Speaker: Dr. Shafat A MirDepartment of Anaesthesia And Critical Care SKIMS ,Srinagar,j&k.India.
“Airway Management remains as much art as science” Perhaps the most important responsibility of the anesthesiologist is “management of the patient‟s airway”.
What should we know about “airwaymanagement”?● Airway anatomy and function● Evaluation of airway● Clinical management of the airway - Maintenance and ventilation - Intubation and extubation - Difficult airway management
The term “airway” refers to the upperairway consisting of● Nasal and oral cavities● Pharynx● Larynx● Trachea● Principal bronchi
Tongue Lingual Tonsil Base of tongue Epiglottis Vallecula Aryepiglottic fold Vestibular folds (False Vocal Cords) Glottis True Vocal Cords Arytenoid CartilageCorniculate Cartilage Esophagus View of the base of the tongue, vallecula, epiglottis, and vocal cords.
1. History2. Physical examination3. Special Investigations
History:• Previous history of difficult airway• Airway-related untoward events• Airway-related symptoms/diseases
Signs And Symptoms related to theairway that should be sought:Snoring (obstructive sleep apnoea)Changes in voiceStridorDysphagiaChipped teethCervical spine pain or limited range of motionUpper extremity neuropathyTMJ pain or dysfunction
Evaluation of the AirwayGeneral Physical ExaminationIdentify obvious problems such as:•Massive obesity•Short muscular neck•Cervical collars•Traction devices•External trauma•Indications of respiratory difficulty such as stridor.•The presence of ear and hand anomalies
General airway assessment:• Patency of nares• Mouth opening• Teeth• Palate• Ability to prognath• Temporo-mandibular joint movement
Syndrome DescriptionDown Large tongue, small mouth make laryngoscopy difficult; Small subglottic diameter possible Laryngospasm is commonGoldenhar ( oculo-auriculo vertebral Mandibular hypoplasia and cervical spineanomalies abnormality make laryngoscopy difficult.Klippel Fiel Neck rigidity because of cervical vertebral fusionPierre Robin Small mouth, large tongue, mandibular anomaly; awake intubation essential in neonateTreacher Collins (mandibulofacial Laryngoscopy is difficult.dysostosis)Turners High likelihood of difficult intubation
Specific tests for assessment of airway:A. Anatomical criteria1. Relative tongue/pharyngeal sizeMallampatti test:
A. Class I : Visualization of the soft palate, fauces; uvula, anterior andthe posterior pillars.B. Class II : Visualization of the soft palate, fauces and uvula.C. Class III : Visualization of soft palate and base of uvula.In Samsoon and Young’s modification (1987) of the Mallampaticlassification, a IV class was added.D. Class IV: Only hard palate is visible. Soft palate is not visible at all.
2. Atlanto occipital joint (AO) extension :Grade I : >35°Grade II : 22°-34°Grade III : 12°-21°Grade IV : < 12°Normal angle of extension is 35° or more
3. Mandibular space:i . Thyromental (T-M) distance (Patil’s test): This measurement helps indetermining how readily the laryngeal axis will fall in line with the pharyngeal axiswhen the atlanto-occipital joint is extended. Alignment of these two axes is difficult ifthe T-M distance is < 3 finger breadths or < 6 cm in adults; 6-6.5 cm is less difficult,while > 6.5 cm is normal.i i . Sterno-mental distance : Savva (1948) estimated the distance from thesuprasternal notch to the mentum. It is measured with the head fully extended on theneck with the mouth closed. A value of less than 12 cm is found to predict a difficultintubation.i i i . Mandibulo-hyoid distance: Measurement of mandibular length fromchin (mental) to hyoid should be at least 4 cm or three finger breadths. It was foundthat laryngoscopy became more difficult as the vertical distance between the mandibleand hyoid bone increased.iv. Inter-incisor distance : It is the distance between the upper and lowerincisors. Normal is 4.6 cm or more; while > 3.8 cm predicts difficult airway.
LEMON airway assessment method :The score with a maximum of 10 points is calculated by assigning 1 point for each of thefollowing LEMON criteria:L = Look externally (facial trauma, large incisors, beard or moustache, largetongue).E = Evaluate the 3-3-2 rule (incisor distance-3 finger breadths, hyoid-mentaldistance-3 finger breadths, thyroid-to-mouth distance-2 finger breadths).M = Mallampati (Mallampati score > 3).O = Obstruction (presence of any condition like epiglottitis, peritonsillar abscess,trauma).N = Neck mobility (limited neck mobility).Patients in the difficult intubation group have higher LEMON scores.
