MANAGEMENT




•  Injury of SLN (external branch) → hoarseness


•  Injury of RLN → unilateral paralysis → paralysis of ipsilateral vocal cord → hoarse voice; bilateral paralysis → stridor & respiratory distress


Airway Assessment


•  History


• Adverse events related to prior airway management


• Radiation/surgical history


• Burns/swelling/tumor/masses


• Obstructive sleep apnea (snoring)


• Temporomandibular joint dysfunction


• Dysphagia


• Problems with phonation


• C-spine disease (disk dz, osteoarthritis, rheumatoid arthritis, Down’s syndrome)


•  Physical examination


• Mallampati score (see also Chapter 1, Preoperative Assessment)


• Symmetry of mouth opening


• Loose/missing/cracked/implanted teeth


• Macroglossia (associated with difficult laryngoscopy)


• High-arched palate (associated with difficulty visualizing larynx)


• Mandible size


• Thyromental distance <3 fingerbreadths suggests poor laryngeal visualization


• Neck examination


• Prior surgeries/tracheostomy scars


• Abnormal masses (hematoma, abscess, goiter, tumor) or tracheal deviation


• Neck circumference & length


• Range of motion (flexion/extension/rotation)




Airway Devices


•  Oral and nasal airways


• Typically inserted secondary to loss of upper airway muscle tone in anesthetized patients → usually caused by tongue or epiglottis falling against posterior pharyngeal wall


• Length of nasal airway estimated by measuring from nares to meatus of ear


• Use caution with insertion in pts on anticoagulation or with basilar skull fractures


•  Mask airway


• Facilitates O2 delivery (denitrogenation) as well as anesthetic gas using airtight seal


• Hold mask with left hand while right hand generates positive-pressure ventilation → (use <20 cm H2O to avoid gastric inflation)


• One-handed technique


• Fit snugly around bridge of nose to below bottom lip


• Downward pressure with left thumb & index finger, middle, & ring finger; grasp the mandible while pinky finger is placed under angle of jaw to thrust anteriorly


• Two-handed technique


• Used in difficult ventilatory situations


• Bilateral thumbs hold mask down while fingertips displace jaw anteriorly


• Edentulous patients may be a challenge to ventilate (difficult to create a mask seal) → consider leaving dentures in place, oral airway, buccal cavity gauze packing


•  Difficult mask ventilation: Maneuvers to maintain airway patency


• Call for additional help (have someone else squeeze bag)


• Insert oral and or nasal airways


• Extend neck & rotate head


• Perform jaw thrust



•  Supraglottic airways (laryngeal mask airways)


• Insertion technique:


• Patient placed in sniffing position


• Deflated LMA cuff is lubricated & inserted blindly to hypopharynx


• Cuff is inflated to create a seal around entrance to larynx


(Tip rests over upper esophageal sphincter, cuff upper border against base of tongue, sides lying over pyriform fossae)


• Indications


• Alternative to endotracheal intubation (not as a replacement) or mask ventilation


• Rescue device in expected/unexpected difficult airway


• Conduit for intubating stylet, flexible FOB, or small diameter ET


• Contraindications: Pharyngeal pathology, obstruction, high aspiration risk, low pulmonary compliance (need peak inspiratory pressures >20 cm H2O), long surgeries


• Disadvantages: Do not protect the airway, can become dislodged



• Endotracheal tubes (ETTs)


• Used to deliver anesthetic gas directly to trachea & provide controlled ventilation


• Modified for a variety of specialized applications: Flexible, spiral-wound, wire-reinforced (armored), rubber, microlaryngeal, oral/nasal RAE (preformed), double-lumen tubes


• Airflow resistance depends on tube diameter, curvature, length


• All ETTs have an imprinted line that is opaque on radiographs



•  Rigid laryngoscopes: Used to examine larynx & facilitate tracheal intubation


• Macintosh blade (curved): Tip inserted into vallecula; use size 3 blade for most adults


• Miller blade (straight): Tip inserted beneath laryngeal surface of epiglottis; use size 2 blade for most adults


