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Direct laryngoscopy and endotracheal intubation in adults

Steven Orebaugh, MD
James V Snyder, MD
Section Editors
Allan B Wolfson, MD
Carin A Hagberg, MD
Deputy Editors
Jonathan Grayzel, MD, FAAEM
Marianna Crowley, MD


Direct laryngoscopy (DL) and endotracheal intubation (ETI) are essential skills for a range of health care practitioners, including anesthesiologists, emergency physicians, and other clinicians expected to serve as first responders in emergency cases requiring advanced airway management. This topic will discuss the indications, contraindications, preparation, equipment, and techniques needed to perform DL and ETI in adults. The use of more sophisticated airway equipment (eg, video laryngoscopes), approaches to airway management in specific clinical circumstances, pediatric laryngoscopy, and rapid sequence intubation are all reviewed separately. (See "Devices for difficult emergency airway management in adults" and "The decision to intubate" and "Emergency endotracheal intubation in children" and "Advanced emergency airway management in adults" and "The difficult airway in adults" and "Rapid sequence intubation for adults outside the operating room" and "Neuromuscular blocking agents (NMBA) for rapid sequence intubation in adults outside the operating room" and "Induction agents for rapid sequence intubation in adults".)


In emergency medicine, the most common indications for tracheal intubation are acute respiratory failure, inadequate oxygenation or ventilation, and airway protection in a patient with depressed mental status. In the perioperative setting, endotracheal tubes may be placed in many clinical circumstances, including patients receiving general anesthesia, surgery involving or adjacent to the airway, unconscious patients requiring airway protection, or surgery involving unusual positioning [1]. Less frequently, intubation is performed for short-term hyperventilation to manage increased intracranial pressure or to manage copious secretions or bleeding from the airway [2]. (See "The decision to intubate".)


There are few absolute contraindications to tracheal intubation. Most involve supraglottic or glottic pathology that precludes placement of an endotracheal tube (ETT) through the glottis or which may be exacerbated by insertion of the ETT or laryngoscope. As an example, blunt trauma to the larynx may cause a laryngeal fracture or disruption of the laryngotracheal junction. In such cases, traction from the laryngoscope blade or pressure from a stylet within an ETT could create a false lumen or complete a partial tear of the trachea [3].

Penetrating trauma of the upper airway may also result in conditions exacerbated by laryngoscopy or ETT placement, such as a hematoma or partial transection of the airway [4]. When examination findings suggest such conditions exist, it may be safer to support oxygenation and ventilation using noninvasive means until a definitive airway can be established or to perform an immediate surgical airway, if necessary. (See "The failed airway in adults" and "Emergency surgical cricothyrotomy (cricothyroidotomy)".)

Other conditions associated with difficult intubation include severe laryngeal or supralaryngeal edema as a consequence of bacterial infection, burns, or anaphylaxis [5]. In these cases, visualization of the laryngeal inlet during laryngoscopy may be impossible, and local trauma caused by the laryngoscope blade or attempts at ETT insertion can lead to increased swelling, rendering mask ventilation difficult or impossible. (See "Epiglottitis (supraglottitis): Clinical features and diagnosis", section on 'Adults'.)


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Literature review current through: Sep 2016. | This topic last updated: Oct 13, 2016.
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  1. Ezri T, Warters RD. Indications for tracheal intubation. In: Benumof's Airway Management: Principles and Practice, 2nd ed, Hagberg CA (Ed), Mosby, Philadelphia 2007. p.371.
  2. Eisenkraft JB, Cohen E, Neustein SM. Anesthesia for thoracic surgery. In: Clinical Anesthesia, 4th ed, Barash PG, Cullen BF, Stoelting RK (Eds), Lippincott Williams and Wilkins, Philadelphia 2001. p.813.
  3. Ford HR, Gardner MJ, Lynch JM. Laryngotracheal disruption from blunt pediatric neck injuries: impact of early recognition and intervention on outcome. J Pediatr Surg 1995; 30:331.
  4. Kendall JL, Anglin D, Demetriades D. Penetrating neck trauma. Emerg Med Clin North Am 1998; 16:85.
  5. Verghese ST, Hannallah RS. Pediatric otolaryngologic emergencies. Anesthesiol Clin North America 2001; 19:237.
  6. Walls RM. The ermergency airway algorithms. In: Manual of Emergency Medicine Airway Management, 3rd ed, Walls RM (Ed), Lippincott Williams and Wilkins, Philadelphia 2009. p.8.
