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.
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
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 Dr. Mohammad Hamid Assistant Professor Department of Anaesthesia Aga khan university Hospital
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
Patients with normal lung compliance 20 to 25 cm H2O pressure adequate
If not consider
Two handed mask
Appropriate position of patient
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
Assess the likely hood and clinical impact of basic management problems:
Difficulty with patient cooperation and consent
Actively pursue oppurtunities to deliver supplemental oxygen throughout the process of difficult airway management
Consider the relative merits and feasibility of basic management choices:
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
Awake intubation BOX A Airway approached by non invasive intubation Invasive airway access Succeed Fail Cancel Consider feasibility of Other options Invasive airway access
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