• Modified laryngoscopes: Wu, Bullard, & Glidescope for use in difficult airways


•  Flexible fiberoptic bronchoscopes


• Indications: Potentially difficult laryngoscopy/mask ventilation, unstable cervical spines, poor cervical range of motion, TMJ dysfunction, congenital/acquired upper airway anomalies


•  Light wand


• Malleable stylet with light emanating from distal tip, over which ETT is inserted


• Dim lights in OR & advanced wand blindly


• Glow in lateral neck → tip in piriform fossa


• Glow in the anterior neck → correctly positioned in trachea


• Glow diminishes significantly → tip likely in esophagus


•  Retrograde tracheal intubation


• Performed in awake & spontaneously ventilating pts


• Puncture cricothyroid membrane with 18-gauge needle


• Introduce guidewire & advanced cephalad (use 80 cm, 0.025 in. wire)


• Visualize wire with direct laryngoscopy & guide ETT through vocal cords


•  Airway bougie


• Solid or hollow, semimalleable stylets usually passed blindly into trachea


• ETT is threaded over bougie into trachea; can feel “clicking” as passes over tracheal rings


• May have internal lumen to allow for insufflation of O2 & detection of CO2


•  Video laryngoscopes (Glidescope®, Storz® V-Mac™, and McGrath®)


• Usually a MAC style blade with a camera at the distal tip attached to a mobile video screen


• Assists with anterior airways, useful in obese pt; usually improves the view of the glottic opening; however, sometimes difficult to pass the ETT, unless a curved stylette is utilized



AIRWAY MANAGEMENT: OROTRACHEAL INTUBATION


•  Elevate height of bed to laryngoscopist’s xiphoid process


•  Place patient in sniffing position: Neck flexion, head extension; aligns oral, pharyngeal, & laryngeal axes to provide the straightest view from lips to glottis


•  Preoxygenate with 100% O2


•  Induce anesthesia


•  Tape pt’s eyes shut to prevent corneal abrasions


•  Hold laryngoscope in left hand, scissoring mouth with right thumb & index finger


→ Insert laryngoscope in right side of mouth, sweeping tongue to left


→ Advance until glottis appears in view


→ Never use laryngoscope as a lever in a pivoting motion (instead lift “up and away”)


•   Using the right hand, pass the tip of the ETT through vocal cords under direct visualization


•  Inflate ETT cuff with least amount of air necessary to create seal during positive-pressure ventilation


•  Confirm correct placement of ETT with (1) Chest auscultation, (2) ETCO2, (3) ETT condensation, (4) palpation of ETT cuff in sternal notch


Earliest manifestation of bronchial intubation ispeak pressure (right mainstem bronchus common)


•  Rapid sequence intubation


• Indication: Pts at ↑ risk for aspiration (full stomach, pregnant, GERD, morbidly obese, bowel obstruction, delayed gastric emptying, pain, diabetic gastroparesis)


• Use rapid paralyzing agent: Succinylcholine (1–1.5 mg/kg) or rocuronium (0.6–1.2 mg/kg)


• Place cricoid pressure (Sellick maneuver) as pt is induced


• Protect from regurgitation of gastric contents to oropharynx


• Help visualize vocal cords during laryngoscopy


• Intubate pt once paralytic takes effect (30–60 sec); do not ventilate pt during this time


• Proper cricoid pressure should be performed with “BURP” technique:


• Displace larynx (B)ackward, (U)pward, (R)ight, with (P)ressure


•  “Modified” rapid sequence intubation


• A variation of the standard RSI technique in which a mask airway is established prior to administration of a paralytic agent


• May also include use of nondepolarizing agent (pts with ↑ K+)


Ehrenfeld, JM. et al. Modified rapid sequence induction and intubation: a survey of United States current practice. Anesth Analg. 2012 Jul;115(1):95–101.