  7. Jaensson M, Olowsson LL, Nilsson U. Endotracheal tube size and sore throat following surgery: a randomized-controlled study. Acta Anaesthesiol Scand 2010; 54:147.
  8. Hu B, Bao R, Wang X, et al. The size of endotracheal tube and sore throat after surgery: a systematic review and meta-analysis. PLoS One 2013; 8:e74467.
  9. Stout DM, Bishop MJ, Dwersteg JF, Cullen BF. Correlation of endotracheal tube size with sore throat and hoarseness following general anesthesia. Anesthesiology 1987; 67:419.
  10. Levitan RM, Pisaturo JT, Kinkle WC, et al. Stylet bend angles and tracheal tube passage using a straight-to-cuff shape. Acad Emerg Med 2006; 13:1255.
  11. Levitan RM. Crossing the RSI line: Skydiving as a metaphor for patient safety in emergency airway management. In: The Airway Cam Guide to Intubation and Practical Airway Management, Levitan RM (Ed), Airway Cam Technologies, Wayne 2004. p.43.
  12. Orebaugh SL. Direct laryngoscopy. In: Atlas of Airway Management, Lippincott Williams and Wilkins, Philadelphia 2006. p.13.
  13. Miller RA. A new laryngoscope. Anesthesiology 1941; 1:317.
  14. MacIntosh RR. A new laryngoscope. Lancet 1943; 1:205.
  15. Phillips OC, Duerksen RL. Endotracheal intubation: a new blade for direct laryngoscopy. Anesth Analg 1973; 52:691.
  16. Henderson JJ. ENT vs anaesthesia "straight" laryngoscopes. Anaesth Intensive Care 2002; 30:250.
  17. Choi JJ. A new double-angle blade for direct laryngoscopy. Anesthesiology 1990; 72:576.
  18. Cheung RW, Irwin MG, Law BC, Chan CK. A clinical comparison of the Flexiblade and Macintosh laryngoscopes for laryngeal exposure in anesthetized adults. Anesth Analg 2006; 102:626.
  19. Racz GB. Improved vision modification of the Macintosh laryngoscope. Anaesthesia 1984; 39:1249.
  20. Nishikawa K, Yamada K, Sakamoto A. A new curved laryngoscope blade for routine and difficult tracheal intubation. Anesth Analg 2008; 107:1248.
  21. Law JA, Hagberg CA. The evolution of upper airway retraction: New and old laryngoscope blades. In: Benumof's Airway Management: Principles and Practice, 2nd ed, Hagber CA (Ed), Mosby, Philadelphia 2007. p.532.
  22. Yardeni IZ, Gefen A, Smolyarenko V, et al. Design evaluation of commonly used rigid and levering laryngoscope blades. Acta Anaesthesiol Scand 2002; 46:1003.
  23. Levitan RM. Advanced concepts in laryngoscope blade design. In: The Airway Cam Guide to Intubation and Practical Airway Management, Levitan RM (Ed), Airway Cam Technologies, Wayne 2004. p.185.
  24. Callander CC, Thomas J. Modification of Macintosh laryngoscope for difficult intubation. Anaesthesia 1987; 42:671.
  25. McCoy EP, Mirakhur RK. The levering laryngoscope. Anaesthesia 1993; 48:516.
  26. Cook TM, Tuckey JP. A comparison between the Macintosh and the McCoy laryngoscope blades. Anaesthesia 1996; 51:977.
  27. Tuckey JP, Cook TM, Render CA. Forum. An evaluation of the levering laryngoscope. Anaesthesia 1996; 51:71.
  28. Baker PA, Raos AS, Thompson JM, Jacobs RJ. Visual acuity during direct laryngoscopy at different illuminance levels. Anesth Analg 2013; 116:343.
  29. Tousignant G, Tessler MJ. Light intensity and area of illumination provided by various laryngoscope blades. Can J Anaesth 1994; 41:865.
  30. Levitan RM, Kelly JJ, Kinkle WC, Fasano C. Light intensity of curved laryngoscope blades in Philadelphia emergency departments. Ann Emerg Med 2007; 50:253.