Radiographic assessment1. From skeletal filmsLateral cervical x-ray film of the patients with head in neutral position closed isrequired for the following measurement:i . Mandibulo-hyoid distance :An increase in the mandibulo-hyoid distance resulted in an increase in difficultlaryngoscopy.i i . Atlanto-occipital gap : A-O gap is the major factor which limits the extension of head on neck. Longer theA-O gap, more space is available for mobility of head at that joint with good axisfor laryngoscopy and intubation. Radiologically there is reduced space between C1and occiput.i i i . Relation of mandibular angle and hyoid bone with cervicalvertebra and laryngoscopy grading : A definite increase in difficult laryngoscopy was observed when the mandibularangle tended to be more rostral and hyoid bone to be more caudal, position ofmandibular angle being more important.
iv. Anterior/Posterior depth of the mandible :White and Kander (1975)18 have shown that the posterior depth of themandible i.e, the distance between the bony alveolus immediately behindthe 3rd molar tooth and the lower border of the mandible is an importantmeasure in determining the ease or difficulty of laryngoscopy.v. Calcified ligaments:Calcified stylohyoid ligaments are manifested by crease over hyoid boneson radiological examination. Laryngoscopy is difficult because of inabilityto lift the epiglottis from posterior pharyngeal wall as it is firmly attachedto the hyoid bone by the hyo-epiglottic ligament.
Fluoroscopy for dynamic imaging (cord mobility,airway malacia, and emphysema).Oesophagogram (inflammation, foreign body,extensive mass or vascular ring).Ultrasonography (assessment of anterior mediastinalmass, lymphadenopathy, differentiates cyst from mass andcellulitis from abscess).Computed tomography/MRI (congenital anamolies,vascular airway compression).Video-optical intubation stylets (combines viewingcapability with the familiar handling of intubationdevices).
Wilson and colleagues developed another scoring system inwhich they took 5 variables. Risk score was developed between 0to 10. They found that higher the risk score, greater the accuracy ofprediction with a lower proportion of false positives.
Predictors of difficult airway in diabeticsPredictors of difficult airway are not the same in diabetics as in non-diabeticgroups.i . Palm print:The patient is made to sit;, palm and fingers of right hand are painted withblue ink, patient then presses the hand firmly against a white paper placed ona hard surface.It is categorized as:Grade 0 – All the phalangeal areas are visible.Grade 1 – Deficiency in the interphalangeal areas of the 4th and 5th digits.Grade 2 – Deficiency in interphalangeal areas of 2nd to 5th digits.Grade 3 – Only the tips of digits are seen.i i . Prayer sign: Patient is asked to bring both the palms together as„Namaste‟ and sign is categorized as–Positive – When there is gap between palms.Negative – When there is no gap between palms.
Clinical Management of the Airway Recognizing Upper Airway Obstruction • Hoarse voice • Decreased air in and out • Stridor • Retraction of suprasternal /supraclavicular/intercostal space • Tracheal tug • Restlessness • Cyanosis
Indication for tracheal intubation● Airway protection● Maintenance of patent airway● Pulmonary toilet● Application of positive pressure● Maintenance of adequate oxygenation
• Checked anaesthesia machine (or oxygen source and self-inflating resuscitator)• Range of anaesthesia masks, LMAs, oropharyngeal and nasopharyngeal airways• Two checked laryngoscope handles• Range of laryngoscope blades (Macintosh and straight)• Range of tracheal tubes• Stylet and introducer• Syringe for cuff inflation• Lubricant jelly• Suction apparatus• Magill forceps• Tape to secure tube• Capnograph
Schematic diagram demonstratingthe head position for endotrachealintubation.A.Successful direct laryngoscopyfor exposure of the glottic openingrequires alignment of the oral,pharyngeal, and laryngeal axes.B.Elevation of the head about 10cm with pads below the occiputand with the shoulders remainingon the table aligns the laryngealand pharyngeal axes.C. Subsequent head extension atthe atlanto-occipital jointcreates the shortest distance andmost nearly straight line from theincisor teeth to glottic opening.
Proper position of the laryngoscope blade during direct laryngoscopy for exposure of the glottic opening.A, The distal end of the curved blade is B, The distal end of the straight bladeadvanced into the space between the (Jackson-Wisconsin or Miller) is advancedbase of the tongue and pharyngeal beneath the laryngeal surface of the epiglottis.surface of the epiglottis (i.e., vallecula).Regardless of blade design, forward and upward movement exerted along the axis of thelaryngoscope blade (arrows) elevates the epiglottis and exposes the glottic opening.
Optimum laryngeal view achieved withthe Macintosh laryngoscope. In thisfigure the epiglottis has been allowed todrop a little posteriorly to show thelaryngoscope in position in the vallecula.