AIRWAY MANAGEMENT: NASOTRACHEAL INTUBATION


•  Indications: Intraoral, facial/mandibular procedures


•  Contraindications: Basilar skull fractures, nasal fractures or polyps, underlying coagulopathies


•  Preparation: Anesthetize & vasoconstrict mucosa with lidocaine/phenylephrine mix or cocaine → select nares that pt can breathe through most easily


•  Lubricated ETT is advanced perpendicular to face below inferior turbinate via selected nares → direct bevel laterally away from turbinates


•  Advance ETT until able to visualize tip in oropharynx under direct laryngoscopy → use Magill forceps with right hand to advance/direct through vocal cords


AIRWAY MANAGEMENT: AWAKE FLEXIBLE FIBEROPTIC INTUBATION


•  Equipment: Ovassapian/Willliams/Luomanen airway, topical anesthetics, vasoconstrictors, antisialagogues, suction, fiberoptic scope with lubricated ETT


•  Indications: Cervical spine pathology, obesity, head & neck tumors, hx of a difficult airway


•  Premedication: Sedation (midazolam, fentanyl, dexmedetomidine, ketamine)


•  Technique:


Take time to topicalize airway (key to success; see table below)


• Place special oral airway or grab tongue with gauze


• Keep fiberoptic scope in midline while advancing until epiglottis appears


• Advance scope beneath epiglottis using antero/retroflexion as needed


• Once vocal cords are visualized, advanced scope into trachea


• Stabilized scope while ETT is advanced off scope into trachea


→ If resistance is encountered, rotate ETT tube 90 degrees


• After insertion, visualize carina with scope to avoid endobronchial intubation





TRANSTRACHEAL PROCEDURES


•  Indications: Emergency tracheal access when an airway cannot be secured via nasal/oral route


•  Percutaneous transtracheal jet ventilation


• Simple & relatively safe means to sustain a patient during a critical situation


• Attach 12, 14, or 16-gauge IV catheter to 10 mL syringe partially filled with saline


• Advance needle through cricothyroid membrane with constant aspiration until you get air


• Advance angiocatheter, disconnect syringe, attach oxygen source


• High-pressure O2 (25–30 psi), insufflation of 1–2 sec, 12/min with 16-gauge needle → will deliver approximately 400–700 mL


• Low-pressure O2 (bag-valve-mask 6 psi, common gas outlet 20 psi)


•  Cricothyroidotomy


• Contraindications: Patients <6 yr/o (upper part of trachea not fully developed) → incision through cricothyroid membrane ↑ risk of subglottic stenosis


• Sterilize skin


• Identify cricothyroid membrane


• Transverse incision with #11 blade ≈1 cm on each side of midline


• Turn blade 90 degrees to create space to pass ETT


• Insert ETT caudally, inflate cuff, confirm breaths sounds


TECHNIQUES OF EXTUBATION


•  Extubation performed when pt either deeply anesthetized (stage 3) or awake (stage 1)


• Extubation during light anesthesia (stage 2) may → laryngospasm/airway compromise


•  Patient’s airway should be aggressively suctioned while on 100% O2 prior to extubation


•  Prior to extubation, pt should be awake, following commands, neuromuscular blockade reversed


•  Untape ETT, deflate cuff, remove ETT while providing small amount of positive pressure


• Removes secretions at distal end of ETT


•  Place mask on pt with 100% O2 while verifying spontaneous & adequate ventilation


•  Consider using 1.5 mg/kg of IV lidocaine 1–2 min before manipulation of airway & extubation (will blunt airway reflexes)


•  Deep extubation


• Indicated to prevent ↑ BP, ICP, IOP, or bronchospasm (in asthmatics)


• Contraindicated in pts at ↑ risk for aspiration or who may have a difficult airway


DIFFICULT AIRWAY ALGORITHM


Originally published in March 1993 & revised in 2003, the ASA Difficult Airway Algorithm (Figure 4-1) is designed to facilitate management of difficult airways & reduce adverse outcomes


Figure 4-1. ASA difficult airway algorithm. (Note: 30% of anesthesia-related deaths stem  from issues of airway management.)



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Aug 28, 2016 | Posted by in ANESTHESIA | Comments Off on MANAGEMENT

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