Recognition And Management Of Difficult Airway


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  • No standard definition Difficult airway depends on patient factor, clinical setting and skill of practitioner
  • Rheumatoid arthritis involve synovial joints in airway
  • XRay to check depth of mandible, spine abnormality and tracheal constriction and deviation
  • Whether displacement of tongue would be easy Poor mallampatti with limited head and neck mobility Low specificity means many false positive Low positive predictive value 4% for grade IV Predictive power of mallampatti improved when mandibe is short.
  • Normal 6.5 or more
  • When you combine Mallampati and TM distance sensitivity increased If pt has short mandible then MP would be able to predict that it will be Grade IV intubation grade.
  • Sniffing position
  • Only extension at atlanto occipital joint required now. Angle between oral and pharyngeal which was perpendicular will change to 125 degree . By Adnet et al. and Chow and Wu also agrees. Three angles model may not be useful.
  • BURP has prove to reduce the incidence of dfailed intubations OELM by Benumof to manipulate larynx, cricoid, hyoid to enhace visibility
  • Limit attempts to four attempt max.
  • Epiglottis supplied by SLN a br of vagus causing laryngospasm, bradycardia, hypertension Valleculae supplied by GPN
  • Mc Coy
  • Modified Cormack and Lehane IIa when part of V C visible IIb when only arytenoid and epiglottis is visible IIIa Epiglottis can be lifted IIIb can not be lifted
  • Box A : Difficulty is anticipated Box B NO difficulty anticipated
  • Is airway control necessary Is there an aspiration risk ( Pt not a candidate for SGA wh i ch are mask and LMA)
  • BOX A chosen when difficulty is anticipated Non invasive intubation: Anaesthesize the airway and blind nasal, blind oral, Awake FOB, Awake look, Retrograde intubation For awake intubation: If awake intubation fails then options are cancellation of case, If cancellation not an option And case is emergency then regional anaesthesia, specialized equipment and persons for return to OR.
  • Cotton tipped in nose for ten min, 4% cocaine potent vasoconstrictor to block greater and lesser palatine nerves and anterior ethmoid nerve. Glossopharyngeal N supply the post 1/3 tongue, valleculae and ant surface of epiglottis (Lingual br), Wall of pharynx (Pharyngeal br), Tonsils (Tonsillar br); Blocked by lidocain gargles, Lidocain soaked cotton at inferior most part of the platoglossal fold, Nebulization or injection at base of tongue close to inferior border of platoglossal fold with spinal needle. Superior laryngeal N has external and internal br. Internal br supplies base of tongue, epiglottis, arytenoid and arryepiglottic folds and blocked at greater cornu of hyoid boe Recurrent laryngeal N supply sensory innervation to vocal folds and trachea 4ml of 2% xylocaine injected by transtracheal injection.
  • No. of intubation attempts should be limited to three even if ventilation adequate. Non emergency pathway includes Blind oral. Blind nasal, FOB, LMA, Bougie, retrograde intubation or surgical airway. Emergency non invasive ventilation includes Esophageal tracheal combitube, Rigid bronchoscopy, Trans tracheal oxygenation or surgical airway
  • ASA guidelines have variety of choices ay all steps which is confusing so DAS (Difficult airway society)
  • 60 cm length and 60 degree angle Useful in grade III intubation Pass blindly under epiglottis, click sound Not useful in Grade IIIb and IV
  • Inflatable silicone mask sits in hypopharynx with anterior surface facing laryngeal aperture. Sizes 1 to 6 Alloe positive pressure ventilation at 20cm of H2O Intra cuff pressure should not exceed 6o cm H2O Reasons for LMA failure are Acute oropharyngeal angle, Obstruction at hypopharynx, Obstruction below vocal folds
  • Simple LMA can be used as conduit fot ETT insertion Size 5 (7mm ID), 3 or 4 (6 mmID) longer ETT of microlaryngeal or nasal RAE tube is effective
