The Difficult Airway: Common Errors During Intubation
- Jun 19th, 2016
- Joshua Bucher
Authors: Joshua Bucher, MD (EM Attending Physician / EMS Fellow, Morristown Medical Center) and Darren Cuthbert, MD, MPH // Edited by: Jamie Santistevan, MD (@Jamie_Rae_EMdoc), Alex Koyfman, MD (@EMHighAK, EM Attending Physician, UTSW / Parkland Memorial Hospital), and Brit Long, MD (@long_brit, SAUSHEC, USAF)
It is vital that emergency physicians are exceedingly skilled at airway management while caring for critical patients in the emergency department (ED). This can be a daunting task due to the variation and complexity of patients that present with critical illness. Problems are frequently encountered in the process of intubation, which can potentially exacerbate a bad situation. Therefore, it is imperative that ED physicians are prepared in dealing with the complications of intubation as with the process in itself.
Current literature reports that up to 12% of intubations will require multiple attempts, leaving surviving patients at an elevated risk of adverse events later on.1 In this post, we will review a case that demonstrates some of the common problems that lead to unsuccessful first-pass intubation attempts. We will then discuss 5 common procedural intubation complications that lead to a failure in proper and timely airway management. A discussion of how to prevent such difficulties while preparing to manage their consequences is provided.
You are a second-year resident working in a high volume ED on a busy night. A 44-year-old morbidly obese African American male walks through the doors, ambulating with the assistance of a female companion due to a left sided hemiplegic gait. He displays a right side facial droop that is noted on initial visual examination while assisting the patient onto the ED stretcher. The patient appears tachypneic, his voice is hoarse and speech is slurred and incomprehensible when determining level of orientation. He can still follow commands. His companion reports acute onset right-sided facial weakness 45 minutes prior to arrival. She adds that his state has progressively worsened, involving his contralateral extremities, and is accompanied by difficulty swallowing. She provides a history consisting of hypertension treated with hydrochlorothiazide with poor compliance and untreated sleep apnea. She denies past cerebrovascular accident (CVA), trauma, or anticoagulant use.
Intravenous access is quickly established and the patient is put on a portable monitor. Just prior to leaving for computed tomography (CT) scan, you notice that the patient has hypoxia with an SpO2 of 74% on 15L NRB, with a RR of 5 with shallow breaths. The decision is then made to intubate. The patient is tachycardic at 108 with adequate distal pulses but is now apneic. Bag valve mask (BVM) ventilation is effectively achieved using ‘EC’ hand positioning for preoxygenation. You think that may be a difficult airway, so a bougie is kept at hand. After administration of etomidate and succinylcholine and scissoring the mouth, the uvula is not visible, only hard palate and large tongue deviated towards the left. After insertion of the laryngoscope, arytenoids and epiglottis are not clearly visible. Bougie is slid along the underside of the tongue and rapidly proceeds with slight resistance. The laryngoscope is removed and the endotracheal (ET) tube is slid over the bougie. Using capnography and breath/abdominal sounds it is quickly determined your first pass has failed. What might have gone wrong?
Error 1: Failure to appropriately evaluate the airway
One of the common mistakes during intubation is failure to perform a difficult airway evaluation. Although this is often performed subconsciously during the decision to intubate, it is important for all emergency providers to consciously evaluate the airway prior to any airway attempt. There are many difficult airway mnemonics to remember. Life in the Fast Lane has a great review of the different types at http://lifeinthefastlane.com/ccc/airway-assessment/. A common mnemonic for difficult intubation is LEMON (look external, 3-3-2 rule, Mallampati score, obstruction, neck mobility).2,3 Next ask if ventilation by bag valve mask (BVM) will be difficult by using the BOOTS mnemonic (Beard, Old, Obese, Toothless, Snoring).
Additionally, prior to any intubation attempt, the neck anatomy should be evaluated in a manner described by Rich Levitan as the “laryngeal handshake.” It involves palpation of the hyoid, thyroid, cricoid, and the cricothyroid membrane.2,3 This allows you to identify the anatomy required to perform an emergent cricothyrotomy if need be.
