Identify the 5 predictors of difficult bag mask ventilation.

Utilize the LEMON rule to assess a patient’s potential airway difficulty.

Review topical anesthetics for oral and nasal airways.

Describe the role of fiberoptic devices in airway management.

Consider the advantages of available intubation devices.

Assessment of the High-Risk Airway

Introduction: American Society of Anesthesiologists’ algorithm for difficult airway basis of current management; however, emergency department (ED) situations differ from those encountered by anesthesiologists; in ED, no opportunity to prepare or defer care; often cannot obtain information or history from patient; environment chaotic, and cost of failure high; review of several airway algorithms reveals common principles

Initial evaluation: assess not only difficulty of intubation but also ability to utilize bag mask ventilation (BMV); if able to use BMV, less important to intubate immediately and can call in help; know who is available to help (eg, colleague in department, pulmonary care, intensivist); be comfortable calling for help; surgical airway end point of all algorithms (learn and maintain that skill set); review difficult airway cart and procedures at least annually; consider awake vs paralyzed patient (rapid sequence intubation [RSI]); simple algorithm—decision to intubate dependent on physician experience, setting, tools needed, and help available

Intubation plan: in case of “crash” airway, may intubate directly without paralytics; if time available, assess whether patient likely to have difficult airway and plan early, eg, move difficult airway cart to bedside (increases success rate 10%-20%); consider which packs likely to be needed, open, and prepare; obesity or presence of cervical collar not contraindication to RSI, but planning required

Decision to intubate: based on several parameters; goes beyond oxygenation and ventilation; influenced by expected course; consider if patient needs early intubation because of expected outcome or treatment plan, or to facilitate therapy; changes based on setting, tools available, and skill set

Incidence of difficult airways: unknown for ED setting; in anesthesia literature <5% Cormack and Lehane grade 4 (unable to see anything) and 20% grade 3 (probably higher in ED practice); evaluating RSI in >12000 cases (data from national emergency registry), 30% of patient cases too difficult to utilize RSI; RSI 99% successful when used (equal to operating room [OR] success rate); incidence of cricothyrotomy in anesthesiology practice 1:5000 or 1:10000; ED rate 0.6% (more than 1 in 200); in 12 000 cases, no patient died secondary to inability to intubate or ventilate

Predictors of difficult ventilation: presence of abnormal or protruding teeth, receding chin, facial hair, full stomach (aspiration risk), or obesity; evaluate potential for difficulty in using BMV, laryngoscopy, or performing cricothyrotomy; study data—5 predictors of difficult BMV; when 2 present, need adjunctive maneuver for successful mask seal (eg, oral-nasal airway, better positioning); 5 predictors—presence of facial hair, obesity, no teeth, elderly patient, and history of snoring; mnemonic MOANS for ability to obtain good mask seal, obesity or obstruction, age >55 yr, no teeth, and stiff lungs

Further patient evaluation: difficult-to-intubate patients often have subtle signs; examine for high anterior cords; anatomy graded based on ability to visualize cords; grades I and II have high success rate; grade III can only see arytenoid cartilage; grade IV cannot visualize anything; utilize bougie or intubating stylet to assist with grade III; evaluate difficulty to intubate before administering succinylcholine, so time available to call for help or use rescue airway; need fast simple approach to ED patients, as half not awake or conscious; try not to utilize medications too quickly, step back and manage airway first

LEMON law: 5 components; 1) look externally; assess whether and why airway difficult (eg, high anterior cords, beard, adipose tissue, airway geometry); 2) evaluate using 3-3-2 rule, ie, place 3 fingers in mouth, 3 fingers between angle of jaw and mentum, and 2 fingers between top of thyroid cartilage and bottom of jaw (if only one finger can be placed, high anterior cord probably present; 3) mandible; is it receding? can it serve as repository for tongue during intubation? can axes be lined up? 4) obstruction; open mouth and determine Mallampati class; can posterior pharynx be visualized? if obstruction present, determine location and whether fixed or mobile, soft or hard; assess how quickly obstruction progressing (eg, epiglottitis); if stridor develops (breathing against inflammatory process) in adult, only 10% to 20% of airway open; example of arterial hematoma (hard pulsatile obstruction that can close off airway); 5) neck mobility; presence of cervical collar; history of fusion; can remove cervical collar (or anterior portion of it) and have someone maintain inline stability during intubation; patients with cervical spine injury more safely intubated with RSI (less neck movement); predictive value of LEMON law—evaluated in study of 150 patients; significant correlation between increasing LEMON score and difficulty of intubation

Difficult-airway cart: be familiar with cart; assign someone to check cart daily; recommended items include one easily accessed drawer for medications and basic equipment; intubating stylet or bougie (can use either one to intubate after visualizing epiglottis); intubating laryngeal mask airway (LMA)—useful for BMV until definitive airway established; however, airway not protected until endotracheal tube (ETT) placed; fiberoptics increase success rate; regular ETT achieves 80% success rate, more expensive ETT 90%, and with fiberoptic assistive device, success rate approaches 100%; intubating LMA expensive, but should be left in place (may not be returned to ED; disposable single-use intubating LMA now available that can safely stay in place several hours); surgical airway kit— essential; speaker does not recommend percutaneous pre-hospital kit (lower success rate and higher complications); recommends wire-guided Seldinger technique, almost as fast as open technique; keep option to use open technique if wire unsuccessful; stock universal kit with both types available; at minimum, stock cart with stylet, disposable intubating LMA, and surgical airway kit

Fiberoptics: if affordable, utilize fiberoptics; speaker uses short nasopharyngoscope 10 times more often than intubating fiberoptic laryngoscope; fiberoptics do not solve airway problems but do help anticipate them; speaker uses more diagnostically than therapeutically

Airway alternatives: consider anatomically, ie, where will rescue item fix problem?

