Anaesthesiology - Airway management Flashcards
Modalities of airway management
Indications of airway management
Indications for airway management:
□ Need for airway protection, eg. upper airway obstruction, risk of aspiration, ↓consciousness
□ Need for ventilation, eg. anaesthesia with NMB, IPPV indicated (for eg. resp failure)
□ Need for oxygenation, eg. significant unrelieved respiratory distress, blood gas abnormalities
Outline PE for airway exam
Features of difficult airway
General exam:
- Anxious, sitting upright or in tripod position
- Diaphoresis
- Cyanosis
- Altered mental status
- Obesity
- Obvious head and neck pathology (e.g. massive goiter)
- Medical equipment (e.g. halo traction, neck collar)
Oro-facial exam:
- Loose teeth/ no teeth, Dentures, SIngle incisors, overbite/ buck teeth
- Beard
Respiratory exam:
- Respiratory distress: Tachypnea, SoB, Use of accessory muscles and in-sucking of ICS
- Hoarseness/ voice change
- Snoring, Stridor, Wheezes, Crackles
- Mediastinal deviation with increased resonance (tension pneumothroax)
- No chest expansion with inspiration
- Silent chest
- No perceivable airflow
List predictive tests for difficult laryngoscopy
- Mallampati Score
- Interincisor Distance
- Thyromental distance
- Cervical spine movement
- Sternomental distance
- Jaw protrusion
Combined test: Mallampati and Thyromental distance are more predictive than individual tests
Outline Mallampati Score for ease of laryngoscopy
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Mallampati score: pillars visible (I), fauces visible (II), base of uvula visible (III), only hard palate visible (IV)
Outline Thyromental distance for ease of laryngoscopy
- Distance >6.5cm is rarely associated with difficulty
- Distance 6-6.5cm may be associated with difficult
laryngoscopy but intubation is usually possible - Distance < 6 associated with difficult direct laryngoscopes
Define the interincisor gap and sternomental distance for ease of laryngoscopy
Interincisor gap
* The distance between the incisors with mouth fully open
* It is affected by TMJ and upper C spine mobility
* <3cm = intubation more difficult
* <2.5cm = SAD insertion more difficult
Sternomental distance
Sternal notch to tip of mandible
* Less than 12.5cm = difficult direct laryngoscopy
Define the Cervical neck movement for ease of laryngoscopy
- Extension of upper cervical spine
- Limited (less than 90 degrees)
= Difficult direct laryngoscopy
List predictors of difficult mask ventilation
- Obese (BMI over 26kg/m2)
- Beard
- Absence of teeth
- Facial abnormalities/ craniofacial syndromes
- Receding chin
- Mallampati 3-4
List predictors of difficult supraglottic airway device
- May be used as rescue plan
- Mouth opening < 2.5cm
- Intraoral and pharyngeal masses
- Obesity
- Poor dentition
First-line investigations for difficult airway
- Nasoendoscopy
- CT or MRI scan
- Ultrasound
- Plain radiographs: CXR, facial X-rays, C-spine X-ray
Monitor: SpO2, BP/P, temperature
List all basic airway management options
Simple airway maneuvers:
- Head-tilt chin-lift: when C-spine injury is NOT a concern ± combination w/ manual in-line stabilization to stabilize C-spine when jaw thrust fail to open airway
- Jaw thrust: when C-spine injury IS a concern (eg. trauma
Simple airway adjuncts:
- Oropharyngeal airway
- Nasopharyngeal airway
Basic ventilation techniques:
- Mouth-to-mouth ventilation (only if no equipment, risk of infection and poor O2 enrichment)
- Mouth-to-mask ventilation (one way valve decrease infection risk)
- Bag-valve-mask (BVM) ventilation with Ambu-Bag
Removal of underlying causes:
- Foreign body aspiration: bough, finger sweep, Heimlich maneuvers, Chest thrust, back blows
- Suction for secretions
Signs of successful ventilation
- Chest expansion
- Exhaled tidal volumes
- Presence of breath sounds
- Listen and feel for air leaks
- Pulse oximetry reading
- Capnography most accurate
Reasons for unsuccessful ventilation
Solutions for unsuccessful ventilation
Causes of unsuccessful ventilation:
- Poor mask seal
- Airway obstruction: partial or complete
- facial hair
- dentures, edentulous, sunken cheek
- obese patients
Solutions:
* 2 person, 2 hand technique
* Ask assistant to support soft tissues of cheek
* Optimize head position and triple maneuver
* Ensure no leak/occlusion in equipment/circuit
* Facial hair: aqueous gel, occlusive dressing
* Considering leaving dentures in place
* Use of oropharyngeal/nasopharyngeal airway
* Supraglottic airway device
Complications of bag mask ventilation
- Aspiration
- Lip and dental trauma
- Ocular pressure injury
- Facial injury
Nasopharyngeal airway
- Indications
- Contraindications
- Selection
- Insertion
Indications: when OPA is difficult/ contraindicated
* Can be rapidly and easily inserted blindly
* presence of gag reflex
* oral trauma
* teeth clenched
Contraindications:
Absolute
- base of skull fracture
- nasal, midface fracture
Relative
- coagulopathy
- large nasal polyps
- recent nasal surgery
- suspected epiglottitis
Selection: tip of nose to angle of mandible
Insertion: coated w/ lubricant/anaesthetic jelly beforehand → inserted along floor of naris into posterior pharynx behind tongue → rotate slightly if resistance is encountered
Endotracheal intubation
- Indications
- Positioning
- Correct insertion
Indication:
- Controlled ventilation and oxygenation
- Airway protection
- High pressure ventilation
- Prolonged postoperative intubation or mechanical ventilation
Position:
- “Sniffing” position: Flexion of the neck, extension of head, head on 7 - 9 cm pillow/firm surface, horizontal alignment of external auditory meatus and sternal notch
Insertion:
→ Tip of ETT at midpoint of trachea ≥2cm above carina → Proximal end of cuff ≥2cm below vocal cord
→ Marking at mouth 20-22cm (F) or 22-24cm (M)
Grade of laryngeal view via direct laryngoscopy
Front of neck airway access
Indications
Techniques
Limitations
Complications
Indications:
* Emergency: Can’t intubate, can’t ventilate
* Acute upper airway obstructions
* severe anatomical deformity
Techniques:
* Needle cricothyroidotomy
* Surgical cricothyroidotomy
Limitations:
- Poor CO2 elimination
- limited to ~30min use, need surgical tracheostomy afterwards
Complications:
* Prolonged execution time
* Aspiration, subcutaneous emphysema
* False placement: oesophagus, pneumothorax
* Catheter issues: Tube obstruction, infection, hemorrhage
* Barotrauma
* Late: Dysphonia, subglottic stenosis