  31. Volsky PG, Murphy MK, Darrow DH. Laryngoscope illuminance in a tertiary children's hospital: implications for quality laryngoscopy. JAMA Otolaryngol Head Neck Surg 2014; 140:603.
  32. Bucx MJ, De Gast HM, Veldhuis J, et al. The effect of mechanical cleaning and thermal disinfection on light intensity provided by fibrelight Macintosh laryngoscopes. Anaesthesia 2003; 58:461.
  33. American College of Surgeons Committee on Trauma. Advanced Trauma Life Support (ATLS) Student Course Manual, 9th ed, American College of Surgeons, Chicago 2012.
  34. Collins JS, Lemmens HJ, Brodsky JB, et al. Laryngoscopy and morbid obesity: a comparison of the "sniff" and "ramped" positions. Obes Surg 2004; 14:1171.
  35. Levitan RM, Mechem CC, Ochroch EA, et al. Head-elevated laryngoscopy position: improving laryngeal exposure during laryngoscopy by increasing head elevation. Ann Emerg Med 2003; 41:322.
  36. 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; 14:335.
  37. 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; 108:715.
  38. Khandelwal N, Khorsand S, Mitchell SH, Joffe AM. Head-Elevated Patient Positioning Decreases Complications of Emergent Tracheal Intubation in the Ward and Intensive Care Unit. Anesth Analg 2016; 122:1101.
  39. Levitan RM. Laryngoscopy Overview. In: The Airway Cam Guide to Intubation and Practical Airway Management, Levitan RM (Ed), Airway Cam Technologies, Wayne 2004. p.71.
  40. Levitan RM, Mickler T, Hollander JE. Bimanual laryngoscopy: a videographic study of external laryngeal manipulation by novice intubators. Ann Emerg Med 2002; 40:30.
  41. Benumof JL, Cooper SD. Quantitative improvement in laryngoscopic view by optimal external laryngeal manipulation. J Clin Anesth 1996; 8:136.
  42. Knill RL. Difficult laryngoscopy made easy with a "BURP". Can J Anaesth 1993; 40:279.
  43. Cormack RS, Lehane J. Difficult tracheal intubation in obstetrics. Anaesthesia 1984; 39:1105.
  44. Ochroch EA, Hollander JE, Kush S, et al. Assessment of laryngeal view: percentage of glottic opening score vs Cormack and Lehane grading. Can J Anaesth 1999; 46:987.
  45. Berry JM. Conventional (laryngoscopic) orotracheal and nasotracheal intubation (single-lumen tube). In: Benumof's Airway Management: Principles and Practice, 2nd ed, Hagberg CA (Ed), Mosby, Philadelphia 2007. p.379.
  46. Al Shamaa M, Jefferson P, Ball DR. Lingual tonsillar hypertrophy: airway management using straight blade direct laryngoscopy. Anesth Analg 2004; 98:874; author reply 874.
  47. Jackson C. Bronchoscopy, Esophagoscopy and Gastroscopy: A Manual of Peroral Endoscopy and Laryngeal Surgery, WB Saunders, Philadelphia 1934.
  48. Henderson JJ. The use of paraglossal straight blade laryngoscopy in difficult tracheal intubation. Anaesthesia 1997; 52:552.
  49. Achen B, Terblanche OC, Finucane BT. View of the larynx obtained using the Miller blade and paraglossal approach, compared to that with the Macintosh blade. Anaesth Intensive Care 2008; 36:717.
  50. Levitan RM. The Airway Cam Guide to Intubation and Practical Airway Management, Levitan RM (Ed), Airway Cam Technologies, Wayne 2004.
  51. Levitan RM. Straight blade laryngoscopy: Paraglossal technique. In: The Airway Cam Guide to Intubation and Practical Airway Management, Levitan RM (Ed), Airway Cam Technologies, Wayne 2004. p.161.
  52. Orebaugh SL. Retraction blades for direct laryngoscopy. In: Atlas of Airway Management: Techniques and Tools, Lippincott Williams and Wilkins, Philadelphia 2006. p.30.
  53. Bonfils P. [Difficult intubation in Pierre-Robin children, a new method: the retromolar route]. Anaesthesist 1983; 32:363.
  54. Johnson DM, From AM, Smith RB, et al. Endoscopic study of mechanisms of failure of endotracheal tube advancement into the trachea during awake fiberoptic orotracheal intubation. Anesthesiology 2005; 102:910.
