DIFFICULT AIRWAY – CANNOT VENTILATE, CANNOT INTUBATE .

Dr.Bharghavi.M 2nd year post graduate Dept of Anaesthesia

Difficult airway According to AMERICAN SOCIETY OF ANAESTHESIOLOGISTS Difficult Airway is defined as, ” A clinical situation in which a conventionally trained anaesthesiologist experiences difficulty with mask ventilation, difficulty with tracheal intubation or both.” It includes: • Difficult mask ventilation • Difficult Laryngoscopy • Difficult intubation.

DIFFICULT MASK VENTILATION

• It is not possible for the anaesthesiologist to maintain SpO2 >90% using 100% Oxygen

after induction and positive pressure mask ventilation in a patient whose SpO2 was > 90% before anaesthetic intervention

SIGNS OF INADEQUATE MASK VENTILATION : • Absent or inadequate chest movement. • Absent breath sounds. • Gastric air entry or dilatation. • Cyanosis. • Haemodynamic changes due to hypoxia or

hypercarbia. • Decreasing oxygen saturation. • Absent or inadequate exhaled CO2

DIFFICULT LARYNGOSCOPY : • It is not possible to visualize any portion of the

vocal cords with conventional laryngoscopy. DIFFICULT ENDOTRACHEAL INTUBATION : • Using conventional laryngoscopy, it requires >3

attempts to insert an ETT by an experienced anaesthesiologist

CAUSES OF DIFFICULT INTUBATION • Patient : Congenital & acquired causes.

• Anaesthesiologist :

Inadequate preoperative assessment Inadequate equipment preparation Inexperience Poor technique

• Equipment : Malfunction / Unavailability

ASSESSMENT OF DIFFICULT AIRWAY • History • Individual indices • Group indices - Wilson’s score - “Lemon” assessment • Radiological assessment

HISTORY • Congenital airway abnormalities:

• Pierre robin syndrome, Treachercollin’s syndrome, Down’s syndrome etc.

• Acquired: • Infections of Larynx, Rheumatoid arthritis, Acromegaly,

tumors of tongue and larynx. • Facial trauma, Obesity , Burns etc.,

• Iatrogenic: • Oral/pharyngeal radiotherapy, Laryngeal/tracheal

surgery, TMJ surgery.

Individual indices • Assessment of TMJ function :

Inter incisor gap with maximal mouth opening of > 5cm / or admits 3 fingers of the patient Significance : easy insertion of 3cm deep flange of laryngoscope blade <3cm : difficult laryngoscopy <2cm : difficult LMA insertion Affected by TMJ and upper cervical spine mobility

Assessment of cervical and AOJ function : Flexion of cervical spine and extension of atlanto – occipital joint • Asking patient to touch his

Manubrium sterni with his chin to assess neck flexion.

• Asking patient to look at ceiling with out raising eyebrows to assess AO joint function.

MODIFIED MALLAMPATI (MMP) GRADING

• Grade 1– Faucial pillars, uvula, soft palate • Grade 2– Uvula ,soft palate visible • Grade 3 – Base of uvula , soft palate • Grade 4 – soft palate not visible

Patient in sitting position Head in neutral position Maximal tongue protrusion

MMP GRADE ZERO

• Visualisation of any part of epiglottis during MMP test

• Associated with easy laryngoscopy • Difficult airway possible Large epiglottis hinder laryngoscopic view.

ASSESSMENT OF MANDIBULAR SPACE THYROMENTAL DISTANCE :

• Distance from the tip of thyroid cartilage to the tip of inside of the mentum.

• >6.5 cm→ No problem with laryngoscopy & intubation • <6.5 cm → Difficult laryngoscopy

HYO MENTAL DISTANCE

Distance between mentum and hyoid bone • Grade I : > 6cm • Grade II: 4 – 6cm • Grade III : < 4cm – Impossible laryngoscopy & Intubation

STERNOMENTAL DISTANCE

• Distance from the upper border of the manubrium to the tip of mentum

• Measured with head in full extension and mouth closed

• >12.5cm predicts normal laryngoscopic intubation

• Single best predictor for laryngoscopic intubation`

CORMACK - LEHANE GRADING AT DIRECT LARYNGOSCOPY

• Grade I: visualization of entire vocal cords • Grade IIa: visualization of posterior part of vocal cords • Grade IIb: visualization of arytenoids only • Grade IIIa: epiglottis liftable • Grade IIIb: epiglottis adherent or only tip visible • Grade IV : no glottic structures seen.

