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Difficult Airway - General Considerations

last modified on: Mon, 11/20/2023 - 10:13

see also: Pediatric Airway; Emergency Airway Cart; Heliox for the difficult airway; Tracheostomy and Upper Airway Management Symposium July 30 2016 IAO and SOHN Iowa City Iowa; Pulse Oximetry Basic Principles and Interpretation; Pulse Oximetry common misconceptions regarding use

General Considerations

  1. Ascertain the lowest level of airway obstruction; attain airway control below that level.

    1. Oral cavity, oropharyngeal, hypopharyngeal, supraglottic, glottis, subglottic, tracheal, bronchial

  2. Be aware of associated medial conditions

    1. Cervical spine: Trauma patients and Down Syndrome patients who are at high risk for injury should be appropriately evaluated pre-operatively - multiple options to be explored including time-honored use of 'sandbagging' with the head in neutral position if necessary

  3. In general select the simplest form of control that is adequate - with multiple back-ups (plan A, B, C, D...).

  4. Call for assistance if difficult airway predicted

Airway assessment

  1. Signs of airway distress:

    1. Stridor:

      1. Inspiratory: obstruction at or above the thoracic inlet

      2. Expiratory: obstruction at or below thoracic inlet

        1. Example: croup, subglottic stenosis

      3. Inspiratory and expiratory: obstruction at true vocal cords

    2. Hoarseness: may suggests injury at the glottic level, suspect severe injury if complete aphonia

    3. Poor air movement

    4. Accessory muscle use: suprasternal retractions and tripod stance

    5. Drooling: may be indicative of hypopharyngeal/laryngeal obstruction

    6. Bleeding: determine if bleeding is below palate, (oral cavity v upper airway)

    7. Subcutaneous emphysema: rupture in aerodigestive tract

    8. Palpable possible fracture:

      1. Thyroid & trachea: laryngeal fracture

      2. Palate or mandible: oropharyngeal airway obstruction

    9. Hypoxia

      1. Restlessness and agitation

      2. Cyanosis

      3. Pulse oximetry

  2. Definition of a difficult airway:

    1. Difficult intubation has been defined as one that requires external laryngeal manipulation, laryngoscopy requiring more than 3 attempts at intubation, intubation requiring nonstandard equipment or approaches, or the inability to intubate at all

    2. ASA practice guidelines “a difficult airway is defined as the clinical situation in which a conventionally trained anesthesiologist experiences difficulty with face mask ventilation of the upper airway, difficulty with tracheal intubation, or both” (ASA Guidelines 2003).

      1. Subdivision of difficult airway into four categories:

        1. Difficult face-mask ventilation

        2. Difficult laryngoscopy

        3. Difficult tracheal intubation

        4. Failed intubation

  3. Indicators of potential difficult airway

    1. Trismus: interincisor distance of 3 cm or less

    2. Small mandible: Thyro-mental distance 6 cm or less

    3. Snoring/sleep apnea, dyspnea when supine

    4. Secretions

    5. Mallampati classification of 3, 4- cannot see uvula when mouth is opened

    6. Poor cardiopulmonary reserve

    7. Anatomic alterations- short neck, thick neck, neck in fixed flexion or poor range of motion, prominent incisors, prominent “overbite”, high arched palate/narrow palate, firm floor of mouth,  post radiation changes, scarring, large masses

