult | 10 minutes during intubation. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Sensitivity of ultrasonographic distance from skin to epiglottis to predict difficult laryngoscopy. | Measurement of Sensitivity of ultrasonographic distance from skin to epiglottis to predict difficult laryngoscopy. Laryngeal view grading according to the modified Cormack and Lehane grading scale where grades 1 and 2a are considered easy laryngoscopy and grades 2b, 3, and 4 are considered difficult laryngoscopy. | 10 minutes during intubation. | 
| Sensitivity of ultrasonographic distance from skin to vocal cords to easy laryngoscopy. | Measurement of Sensitivity of ultrasonographic distance from skin to epiglottis to predict easy laryngoscopy. Laryngeal view grading according to the modified Cormack and Lehane grading scale where grades 1 and 2a are considered easy laryngoscopy and grades 2b, 3, and 4 are considered difficult laryngoscopy. | 10 minutes during intubation. | 
| Specificity of ultrasonographic distance from skin to epiglottis to predict difficult laryngoscopy. | Measurement of Specificity of ultrasonographic distance from skin to epiglottis to predict difficult laryngoscopy. Laryngeal view grading according to the modified Cormack and Lehane grading scale where grades 1 and 2a are considered easy laryngoscopy and grades 2b, 3, and 4 are considered difficult laryngoscopy. | 10 minutes during intubation. | 
| Specificity of ultrasonographic distance from skin to vocal cords to easy laryngoscopy. | Measurement of Specificity of ultrasonographic distance from skin to epiglottis to predict easy laryngoscopy. Laryngeal view grading according to the modified Cormack and Lehane grading scale where grades 1 and 2a are considered easy laryngoscopy and grades 2b, 3, and 4 are considered difficult laryngoscopy. | 10 minutes during intubation. |