Group indices - Wilson’s score

Total score of 10 : score <5 = easy laryngoscopy score 6-7 = moderate difficulty 8-10 = severe difficulty

“LEMON” ASSESSMENT

• L - Look externally (facial trauma, large incisors, beard, large tongue)

• E - Evaluate 3-3-2 rule 3 - Inter incisor gap 3 - Hyo-mental distance 2 - Distance between thyroid cartilage and floor of the mouth(thyrohyoid). • M- Modified Mallampati score • O - Obstruction • N - Neck mobility.

Radiological assessment

X-ray neck cervical spine • Occiput - C1 spinous process distance < 5mm • C 1 – C 2 gap < 5mm • Tracheal compression /deviation • Mandibular length / depth ratio

Difficult bag mask ventilation

BONES • Bearded individuals • Obese individuals • No teeth • Elderly • Snorers

Difficult supra glottic airway

RODS • Restricted mouth opening • Obstructed upper airway • Disrupted upper airway • Stiff lungs

Assessment for

RAPID AIRWAY ASSESSMENT

• Applicable in emergency situations • Time taken <15 sec

Rule of 1-2-3 • Ability to insert one finger infront of the tragus for assessment

of TMJ • Minimum two finger breadth opening of the mouth • Three finger breadth submandibular space

• Architecture of teeth

UPPER LIP BITE /CATCH TEST (RAPID AIRWAY ASSESSMENT)

Equipment for the Difficult airway cart

MANDATORY • Manual self inflating bag • Working laryngoscopes with • Macintosh blades • Face masks • ETTs • Magill forceps • Stylet • Bougie • Oropharyngeal airway and • nasopharyngeal airway • Nasogastric tube

• Airway exchange catheter • Cricothyroidotomy kit • Supra glottic airway device

/intubating SAD • Tracheostomy kit. DESIRABLE • McCoy laryngoscope blades • Video laryngoscope • Flexible fibre-optic bronchoscope • Equipment for high-flow nasal oxygenation.

“Cannot Ventilate ,Cannot Intubate” (CVCI) • Cannot ventilate, cannot intubate situation • Incidence- 1 in 10,000 (0.0001-0.02%)

How to manage?

• CALL FOR HELP • Using two hands to hold the mask and an

assistant to squeeze the bag may make a significant difference

• Do not persist with intubation attempts, limit to 3

MANAGEMENT OF CVCI

Surgical Airway

Unable to intubate

• Re-establish mask ventilation • Ensure optimal positioning (sniffing ) • Consider using a different blade • LMA • Alternative techniques • Awaken the patient • Surgical Airway

Oral and nasal airway • Oro pharyngeal airway • Nasopharyngeal airway bypasses obstruction at the level of the soft palate • LMA, Combitube

Mask ventilation

• Although tracheal intubation is the ultimate goal in

airway management, the ability to provide effective mask-ventilation is life-saving

One-handed face mask technique two-handed technique

LMA (laryngeal mask airway)

LMA-C(CLASSIC) LMA-Flexible LMA- Proseal LMA- FASTRACH LMA `C` TRACH

LMA ‘c’ TRACH

Combitube

• The Combitube is a double lumen tube with esophageal obturator lumen and tracheal lumen.

• The proximal (large) oropharyngeal balloon serves to seal off the mouth and nose,

• The distal balloon (cuff) seals either (oesophagus or trachea)

• Oesophagus (95%), trachea (5%).

Trans tracheal Jet Ventilation (TTJV) • Oxygen injected under high pressure (10-50 PSI) directly into the

trachea. • This is done by inserting a 14 gauge IV catheter or similar device

through the cricothyroid membrane • intermittent bursts of

oxygen through this catheter

Cricothyrotomy Surgical airway

Incision through crico - thyroid Membrane.

Tracheostomy Tracheostomy is an operative procedure that creates a surgical airway in the cervical trachea