2Anesthesia for patients with compromised airway Adel Mikhail Fahmy, MDAssistant professor of AnesthesiaAin Shams University
3Goals of airway management 1Oxygenation2Ventilation3Protection of the airway from injury
4Some factors in airway evaluation HistoryPrevious difficulty during intubationDental traumaTracheostomy scarMouth opening (3 cm or more)TMJ diseasesTrismusMallampati classIIIIIIIV
5Two Important Airway Classifications: A Cormack and Lehane classification of the view at laryngoscopy. Grade I: most of the glottis is seen Grade II: only posterior portion of glottis can be seen Grade III: only epiglottis seen (none of glottis seen) Grade IV: neither epiglottis nor glottis can be seen B Mallampati classification of the oropharyngeal view; done with patient sitting, the head in the neutral position, the mouth wide open, and the tongue protruding to the maximum. Class I: visualization of the soft palate, fauces, uvula, anterior and posterior pillars. Class II: visualization of the soft palate, fauces and uvula. Class III: visualization of the soft palate and base of uvula. Class IV: soft palate is not visible.
6Some factors in airway evaluation Thyro-mental distance(6 cm or more)TeethEdentulous patientsProminent teethTongueLargeImmobileedematous
7Some factors in airway evaluation Neck thicknessThick neck can cause difficult airwayHead mobilityLimited neck extension can lead to poor laryngeal viewMandibular protrusion & submandibular tissue compliance
8What is the difficult airway? Difficult intubation:Inability to intubate within a certain time (10 min).Inability to intubate within a number of attempts at direct laryngoscopy (3).Cormack and Lehane Grade 3 or 4 view of larynx (epiglottis only or no laryngeal structures).Requirement for additional equipment other than traditional laryngoscope.Difficult ventilation:Inability to keep oxygen saturation > 90% with 100% oxygen by facemask.Catastrophic failure of mask ventilation leads to morbidity or mortality.
9Causes of Difficult Airway: I. Non-patient factors:Who is intubating and who helps him.Where is the intubation technique performed.What are the equipment and drugs used.What is the position of the patient during intubation.
10Causes of Difficult Airway: II. Patient factors:Stiffness/deformities: (Immobility of the neck or inability to open the mouth) Arthritis, ankylosing spondylitis, scleroderma, burn or radiotherapy contractures and cranio-cervical fixation devices. Also, oral submucous fibrosis and joint stiffness in DM.Swelling: morbid obesity, infections e.g. epiglottitis or Ludwig’s angina, tumors, trauma e.g. post-surgical oedema or hematoma, neck swellings e.g. thyroid & mediastinal tumors, lingual tonsils.
11Limited mouth opening as a result of TMJ disease
12Stiffness. Rheumatoid arthritis affecting cervical spine and temporomandibular joint
13Obese individuals may be both difficult to ventilate and also difficult to intubate as a result of redundant folds of oropharyngeal tissue and decreased chest wall compliance
14Glottic rheumatoid arthritis Glottic rheumatoid arthritis. The arytenoids and ary-epiglottic folds are swollen and the airway is narrow
18Causes of Difficult Airway: II. Patient factors:Foreign bodies: Accidental inhalation in children or alcoholic adults, dentures, vomiting & aspiration of solids and liquids during induction of anesthesia.High tariff: uncooperative patients, full stomach, difficult venous access, and VIPs. These stressful factors can degrade performance.
19Two classic difficult airways: Rheumatoid arthritis:Cranio-cervical junction involved.Temporo-mandibular joint involved.Glottic stenosis.Direct laryngoscopy often difficult.Stridor common on extubation.Acromegally:Tissue hypertrophy.Mask ventilation can be difficult.Direct laryngoscopy can be difficult.Complete obstruction on extubation.
20Procedural classification: Mask anesthesia: Having to use 2 hands to control the airway, with an assistant squeezing the bag, and oral and nasal airways in situ is defined as difficult airway.Predictors of Difficult Mask Ventilation• Age over 55 years• Body mass index exceeding 26 kg/m2• Presence of a beard• Lack of teeth (edentulous)• History of snoring
21Procedural classification: Difficult LMA insertion: Insertion of LMA becomes more difficult when mouth opening is restricted. The lower limit of normal mouth opening in young adults is 3.7 cm, but LMA can be inserted with about 2.5 cm of inter-incisor distance.
22Procedural classification: Difficult direct laryngoscopy: This is used to be referred to as the difficult airway. A difficult direct laryngoscopy patient may be easily intubated with a fiberoptic endoscope.The Cormack and Lehan system:Grade 1: the whole glottis is seen till the anterior commissure.Grade 2a: part of the vocal cords is visible.Grade 2b: only the arytenoids are visible.Grade 3: only the epiglottis is visible.Grade 4: No glottic structure is visible.N.B: Grade 2b and many of grade 3 patients can be intubated with the aid of a gum-elastic bougie.
23Two Important Airway Classifications: A Cormack and Lehane classification of the view at laryngoscopy. Grade I: most of the glottis is seen Grade II: only posterior portion of glottis can be seen Grade III: only epiglottis seen (none of glottis seen) Grade IV: neither epiglottis nor glottis can be seen B Mallampati classification of the oropharyngeal view; done with patient sitting, the head in the neutral position, the mouth wide open, and the tongue protruding to the maximum. Class I: visualization of the soft palate, fauces, uvula, anterior and posterior pillars. Class II: visualization of the soft palate, fauces and uvula. Class III: visualization of the soft palate and base of uvula. Class IV: soft palate is not visible.
