Let’s Revisit Awake Intubation

Clifford Gonzales CRNA, PhD

Wake Forest School of Medicine Nurse Anesthesia Program

Objectives

• After the presentation, participants will be able to:

Identify physical assessments for ventilation and tracheal intubation.

Describe the innervation of the airway.

State the modalities of anesthetizing the airway.

Closed Claims

• 1984- ASA Closed Claims Project

Anesthesiol. 1999; 91:552-556

Closed Claims

• 1970-2007 Closed claims analysis

Best Pract Res Clin Anaesthesiol. 2011; 25:263-276

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Closed Claims

1980-2011 Closed Claims Analysis

• 10,093 closed claims

• Airway injuries from general anesthesia.

https://depts.washington.edu/asaccp/pubs/herring-jc-posner-kl-domino-kb-airway-injuries-associated-general-anesthesia-closed-claims

Airway Management Closed Claims

1980-2011 Closed Claims Analysis

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Difficult Intubation (DI) Pharyngeal/Esophageal Perforation (P/EP)

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2000-2011

https://depts.washington.edu/asaccp/pubs/herring-jc-posner-kl-domino-kb-airway-injuries-associated-general-anesthesia-closed-claims

Closed Claims

Limitations of closed claims

Inaccurate numerator and denominator

Geographical representations

Retrospective studies

Closed Claims

Lessons from closed claims

Securing an airway is a team effort

Avoid haste with preparation (assessment, planning, communication)

Anatomy and physiology, pharmacological, and equipment knowledge needs to be current

Airway Assessment

Table 4a: Comparison of various predictive tests

Assessment Sensitivity (%) Specificity (%) PPV (%) NPV (%)

IIG 13.43 98.31 56.25 87.50

HNM 07.46 93.95 16.67 86.22

MMT 70.15 61.02 22.60 92.65

TMD 07.46 98.06 38.46 86.72

RHTMD 71.64 92.01 59.26 95.24

ULBT 74.63 91.53 58.82 95.70

IIG=Inter-incisor gap; HNM=Head and neck movement; MMT=Modified mallampatti test; TMD=Thyromental distance; RHTMD=Ratio of height to thyromental distance; ULBT=Upper lip bite test

J Aenesthesiol Clin Pharmacol, 2013, 29(2): 191-195

Airway Assessment

Assessment of ability to mask ventilate M O A N S

Mask seal Obese Age Nose, no teeth, neck mobility stiffness

Airway Assessment

Assessment of ability to intubate

L E M O N

Look externally Evaluate (TMD, RHTTMD, ULBT) Mallampati Obstruction Neck mobility

Multivariate assessment to predict DI

Difficulty Airway Algorithm • ASA Difficult Airway Algorithm

• 1. Assess the likelihood and clinical impact of basic management problems:

• Difficulty with patient cooperation or consent

• Difficult mask ventilation

• Difficult supraglottic airway placement

• Difficult laryngoscopy

• Difficult intubation

• Difficult surgical airway access

• 2. Actively pursue opportunities to deliver supplemental oxygen throughout the process of difficult airway management.

• 3. Consider the relative merits and feasibility of basic management choices:

• Awake intubation vs. intubation after induction of general anesthesia

• Non-invasive technique vs. invasive techniques for the initial approach to intubation

• Video-assisted laryngoscopy as an initial approach to intubation

• Preservation vs. ablation of spontaneous ventilation

Anesthesiology 2013; 118:251-270

Difficulty Airway Algorithm • ASA Difficulty Airway Algorithm

Anesthesiology 2013; 118:251-270

Difficulty Airway Algorithm

• Unanticipated Difficulty Airway Algorithm

Brit J of Anesthet, 2015; 115(6):827-848

Awake Intubation

• Indications

Co-morbidities (cervical conditions, intolerance to apnea, etc.)

Risk of aspirations

Difficult airway assessment

Emergency

Awake Intubation

• Explanation to patient • Pharmacological • Equipment • Personnel

Awake Intubation

• Pharmacological Antisialagogue Dilators Sedation Topical anesthesia Emergency

Awake Intubation

• Equipment Airway visualization Adjuncts Monitors Emergency

Awake Intubation

• Personnel Other anesthesia providers Surgeon/s Nurses

Awake Intubation

• Various local anesthetics (LA) can be used for anesthetizing the airway.

• Lidocaine has an advantage because of:

Availability of different formularies and preparation.

Wider margin of safety

Awake Intubation

Airway innervation • Nasopharynx- Trigeminal nerve

(opthalmic and maxillary branch) • Oropharynx- CNIX

(Glossopharyngeal nerve) • Laryngopharynx- superior

laryngeal nerve • Larynx and trachea- recurrent

laryngeal nerve

Common Methods of Anesthetizing the Airway

Nasopharynx

• ½ in of lidocaine 5% at each nares (50mg)

OR

• 2 ml Lidocaine 4% aerosol spray (80mg)

Common Methods of Anesthetizing the Airway

Oropharynx •Apply 2 inches of 5% Lidocaine ointment on a tongue depressor (200mg)

OR • Instruct patient to gurgle 5 ml of

Lidocaine 4% topical solution (may need to do this twice) (200 mg or 400mg)

Common Methods of Anesthetizing the Airway

Oropharynx

OR • Place ½ in. of 5% lidocaine at a cotton tip

applicator and apply it at the base of palatoglossal arch (5 min each side) (100 mg)

OR • Using a 22g spinal needle, administer 2% of

Lidocaine injection solution to both bases of the palatoglossal arch (80mg)

Common Methods of Anesthetizing the Airway

Laryngopharynx (Superior Laryngeal Nerve) •Administer 5 ml of 4% lidocaine injection solution via nebulization (200 mg)

OR •Drip 5 ml of 2% lidocaine viscous solution to the back of the patient’s tongue (1-2 min) (200mg)

Common Methods of Anesthetizing the Airway

Laryngopharynx (Superior Laryngeal Nerve) OR

• Using a 23 G needle, administer 3 ml of 2% lidocaine injection solution at both lateral sides of the neck between the thyroid cartilage and hyoid bone (120mg).

Common Methods of Anesthetizing the Airway

Recurrent Laryngeal Nerve • Lidocaine nebulization may suffice

OR • Using epidural cath through the fiberoptic,

5ml of lidocaine 4% to the trachea (200mg) OR

• Using a 20 G needle, administer 5 ml of 4% lidocaine injection solution to the Cricothyroid membrane (200mg)

Awake Intubation

Calculation of lidocaine total administered dose: 1. Nasopharynx (ointment)= 50mg 2. Glossopharyngeal nerve= 80mg 3. Superior Laryngeal nerve= 120mg 4. Recurrent Laryngeal nerve=200mg Total without nasopharynx = 400mg Total with nasopharynx = 450mg

Awake Intubation

Lidocaine toxicity

• Legendary: 5mg/kg

• Normal therapeutic range for ventricular arrythmias: 2-5mcg/ml

• Various pharmacological factors affect lidocaine plasma level

Awake Intubation