Airway Management in Adults
First Things First (assess for & treat the following)
- They call it the “ABCs” for a reason!
- Assess airway & breathing first.
- Call for help.
- Are there signs of partial airway obstruction?
- Stridor, cyanosis, increased work of breathing
- If so, this is a medical emergency. Get emergent ENT, anesthesia consultation & prepare to move pt to OR.
- Is pt’s airway open?
- Is pt breathing?
- If not, support ventilation.
- Is pt oxygenating?
- Always add supplemental oxygen.
- Is there impending respiratory failure?
- Prepare for intubation & support of ventilation.
History and Physical (assess for the following)
Clinical signs of impending respiratory failure
- Rapid (>25-35 breaths/min), shallow breathing
- Tachycardia and/or hypertension
- Wheezing or decreased breath sounds
- Use of accessory muscles
- Inability to speak/dysphonia
- Retraction of suprasternal, supraclavicular, intercostal spaces
Potentially difficult intubation if:
- Morbid obesity/edematous head & neck
- Limited mouth opening (< 40 mm or two fingerbreadths)
- Big tongue (i.e., Down’s)
- Receding mandible
- Mandible to hyoid distance < 40 mm
- Limited neck extension
- Mandible to thyroid distance < 60 mm or three fingerbreadths
- Bleeding in mouth, nose, pharynx, airway
Note: Several minor abnormalities in combination may result in difficult intubation. Alternatively, difficult intubation can also occur without obvious abnormalities.
- Blood gases in acute mgt, but do not wait for blood gas results before assisting ventilation or administering oxygen
General Management Principles
- Provide unobstructed airway.
- Provide supplemental oxygen.
- If not breathing, support ventilation via self-inflating bag-valve mask.
- Cricoid pressure: Have assistant maintain firm pressure over cricoid cartilage during airway manipulations to minimize potential for regurgitation & aspiration.
- Indications for intubation
- Inability to protect airway
- GCS < 8
- Inadequate oxygenation
- Inadequate ventilation
- Need for paralysis/sedation/mechanical ventilation (i.e., barbiturate coma for elevated ICP)
- Outside OR, it is probably safest to preserve spontaneous ventilation & perform intubation on an awake or minimally sedated patient w/ topical anesthesia, avoiding neuromuscular blockers if possible.
Minimum equipment needed:
- Self-inflating bag-valve device
- Large-bore tonsil tip (Yankauer) & endotracheal tube suction catheters
- Laryngoscope handles/blades & back-ups
- Alternative airways (LMA/Combitube/jet ventilation equipment)
- Bag-valve device
- Can deliver 100% oxygen & adequate ventilation
- Proper bag-valve mask ventilation is as important as securing airway in an emergency.
- Mask sizes: adult small/medium/large
- Hold firmly on face, w/ fingers on bone of mandible, not soft tissues.
- Unconscious victims lose muscle tone in tongue, resulting in posterior tongue displacement & upper airway obstruction.
- Foreign bodies
- Inflammatory & infectious
- Conscious pts showing signs of airway obstruction (cyanosis, stridor, increased work of breathing) need to be rapidly evaluated by ENT/anesthesia.
- Relief of obstruction
- Manual maneuvers
- First, try head tilt with anterior displacement of mandible by chin lift or jaw thrust.
- Holding the mask with 2 hands, while assistant ventilates, may help in some situations.
- DO NOT PERFORM HEAD TILT IN TRAUMA PATIENTS WITH SUSPECTED C-SPINE INJURY. Attempt to open the airway by only performing chin lift.
- Mechanical devices
- Oral airways
- In patients with depressed levels of consciousness, with airway obstruction after appropriate positioning, an oral airway may help.
- Place airway into mouth by displacing tongue with a tongue blade, or with the concavity facing palate, then rotating 180 degrees when it is near posterior pharynx. IN CONSCIOUS PATIENTS AN ORAL AIRWAY MAY STIMULATE VOMITING & POSSIBLE ASPIRATION.
- Nasal airways
- In semiconscious pts, those who do not tolerate an oral airway or those who remain obstructed after these maneuvers have failed, a nasal airway may help. Topical vasoconstrictors & lubrication with local anesthetic jelly can be applied to nares before placement. If resistance is met, rotation of device may allow it to be placed. Contraindications are the same as those for nasotracheal intubation.
- LMA (See below.)
- Methods of intubation
- Topical anesthesia: Many methods; 5% lidocaine ointment on end of oral airway, slowly insert over 3-5 min, recoating end w/ ointment, until fully placed in oropharynx. Then spray 5 cc of 4% lidocaine suspension into oral airway while having patient inhale deeply.
- Awake ± topical anesthesia, esp. for difficult intubations, spine injuries
- Sedated ± topical anesthesia; used for most ICU intubations
- General anesthesia: best used in OR or other controlled environment
- Routes to airway mgt
- Blind approach useful in spontaneously ventilating patients
- Midface fractures (“Lefort”)
- Basilar skull fractures
- Head trauma with CSF leak
- Lubricate nares/progressive dilation with NP airways
- Small (6.0-7.0 mm) uncut endotracheal tube
- Listen for breath sounds as you slowly advance tube.
