- Direct laryngoscopy is the use of the laryngoscope to visualise the vocal cords (larynx) under direct vision, usually to facilitate endotracheal intubation.
- As described by Richard Levitan, the procedure involves 4 key steps:
- Positioning and preparation
- epiglottoscopy (identification of the epiglottis)
- laryngeal exposure
- delivery of the tube
PROCEDURE FOR OPTIMAL DIRECT LARYNGOSCOPY
This description is for a Macintosh laryngoscope (curved) blade in an adult patient based on the Levitan approach
Positioning and preparation
- Position yourself for optimal visualisation of glottic structures — use your dominant eye (find out how to determine ocular dominance here) — position yourself 12 to 18 inches from the target (optimal distance varies between individuals according to their eyesight – your laryngoscope holding arm should be somewhere between 90 degrees flexed and fully extended) — Right-eyed laryngoscopists keep their head straight toward the target. Left eyed laryngoscopists rotate their head slightly to the right, bringing the left eye closer to the target.
- Position the patient with ear-to-sternal notch alignment (also known as the HELP aka Head Elevated Laryngoscopy Positioning) — either put pillows under the head or tilt the head of the bed up (e.g. cervical sign precautions) (this also has benefits in improving preoxygenation and may decrease aspiration risk) — the external auditory meatus should be at or above the horizontal plane passing through the sternal notch and the the patient’s face plane parallel to the ceiling — in the morbidly build a ramp under the patients and shoulders to achieve this — avoid excessive atlanto-occipital extension which leads to ‘epiglottis camoflage’,where the epiglottis edge disappears against the pharyngeal mucosa
- Adjust the height of the bed to optimal height — the patient should be no higher than the operator’s xiphoid process
- Hold the laryngoscope correctly to provide maximum control and mechanical advantage — the laryngoscope handle should be gripped as low down as possible — Elbow should be kept close to the body
- Open the mouth as wide as possible using a scissor technique — use the first and third digit for maximum mechanical advantage
- Insert the laryngoscope 1 inch into the mouth — aggressive sweeping of the tongue to the left is not necessary — if breast tissue prevents insertion of the laryngoscope blade either use a short handle or insert the blade with the laryngoscope handle pointing to the right, once in the mouth the laryngoscope blade can be rotated to the midline
- Move progressively down the tongue with the laryngoscope blade identifying relevant anatomy as you go and always find the epiglottis — ‘epiglottoscopy’ is a prerequisite to exposure of the larynx, it is a gentle procedure — initial blade insertion is with the laryngoscope handle pointed at the patient’s feet. The tongue and jaw are distracted downward to insert the blade — once the tip of the blade gets around base of tongue, the angle of distraction is altered so that the tongue is lifted, which transmits force via the hyoepiglottic ligament to lift the epiglottis edge is lifted off the posterior pharynx — when the blade tip is in the vallecula the angle of lifting changes to ~40 degrees from the horizontal. Tip position (not force) is the main determinant of glottic exposure. External laryngeal manipulation may help help open up the vallecular space to allow the blade tip to be appropriately positioned
- If the epiglottis is not found — use suction to clear secretions that pool in the posterior pharynx to obscure the epiglottis — perform methodical midline advancement of the blade down the tongue which is a reliable way to find the epiglottis
- Identify glottic structures — the first glottic structures seen are the posterior cartilages (arytenoids) and interarytenoid notch, before the glottic opening and the vocal cords
- If the view of glottic structures is poor then: — perform bimanual laryngoscopy: externally manipulate the thyroid cartilage to drive the tip of the blade into proper position in the valecula, which optimises the mechanics of indirect epiglottis elevation. Get an assistant to hold the larynx in position externally. — perform dynamic head elevation: use your right hand to lift the patient’s occiput, or ask an assistant to lift the head (cannot be performed on the morbidly obese or if cevical spine precautions) — do not get an assistant to perform cricoid pressure or BURP (backwards upwards rightwards pressure) – operator-performed bimanual laryngoscopy has the advantage of immediate visual feedback
- Use a bougie or a malleable stylet — use the stylet to shape the endotracheal tube so that it is ‘straight to the cuff’ with a 35 degree bend at the tip (similar to a bougie with coude tip) — ensure the tip of the stylet stops short of the Murphy’s eye of the endotracheal tube
- Tracheal tubes should always be inserted from below the line of sight, using the right hand corner of the mouth, initially placing the tube behind the maxilla. — always keep the tube tip below the line of vision and watch it travel upward to the larynx — ensure that the tip passes anterior to the interarytenoid notch — rotation of the tube allows excellent control of the tip in the vertical plane with a ‘straight to the cuff’ stylet and 35 degree bend at the tip
- Deliver the tracheal tube over the stylet once the cuff is below the cords — If there is resistance to tube insertion, a clockwise (rightward) turn will lower the leading edge of the tube (disengaging it from the rings) — withdrawing the stylet may also allow tube advancement into the trachea
George Kovacs demonstrates his approach to optimising the view with direct laryngoscopy
Scott Weingart demonstrates the steps of direct laryngoscopy
Keith Greenland on ‘Reinventing the Approach to Direct Laryngoscopy’
References and Links
Journal articles and textbooks
- Benumof JL, Cooper SD. Quantitative improvement in laryngoscopic view by optimal external laryngeal manipulation. J Clin Anesth. 1996 Mar;8(2):136-40. PMID: 8695096.
