Difficult AirwayDepartment of Anesthesiology

University of Colorado Health Sciences Center(prepared by Brenda A. Bucklin, M.D.)

Objectives

• Definition & incidence of the difficult airway• Evaluation of the airway• Co-morbidities and the difficult airway• Management of the known difficult airway• Management of the unrecognized difficult

airway

Definition & Incidence ofDifficult Airway

A difficult airway is defined as the clinical situationin which a conventionally trained anesthesiologistexperiences difficulty with mask ventilation, difficultywith tracheal intubation, or both.

Incidence:

• Non-obstetric population: up to 1:2500• Obstetric population: 1:250

http://www.asahq.org/publicationsAndServices/Difficult%20Airway.pdf

Components of Airway Exam

Narrow or high-archedShape of palate

Prominent “overbite”Relation of upper & lower jaw

LimitedNeck range of motion“Thick”Thickness of neckShortLength of neckLess than 3cmThyromental distance

Mallampati class > IIVisibility of uvula

Relatively longUpper incisor lengthNon-reassuring FindingComponent

Mallampati Classification &Glottic View

Mallampati Classification

Glottic View

Factors Related to DifficultAirway

• Obesity• Pregnancy• Tumor• Infection• Inflammatory

disorders

• Acromegaly• Cervical spine

problems• Gastric reflux• Congenital

syndromes• Trauma

The ASA Algorithm for Recognizedand Unrecognized Difficult Airways

Recognized Difficult Airway

• Regional anesthesia, if possible• Can we be sure the regional will work?

• Awake intubation

The Recognized DifficultAirway

Role of the laryngeal mask airway (LMA) in the American Society of Anesthesiologists (ASA) Difficult Airway Algorithm. (Adapted from Benumof JL: Laryngeal maskairway and the ASA difficult airway algorithm. Anesthesiology 84:686, 1996.)

Recognized

Preparation for AwakeIntubation

• Intravenous drying agent: glycopyrrolate• Topical upper airway anesthesia

– Pledgets soaked with local anesthetic– Atomized local anesthetic

• + Superior laryngeal nerve block• + Transtracheal nerve block

Suggested Difficult AirwayCart Contents

• Rigid laryngoscope blade of different sizesand designs

• Assorted endotracheal tubes• Endotracheal tube guides• Supragottic airway devices (e.g. LMA)• Fiberoptic intubation equipment• Retrograde intubation equipment• Equipment for emergency surgical airway• Exhaled carbon dioxide detector

http://www.asahq.org/publicationsAndServices/Difficult%20Airway.pdf

Awake Intubation:superior laryngeal nerve block

Superior laryngeal nerve block is performedby passing a needle through the thyrohyoidmembrane and depositing local anestheticbilaterally.

In the absence of tumor or infection, the superiorlaryngeal nerve block can be used to anesthetizethe airway above the glottis as well as theepiglottis and arytenoepiglottic folds. Because itremoves some protective reflexes, it should beused with caution in patients with full stomach.

Superior Laryngeal Nerve Block

Transtracheal Nerve Block

Transtracheal nerve block is performed bypassing a needle through the cricothyroidmembrane and depositing local anesthetic.

The transtracheal injection blocks sensoryinnervation supplied by the vagus nerve via therecurrent laryngeal nerve. Lidocaine is used forthis block and is rapidly absorbed into thesystemic circulation via the trachea. A maximumsafe dose of topical lidocaine in the trachea(atomizer + transtracheal) is 4mg/kg.

Transtracheal Nerve Block

Awake Fiberoptic Intubation

An alternative in theuncooperative patient: LMA

(laryngeal mask airway)

Other technique: retrogradeintubation

Retrograde Wire

Fiberoptic-assisted Retrograde Wire

The Unrecognized DifficultAirway

Figure 42-24 Role of the laryngeal mask airway (LMA) in the American Society of Anesthesiologists (ASA) Difficult Airway Algorithm. (Adaptedfrom Benumof JL: Laryngeal mask airway and the ASA difficult airway algorithm. Anesthesiology 84:686, 1996.)

Downloaded from: Miller's Anesthesia (on 27 March 2007 08:48 PM)© 2007 Elsevier

Unrecognized

The LMA can be lifesaving inthe can’t ventilate/intubate

situation.

Alternative Airways

Bullard Laryngoscope

Fiberoptic Intubation through LMA

LMA

Emergency Cricothyrotomy

Anatomic Landmarks

Rescue technique: cricothyrotomy andtracheostomy

Canadian Journal of Anesthesia 52:765-769 (2005)

Conclusion: The ASA DifficultAirway Algorthm