Difficult Airway Department 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 of Difficult Airway A difficult airway is defined as the clinical situation in which a conventionally trained anesthesiologist experiences difficulty with mask ventilation, difficulty with 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 Component Upper incisor length Relation of upper & lower jaw Non-reassuring Finding Relatively long Prominent overbite Visibility of uvula Shape of palate Thyromental distance Length of neck Thickness of neck Neck range of motion Mallampati class > II Narrow or high-arched Less than 3cm Short Thick Limited
Mallampati Classification & Glottic View Mallampati Classification Glottic View
Factors Related to Difficult Airway Obesity Pregnancy Tumor Infection Inflammatory disorders Acromegaly Cervical spine problems Gastric reflux Congenital syndromes Trauma
The ASA Algorithm for Recognized and Unrecognized Difficult Airways
Recognized Difficult Airway Regional anesthesia, if possible Can we be sure the regional will work? Awake intubation
The Recognized Difficult Airway Recognized Role of the laryngeal mask airway (LMA) in the American Society of Anesthesiologists (ASA) Difficult Airway Algorithm. (Adapted from Benumof JL: Laryngeal mask airway and the ASA difficult airway algorithm. Anesthesiology 84:686, 1996.)
Preparation for Awake Intubation 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 Airway Cart Contents Rigid laryngoscope blade of different sizes and 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 performed by passing a needle through the thyrohyoid membrane and depositing local anesthetic bilaterally.
Superior Laryngeal Nerve Block In the absence of tumor or infection, the superior laryngeal nerve block can be used to anesthetize the airway above the glottis as well as the epiglottis and arytenoepiglottic folds. Because it removes some protective reflexes, it should be used with caution in patients with full stomach.
Transtracheal Nerve Block Transtracheal nerve block is performed by passing a needle through the cricothyroid membrane and depositing local anesthetic.
Transtracheal Nerve Block The transtracheal injection blocks sensory innervation supplied by the vagus nerve via the recurrent laryngeal nerve. Lidocaine is used for this block and is rapidly absorbed into the systemic circulation via the trachea. A maximum safe dose of topical lidocaine in the trachea (atomizer + transtracheal) is 4mg/kg.
Awake Fiberoptic Intubation
An alternative in the uncooperative patient: LMA (laryngeal mask airway)
Other technique: retrograde intubation Retrograde Wire Fiberoptic-assisted Retrograde Wire
The Unrecognized Difficult Airway Unrecognized Figure 42-24 Role of the laryngeal mask airway (LMA) in the American Society of Anesthesiologists (ASA) Difficult Airway Algorithm. (Adapted from 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
The LMA can be lifesaving in the can t ventilate/intubate situation.
Alternative Airways LMA Bullard Laryngoscope Fiberoptic Intubation through LMA
Emergency Cricothyrotomy Canadian Journal of Anesthesia 52:765-769 (2005) Anatomic Landmarks Rescue technique: cricothyrotomy and tracheostomy
Conclusion: The ASA Difficult Airway Algorthm