- Collins JS, Lemmens HJ, Brodsky JB, Brock-Utne JG, Levitan RM. Laryngoscopy and morbid obesity: a comparison of the “sniff” and “ramped” positions. Obes Surg. 2004 Oct;14(9):1171-5. PMID: 15527629.
- El-Orbany M, Woehlck H, Salem MR. Head and neck position for direct laryngoscopy. Anesth Analg. 2011 Jul;113(1):103-9. Epub 2011 May 19 PMID: 21596871. [Free Full Text]
- Greenland KB, Edwards MJ, Hutton NJ, Challis VJ, Irwin MG, Sleigh JW. Changes in airway configuration with different head and neck positions using magnetic resonance imaging of normal airways: a new concept with possible clinical applications. Br J Anaesth. 2010 Nov;105(5):683-90. PMID: 20846964. [Free Full Text]
- Greenland KB, Edwards MJ, Hutton NJ. External auditory meatus-sternal notch relationship in adults in the sniffing position: a magnetic resonance imaging study. Br J Anaesth. 2010 Feb;104(2):268-9. PMID: 20086071. [fulltext]
- Hochman II, Zeitels SM, Heaton JT. Analysis of the forces and position required for direct laryngoscopic exposure of the anterior vocal folds. Ann Otol Rhinol Laryngol. 1999 Aug;108(8):715-24. PMID: 10453776.
- Kitamura Y, Isono S, Suzuki N, Sato Y, Nishino T. Dynamic interaction of craniofacial structures during head positioning and direct laryngoscopy in anesthetized patients with and without difficult laryngoscopy. Anesthesiology. 2007 Dec;107(6):875-83. PMID: 18043055. [Free Full Text]
- Levitan, RM, The Mystique of Direct Laryngoscopy. Respiratory Care. 2007 Jan;52(1):21-3. PMID: 17194312 [Free Full Text]
- Levitan RM, Heitz JW, Sweeney M, Cooper RM. The complexities of tracheal intubation with direct laryngoscopy and alternative intubation devices. Ann Emerg Med. 2011 Mar;57(3):240-7. Epub 2010 Jul 31. PMID: 20674088.
- Levitan RM, Pisaturo JT, Kinkle WC, Butler K, Everett WW. Stylet bend angles and tracheal tube passage using a straight-to-cuff shape. Acad Emerg Med. 2006 Dec;13(12):1255-8 PMID: 17079788.
- Levitan RM, Kinkle WC, Levin WJ, Everett WW. Laryngeal view during laryngoscopy: a randomized trial comparing cricoid pressure, backward-upward-rightward pressure, and bimanual laryngoscopy. Ann Emerg Med. 2006 Jun;47(6):548-55.PMID: 16713784.
- Levitan RM, Mechem CC, Ochroch EA, Shofer FS, Hollander JE. Head-elevated laryngoscopy position: improving laryngeal exposure during laryngoscopy by increasing head elevation. Ann Emerg Med. 2003 Mar;41(3):322-30. PMID: 12605198.
- Levitan RM, Higgins MS, Ochroch EA. Contrary to popular belief and traditional instruction, the larynx is sighted one eye at a time during direct laryngoscopy. Acad Emerg Med. 1998 Aug;5(8):844-6. PMID: 9715250.
- Levitan RM, Mickler T, Hollander JE. Bimanual laryngoscopy: a videographic study of external laryngeal manipulation by novice intubators. Ann Emerg Med. 2002 Jul;40(1):30-7 PMID: 12085070.
- Schmitt HJ, Mang H. Head and neck elevation beyond the sniffing position improves laryngeal view in cases of difficult direct laryngoscopy. J Clin Anesth. 2002 Aug;14(5):335-8. PMID: 12208436.
FOAM and web resources
- Airwaycam.com — Direct laryngoscopy by Richard Levitan
- ALIEM — The mystique of direct laryngoscopy: Learning and teaching the procedure
- EMCrit Podcast 70 – Airway Management with Rich Levitan (2012)
- EP Monthly — Avoiding Common Laryngoscopy Errors and Avoiding Common Laryngoscopy Errors, Part II by Richard Levitan (2011)
- EP Monthly — Video + Direct Laryngoscopy by Richard Levitan
- EP Monthly — Demystifying Pediatric Laryngoscopy by Richard Levitan
- PHARM Podcast 51: Dr Richard Levitan speaks on VL vs DL