Supraglottic: will it require oral airway access? BMV backup of choice; nonintubating LMA does not protect airway, so less useful; light wand helpful with practice, especially if patient’s neck cannot be moved or mouth cannot open >1 cm; preferable to have fiberoptics in stylet instead of laryngoscope; consider Combitube or King laryngeal tube (LT); blind nasotracheal intubation still has role (preferred before RSI); if unable to place nasotracheal tube on 1 to 2 attempts, use another alternative; nasal fiberoptics easier to pass and allow easier anesthetization

Infraglottic: cannot BMV or intubate if access required below cords; prepare for cricothyrotomy; if pediatric patient <10 yr of age, consider transtracheal jet ventilation; fewer options available to pediatric population as fewer of these patients have difficult airways

Intubation equipment: maintain preventive approach, anticipate needs early, and may be able to avoid intubation; utilize more aggressive continuous positive airway pressure (CPAP); consider intubation in OR; for blind intubations, consider intubating LMA or bougie; disposable blade version of GlideScope; video scope; be comfortable with Combitube removal; Emergency Medical Services (EMS) utilizing King LT more often because of easier field insertion; also simpler to change to ETT; can place King LT without interrupting cardiopulmonary resuscitation (CPR), but assume some placement-associated edema; disposable LMA as effective as nondisposable LMA; newer blades utilize video camera or wireless device at end of laryngoscope; complications of these include fogging and inability to visualize airway after intubation; LMA with track does not require fiberoptics to line it up; GlideScope preferred over laryngoscope; GlideScope gets around tongue easily; insert with patient in neutral position, do not go far in (just over midline of tongue), crank back slightly, and cords immediately visible on screen; advantages of GlideScope include absence of fogging, and ability to see, even in presence of sputum, blood, and vomit; laryngoscope likely obsolete in 5 to 10 yr

Oxygen saturation: patients with asthma who present with wheezing and coughing at risk for respiratory fatigue and subsequent oxygen desaturation; speaker prefers not to intubate asthmatics, as ETT further increases pulmonary resistance; support with ventilation; pediatric patients desaturate faster; succinylcholine lowers saturations, despite best efforts at pre-oxygenation in patients with asthma, especially pediatric population; study—volunteers paralyzed with succinylcholine to determine how long until oxygen saturation decreased; well man at 70-kg body weight took ≈8 min to decrease oxygen saturation to <90%; then rapidly dropped to 60% (within 1 min); if patient well preoxygenated, oxygen reservoir may outlast succinylcholine effects; moderately ill adult starts decreasing oxygen desaturation at 5 to 6 min; normal pediatric patient at 10-kg body weight starts decreasing at 3.5 min; children utilize oxygen at twice adult rate (6 mL/kg per minute vs 3 mL/kg per minute); pre-oxygenation—critical, even if initial saturations 100%, to increase oxygen reservoir; utilizing non-rebreather mask buys apnea time and helps wash out nitrogen; pediatric patient with acute asthma likely to desaturate within 30 sec, so anticipate; have 2 people to help; have bag and correct ETT ready

Intubation checklist: review steps ahead of time; check intravenous (IV) access and patency; suction functional; oxygen attached and flowing; typically find at least one issue

Awake intubation: practice before needed, eg, use fiberoptics to evaluate sore throats; topical anesthesia options—lidocaine with epinephrine; lidocaine 4% with oxy-metazoline (Afrin); cocaine (topical anesthetic and vasoconstrictor); utilize by dipping cotton-tipped swabs in lidocaine/oxymetazoline combination, and place 2 to 3 in nose every 2 min, going progressively deeper; have items available in cart; use GlideScope on awake patients by moving blade down tongue to visualize cords, then back off, give succinylcholine, and intubate; can nebulize lidocaine 4% (2.5 mL equals 100 mg) over 10 to 15 min to numb oral airway and lose gag reflex; can also use viscous lidocaine on end of tongue blade, move blade down tongue until gag point, then flip over and wipe lidocaine on back of tongue; it will warm up and drip down to anesthetize laryngeal and glossopharyngeal nerves, with good results; if need to move from visualization to intubation on awake patient, consider sedation with ketamine; if concerned about increased secretions with ketamine, give antisialagogue first, eg, atropine, glycopyrrolate

Case presentations: first—woman lit self on fire in car, transported by ambulance over 1 hr to hospital with burn unit; patient very agitated and suicidal; EMS unable to place peripheral IV or obtain vital signs; in ED, speaker placed femoral line; patient became sedated quickly with succinylcholine, and intubated via bougie; oxygen saturation 80%; speaker assessed management as too rushed; complete assessment of airway and evaluation of patient should have been performed; second—child presented to ED after choking on peanuts; evaluated and on way to OR for bronchoscopy when child suddenly collapsed and stopped breathing; speaker unable to visualize obstruction, placed ETT but unable to ventilate; foreign body obstruction below cords; speaker pushed obstruction down right main stem bronchus, then pulled tube back and ventilated left lung; lesson not to waste time with surgical airway for obstructed airway; third—man fell off scaffolding onto metal upright divider and sheared off half his face; speaker could intubate orally but was ready for surgical airway; if unable to visualize landmarks secondary to trauma, follow tongue back to its base, with suctioning, and look for epi-glottis; can then identify cords behind epiglottis; at same time, have someone prepare neck for surgical airway; when placing surgical airway, locate cricothyroid membrane by placing hand with fifth finger in sternal notch, lay other 3 fingers along neck in neutral position; cricothyroid membrane under fourth finger; practice surgical airway with equipment available to you

Summary: need organized simple approach; think about potential for difficult airway with every airway managed, even if stable initially; think about why airway difficult and develop plan; ensure you have what you need to enact plan