Airway Management and Intubation

The difficult airway algorithm starts with prediction: before attempting intubation, assess the LEMON mnemonic: L = Look externally (facial trauma, burns, stridor, large tongue), E = Evaluate the 3-3-2 rule (can three of your fingers fit between the teeth? Between the hyoid and mentum? Between the hyoid and thyroid?), M = Mallampati score (visualize soft palate; see full soft palate = easier; see only hard palate = harder), O = Obstruction (stridor, epiglottitis, foreign body), N = Neck mobility (cervical collar, fixed neck, arthritis). A patient with two or more LEMON signs is a difficult airway. Plan accordingly: preoxygenate aggressively (100% oxygen for 3–5 minutes), have a backup plan (LMA, video laryngoscope, fiberoptic), position optimally (sniffing position: neck flexed, head extended), and consider waking the patient if no emergency requires immediate intubation.

RSI (Rapid Sequence Intubation): used when the patient is in cardiac arrest or critically ill and intubation cannot be delayed. Sequence: preoxygenate, administer a sedative (etomidate, ketamine) + paralytic (rocuronium, succinylcholine), apply cricoid pressure (prevent aspiration of stomach contents), visualize the cords, insert the tube, confirm placement with capnography, secure the tube. The whole process takes 30–60 seconds. DSI (Delayed Sequence Intubation): used for a patient with respiratory distress who is still maintaining airway but deteriorating. Give oxygen and a small dose of sedative (fentanyl) to improve comfort and oxygenation while you prepare for intubation; delay paralysis and intubation until the patient is fully optimized. DSI reduces crash intubations and unintended extubations. Context determines which one.

BVM: place the mask (circle or triangular) over the nose and mouth, seal the edges tightly, position the head in the sniffing position (neck flexed, head extended), and squeeze the bag smoothly at a rate of 12–20 breaths per minute (one breath every 3–5 seconds). Use one hand to hold the mask (C grip: thumb and index on the mask, other fingers lifting the mandible), or two-hand technique if you have an assistant compressing the bag. Adequate ventilation signs: chest rises with each breath, you feel compliance (not too stiff, not too floppy), breath sounds are audible, and capnography shows end-tidal CO2 rising. Inadequate: no chest rise, resistance to squeezing (blocked airway), or no CO2 on capnography. Troubleshoot: reposition the head, perform a jaw thrust, clear the airway of secretions, or place an oral airway.

Laryngoscopy: position the patient sniffing (neck flexed, head extended), preoxygenate with 100% O2, insert the blade (straight blade lifts the epiglottis; curved blade goes in the vallecula below the epiglottis), lift the handle upward and toward the patient's feet (not backward, which damages teeth), visualize the vocal cords (a thin white line in the midline of the airway), and pass the endotracheal tube through the cords, watching the tube disappear 1–2 cm past the cords (halfway down the tube = 21 cm at the teeth for an adult male, 19 cm for female). If you cannot see the cords: reposition, use the BURP maneuver (backward, upward, rightward pressure on the larynx), suction blood or secretions, or call for backup. Do not make more than 3–4 attempts; move to a video laryngoscope, LMA, or surgical airway.

Confirmation: (1) Visualize the tube passing through the cords (direct visualization). (2) Capnography—place a capnography sensor on the breathing circuit or at the tube connector; CO2 should appear within 6 breaths (proves the tube is in the trachea, not the esophagus). (3) Chest X-ray—verify position (tube should be 2–4 cm above the carina, centered in the trachea). (4) Listen for bilateral breath sounds in the axillae; if unilateral, the tube is likely in the right main-stem bronchus, so pull it back slightly. NEVER assume placement without capnography; misplaced tubes in the esophagus cause no ventilation and hypoxia. To prevent aspiration: use cricoid pressure during RSI, keep the patient NPO (nothing by mouth) before elective intubation, use a high-volume low-pressure cuff, and maintain cuff pressure at 25–30 cm H2O (prevents leakage but does not damage the trachea).

A surgical airway (cricothyrotomy or tracheostomy) bypasses the mouth and vocal cords, going directly into the trachea through a small incision in the neck. Used when: (1) You cannot see the vocal cords and cannot pass an oral tube, (2) the airway is obstructed by blood, vomit, or foreign body that you cannot clear, (3) there is severe facial trauma or airway swelling, or (4) you have made 3 failed attempts at intubation. Cricothyrotomy technique: palpate the cricoid cartilage (between the thyroid and cricoid, a small soft depression), make a small incision (1–2 cm), insert a bougie or small tube, then advance an endotracheal tube over it. Landmark = the cricoid cartilage. This buys time and opens an airway that cannot be opened any other way. Surgical airway is a last resort, but in a 'can't intubate, can't oxygenate' scenario, it is life-saving.

Plan ahead: (1) Review previous anesthesia records if available—what worked, what did not. (2) Call the difficult airway team (anesthesia, ENT) before you need it. (3) Consider fiberoptic intubation (look at the airway through a scope, guide the tube under direct visualization) if the patient is not in cardiac arrest. (4) Use a video laryngoscope (provides a side-view or full-view of the airway, easier than direct laryngoscopy). (5) Have an LMA (laryngeal mask airway) ready—sits on the larynx without needing to see the cords. (6) If elective (planned), intubate awake (give sedation and topical anesthetic, then intubate so the patient can breathe if you fail). (7) Prepare for surgical airway—have a cricothyrotomy kit at the bedside. Difficult airway does not mean impossible; it means prepare, use the right tools, and call for help early.