- Orotracheal: most common route
- Transtracheal jet ventilation: 14g IV placed through cricoid cartilage
- Surgical airways
Airway management tools
- Endotracheal tubes
- 2.5-9.0 mm inner diameter with high-volume, low-pressure cuff
- 7.0-8.0 mm adequate for most adults
- Miller (straight blade)
- Placed under epiglottis, exposing vocal cords
- Sizes: 0 (smallest) to 4; 3 for most adults
- Macintosh (curved blade)
- Placed in vallecula, anterior to epiglottis, exposing vocal cords
- Sizes: 1 (smallest) to 4; 3 for most adults
Difficult airway management
- (See Difficult Airway Algorithm developed by ASA task force on guidelines for difficult airway management.)
- In general, if unsuccessful intubation, GET MORE HELP.
- If spontaneously ventilating, get help.
- If pt is not spontaneously ventilating but you are able to mask ventilate adequately, use alternative intubation strategy.
- If not spontaneously ventilating, with inadequate mask ventilation
- Rapidly obtain alternative surgical or nonsurgical airway (LMA, Combitube, jet ventilation).
- Stylets (6-mm Elaste Bougies): with difficult intubation, stylet can be blindly placed into trachea & then ETT can be placed over stylet.
- Light wands: fiberoptically lighted stylets that are blindly placed into trachea by transillumination of anterior neck
- Fiberoptic techniques: fiberoptic bronchoscopes can be placed into trachea & used as a stylet
- Laryngeal mask airway: device that is placed blindly into oropharynx until resistance is met. Cuff is inflated & patient can be positive-pressure ventilated at low pressure.
- Combitube: device w/ two lumens & two cuffs that is blindly placed into oropharynx. Ventilate tracheal lumen first; if no breath sounds, ventilate esophageal lumen.
- Transtracheal jet ventilation
- Can provide adequate oxygenation (& ventilation) while more definitive options are being organized.
- NOTE: PATENT UPPER AIRWAY IS REQUIRED TO ALLOW ADEQUATE EXPIRATION.
- 14-g IV catheter placed through cricothyroid membrane
- Attach to low-compliance tubing to high-pressure oxygen source.
- Or oxygen tubing at highest flow rate possible, connected to 3-way stopcock in “all open” position, connected to catheter. Occlude stopcock, watch for chest rise, then open stopcock & allow exhalation.
- Or 8-mm ETT tube adapter, inserted into empty 3-cc syringe attached to catheter. Can then attach self-inflating bag-valve to ETT adapter to provide oxygen.
Pharmacologic tools (all doses assume IV administration)
- Muscle relaxants: outside the OR, would use only if attempts at sedation/topical fail & you need rapid airway control.
- 0.5-1.0 mg/kg, onset within 60 sec, duration 3-5 min
- Side effects: hyperkalemia MAY BE SEVERE ENOUGH TO CAUSE CARDIAC ARREST (with unhealed burns, denervation with skeletal muscle atrophy, severe skeletal muscle injury, upper motor neuron lesions), sustained skeletal muscle contraction, increased IOP, increased ICP, myalgia
- 0.6 mg/kg IV, onset 90-120 sec, duration 30-45 min
- Sedatives: Use small doses, titrate to effect. These ALL can cause hypotension & respiratory depression in critically ill pts.
- Sedation: 0.5-1.0 mg boluses
- Induction of anesthesia: 0.1-0.2 mg/kg
- Sedation: 2-4 mg boluses
- Induction of anesthesia: 0.2-0.4 mg/kg
- 20-50 mg boluses
- Induction of anesthesia: 1.5-2.5 mg/kg
- Sedation: 25-50 mg boluses
- Induction of anesthesia: 3-5 mg/kg
Who can be managed without intubation?
- Neurologically intact, otherwise stable patients: could try noninvasive mechanical ventilation (Bi-PAP) with close monitoring & observation
- Confirm ETT placement & ensure adequate oxygenation/ventilation.
- Proper placement can be confirmed via many methods:
- Direct visualization of ETT through vocal cords
- Auscultate for bilateral breath sounds & absence of epigastric sounds
- Symmetrical chest expansion
- End-tidal CO2 detection
- Qualitative: devices that change color with exposure to CO2. Can have both false-positive results (color change, but ETT is in esophagus) & false-negatives (no or very low CO2 delivery from low or no cardiac output). Need to see color change repeat over course of 5 breaths.
- Quantitative: capnometer will provide actual value of expired CO2; capnograph will provide both a number & display CO2 waveform during respiration.
- Pulse oximetry
- Blood gases are useful to monitor & adjust ventilation & oxygenation.
- Failed intubation
- Esophageal intubation
- Laceration of lips/tongue
- Chipped teeth
- Vocal cord trauma
- Michael H. Wall, MD, & Pamela R. Roberts, MD
Airway Management in Adults
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