  • Intubating LMA upt o size ETT 8ID can be introduced Dedicated silicone tube Straight armored, silicone ETT Sizes 3,4,5 Learning curve of 20 insertions, bronchoscope can also be used to intubate through LMA
  • Recognition And Management Of Difficult Airway

    1. 1. Recognition and Management of difficult airway Dr. Mohammad Hamid Assistant Professor Department of Anaesthesia Aga khan university Hospital
    2. 2. Difficult airway <ul><li>A clinical situation in which a conventionally trained anaesthesiologist experiences difficulty with mask ventilation of upper airway, difficulty with tracheal intubation, or both </li></ul><ul><li>(ASA task force, Anaesthesiology 2003) </li></ul>
    3. 3. Definitions <ul><li>Difficult laryngoscopy </li></ul><ul><ul><li>Not being able to see any part of the vocal cords with conventional laryngoscopy (i.e, Grade III or IV laryngoscopic view ) </li></ul></ul><ul><li>Difficult intubation </li></ul><ul><ul><li>Tracheal intubation requires multiple attempts, in the presence or absence of tracheal pathology. </li></ul></ul><ul><li>Failed intubation </li></ul><ul><ul><li>Placement of the endotracheal tube fails after multiple intubation attempts. </li></ul></ul>
    4. 4. Incidence <ul><li>Incidence of failed intubation </li></ul><ul><ul><li>0.05 to 0.35 % </li></ul></ul><ul><li>Failed intubation/ Inability to perform mask ventilation </li></ul><ul><ul><li>0.01 to 0.03 % </li></ul></ul><ul><li>24% Liability claims in ASA Closed claims data base related to adverse respiratory events </li></ul><ul><ul><ul><li>75% of those related to </li></ul></ul></ul><ul><ul><ul><ul><li>Inadequate ventilation </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Esophageal intubation </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Difficult tracheal intubation </li></ul></ul></ul></ul>
    5. 5. Outcome Brain injury Unnecessary tracheostomy Cardiopulmonary arrest Damage to teeth Airway trauma Death Adverse Outcome
    6. 6. Difficult mask ventilation <ul><li>Difficult mask ventilation incidence 5% </li></ul><ul><li>Impossible to ventilate 1/ 1502 patients </li></ul>
    7. 7. Signs of inadequate face mask ventilation include (but are not limited to) <ul><ul><li>A bsent or inadequate chest movement </li></ul></ul><ul><ul><li>A bsent or inadequate breath sounds </li></ul></ul><ul><ul><li>A uscultatory signs of severe obstruction, cyanosis, gastric air entry or dilatation </li></ul></ul><ul><ul><li>D ecreasing or inadequate oxygen saturation (SpO2) </li></ul></ul><ul><ul><li>A bsent or inadequate exhaled carbon dioxide </li></ul></ul><ul><ul><li>A bsent or inadequate spirometric measures of exhaled gas flow </li></ul></ul><ul><ul><li>H emodynamic changes associated with hypoxemia or hypercarbia (e.g., hypertension, tachycardia, arrhythmia) </li></ul></ul>
    8. 8. Grades of Difficult Mask Ventilation ( Kheterpal et al, 2006 ) <ul><li>Grade 1 (77.4% incidence in 22,660 cases) </li></ul><ul><ul><li>Ventilated by mask </li></ul></ul><ul><li>Grade 2 (21.1%) </li></ul><ul><ul><li>Ventilated by mask with oral airway/adjuvant with or without muscle relaxant </li></ul></ul><ul><li>Grade 3 (1.4%) </li></ul><ul><ul><li>Difficult ventilation (inadequate, unstable, or requiring two providers) with or without muscle relaxants </li></ul></ul><ul><li>Grade 4 (0.16%) </li></ul><ul><ul><li>Unable to mask ventilate with or without muscle relaxant </li></ul></ul>
    9. 9. Assessment and prediction of DMV <ul><li>Criteria for difficult mask ventilation </li></ul><ul><ul><li>Inability for one anaesthesiologist to maintain SO 2 >92% </li></ul></ul><ul><ul><li>Significant gas leak around face mask </li></ul></ul><ul><ul><li>No chest movement </li></ul></ul><ul><ul><li>Two handed mask ventilation </li></ul></ul><ul><ul><li>Change of operator required </li></ul></ul>
    10. 10. Independent risk factor for DMV <ul><ul><li>Presence of beard </li></ul></ul><ul><ul><li>BMI >27 </li></ul></ul><ul><ul><li>Lack of teeth </li></ul></ul><ul><ul><li>Age >55 </li></ul></ul><ul><ul><li>History of snoring </li></ul></ul>
