Difficult Airways

Presented by Ri 龔律至 Ri 李又文

Brief history 59 y/o male Oropharyngeal ca.(SCC) s/p CCRT in 2000 Local recurrent oropharyngeal ca. s/p Nd-Y

AG laser tonsillectomy in 2001 Denied any other systemic disease Alcohol, betelnut, or cigarette consumption:

denied

Present Illness Dysphagia was noted since 2002 Sep. PES with biopsy showed middle and lower

esophageal squamous cell carcinoma. CCRT (4000cGy / 20 Fractions) was perfor

med and he was referred for subtotal esophagectomy.

Pre-op evaluation ASA class II Previous intubation hx: No difficult airway w

as noted. Mouth opening < 2 cm

Awake Fiberoptic Intubation RobinulFentanyl lidocaine +Neo-Synesi

n for nasopharynx topical use transtracheal injection of lidocaine successful ETT intubation Pentothal Tracrium

Post op evaluation Sore throat : (-) Vomiting, headache : (-) Pain control : Epidural Pain score : 4 / 10 The patient was satisfied with the quality of

the anesthetic process.

Difficult Airways

Difficult airway is defined when trained anesthesiologist experiences difficulty with mask ventilation (unable to maintain SpO2>90% using 100% O2) and/or inability to place ETT with conventional laryngoscopy (>3 attempts or > 10 mins)

Difficult Airways Include both difficult intubations and

compromised airways. Compromised airways implies partial

obstruction to air flow and the risk of total obstruction if tumor, infection, or disease further narrows the airway.

All compromised airways are difficult intubations!

Difficult Intubation During routine anesthesia the incidence of

difficult tracheal intubation has been estimated 3~18%.

Difficult IntubationThe best view of the larynx seen at laryngoscopy

Cormack classification Class I: the vocal cords are visible

Class II: the vocals cords are only

partly visibleClass III: only the epiglottis is

seenClass IV: the epiglottis cannot be

seen

Predicting Difficult Intubation

History A.Previous intubation history B.Facial/maxillary trauma C.Small mandibles or intra-oral pathology such as infections or tumors D.Rheumatoid disease of the neck or degenerative spinal diseases E.Spinal cord injury F.Poor teeth and the inability to open the mouth

Specific Screening Tests to Predict Difficult Intubation

View obtained during Mallampati test:1.Faucial pillars, soft palate

and uvula visualised 2.Faucial pillars and soft palate visualised, but uvula masked by the base of the tongue 3.Only soft palate visualised 4.Soft palate not seen.

Specific Screening Tests to Predict Difficult Intubation

1. Thyromental distance

2. Sternomental distance

3. Protrusion of the mandible

4. Mouth opening

5. Ability to flex and extend the neck maximally

6. X-ray studies

7. Preoperative assessment

Thyromental distance Frerk showed that patient

s who fulfilled the criteria of Gr 3 or 4 Mallampati who also had a thyromental distance of less 7 cm were likely to present difficulty with intubation

Sternomental distance Measured from the sternum to the tip of the

mandible with the head extended and is influenced by a number of factors including neck extension.

A Sternomental distance of 12.5 cm or less predicted difficult intubation.

Mouth Opening Mouth opening, which is largely a function o

f the temporomandibular, is a prime importance to allow the insertion of a blade and subsequent glottic visualization.

Adults should be able to open their mouth >3~4 cm (between upper and lower incisors).

Protrusion of the mandible An indication of the mobility of the mandible.

If the patient is able to protrude the lower te

eth beyond the upper incisors, intubation is usually straightforward

Limitation Wilson et al studied a combination of these

factors in a surgical population assigning scores. Although their method can predict many difficult intubations, it also produces a high incidence of false positives (someone who is assessed as a likely difficult intubation, but who proves easy to intubate when anesthetised) which limits its usefulness.

Special techniques for intubation: Awake Intubation

=Conscious intubation After appropriate sedation, topical anethesia, an

d nerve blocks, such intubations can be performed with minimal discomfort in the conscious patient.

Nasal intubation is the best method of awake intubation using a fiberoptic bronchoscope.

Awake Intubation

Sedation: fentanyl is recommended. Anticholinergic agent, such as Robinul is st

rongly advised. Anethesia of the nares and nasopharynx sh

ould be accompanied by vasoconstriction to widen the passage and decrease bleeding.

Awake Intubation Nasopharygeal anesthesia:

(1) Cocaine (4%) up to 1.5 mg/kg

(2) Lidocaine (4%) + Neo-Synesin (1%) in a

3:1 combination Transtracheal (translaryngeal) anesthesia wit

h 2~3 ml 2% lidocaine injection. Glossopharyngeal block

Special techniques for intubation

The Laryngeal Mask Airway The McCoy laryngoscope Light wand The Combi-tube Retrograde endotracheal intubation Surgical airway

The Laryngeal Mask Airway

The McCoy laryngoscope

The McCoy laryngoscope is designed with a movable tip which allows the epiglottis to be lifted and intubation often made easier.

The Combi-tube The Combi-tube is a tu

be which may be inserted blindly and used to ventilate the patient in an emergency. It is designed in such a way that the tube can be used for ventilation whether it enters the esophagus or the trachea.

Retrograde endotracheal intubation

Transtracheal Jet Ventilation(TTJV)

Benumof noted that the incidence of “ cannot ventilate-cannot intubate” situation may be as high as 1/ 5000 anesthesics.

TTJV is a quick, easy, safe solution to the problem of “ cannot ventilate-cannot intubate”.