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Airway Management. Augusto Torres, MD Department of Anesthesiology MetroHealth Medical Center. Outline. Review of airway anatomy Airway evaluation Mask ventilation Endotracheal intubation The difficult airway. Airway Anatomy. Ab-ductor Posterior cricoarytenoid Tensor Cricothyroid
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Airway Management Augusto Torres, MD Department of Anesthesiology MetroHealth Medical Center
Outline • Review of airway anatomy • Airway evaluation • Mask ventilation • Endotracheal intubation • The difficult airway
Airway Anatomy • Ab-ductor • Posterior cricoarytenoid • Tensor • Cricothyroid • Ad-ductors • All the rest
Airway Anatomy • Innervation • Vagus n. • Superior laryngeal n. • External branch – motor to cricothyroid m. • Internal branch – sensory larynx above TVC’s • Recurrent laryngeal n. • Right – subclavian • Left – Aortic arch (board question) • Motor to all other muscles, Sensory to TVC’s and trachea
Airway Anatomy • Innervation of oropharynx • Glossopharyngeal n. innervates tongue base and oropharynx
Airway Anatomy • Membranes • Thyrohyoid • Cricothryoid • Cartilages • Hyoid • Thyroid • Cricoid
Airway Evaluation • Take very seriously history of prior difficulty • Head and neck movement (extension) • Alignment of oral, pharyngeal, laryngeal axes • Cervical spine arthritis or trauma, burn, radiation, tumor, infection, scleroderma, short and thick neck
Airway Evaluation • Jaw Movement • Both inter-incisor gap and anterior subluxation • <3.5cm inter-incisor gap concerning • Inability to sublux lower incisors beyond upper incisors • Receding mandible • Protruding Maxillary Incisors (buck teeth)
Airway Evaluation • Obesity • Distribution, i. e. short, thick neck more concerning • Neck circumference
Airway Evaluation • Thyromental distance: bony point on mentum (mandible) to thyroid notch • If short (<3FB’s or 6cm), pharyngeal and laryngeal axis off
Airway Evaluation • Oropharyngeal visualization • Mallampati Score • Sitting position, protrude tongue, don’t say “AHH”
Airway Evaluation • Difficulty ventilating • Age >55 • Beard • History of snoring • Lack of teeth • BMI >26
Preoxygenation • Replaces the nitrogen volume of the lungs (69% of FRC) with oxygen • Functional residual capacity (residual volume and expiratory reserve volume) • Preoxygenation with 100% oxygen via tight-fitting mask for 5 minutes up to 10 min of oxygen reserve following apnea • Four vital capacity breaths over 30 seconds (time to desaturation quicker)
Patient Positioning • Sniffing position • Lower neck flexion • Upper neck extension • Important in obesity
Mask Ventilation • Induction of anesthesia produces upper airway relaxation and possible collapse • Downward displacement of mask with thumb and index finger www.aic.cuhk.edu.hk
Mask Ventilation • Upward traction of remaining fingers upward • Fingers on bony mandible • Fifth digit at angle displacing mandible anteriorly www.aic.cuhk.edu.hk
Mask Ventilation • Oral airway • Two-handed technique www.aic.cuhk.edu.hk www.haworth21.karoo.net
LMA Placement • Carries prominent position in ASA algorithm • May be held like a pencil • Balloon partially inflated • Directed posteriorly and upwards towards the palate • Jaw thrust and sniffing position may help placement www.brandianestesia.it/Images/LMA-ins.jpg
LMA Placement • Verify placement by ventilating • Check for good chest rise, ETCO2, and adequate tidal volumes • Check for leak – if significant leak at around 10cm H2O problematic • May try size larger or smaller • May try to inflate/deflate cuff to obtain better seal • If difficulty passing may try inserting upside down and then flipping around
Endotracheal Intubation • Open the mouth with right hand • Scissor technique • Gently insert laryngoscope into right side of mouth pushing tongue to the left • Careful with insertion not to hit teeth • Advance laryngoscope further into oropharynx with applied traction 45 degrees
Endotracheal Intubation • Look for epiglottis • If initially not found insert laryngoscope further • If this maneuver does not work slowly pull laryngoscope back • Once epiglottis visualized, push laryngoscope into vallecula and apply traction at 45 degree angle to “push” epiglottis up and out of the way www.int-med.uiowa.edu/Research/TLIRP/Bronchos
Endotracheal Intubation • Look for vocal cords or arytenoid cartilages and try to optimize view • (i.e. lift head, apply more traction at 45 degree angle if necessary) • Do not move once view is optimized! • Assistant will hand you ETT • Insert ETT into far right aspect of mouth • Traction of laryngoscope slightly to left may assist • Traction of laryngoscope at 45 degrees will also help keep mouth open
Endotracheal Intubation • Insert ETT above and between arytenoids and through vocal cords • Try to visualize the ETT passing between the vocal cords • If this is not possible, then you must visualize the ETT passing above and between the arytenoids
Endotracheal Intubation • Common problems: • “I can’t see anything!” • Make sure tongue is swept to the left • You are probably too shallow or too deep. Even with difficult intubations the epiglottis can be visualized • Insert laryngoscope in further looking for epiglottis • Pull laryngoscope back if this fails
Endotracheal Intubation • Common problems • “I can’t see the cords!” • Epiglottis is visualized, vocal cords are not • Removing the epiglottis partly from view is necessary to visualize the vocal cords below • Push the end of the laryngoscope blade further into the vallecula and “toe up” • Lifting the patient’s head with your other hand may improve the sniffing position and bring the vocal cords into view
Endotracheal Intubation • Common problems • “I can see the cords. But I can’t get the tube there!” • You may not be giving yourself adequate room in the oral cavity • Push up and to the left with the laryngoscope to make sure the mouth is still fully opened and the tongue adequately swept away • Slide the ETT in the mouth all the way to the right side, perhaps even sideways
Difficult Intubation • ASA Difficult Airway Algorithm • www.metrohealthanesthesia.com
Fiberoptic Intubation • Oral or nasal routes • Topicalization is key • Aerosolized lidocaine 4% • Airway blocks • Thin bronchoscope inserted into trachea
Other airway options • GlideScope • Needle cricothyroidotomy
Conclusion • Airway management is an extremely important aspect of the practice of anesthesiology and critical care • A firm basis in airway anatomy is needed • Skills such as mask ventilation, endotracheal intubation, LMA placement are necessary • In the case of a difficult airway, a logical algorithm and airway equipment assist the physician in safely managing the situation