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ASSESMENT OF AIRWAY FOR INTUBATION

The patient must be assessed for difficult intubation, difficult bag and mask ventilation and for difficult cricothyrotomy.

Neuromuscular block must be avoided in patients where a high difficulty of intubation is predicted.

L – Look externally

E - Evaluate 3-3-2

M - Mallamapti score

O - Obstruction

N – Neck mobility

• Look Externally

• Difficulty with Mask seal due to beard, trauma

• Obesity

• Advanced age.

• odentulousness (No teeth)

• Stiffness or resistance in ventilation due to obstructive or restrictive lung disease, term pregnancy.

• High arched palate and large tongue makes the laryngscopy difficult.

• Any disturbance in ability to locate and access the landmarks of the anterior airway via neck like tumour , abscess, previous surgical scar, obesity, subcutaneous air, oedema will make cricothyrotomy difficult.

• Evaluate 3-3-2

• Direct laryngoscopy requires the ability to visualise the glottis by direct vision through the mouth, using alignment of the oral, pharngeal and laryngeal axis.

• Mouth opening should be adequate about 30 – 40 mm distance between the upper and lower incisor ( 3 finger breadth).

• Submandibular space (Distance between hyoid bone & chin) should be adequate enough to accommodate the tongue about 50mm or 3 finger breadth.

• Position of larynx : the larynx should be low enough in the neck to be accessible. Two fingers from the laryngeal prominence (thyroid notch) to floor of the mouth.



• Mallampati Score

  • CLASS I : Soft palate , Uvula , fauces , pillars are visible

  • CLASS II: Soft palate, uvula, fauces are visible

  • Class III: is characterized by visualization base of the uvula and soft palate.  

  • Class IV:Only hard palate is visible.

  
  

Attribute :"Mallampati" by Jmarchn - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Mallampati.svg#mediaviewer/File:Mallampati.svg

Class I and class II predicts adequate oral access. Class III predicts moderate difficulty, Class IV predicts high degree of difficulty.

• Obstruction

  • Upper airway obstruction may make visualisation of the glottis or intubation itself mechanically difficult. Conditions like epiglottitis, laryngeal tumor, Ludwing's agina, neck hematoma or glottic polyps can compromise laryngoscopy, passage of endotracheal tube.

• Neck Mobility

  • Neck mobility is essential to allow the angled axes of the upper airway to be sufficiently repositioned to permit direct visualisation of the glottis and is assessed by having the patient flex and extend the head and neck through a full range of movement.

  • Modest limitation of the motion donot serious impair laryngoscopy but severe loss of motion may render laryngoscopy impossible.

• Measurement of Intubation Difficulty
  CORMACK & LEHANE

  • Grade 1: The entire glottic structure can be seen.

  • Grade 2: Laryngoscopy only visualise a portion of glottis (10-30%)

    • 2a: Arytenoid and a portion of vocal cord can be seen.

    • 2b: Only arytenoids are seen.

  • Grade 3:Laryngoscopy only visualise the epiglottis.(intubation is extreme difficult <5%).

  • Grade 4 : Even epiglottis is not visible. ( impossible intubation <1%)

DIFFICULTY IN MASK VENTILATION

• Age >55yrs

• BMI >26

• Lack of teeth

• Presence of beard

• History of snoring

• If two are more factors are present chance of difficult ventilation is high.

Predicting difficulty in ICU :MACOHA Score

A score of zero suggest easy intubation, whereas a score of 12 suggests difficult intubation.

Manuevers To Improve Laryngoscopic Visulaisation

• BACK MANUEVER : Simple back pressure on the cricoid or thyroid cartilage , they displaces the larynx posteriorly & reduces the failure rate to visualize any part of glottis from 9.2 to 1.6%.

• Burp manuever: Backward, upward & rightward displacement of larynx improves visualisation of larynx.

• JAW THRUST Maneuver: This technique is used to relieve laryngeal obstruction by tongue. They can improve visualisation during nasal fibreoptic laryngoscopy.

• BURP + Jaw thrust may improve visualisation.

Updated on 7/3/2015

REFERENCE

• ROSEN'S EMERGENCY MEDICINE

• TINTINALLI'S TEXTBOOK OF EMERGENCY MEDICINE

• Practical pulmonary & critical care medicine ; Edited by : Zab mosenifa