Optimization of view at direct laryngoscopy• Maximum head extension• Tongue entirely to the left of the laryngoscope• Maximum mouth opening• Optimum depth of laryngoscope insertion• Maximum lifting force applied in the correctdirection• ELM – applied with anaesthetist’s own righthand• Lift occiput with right hand• Mandibular protrusion by assistant
Visual confirmation of tracheal intubationwith the straight laryngoscope
Confirmation of tracheal intubation •Techniques not requiring manual ventilation •Inspection of the vocal cords •Palpation of the trachea •Use of esophageal detector device •Techniques requiring manual ventilation •Sounds •Compliance •Inspection of the chest •Auscultation of the chest •Auscultation of the epigastrium •CO2 Detection •Capnography •Endoscopy •Radiography
Examples of the most frequently used detachable laryngoscope blades,which can be used interchangeably on the same handle. The upper blade isthe straight or Jackson-Wisconsin design. The middle blade incorporates acurved distal tip (Miller). The lower blade is the curved or MacIntoshblade. All three blades are available in lengths appropriate for neonates andadults.
Laryngoscopes used with Macintosh technique.Left to right are: Standard Macintosh (size 4), McCoy with tip elevatedand left-entry Macintosh. The styleted tracheal tube has been preformedin the shape of an ice-hockey stick. The stylet must be plastic coated andmust not protrude beyond the tip of the tracheal tube.
Laryngoscopes used with paraglossal straight laryngoscopytechnique. Left to right: Miller, Belscope, Piquet-Crinquette-Vilette (PCV) and Henderson.Although the PCV has a gentle curve, it is possible to obtain aLOS through the lumen. The PCV and Henderson have a semi-tubular cross-section to facilitate passage of the tracheal tube.
Diagrammatic representation of key distances relating to endotracheal tube position.
Employed for patients at a particular risk for aspiration &there is reasonable certainty that intubation should not be difficultFull stomach (<8-hour fast)TraumaIntra-abdominal pathology Intestinal obstruction, inflammation Gastric paresis (drugs, diabetes, uremia, infection)Esophageal disease Symptomatic reflux Motility disordersPregnancyObesityUncertainty about intake of food or drink
1.Preoxygenation2.Induction, Paralysis And Cricoid Pressure.3.Confirmation of correct tube position.
Techniques for difficult intubationAlternative laryngoscope bladesAwake intubationBlind intubation (oral or nasal)Fiberoptic intubationIntubating stylet or tube changerLaryngeal mask airway as anintubating conduitLight wandRetrograde intubationInvasive airway access
Suggested Contents of the Portable Storage Unit for Difficult Airway Management1. Rigid laryngoscope blades of alternate design and size from thoseroutinely used; this may include a rigid fiberoptic laryngoscope2. Tracheal tubes of assorted sizes3. Tracheal tube guides. Examples include (but are not limited to) semirigidstylets, ventilating tube changer, light wands, and forceps designed tomanipulate the distal portion of the tracheal tube4. Laryngeal mask airways of assorted sizes; this may include the intubatinglaryngeal mask airway and the LMA-ProsealTM5. Flexible fiberoptic intubation equipment6. Retrograde intubation equipment7. At least one device suitable for emergency noninvasive airway ventilation.Examples include (but are not limited to) an esophageal trachealCombitube, a hollow jet ventilation stylet, and a transtracheal jet ventilator8. Equipment suitable for emergency invasive airway access (e.g.,cricothyrotomy)9. An exhaled CO2 detector
Insertion of the laryngeal mask airway (LMA). A, The tip of the cuff is pressed upward against thehard palate by the index finger while the middle finger opens the mouth. B, The LMA is pressedbackward in a smooth movement. Notice that the nondominant hand is used to extend the head. C,The LMA is advanced until definite resistance is felt. D, Before the index finger is removed, thenondominant hand presses down on the LMA to prevent dislodgment during removal of the indexfinger. The cuff is subsequently inflated, and outward movement of the tube is often observed duringthis inflation.
Insertion of the Combitube.A.The tongue and mandibleare lifted with one hand,and the Combitube isinserted in the direction ofthe natural curvature of thepharynx with the otherhand. The printed ring isaligned with the teeth. B,The pharyngeal cuff isinflated with 100 mL of air,and the distal cuff isinflated with 15 mL. C.Ventilation is begunthrough the longer no. 1tube because placement isusually in the esophagus.D. If ventilation is absentand the stomach is beinginsufflated, beginventilation through the no.2 connecting tube.
Steps in emergency needle cricothyroidotomy• Extend the chin and neck to improve access• Place syringe on needle/cannula.• Identify CTM and stabilize larynx with onehand.• Insert needle through the CTM, aspiratingto confirm intratracheal location• Once in the trachea keep needle still• Slide cannula off inserted needle• Remove needle only when cannula fullyinserted• Aspirate free air through cannula toconfirm correct placement• Secure the cannula with hand initially orties around neck later• Apply short burst of high-pressure oxygen• Watch chest rise appropriately and fall• Maintain upper airway patency withlaryngeal mask or oral airway for exhalation