DIFFICULT AIRWAY IN 2003 THE ASA COMMITTEE ON STANDARDS AND PRACTICE PARAMETERS published GUIDELINES ON DIFFICULT AIRWA. In 2011 this same Practice committee elected to collect new evidence to determine whether the recommendations in the existing Practice Guidelines were supported by current evidence. The ASA did not change the Guidelines but found the 2002 guidelines supported by the collected new evidence

OBJECTIVES  IDENTIFY THE ADULT DIFFICULT AIRWAY : REVIEW Patient history and Physical exam  Prepare FOR THE DIFFICULT AIRWAY  KNOW THE STRATEGY :COMMUNICATE THE PRIMARY PLAN AND COMMUNICATE THE BACK-UP PLAN BEFORE ARRIVAL IN THE OR  FOLLOW THE DA ALGORITHM  DISCUSS HOW TO WAKE UP THE DIFFICULT AIRWAY TRACK THE DA AIRWAY POPULATION IN YOUR INSTITUTION

IDENTIFY THE DIFFICULT AIRWAY HISTORY 1.B2-H evidence :. Obesity, OSA, Snoring, Hx of DA. 2.B3-H evidence : Mediastinal Mass 3.B4-H evidence : ankylosis, degenerative arthritis, lingual thyroid, tonsillar hypertrophy, Treacher-Collins, Pierre Robin Syndrome, Down syndrome

Physical Exam : EXAMINE THE HEAD AND NECK  Length of upper incisors, voluntary protrusion of incisors  Micrognathia  Visibility of uvula  Shape of palate  Thyromental distance  Thickness of neck  ROM of head and neck (previous cervical injury)

Definition of a Difficult Airway Difficult face mask, LMA or ILMA ventilation, tracheal intubation, Suprglottic airway (SGA) or all of the above because of  1. inadequate ventilation due to inadequate mask or gas seal, excessive gas leak or excessive resistance.  2. S/S of inadequate ventilation include absent chest movement, absent or inadequate breath sounds, ausculatory sounds of severe obstruction, cyanosis, gastric air entry, decreasing O2 sat, absent exhaled CO2.

Basic Preparation for DA management beyond the DA cart  1. Inform the patient of special risks and plan of care.  2. Ascertain at least one additional individual immediately available to serve as an assistant.  3. Administer pre-oxygenation for 3-6 minutes mindful the uncooperative pediatric patient may impede this opportunity.  4. Actively pursue opportunities to deliver supplemental o2 via NC, AFM, LMA or blow-by throughout management at all times.

Strategy : Communicate your Plan  1. awake intubation  2.video assisted laryngoscopy ( Glidescope )  3.intubating stylets or tube changers  4. SGAs: LMAs, Intubating LMAs  5. Rigid larygoscopes of varying designs and sizes  6. Fiberoptic-guided intubation  7. Llighted stylets or light wands  8. Surgical access

Pre-oxygenation  Times to desaturation thresholds of % O2 concentration are longer for 3 minutes pre-oxygenation than 1 minute pre-oxygenation but are equivocal with fast track pre-oxygenation of 4 deep breaths in 30 seconds.

WHAT tool you use first  Is dependent on :  1. surgical need  2. skill of the provider and  3. preview of DA history and physical exam of the patient.

Awake intubation  Successful %.  Is more successful with topical anesthesia first.

Video-assisted (Glidescope )  Improved laryngeal views, higher frequency of successful intubations and a higher frequency of first attempt intubations.  No significance in degree of cervical spine deviation  No differences in time to intubation  No difference in lip/gum / dental trauma

Intubating Stylets or tube changers  Successful % time  Possibly more mild mucosal bleeding, sore throat  Complications include Lung laceration and gastric perforation

SGAs (LMAs)  Provide successful rescue intubation in 94.1% of patients who cannot be mask ventilated  Complications include broncospasm, difficulty swallowing, laryngeal nerve injury, edema, and hypoglossal nerve paralysis  Can provide adequate ventilation for 95 % patients with pharyngeal and laryngeal tumors.

ILMAs (Intubatng LMAs)  % successful.  Complications include sore throat, hoarseness and pharyngeal edema

Rigid Larygoscopes Observational studies indicate threat the use of rigid larnygoscope blades of alternative design may improve glottic visualization and facilitate successful intubation for difficult airway patients.

Lighted Stylets and Light Wands  % successful.  Equivocal findings indicate that no matter what rigid scope you use: Wuscope, Bullard scope and Upsher scope --time to successful intubation was equivocal.

All agree on these four likelihoods These 6 things may occur alone or in combination 1.1. Difficult patient cooperation or consent 2.2. Difficult mask ventilation 3.3. Difficult laryngoscopy 4.4. Difficult SGA placement 5.5. Difficult intubation 6.6. difficult surgical access

All agree on the relative merits/ feasibility of 4 management choices of  1. Awake vs. GA after induction  2. Non-invasive always first…then invasive (surgical, jet ventilation or retrograde)  3. Video-assisted is a great choice initially  4. Preservation of spontaneous ventilation vs ablation of it

All agree on the recommended STRATEGY for Difficult Airway  That the anesthesia provider must identify a preferred or primary approach to  1. AWAKE intubation  2. the patient who can be adequately ventilated but is difficult to intubate  3. the life-threatening situation wherein the patient cannot be ventilated or intubated

All agree that an alternative approach can be used if the primary approach is not feasible  Uncooperative pediatric patient may restrict the preferred option  The conduct of surgery using local anesthetic infiltration or regional blockade but note that this approach does not represent a solution to the presence of a difficult airway

Strategy for extubation (12 % closed claims) is a logical extension of the intubation management  All agree that there are :  1 Merits of awake extubation vs extubation before return to consciousness  2. If patient is not able to maintain his/her own airway after extubation a PREFFERRED PLAN be implemented  3. Short term us of a device that can serve as a method for expedited reintubation such as an intubating bougie, a hollow stylet or any conduit that can be inserted before extubation that has a lumen through which oxygen can be temoporarily infused such a an LMA or intubating LMA.

Follow-up care: The Anesthesia provider must :  1. PROVIDE AN ACCURATE DESCRIPTION of the difficulties encountered ON THE MEDICAL RECORD to provide and facilitate the delivery of future care.  This description should include the extent to which these devices used served a beneficial or detrimental role.  2. Provide a definite letter to the patient on how the intubation was accomplished, excellent communication with the surgeon, perhaps a notification bracelet and a flagged chart for directing future care.  3. A logged entry list/ book kept on file at the institution.

Electronic tracking  A tracking system for the Difficult Airway automatically popping up when the patients name is data entered to alert all personnel involved in the patients FUTURE care that he/she is a difficult intubation risk.

Bibliography  Anesthesiology, Volume 118,No2, Practice Guidelines of Management of the Difficult Airway An Updated Report by the ASA Task Force on Management of the Difficult Airway  Carin A. Hagberg MD, ASA Newsletter Sept 1, 2013 Volume 77 No 9 “ASA Difficult Airway Management Guidelines: What’s New ?”