    11. 11. Evaluation of airway <ul><li>Airway history </li></ul><ul><ul><li>Snoring </li></ul></ul><ul><ul><li>Chipped teath </li></ul></ul><ul><ul><li>Change in voice </li></ul></ul><ul><ul><li>Cervical spin pain or limited range of motion </li></ul></ul><ul><ul><li>Stridor </li></ul></ul><ul><ul><li>Temporomandibular joint pain or dysfunction </li></ul></ul><ul><ul><li>Significant or prolonged sore throat after previous anaethetic </li></ul></ul><ul><ul><li>Previous anaesthetic record </li></ul></ul><ul><ul><li>Congenital and acquired syndrome </li></ul></ul>
    12. 12. Evaluation of airway <ul><li>Physical evaluation </li></ul><ul><ul><li>Simple bed side evaluation tools </li></ul></ul><ul><li>Endoscopic examination </li></ul><ul><li>Radiological examination </li></ul>
    14. 14. Patient can not touch tip of chin to chest or cannot extend neck Range of motion of head and neck Thick Thickness of neck Short Length of neck Stiff, indurated , Occupied with mass Compliance of mandibular space High arched or very narrow Shape of palate Less than 3 cm Inter incisor distance Patient can not bring mandibular incisors in front Relation of maxillary and mandibular incisors during voluntary protusion of mandible Prominent “overbite” (maxillary incisors anterior to mandibular incisors) Relation of maxillary and mandibular incisors during normal jaw closure Relatively long Length of upper incisors Non reassuring Findings Airway Examination Component
    15. 15. Mallampati classification <ul><li>Modified by Samsoon and young </li></ul><ul><li>Estimate size of tongue relative to oral cavity </li></ul><ul><li>Mouth opening </li></ul><ul><li>Test influenced by </li></ul><ul><ul><li>Size and mobility of tongue </li></ul></ul><ul><ul><li>Movement at at craniocervical junction </li></ul></ul><ul><ul><li>Phonation </li></ul></ul>
    16. 16. Mallampati Classification
    17. 17. Thyromental distance <ul><li>Indicator of mandibular space </li></ul><ul><li>Displacement of tongue by blade would be easy or difficult </li></ul><ul><li>Short thyromental distance leads to an acute angle between pharyngeal and laryngeal axis. </li></ul><ul><li>Head maximally extended position </li></ul><ul><li>Cutoff criterion ≤ 6 </li></ul>
    18. 19. Sternomental distance <ul><li>Indicator of head and neck mobility </li></ul><ul><li>Cut off point 12.5 to 13.5 cm </li></ul><ul><li>Few studies done </li></ul>
    19. 20. Mouth opening <ul><li>Indicate movement of temporo mandibular joint (TMJ) </li></ul><ul><li>Inter incisor distance </li></ul><ul><li>Inter alveoulus distance in edentulous </li></ul>
    20. 21. Head and neck movement <ul><li>Range of motion </li></ul><ul><li>Normally 35 degree of extension </li></ul><ul><li>Class I ---- No reduction of exten sion </li></ul><ul><li>Class II --- 1/3 reduction </li></ul><ul><li>Class III – 2/3 reduction </li></ul><ul><li>Class IV –Complete reduction </li></ul>
    21. 23. 69.0 99.8 4.5 History of difficult intubation 11.8 94.6 11.1 Body weight >110 20.6 95.8 16.5 Inability to prognath 29.5 98.4 10.4 Neck movement <80 21 89.0 44.7 Mallampati Class III 38.5 99.2 7 Thyromental distance (<6cm) 25 94.8 26.3 Mouth opening (<4cm) Positive predictive value Specificity % Sensitivity%
    22. 24. Functional airway assessment (FAA) <ul><li>FAA is a method of examining the functional nature of each of the anatomicall y correlates of the commonly used assessment indices. </li></ul><ul><li>Emphasis on interdependence of these anatomic characterstics </li></ul>
    23. 25. Management of airway <ul><li>Pre oxygenation </li></ul><ul><li>Appropriate selection of face mask </li></ul><ul><li>Patients with normal lung compliance 20 to 25 cm H2O pressure adequate </li></ul><ul><ul><li>If not consider </li></ul></ul><ul><ul><ul><li>Two handed mask </li></ul></ul></ul><ul><ul><ul><li>Adjust mask </li></ul></ul></ul><ul><ul><ul><li>Airways </li></ul></ul></ul><ul><li>Appropriate position of patient </li></ul>
    24. 26. Aligning Axes of Upper Airway Extend-the-head-on-neck (“look up”): aligns axis A relative to B Flex-the-neck-on-shoulders (“look down”): aligns axis B relative to C C A B A B C Trachea Pharynx Mouth
