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CTRI Number  CTRI/2025/10/096683 [Registered on: 30/10/2025] Trial Registered Prospectively
Last Modified On: 30/10/2025
Post Graduate Thesis  Yes 
Type of Trial  Interventional 
Type of Study   Surgical/Anesthesia 
Study Design  Single Arm Study 
Public Title of Study   To assess the distance between hyoid bone and chin ratio using ultrasound to predict difficulty in direct laryngoscopy and intubation 
Scientific Title of Study   Evaluation of Hyomental Distance Ratio using ultrasound as a diagnostic predictor of difficult direct laryngoscopy and intubation 
Trial Acronym  NIL 
Secondary IDs if Any  
Secondary ID  Identifier 
NIL  NIL 
 
Details of Principal Investigator or overall Trial Coordinator (multi-center study)  
Name  Amruthavarshini E 
Designation  Post Graduate  
Affiliation  DR B R Ambedkar medical college and hospital  
Address  Department of Anaesthesiology,DR.B R Ambedkar medical college and hospital , Gandhi nagar , Kadugondanahalli , Bengaluru , Karnataka 560045

Bangalore
KARNATAKA
560045
India 
Phone  9482641500  
Fax    
Email  varsha5sep@gmail.com  
 
Details of Contact Person
Scientific Query  
Name  DR M Salim Iqbal 
Designation  Professor  
Affiliation  DR B R Ambedkar medical college and hospital  
Address  Department of Anaesthesiology ,DR B R Ambedkar medical college and hospital , Gandhi nagar , Kadugondanahalli , Bengaluru - 560045

Bangalore
KARNATAKA
560045
India 
Phone  9964651079  
Fax    
Email  drsalim_iqbal@yahoo.co.in   
 
Details of Contact Person
Public Query  
Name  DR M Salim Iqbal 
Designation  Professor  
Affiliation  DR B R Ambedkar medical college and hospital  
Address  Department of Anaesthesiology ,DR B R Ambedkar medical college and hospital , Gandhi nagar , Kadugondanahalli , Bengaluru - 560045

Bangalore
KARNATAKA
560045
India 
Phone  9964651079  
Fax    
Email  drsalim_iqbal@yahoo.co.in   
 
Source of Monetary or Material Support  
DR B R Ambedkar medical college and hospital , Bengaluru-560045,Karnataka, India  
 
Primary Sponsor  
Name  Department of Anaesthesiology DR B R Ambedkar medical college and hospital 
Address  DR B R Ambedkar medical college and hospital , Bengaluru -560045,Karnataka ,India 
Type of Sponsor  Private medical college 
 
Details of Secondary Sponsor  
Name  Address 
NIL  NIL 
 
Countries of Recruitment     India  
Sites of Study  
No of Sites = 1  
Name of Principal Investigator  Name of Site  Site Address  Phone/Fax/Email 
Dr Amruthavarshini E  Dr B R Ambedkar medical college and hospital  Department of Anesthesiology ,DR B R Ambedkar medical college and hospital , gandhi nagar , Kadugondanahalli , Bengaluru-560045
Bangalore
KARNATAKA 		 9482641500

varsha5sep@gmail.com 
 
Details of Ethics Committee  
No of Ethics Committees= 1  
Name of Committee  Approval Status 
Institutional Ethics Committee  Approved 
 
Regulatory Clearance Status from DCGI  
Status 
Not Applicable 
 
Health Condition / Problems Studied  
Health Type  Condition 
Healthy Human Volunteers  ASA 1 & 2 healthy patients  
 
Intervention / Comparator Agent  
Type  Name  Details 
Intervention  Direct laryngoscopy and endotracheal intubation  15 SECONDS 
Comparator Agent  NIL  NIL 
 
Inclusion Criteria  
Age From  18.00 Year(s)
Age To  75.00 Year(s)
Gender  Both 
Details  1.Patients posted for elective surgeries needing General Anaesthesia .
2.Aged 18-75 yrs
3.American Society of Anaesthesiologits (ASA) class I,II,III patients . 
 
ExclusionCriteria 
Details  1. Patient refusal to take part in the study.
2. Patients with maxillofacial deformities or cervical fractures.
3. Patients with pre-operatively anticipated difficult airway.
4. Anatomical deformity of neck or face region.
5. Patients with long standing diabetes
6.BMI more than 35





 
 
Method of Generating Random Sequence   Not Applicable 
Method of Concealment   Not Applicable 
Blinding/Masking   Participant and Investigator Blinded 
Primary Outcome  
Outcome  TimePoints 
To determine sensitivity and specificity of HMDR measurement in detecting difficult laryngoscopy   15 minutes before the induction of the patient 
 
Secondary Outcome  
Outcome  TimePoints 
Use of BURP(backward , upward, rightward pressure )manoeuvre .  15 seconds 
Use of any bougie or stylet during the procedure .  15 seconds 
Usage of Mackintosh blade 4 .  15 seconds  
Number of attempts at intubation .  15 seconds 
 
Target Sample Size   Total Sample Size="100"
Sample Size from India="100" 
Final Enrollment numbers achieved (Total)= "Applicable only for Completed/Terminated trials"
Final Enrollment numbers achieved (India)="Applicable only for Completed/Terminated trials" 
Phase of Trial   N/A 
Date of First Enrollment (India)   17/11/2025 
Date of Study Completion (India) Applicable only for Completed/Terminated trials 
Date of First Enrollment (Global)  Date Missing 
Date of Study Completion (Global) Applicable only for Completed/Terminated trials 
Estimated Duration of Trial   Years="1"
Months="6"
Days="0" 
Recruitment Status of Trial (Global)   Not Applicable 
Recruitment Status of Trial (India)  Not Yet Recruiting 
Publication Details   N/A 
Individual Participant Data (IPD) Sharing Statement

Will individual participant data (IPD) be shared publicly (including data dictionaries)?  

Response - NO
Brief Summary   An unexpected difficult intubation can be highly challenging and significantly increases patient’s morbidity if not managed well . Identifying patients at risk for difficult laryngoscopy preoperatively is imperative to implement safer and more effective strategies during induction and airway management.  The hyo-mental distance (HMD) is the distance between the hyoid bone and the tip of the chin.  The hyo-mental distance ratio (HMDR) is the ratio between the hyo-mental distance (HMD) (the distance between the hyoid bone and the tip of the chin) at the extreme of head extension (HMDe) and the one in the neutral position (HMDn).  Patients of American Society of Anaesthesiologists Physical Status Class I, II, III scheduled to undergo elective surgeries under general anaesthesia will be selected based on the inclusion criteria. All enrolled patients will undergo ultrasonographic measurement hyo-mental distance in the pre-operative room prior to being shifted to the operating room. Ultrasound scanning of the submandibular region will be performed with a curvilinear transducer. We will measure the HMD between the hyoid bone and the posterior border of the symphyis menti in two positions, namely: neutral and maximum hyperextended. We define HMDR (hyo-mental distance ratio) as the ratio between the HMD in the maximum hyperextended position to that in the neutral position. During intraoperative laryngoscopy, Modified Cormack-Lehane grading will be recorded. Difficult intubation will be defined by the usage of any one or more of the following- The usage of BURP manoeuvre ,the use of adjuncts like bougie or stylet during the procedure ,the use of Macintosh 4 blade for intubation and the number of attempts to facilitate intubation and the duration of time taken from visualisation of vocal cords to successful intubation will be noted.  
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