24DIFFICULT AIRWAY EMERGENCY KIT 1. Rigid laryngoscope blades of alternate design and size from those routinely used; this may include a rigid fiberoptic laryngoscope (e.g., Bullard laryngoscope). 2. Tracheal tubes of assorted sizes. 3. Tracheal tube guides. Examples include (but are not limited to) semirigid stylets, ventilating tube changer, and forceps (e.g., McGill forceps) designed to manipulate the distal portion of the tracheal tube. 4. Laryngeal mask airways of assorted sizes; this may include the intubating laryngeal mask airway.
25DIFFICULT AIRWAY EMERGENCY KIT 5. Flexible fiberoptic intubation equipment. 6. Retrograde intubation equipment. (e.g., kit from Cook) 7. At least one device suitable for emergency noninvasive airway ventilation. Examples include (but are not limited to) an esophageal tracheal combitube (Tyco Healthcare Nellcor Mallinckrodt, Pleasanton, CA, a hollow jet ventilation stylet and a transtracheal jet ventilator. 8. Equipment suitable for emergency invasive airway access (e.g., Melker cricothyrotomy kit from Cook). 9. An exhaled CO2 detector.
27McCoy Laryngoscope with an articulating tip that can be used to lift a big epiglottis out of the way.
28CAN VENTILATE, CAN’T INTUBATE • Ensure help is available and pulse oximeter and capnography are in place before starting. • Preoxygenate generously. • Make sure head position is optimized (“sniffing position”). • Note the “grade” of view at laryngoscopy. (This will be needed when you write a note in the patient’s chart about why the patient was difficult to intubate.) • Ensure normocapnia and adequate depth of anesthesia between intubating attempts.
29CAN VENTILATE, CAN’T INTUBATE • Decide how to approach your second attempt. Would a larger blade (e.g., MAC 4) help? Would a straight blade (e.g., Miller) help? Would a McCoy blade help lift the epiglottis out of the way? Would a Gum Elastic Bougie help? Would external laryngeal manipulation help to move the larynx into a less anterior position? • You are allowed one final third attempt. Wisdom may dictate that you give this chance to an experienced anesthesiologist.
30CAN VENTILATE, CAN’T INTUBATE • If the patient can’t be intubated after three tries, allow the patient to awaken and proceed with awake intubation using a FOB technique. • Alternatives to consider: Trachlight; Gum Elastic Bougie (Echman stylet); Insert intubating LMA (Fastrach); Insert an LMA ProSeal or a Combitube to allow application of high ventilatory pressures and to help prevent aspiration; Use a Syracuse-Patil face mask to facilitate fiberoptic intubation (keeping patient asleep); Retrograde intubation technique
33Bail-Out" Algorithm CAN’T VENTILATE WELL CAN’T INTUBATE To awaken patient after failed intubation, where ventilation is difficult. This is a setting where you simply want the patient to wake up and breathe spontaneously. 1. Ensure that the patient is not in laryngospasm and that the patient’s head and jaw are positioned properly. Call for help. Insert an airway of some kind • oral airway • nasopharyngeal airway • LMA (Laryngeal Mask Airway) • ILMA (Intubating LMA) • Combitube (especially with LMA placement failures) • Laryngeal tube 2. In some cases it will be helpful to utilize a two-person technique whereby one person manages the mask and holds the jaw in position using both hands (“jaw thrust maneuver”), while the other ventilates the patient by hand using the rebreathing bag and the emergency oxygen flush as needed. 3. As a last resort, a surgical airway (e.g., cricothyrotomy) or TTJV is sometimes needed.
34Induction of Anesthesia in patients with compromised airway
35Inhalational induction: Obstruction of the airway and loss of pulmonary ventilation causes cessation of administration of anesthetic agent and gradual re-awakening (automatic feedback).Sevoflurane has almost universally replaced halothane.Awake fiberoptic intubation:In elective surgeries of patients with known difficult airway.The awake patient maintains his or her own airway until it is secured.Awake tracheostomy:Very safe for patients with perilaryngeal tumors and stridor.
36Propofol with or without remifentanil in controlled infusion induction: Can be used for patients with difficult airways, by gradually increasing the rate of infusion to allow deepening of anesthesia, whilst maintaining spontaneous ventilation.If patient suffers central or obstructive apnea, the infusion can be stopped and rapid redistribution will allow lightening of anesthesia or full awakening.These properties – maintenance of spontaneous ventilation and redistribution during apnea – have previously been the reasons for employing inhalational induction in difficult airways.
37The advantage of inhaled agents over propofol is that, on apnea, delivery ceases immediately and automatically. Balanced against this are the advantages of propofol:suppression of airway reflexes.achievement of adequate anesthesia not affected by poor ventilation.lack of lightening of anesthesia during airway intervention.For awake fiberoptic intubation, the patient experience and ease of the technique can be improved by careful sedation with propofol or remifentanil; these may be used singly or in combination. The ultra-short acting opioid remifentanil allows easy titration and rapid reversibility of deep levels of analgesia sedation.