    25. 27. Maneuvers to improve laryngeal view <ul><li>BURP </li></ul><ul><li>Optimal external laryngeal manipulation (OELM) </li></ul>
    26. 28. INTUBATION (Requirement) <ul><li>First attempt is always the best attempt </li></ul><ul><li>Most skilled anaesthetist should intubate in critically ill patients </li></ul><ul><li>Effective plan and back up plan A,B,C,D </li></ul><ul><li>Maintenance of oxygenation takes priority in each plan </li></ul><ul><li>Limit intubation attempts </li></ul>
    27. 29. INTUBATION (Requirement) <ul><li>Equipment for intubation </li></ul><ul><li>Equipment for ventilation </li></ul><ul><li>Equipment for difficult intubation </li></ul><ul><li>Confirmatory equipment </li></ul>
    28. 30. Choice of blade <ul><li>Macintosh </li></ul><ul><ul><li>Stimulate vallecula </li></ul></ul><ul><ul><li>Small mouth </li></ul></ul><ul><li>Miller </li></ul><ul><ul><li>Stimulate epiglottis </li></ul></ul><ul><ul><li>Small mandibular space </li></ul></ul><ul><ul><li>Large incisor </li></ul></ul><ul><ul><li>Large epiglottis </li></ul></ul>
    29. 31. Mc Coy Laryngoscope
    30. 33. Cormack and Lehane <ul><li>Grades of Difficult Laryngoscopy: </li></ul><ul><li>Grade I : Most of glottis is seen </li></ul><ul><li>Grade II : Only posterior portion of glottis can be seen </li></ul><ul><li>Grade III : Only tip of epiglottis may be seen </li></ul><ul><li> (ASA Task Force &quot;difficult.&quot;) </li></ul><ul><li>Grade IV : Neither epiglottis nor glottis can be seen, only soft palate </li></ul><ul><li> (ASA Task Force &quot;difficult.&quot;) </li></ul>
    31. 34. ASA Difficult airway algorithm <ul><li>Developed by ASA task force in 1993 </li></ul><ul><li>Revised in 2003 </li></ul><ul><li>Model for </li></ul><ul><ul><li>Anaesthesiologist </li></ul></ul><ul><ul><li>Emergency medicine </li></ul></ul><ul><ul><li>Physician </li></ul></ul><ul><ul><li>Prehospital personnel </li></ul></ul>
    32. 36. Difficult airway (ASA Algorithm) <ul><li>Assess the likely hood and clinical impact of basic management problems: </li></ul><ul><ul><li>Difficult ventilation </li></ul></ul><ul><ul><li>Difficult intubation </li></ul></ul><ul><ul><li>Difficulty with patient cooperation and consent </li></ul></ul><ul><ul><li>Difficult tracheostomy </li></ul></ul><ul><li>Actively pursue oppurtunities to deliver supplemental oxygen throughout the process of difficult airway management </li></ul><ul><li>Consider the relative merits and feasibility of basic management choices: </li></ul>Awake intubation Intubation attempt after induction of general anaesthesia Non invasive initial approach for intubation Invasive initial approach for intubation Preservation of spontaneous ventilation Ablation of spontaneous ventilation
    33. 37. Awake intubation BOX A Airway approached by non invasive intubation Invasive airway access Succeed Fail Cancel Consider feasibility of Other options Invasive airway access
    34. 38. Awake intubation <ul><li>Explain to the patient </li></ul><ul><li>Prepare physically and mentally </li></ul><ul><li>Mild sedation with midazolam, </li></ul><ul><li>Titrate Opioids for sedation and anti tussive effect </li></ul><ul><li>Anti sialogogue, </li></ul><ul><li>Vasoconstriction of nasal passages </li></ul><ul><li>Local anaesthetics </li></ul><ul><ul><li>Base of tongue to bronchi </li></ul></ul>
    35. 39. Airway
    36. 41. BOX B
    38. 44. Gum Elastic Bougie (Eschmann tracheal tube introducer)
    39. 45. Laryngeal Mask Airway( LMA )
    40. 46. LMA position
    41. 47. Intubating LMA
    42. 48. Esophageal-Tracheal Combitube
    43. 49. Esophageal-Tracheal Combitube Inserted in Esophagus A = esophageal obturator; ventilation into trachea through side openings = B D = pharyngeal cuff (inflated) F = inflated esophageal/tracheal cuff H = teeth markers; insert until marker lines at level of teeth D A D B F H
    44. 50. FIBEROPTIC
    47. 54. Conclusion <ul><li>No test is likely to be perfect, therefore,it remains essential that every anaesthetist must be trained and equipped to deal with the now much less common, unexpected failure to intubate. </li></ul>
    48. 55. Thank You