DEVELOPMENT OF A SCORING SYSTEM FOR PREDICTING DIFFICULT INTUBATION USING

ULTRASONOGRAPHY

DR DAGGUPATI HARITHREG. NO: 1601021001 | JUNE/2016MD., Anaesthesia, MGMCRI

GIUDE DR. RAVISHANKAR (PROFESSOR & DEAN)DEPARTMENT OF Anaesthesia, MGMCRI

Co-GUIDEDR.ROSHAN (ASSOCIATE PROFESSOR)

DEPARTMENT OF Anaesthesia MGMCRI

INTRODUCTION• Examination of the airway is an essential component of the

anesthesiologist’s preoperative assessment. Prediction of a difficult airway has led to better preparedness and reduced the incidence of airway related morbidity and mortality.

• • Study has been designed so as to include an ultrasonographic

parameter, to the existing airway assessment strategy, to develop a score with better sensitivity and a more positive predictor for the difficult airway.

Wilson score LEMON scoreWeight Look Head and neck movement Evaluate 3-3-2 Jaw movement MallampatiReceding mandible ObstructionBuck teeth Neck movement

LEMON score, Wilson score but still difficult intubation :1-8%

REVIEW OF LITERATURE

• Ambesh et al studied a combination of the modified Mallampati score, thyromental distance, anatomical abnormality, and cervical mobility (M-TAC) to predict difficult laryngoscopy better than Mallampati classification alone. They concluded that M-TAC scoring system had provided a higher sensitivity and specificity in predicting difficult laryngoscopy in comparison with Mallampati classification alone.

• Adhikari et al conducted a pilot Study to determine the utility of point-of-care ultrasound assessment for prediction of difficult laryngoscopy. They found that clinical screening tests did not correlate with US measurements, however US was able to detect difficult laryngoscopy, indicating limitations of the conventional screening tests for prediction of difficult laryngoscopy.

AIM AND OBJECTIVESAim : To develop a scoring system for predicting difficult intubation

OBJECTIVES1. To analyse the value of the ultrasonographic measurements along with clinical tests

in predicting difficult intubation using Cormack and Lehane grading of glottis view as a guide.

2. To develop a scoring system incorporating the sonographic measurements into conventional scoring system.

HYPOTHESIS

• INCORPORATION OF ULTRASONIC MEASUREMENTS MAY NOT IMPROVE THE PREDICTIVE VALUE OF THE CONVENTIONAL SCORING SYSTEM.

Criteria for recruitment INCLUSION CRITERIA• ASA I,II AND III• AGE 18-70 YEARS• Patient undergoing surgery

under GA with endotracheal intubation

EXCLUSION CRITERIA• Mouth opening <3 cm.• Intubation done with

instrument other than MacIntosh Laryngoscope.

• Airway with Anatomical abnormality.

• Emergency surgeries.

Ethical committee approval

Patients planned for Elective surgery under General Endotracheal Anaesthesia, after satisfying inclusion and exclusion criteria, will be enrolled for the study, after obtaining informed consent

Preop Airway assessment done by the primary investigator at the bedside, the day before the surgery.

1. Mentohyoid distance2. Neck extension3. Mandibular subluxation4. Ultrasonographic measured skin to epiglottis distance

On the day of surgery, following institution protocol of premedication, monitoring and induction of general anaesthesia, laryngoscopy will be done by consultant anaesthesiologist. 5The Cormack lehane grade as determined by the consultant will be

To develop a scoring system including the ultrasonographic parameter with clinical tests after correlation with cormack lehane grade.

STUDY PARAMETERS1. Mentohyoid distance: Distance between mentum and hyoid bone

Grade I : > 6cm Grade II: 4 – 6cm Grade III : < 4cm

2. Mandibular subluxation - By upper lip bite test

+1 Lower incisors can bite the upper lip above vermilion line 0 can bite the upper lip below vermilion line-1 cannot bite the upper lip

3. Neck Extension Patient lying on a flat bed with a 7 cm pillow below the neck and a scale placed perpendicular to the upper lip, then asked to extend the neck

Grade 1 – Line of upper incisor beyond scaleGrade 2 - Line of upper incisor inline with scaleGrade 3 - Line of upper incisor below the scale

SCALE

STUDY PARAMETERS4. Sonographic measurement

5. Cormack and Lehane grading of Glottis, On direct laryngoscope

Grade I – complete visibility of the glottisGrade II – anterior glottis not seenGrade III – epiglottis seen but not glottisGrade IV – epiglottis not seen

With probe placed midway between the hyoid bone and thyroid cartilage, The skin to epiglottis will be measured.

SAMPLE SIZE AND STATISTICAL METHODSSAMPLE SIZEBased on previous study done by Ambesh et al, traditional methods had a 28 % positive prediction for difficult intubation. By using the below mentioned formula sample size of 310n = Z 2

1- α /2 P(1-P)/d2. We are assuming predictive value of 33%.(n= sample size p=Proportion of difficult intubation d= 0.05 (5%) α = 0.05, Power of the study=80% )

STATISTICAL METHODS• Percentages ,Mean ,SD , Sensitivity, specificity using ROC curve are

used to describe the data,positive and negative predictive value of the scoring including Odd’s ratio

• Chi square test as inferential statistics

ETHICAL ISSUES

• This study involves human, with age between 18-70 including geriatric age group.

• Procedure will be clearly explained to the patients.

REFERENCES• Miller’s Anaesthesia. In: 8th ed. ELSVIER; 2015. p. 3270 1085-93. Available from:

www.elsevier.com/permissions. • Arné J, Descoins P, Fusciardi J, Ingrand P, Ferrier B, Boudigues D, et al. Preoperative

assessment for difficult intubation in general and ENT surgery: predictive value of a clinical multivariate risk index. Br J Anaesth. 1998 Feb;80(2):140–6

• Reed MJ,Dunn MJG, McKeown DW. Can an airway assessment score predict difficulty at

intubation in the emergency department? Emerg Med J. 2005 Feb;22(2):99–102 • Kamalipour H, Bagheri M, Kamali K, Taleie A, Yarmohammadi H. Lateral neck radiography for

prediction of difficult orotracheal intubation. Eur J Anaesthesiol. 2005 Sep;22(9):689–93 • Adhikari S, Zeger W, Schmier C, Crum T, Craven A, Frrokaj I, et al. Pilot study to determine the

utility of point-of-care ultrasound in the assessment of difficult laryngoscopy. Acad Emerg Med. 2011 Jul;18(7):754–8.