Evaluation of Mandibular Mental Angle and Mandibular Profile Angle

Study Overview
=================
Brief Summary
-----------------
Airway management is extremely important for providing safe anesthesia. Endotracheal intubation, on the other hand, is the most important step in airway management, especially since it requires rapid and successful execution. Inadequate airway management; is associated with complications that require high-level care and cost, such as death, brain damage, increased need for intensive care, prolonged recovery period, and emergency tracheostomy. 15-25% of anesthesia-related deaths are associated with airway management. 17% of settled cases against anesthesiologists are composed of airway-related events (often difficult intubation, inadequate oxygenation/ventilation, and pulmonary aspiration). An important point in ensuring airway patency is preoperative evaluation. Difficulties arising from anatomical features can be revealed by careful evaluation of mouth opening, the structure of tongue and palate, thyromental distance (TMM), sternomental distance (SMM), mobility of cervical vertebrae, jaw occlusion, and necessary precautions can be taken. The most commonly used tests to determine the degree of difficulty of intubation are the modified Mallampati test, the thyromental distance, the upper lip bite test, the inter incisor space, and the sternomental distance. Recent studies are trying to confirm the sensitivity and specificity of existing tests. However, there is no test with 100% specificity and sensitivity in predicting difficult laryngoscopy and intubation.

Detailed Description
-----------------
In this prospective observational study, two new parameters mandibular profile angle and mandibular mental angle will be evaluated with the Cormack-Lehane Score during laryngoscopy as a predictor of difficult laryngoscopy. Modified Mallampati test, neck circumference, thyromental distance, sternomental distance, and many other tests have been used for predicting difficult intubation however, none of them are able to predict difficult intubation exactly. mandibular profile angle and mandibular mental angle may provide new horizons for predicting difficult intubation. These two measurements will be compared with the Cormack-Lehane score during laryngoscopy for sensitivity, specificity, and positive or negative predictive values. As well as the Cormack-Lehane Score, we will be comparing these angle measurements' predictive values with the other specified predictive tests such as Modified Mallampati test, neck circumference, thyromental distance, sternomental distance. Having received informed consent, 1000 ASA I-III patients aged between 18-80, who will be operated under general anesthesia, will be included in this prospective observational study. The number of patients is determined according to the numbers in previous studies, but will be finalized as 90% power and 5% error as a result of the power analysis after the prior study. Before the anesthesia induction the Modified Mallampati test, neck circumference, thyromental distance, sternomental distance will be measured as well as mandibular profile angle and mandibular mental angle. Mandibular profile angle is defined as; The angle between the mentum of the mandibula and the lateral tips of the mandibula where the profiler ends. Mandibular mental angle is defined as; the angle between the mentum of the mandibula and the two ends of the mandibular arch. After induction of anesthesia, the difficulty of laryngoscopy will be determined by Cormack-Lehane Score by a senior anesthesiologist. Having received the measurements, tests for sensitivity and specificity, and negative/positive predictive values for difficult intubation will be processed.

Official Title
-----------------
Evaluation of Mandibular Mental Angle and Mandibular Profile Angle in Prediction of Difficult Intubation and Comparison With Other Tests

Conditions
-----------------
Intubation; Difficult or Failed

Intervention / Treatment
-----------------
* Diagnostic Test: Mental Angle


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: General Anesthesia ASA I,II,III Exclusion Criteria: Patients with upper respiratory tract tumors history of surgery, burns and trauma to the upper respiratory tract congenital head-neck anomaly, giant goiter, and pregnancy

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Intervention/Treatment |
| --- |
|Diagnostic Test: Mental Angle|In order to standardize and measure the mental angle, the projection of the mental will be accepted as the midline, the jaw structure will be transferred to the paper using the profile contour meter, and the angle between the angulus mandible and the mental will be measured and recorded with a digital protractor.|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mandibular mental angle to predict the degree of difficulty in intubation | The angle between the mentum of the mandibula and the lateral tips of the mandibula where the profiler ends | 5 min before intubation | 
| Mandibular profile angle to predict the degree of difficulty in intubation | Mandibular mental angle is defined as; the angle between the mentum of the mandibula and the two ends of the mandibular arch. | 5 min before intubation | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Cormack- Lehane grading system | It will be measured by an anesthesiologist during the use of direct laryngoscopy during intubation | Procedure (During the use of direct laryngoscopy for intubation) | 
| Modified Mallampati test | The modified Mallampati test (MMT) is based on the visibility of the pharyngeal structures by opening the mouth as much as possible and sticking out the tongue while the patient is in a sitting position and the head is in a neutral position. | 5 min before intubation | 
| Neck circumference | Neck circumference is measured using a tape measure at the level of the thyroid cartilage with the head in a neutral position. | 5 min before intubation | 
| Thyromental distance | The thyromental distance is found by measuring the distance between the mental prominence of the mandible and the thyroid cartilage when the patient's head is in full extension. | 5 min before intubation | 
| Sternomental distance | Sternomental distance, when the patient's head is in full extension; It is determined by measuring the distance between the upper border of the manbrium sterni and the mental prominens of the mandible. | 5 min before intubation | 
| Upper lip bite test | The upper lip bite test is found by measuring the degree of biting the upper lip with the lower incisors. | 5 min before intubation | 
| Evaluation of mouth opening | It is found by measuring the distance between the upper and lower anterior incisors when the mouth is at its maximum opening. | 5 min before intubation |