  4. Disease states associated with difficult airway management

    1. Congenital

      1. Pierre Robin Syndrome

      2. Treacher-Collins syndrome

      3. Goldenhar’s syndrome

      4. Mucopolysaccharidoses

      5. Achondroplasia

      6. Micrognathia

      7. Down’s syndrome

    2. Acquired

      1. Morbid obesity

      2. Acromegaly

      3. Airway infections (Ludwig’s angina)

      4. Rheumatoid arthritis

      5. Obstructive sleep apnea

      6. Ankylosing spondylitis

      7. Tumors involving airway

      8. Trauma

  5. Predictors of a significantly difficult or impossible intubation in pediatric population

    1. Small mouth aperture, hyomental distance 1.5 cm or less in a newborn or infant and 3 cm or less in a child

    2. Head and neck impaired mobility

    3. Micrognathia, retrognathia, mandibular dysplasia/ hypoplasia, macroglossia

    4. Space occupying airway lesions

    5. Supralaryngeal inflammatory pathology

    6. Nasal airway obstruction or craniofacial abnormalities

    7. Obesity

Tools to use in Non-Emergent Situation

  1. Temporary options, Simple ways to stabilize the airway

  2. Awake Patient

    1. Humidified Oxygen

    2. Positioning: neck extension, chin lift (Fingers placed under mandible to lift open, thumb used to open lips)

    3. Nasal Airway

      1. Obtunded patient with mandibular retrusion

      2. Oral cavity/oropharyngeal obstruction

      3. Better tolerated than oral airway in responsive patient.

      4. Don’t use if suspected skull base fractures

    4. Bag-Mask Ventilation with goal to maintain saturation >90%

      1. If not, this is failed airway

      2. Risk factors for poor bag mask ventilation: >55, BMI >26 kg/meter squared, beard, lack of teeth, and history of snoring, large hypopharyngeal tongue, lingual tonsil hyperplasia

  3. Anesthetized patient: same as above

    1. Jaw thrust: Grasping the angles of the lower mandible, one hand on each side, to displace mandible forward

    2. Oral airway: base of tongue obstruction in altered patient, not tolerated well in awake patient, make sure to position correctly

    3. Trans-tracheal needle ventilation

      1. Used if Bag Mask cannot keep above 90% and determined difficult airway

      2. Provides rapid oxygenation while more definitive management is underway (best in kids)

        1. 12-14 gauge needle through cricothyroid membrane into trachea

        2. Connect to wall oxygen 15 l/min

        3. Intermittent insufflation with one second on, 3-4 seconds off

        4. 30-45 minutes maximum due to CO2 accumulation

  4. Medications/Non Surgical Adjuncts

    1. Steroids

    2. Racemic epinephrine

    3. Heliox: (at least 70% Helium to be effective)

      1. Glottic obstruction- use low flow rates (5-7 l/min) due to risk of tension pneumothorax

      2. Helium is of lower density than the nitrogen found in air, and thus, its use instead of nitrogen decreases airway resistance, lessens the work of respiration, and may help alleviate oxygenation deficits secondary to obstruction.

Definitive Airway: advanced ways of stabilizing the airway

  1. Indications for Definitive Airway

    1. Apnea

    2. Inability to maintain a patent airway by other means

    3. Protection of the lower airway from aspiration of blood or vomitus (GCS<8)

    4. Closed head injury requiring prolonged comatose state

    5. Airway in the Trauma Patient

    6. Potential Airway Issues

      1. Laryngeal fractures

      2. Airway and pharyngeal burns

      3. Tongue swelling

      4. Neck injuries

  2. Oral Intubation

    1. Indications:

      1. Progressive upper airway obstruction

      2. Worsening pulmonary status

      3. Loss of respiratory drive

    2. Contraindications (all are relative)

      1. C-spine fracture (hyperextension)

      2. Laryngeal trauma (difficult to intubate, may make trauma worse)

      3. Severe oral trauma (unable to visualize glottis for intubation)

    3. Consideration of basic management choices

      1. Awake intubation versus intubation after anesthesia given

      2. Invasive (cricothyrotomy/tracheostomy) versus non-invasive techniques

      3. Spontaneous ventilation versus ablation of spontaneous ventilation

  3. Flexible Fiberoptic Nasal Intubation

    1. Indications

      1. C-spine injury

      2. Oral cavity injury

    2. Advantages

      1. Laryngeal visualization

      2. Suction

      3. Can be done awake

        1. For an awake fiberoptic intubation, the patient should be given a full explanation

        2. Topical oral or nasal anesthesia, tracheal and laryngeal local anesthesia, and minimal sedation.

        3. An antisialagogue should be administered, and if nasal intubation is used, the nasal mucosa should be anesthetized and vasoconstricted with a lidocaine-phenylephrine combination.