  55. Kristensen MS. The Parker Flex-Tip tube versus a standard tube for fiberoptic orotracheal intubation: a randomized double-blind study. Anesthesiology 2003; 98:354.
  56. Walls RM, Samuels-Kalow M, Perkins A. A new maneuver for endotracheal tube insertion during difficult GlideScope intubation. J Emerg Med 2010; 39:86.
  57. Butler J, Sen A. Best evidence topic report. Cricoid pressure in emergency rapid sequence induction. Emerg Med J 2005; 22:815.
  58. Grmec S. Comparison of three different methods to confirm tracheal tube placement in emergency intubation. Intensive Care Med 2002; 28:701.
  59. MacLeod BA, Heller MB, Gerard J, et al. Verification of endotracheal tube placement with colorimetric end-tidal CO2 detection. Ann Emerg Med 1991; 20:267.
  60. Sum-Ping ST, Mehta MP, Anderton JM. A comparative study of methods of detection of esophageal intubation. Anesth Analg 1989; 69:627.
  61. Trevino RP, Bisera J, Weil MH, et al. End-tidal CO2 as a guide to successful cardiopulmonary resuscitation: a preliminary report. Crit Care Med 1985; 13:910.
  62. Schaller RJ, Huff JS, Zahn A. Comparison of a colorimetric end-tidal CO2 detector and an esophageal aspiration device for verifying endotracheal tube placement in the prehospital setting: a six-month experience. Prehosp Disaster Med 1997; 12:57.
  63. Bair AE, Smith D, Lichty L. Intubation confirmation techniques associated with unrecognized non-tracheal intubations by pre-hospital providers. J Emerg Med 2005; 28:403.
  64. Jenkins WA, Verdile VP, Paris PM. The syringe aspiration technique to verify endotracheal tube position. Am J Emerg Med 1994; 12:413.
  65. Pelucio M, Halligan L, Dhindsa H. Out-of-hospital experience with the syringe esophageal detector device. Acad Emerg Med 1997; 4:563.
  66. Zaleski L, Abello D, Gold MI. The esophageal detector device. Does it work? Anesthesiology 1993; 79:244.
  67. Oberly D, Stein S, Hess D, et al. An evaluation of the esophageal detector device using a cadaver model. Am J Emerg Med 1992; 10:317.
  68. Wee MY. The oesophageal detector device. Assessment of a new method to distinguish oesophageal from tracheal intubation. Anaesthesia 1988; 43:27.
  69. Davis DP, Stephen KA, Vilke GM. Inaccuracy in endotracheal tube verification using a Toomey syringe. J Emerg Med 1999; 17:35.
  70. Bair AE, Laurin EG, Schmitt BJ. An assessment of a tracheal tube introducer as an endotracheal tube placement confirmation device. Am J Emerg Med 2005; 23:754.
  71. Smith GM, Reed JC, Choplin RH. Radiographic detection of esophageal malpositioning of endotracheal tubes. AJR Am J Roentgenol 1990; 154:23.
  72. Chou HC, Tseng WP, Wang CH, et al. Tracheal rapid ultrasound exam (T.R.U.E.) for confirming endotracheal tube placement during emergency intubation. Resuscitation 2011; 82:1279.
  73. Kristensen MS. Ultrasonography in the management of the airway. Acta Anaesthesiol Scand 2011; 55:1155.
  74. Chun R, Kirkpatrick AW, Sirois M, et al. Where's the tube? Evaluation of hand-held ultrasound in confirming endotracheal tube placement. Prehosp Disaster Med 2004; 19:366.
  75. Galicinao J, Bush AJ, Godambe SA. Use of bedside ultrasonography for endotracheal tube placement in pediatric patients: a feasibility study. Pediatrics 2007; 120:1297.
  76. Das SK, Choupoo NS, Haldar R, Lahkar A. Transtracheal ultrasound for verification of endotracheal tube placement: a systematic review and meta-analysis. Can J Anaesth 2015; 62:413.
  77. Gottlieb M, Bailitz J. Can Transtracheal Ultrasonography Be Used to Verify Endotracheal Tube Placement? Ann Emerg Med 2015; 66:394.
  78. Chou EH, Dickman E, Tsou PY, et al. Ultrasonography for confirmation of endotracheal tube placement: a systematic review and meta-analysis. Resuscitation 2015; 90:97.
