Comparison of acromio axillo suprasternal notch index (AASNI) vs ultrasound guided epiglottis to vocal cord (EVC) distance predicting difficult visualization of larynx

AIM OF STUDY

To compare the Acromio Axillo Suprasternal Notch Index (AASNI) with USG guided airway assessment for predicting Cormack Lehane’s Grading for difficult intubation.

OBJECTIVES

PRIMARY OBJECTIVE

·       To compare two variable method to predict the Cormack lehane’s grading for difficult intubation with direct laryngoscopy.

SECONDARY OBJECTIVE

Comparison of predictive abilities of the above methods with each other to establish the best test for airway assessment amongst them.

STUDY PROTOCOL

·   ETHICAL CONSIDERATION this study will be conducted after obtaining ethical approval by local ethical committee of GMERS MEDICAL COLLEGE AND HOSPITAL, Vadodara and topic being registered with CTRI (clinical trial registry of India)

STUDY DESIGNProspective Randomized control, single blind clinical study with allocation concealment and a uniform allocation

·  STUDY PLACE General surgery operating unit in a tertiary care teaching hospital ( GMERS Medical college and Hospital, Vadodara)

· STUDY PERIOD over the period 6 months after the approval from ethical committee.

·  STUDY POPULATION Patient hospitalised for Elective surgery under general anaesthesia GMERS hospital college.

·   SAMPLE SIZE   we will take 100 cases based on previous studies.

INCLUSION CRITERIA

·      Patients in ASA class l-ll

·      patients aged between 18 to 50 years

·      Either sex

· All patients undergoing elective surgery under general anaesthesia with endotracheal intubation with direct laryngoscopy.

EXCLUSION CRITERIA

·       Unwilling patient

·       Patients with prior facial, cervical and pharyngeal and epiglottis surgery or trauma history

·       Patients history of difficult intubation

·       Edentulous patients

·       Patient with a mouth opening of less than 3 cms

·       Patients with head and neck pathologies

·       Patients with tracheostomy tube in situ

·       Pregnancy

·       BMI more than 30 kg/m2

METHODOLOGY

As per the departmental protocol the patients posted for elective surgery  were investigated for hematological tests ( hemoglobin , total count, differential count, platelet count), biochemical tests (renal and liver function tests ),Random blood sugar, Chest X-ray and 12 lead Electrocardiograph.

ACROMIO AXILLO SUPRASTERNAL NOTCH INDEX (AASNI)

With the patients lying in a supine position and their upper extremities resting at the sides of the body, AASNI was calculated based on the following measurements:

(1) Using a ruler, a vertical line will be drawn from the top of the acromion process to the superior border of the axilla at the pectoralis major muscle (line A).

(2) A second line will be drawn perpendicular to line A from the suprasternal notch (line B)

(3) The portion of line A that lay above the point at which line B intersected line A will be line C. AASNI was calculated by dividing the length of line C by that of line A (AASNI C/A).

ULTRASOUND

In the operative room, the ultrasound view of the airway of all study patients was assessed. The patients were asked to lie down supine with active head in sniffing position. The probe was placed in the submandibular area in the midline. Without changing the position of the probe, the linear array of the ultrasound probe was rotated in the transverse planes from cephalad (coronal) to caudal (oblique transverse)

The distance from the epiglottis to the midpoint of the distance between the vocal cords (EVC)

The patients were subsequently induced using propofol 2mg/kg, fentanyl 2mcg/kg and vecuronium 0.1mg/kg. Endotracheal intubation was carried out by an anaesthesiologist with atleast two years of experience performing the procedure. During direct laryngoscopy, the Cormack and Lehane grading was recorded as per the following

1. Grade I visualization of the entire laryngeal aperture

2. Grade II visualization of parts of the laryngeal aperture or the arytenoids

3. Grade III visualization of only the epiglottis

4. Grade IV visualization of only the soft palate.

STATISTICAL ANALYSIS

·       The study will be Randomised controlled single blinded clinical study.

·     Sensitivity, specificity, Chi square test will be done for comparison of both variable methods.