    3. Disadvantages

      1. Requires expertise

      2. Bleeding dramatically decreases visibility

      3. Slower than orotracheal intubation

      4. Common epistaxis

    4. Technique

      1. Decongest nasal cavity with Afrin

      2. Transnasal placement of flexible scope after passing through the endotracheal tube

      3. Passed through the nose, nasopharynx, palate, oral cavity, and supraglottis. 

      4. Spray local onto the vocal cords through side port, suction and/or oxygen can be hooked up as well

      5. Endoscope introduced into the subglottic trachea and endotracheal tube passed over the endoscope

    5. Blind Nasotracheal Intubation

      1. Can be performed without visualizing larynx (this is advantage and disadvantage)

      2. Indications:

        1. Fiberoptic equipment unavailable

      3. Contraindications:

        1. Severe midfacial fractures or basilar skull fracture (“nasocranial intubation”)

  4. Direct Laryngoscopy/Bronchoscopy

    1. Indications: unable to visualize larynx with other methods

    2. Advantages: Direct visualization, ability to ventilate patient directly through bronchoscope

    3. Disadvantages: May difficult to safely perform if C-spine injury suspected

    4. Must have equipment immediately available

    5. Lighted stylet is one option to assist intubate and examine concurrently

    6. Cormack-Lehane View Classification (Cormack and Lehane 1984)

      1. Grade 1: entire glottis visible

      2. Grade 2: only the posterior portion of the glottis can be seen

      3. Grade 3: only epiglottis can be seen

      4. Grade 4: cannot see epiglottis

    7. External laryngeal manipulation may help

  5. Laryngeal Mask Airway

    1. Advantages

      1. This is supraglottic device , you do not need to visualize glottis to use technique.

      2. A decreased rate of laryngospasm has been shown through the use of an LMA

      3. An intubating LMA can be used as a quick way to secure an airway in an unstable situation.  A 2.0 intubating LMA can be placed, and a 4.0 ET tube can be threaded through this secured LMA and subsequently placed into the airway.  Placement of this tube should be performed over a flexible fiberoptic scope.  A stylet is then placed on the end of the ET tube to hold it in place while the intubating LMA is withdrawn.

      4. May be used to pass bronchoscope/tube changer to intubate

    2. Disadvantages:

      1. Not as secure an airway as intubation (may become displaced)

      2. Non-traumatic settings when obstruction is thought to be temporary

  6. Combitube

    1. Double lumen tube

    2. Blind intubation into trachea or esophagus

    3. Proximal and distal cuffs

    4. Determine which lumen ventilates lung after placement.

  7. King LT

    1. Similar to Combitube- single lumen, larger proximal cuff

    2. UIHC experience: can make subsequent evaluation difficult (Khaja et al., Arch Otolaryngol Head Neck Surg Sep 2010)

  8. Cricothyroidotomy if unable to ventilate with a mask and failed attempts at tracheal intubation with advanced airway  

    1. Indications:

      1. Unable to Mask and Failure of intubation

      2. No laryngeal injury

      3. Failed ventilation with advanced airway

    2. Advantages

      1. Direct entry to airway à good airway control

      2. More rapid than tracheotomy

    3. Disadvantages:

      1. Surgical procedure

      2. Can cause acute & chronic laryngeal injury

    4. Needle Cricothyroidotomy Technique:

      1. Needle inserted through skin and cricothyroid membrane, downward 45 degree angle while withdrawing

      2. Attach to oxygen delivery device

    5. Slash Cricothyroidotomy Technique:

      1. Palpate landmarks: laryngeal prominence, cricoid prominence

      2. Stabilize and compress skin over larynx and cricoid

      3. Stay in the midline with 3 cm vertical skin incision, transverse stab incision through cricothyroid membrane, rotate 90 degrees or clamp spread in membrane

      4. Insert finger to dilate/confirm access

      5. Estimated time~20 seconds with blade, hook, tube, and sponge

      6. 6-0 ETT or appropriate sized ETT into airway

      7. After airway secured and patient stabilizes, convert to tracheotomy to prevent long-term complications

  9. Tracheotomy

    1. Indications (multiple, several listed below):

      1. laryngeal trauma

      2. failure of above techniques

      3. URGENT need for airway

    2. Advantages:

      1. direct, well-visualized access into airway

      2. avoids entry into larynx

    3. Disadvantages:

      1. more time consuming

      2. more difficult to perform in emergent setting

    4. Technique for slash tracheotomy

      1. Vertical incision from cricoid to sternal notch

      2. Vertical dissection down to the airway

      3. Palpate cricoid to assess location of 2nd tracheal ring

      4. Transverse incision into airway below 2nd ring

  10. Emergency airway kits- adjuncts to armamentarium

    1. A bougie is a semirigid elastic tube that is a 60-cm, 15-French stylet with a curve 3.5 cm from the distal tip

    2. The bougie may be inserted under the tip of the epiglottis when the vocal cords cannot be visualized using DVL and cricoid pressure