  79. Göksu E, Sayraç V, Oktay C, et al. How stylet use can effect confirmation of endotracheal tube position using ultrasound. Am J Emerg Med 2010; 28:32.
  80. Pfeiffer P, Rudolph SS, Børglum J, Isbye DL. Temporal comparison of ultrasound vs. auscultation and capnography in verification of endotracheal tube placement. Acta Anaesthesiol Scand 2011; 55:1190.
  81. Bissinger U, Lenz G, Kuhn W. Unrecognized endobronchial intubation of emergency patients. Ann Emerg Med 1989; 18:853.
  82. Schwartz DE, Lieberman JA, Cohen NH. Women are at greater risk than men for malpositioning of the endotracheal tube after emergent intubation. Crit Care Med 1994; 22:1127.
  83. Reed DB, Clinton JE. Proper depth of placement of nasotracheal tubes in adults prior to radiographic confirmation. Acad Emerg Med 1997; 4:1111.
  84. Sitzwohl C, Langheinrich A, Schober A, et al. Endobronchial intubation detected by insertion depth of endotracheal tube, bilateral auscultation, or observation of chest movements: randomised trial. BMJ 2010; 341:c5943.
  85. Roberts JR, Spadafora M, Cone DC. Proper depth placement of oral endotracheal tubes in adults prior to radiographic confirmation. Acad Emerg Med 1995; 2:20.
  86. Ramsingh D, Frank E, Haughton R, et al. Auscultation versus Point-of-care Ultrasound to Determine Endotracheal versus Bronchial Intubation: A Diagnostic Accuracy Study. Anesthesiology 2016; 124:1012.
  87. Gardner A, Hughes D, Cook R, et al. Best practice in stabilisation of oral endotracheal tubes: a systematic review. Aust Crit Care 2005; 18:158, 160.
  88. Hagberg CA, Boin MH. Management of the airway: Complications. In: Anesthesia and Perioperative Complications, 2nd ed, Saidman LJ, Benumof JL (Eds), Mosby, St. Louis 1999. p.3.
  89. Hasegawa K, Shigemitsu K, Hagiwara Y, et al. Association between repeated intubation attempts and adverse events in emergency departments: an analysis of a multicenter prospective observational study. Ann Emerg Med 2012; 60:749.
  90. Rosenberg MB. Anesthesia-induced dental injury. Int Anesthesiol Clin 1989; 27:120.
  91. Gamlin F, Caldicott LD, Shah MV. Mediastinitis and sepsis syndrome following intubation. Anaesthesia 1994; 49:883.
  92. Kambic V, Radsel Z. Intubation lesions of the larynx. Br J Anaesth 1978; 50:587.
  93. Cavo JW Jr. True vocal cord paralysis following intubation. Laryngoscope 1985; 95:1352.
  94. Domino KB, Posner KL, Caplan RA, Cheney FW. Airway injury during anesthesia: a closed claims analysis. Anesthesiology 1999; 91:1703.
  95. Salathé M, Jöhr M. Unsuspected cervical fractures: a common problem in ankylosing spondylitis. Anesthesiology 1989; 70:869.
  96. Olsson GL, Hallen B, Hambraeus-Jonzon K. Aspiration during anaesthesia: a computer-aided study of 185,358 anaesthetics. Acta Anaesthesiol Scand 1986; 30:84.
  97. Kumeta Y, Hattori A, Mimura M, et al. [A survey of perioperative bronchospasm in 105 patients with reactive airway disease]. Masui 1995; 44:396.
  98. Caplan RA, Posner KL, Ward RJ, Cheney FW. Adverse respiratory events in anesthesia: a closed claims analysis. Anesthesiology 1990; 72:828.
  99. Cheney FW, Posner KL, Caplan RA. Adverse respiratory events infrequently leading to malpractice suits. A closed claims analysis. Anesthesiology 1991; 75:932.
  100. Bedford RF. Circulatory responses to tracheal intubation. Probl Anesthesia 1998; 2:201.
  101. Edwards ND, Alford AM, Dobson PM, et al. Myocardial ischaemia during tracheal intubation and extubation. Br J Anaesth 1994; 73:537.
  102. Kastanos N, Estopá Miró R, Marín Perez A, et al. Laryngotracheal injury due to endotracheal intubation: incidence, evolution, and predisposing factors. A prospective long-term study. Crit Care Med 1983; 11:362.
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