Pediatric Airway Cart Checklist (last updated before 2017))

  1. Mask with Face Shield

  2. Wire Cutter in sterile package from central processing

  3. Surgical Lubricant

  4. 18 gauge needle

  5. Sterile 4x4

  6. 16, 18, 20, 22 gauge angiocatheters

  7. Tongue Blades

  8. Sterile Cotton Swabs

  9. 10, 14  French oxygen catheters

  10. Yankauer suction

  11. Infant, Pediatric and Adult tracheal dilator in sterile package from central processing

  12. 16, 18, 20, 22, 24, 26, 28, 30, 32, 34 French Nasopharyngeal Airway 

  13. 9, 10 cm Williams Intubator Airway (pink Oropharyngeal airway used for Flexible fiberoptic intubations, cannot be removed while FFL is being used in patient)

  14. 5, 6,7, 8, 9 cm Gudedel Airway (clear Oropharyngeal airway, color ring at mouth opening coordinated with size)

  15. 8, 9, 10 cm Berman Intubating/Pharygeal Airway (color/size coordinated Oropharyngeal airway used for Flexible fiberoptic intubations, open groove allows airway to be removed with FFL in place)

  16. Pediatric and Adult Tracheal Light Wand

  17. Light Wand Handles

  18. AA Batteries

  19. LMA 1 with 5ml syringe, LMA 1.5 with 10ml syringe, LMA 2 with 20ml syringe, LMA 2.5 with 20ml syringe, LMA 3 with 30ml syringe, LMA 4 with 30ml syringe, LMA 5 with 60ml syringe,

  20. LMA Fasttrach ETT #3, #4, #5 in sterile package from central processing

  21. Pediatric ( > 3mm), Small ( > 4mm), Medium ( > 5mm), Large ( > 7mm) Cook Airway 14 French Cook Retrograde Intubation Kit

  22. 6mm, 4mm, 3.5mm Melker Emergency Cricothrotomy Kit

  23. Emergency Transtracheal Airway Catheter (6f x 7.5cm)

  24. End Oxygen Flo Modulator set 100 (6f x 7.5cm)

  25. Rigid laryngoscope in multiple sizes with both straight and curved blade

  26. Cuffed endotracheal tubes ranging from 2.0 to 8 mm ID

  27. CO2 detector 

References

Practice Guidelines for Management of the Difficult Airway. Anesthesiology May 2003. pp 1269-1277.

  updated: Jeffrey L. Apfelbaum, Carin A. Hagberg, Richard T. Connis, Basem B. Abdelmalak, Madhulika Agarkar, Richard P. Dutton, John E. Fiadjoe, Robert Greif, P. Allan Klock, David Mercier, Sheila N. Myatra, Ellen P. O’Sullivan, William H. Rosenblatt, Massimiliano Sorbello, Avery Tung; 2022 American Society of Anesthesiologists Practice Guidelines for Management of the Difficult Airway. Anesthesiology 2022; 136:31–81 doi: https://doi.org/10.1097/ALN.0000000000004002

Berkow.  Strategies for airway management.  Best practice & research clinical anesthesiology.  Vol 18. No 4, pp 531-548, 2004

Baileys and Johnson.  Head and Neck Surgery: Otolaryngology. Sixth ed. 2006

Lewis. Cummings Otolaryngology: Head and Neck Surgery. Fourth ed. 2007 

Khaja et al.  Arch Otolaryngol Head Neck Surg. Sep 2010

CORMACK, R.S. and LEHANE, J. (1984), Difficult tracheal intubation in obstetrics. Anaesthesia, 39: 1105-1111. https://doi.org/10.1111/j.1365-2044.1984.tb08932.x