In the case of the obese or spinally immobilized patient, the laryngeal handshake can be found difficult due to increased adiposity or obstruction. Ultrasound can be an effective tool in this scenario for identification of anatomic structures in the supraglottic, glottic, and subglottic regions, as well as helpful in the process of placement confirmation. 4,5,10 The American College of Emergency Physicians (ACEP) provides a helpful Focused Ultrasound for Airway Management tutorial that walks through the steps of this utility.5
If a difficult intubation is predicted, and you are forced to act now, then be prepared with a Bougie and consider video laryngoscopy as well as prepping the neck for surgical airway. If there is predicted difficulty of ventilation then consider having a nasal and oral airway handy as well as backup devices for ventilation if two-hand BVM fails. This might include laryngeal mask airway (LMA), supraglottic device such as the King laryngeal tube airway (LTA).
Error 2: Failure of positioning of the airway
First pass intubation is dependent upon sufficient visual appreciation of pharyngeal/laryngeal structures leading up to the cords. Obstruction via anatomic differences in the mouth, teeth, tongue, and epiglottis in conjunction with blade size is commonplace. An edematous airway, or that of a patient with obesity, can also make intubation visually challenging.6 Therefore, proper positioning of the patient and yourself while placing the endotracheal tube is vital.
The patient first necessitates ear-to-sternal notch alignment where their external auditory meatus is even or above a horizontal plane with the sternal notch. This is achieved by what is known as ‘HELP’ positioning, or head elevated laryngoscopy positioning.6,7 To assist in this the head of the bed can be elevated, or a pillow or blanket can be placed under the patient’s head or shoulders as needed. In a patient with spinal immobilization, avoid head elevation and you can utilize the reverse Trendelenburg position. In the obese patient, more than one pillow or a ‘ramp’ may be necessary.6,7 Not only does the HELP positioning aid in airway visualization, but it increases ability to preoxygenate while also decreasing aspiration risk.6 This should all be done with the height of the stretcher being close to, but not above, the sternum of the laryngoscope operator.
After proper positioning and insertion of laryngoscope, visualization is attained through monocular focusing 12-18 inches away from your visual target, with your left arm angled anywhere between 90 degrees and full extension.6,7 It is important for the novice to know eye dominance, as a left eye dominant practitioner usually needs to tilt or turn their head slightly to the right bringing the left eye in line with the cords. The physician with right eye dominance just needs to look straight ahead, keeping the plane of sight straight relative to the patient.6 For information on eye dominance and its relationship to direct laryngoscopy, look here: http://epmonthly.com/article/avoiding-common-laryngoscopy-errors/
On a final note, avoid atlanto-occipital overextension. This creates what Levitan refers to as “epiglottis camouflage,” where the epiglottis gets pushed back over the pharyngeal mucosa making it harder to identify.8 If you find yourself in this situation, have suction readily available to clear accumulated fluids over the epiglottis.6,8
Error 3: Failure to prepare a backup plan
Intubation is a complex process requiring multiple pieces, with an in depth understanding of each, in order to accurately complete the puzzle. It is crucial that all the tools necessary for each step, as well those needed in troubleshooting airway management problems, are readily available in the ED. Every equipment tray or cart should be stocked with extra pieces of each item in every size. Know the size of your patient and the potential difficulty of the airway. The type of equipment used (ET tube length, blade shape) can determine complications with placement and malpositioning.7,12 Likewise, nasal or oral airways should be available at the bedside. These will assist with keeping a patent airway and will help ventilate, if needed. If there is predicted difficulty with intubation and/or ventilation, a rescue device, such as a laryngeal mask airway (LMA), or supraglotic device such as the King LTA or CombiTube should be available at the bedside for quick use.12
It is common that the difficult airway presents with little time for preparation, or the difficulty of an airway is underestimated upon initial evaluation. When time is of the essence it is more likely that an error in judgment will occur. In such cases, elastic bougie, needle cricothyroidotomy set, cricothyrotomy equipment (scalpel, bougie, trach), fiberoptics, ultrasound, and video laryngoscopy should always be available. Practitioners should not be hesitant to use them if need be. If glottic structures are not discernable than bougie may facilitate a blind attempt at endotracheal intubation. If this is not effective, then progress to fiberoptics or glidescope.7 If trouble persists despite resources expended within the ED; backup from anesthesia and surgical specialties, if available, is warranted. Johns Hopkins in Baltimore, Maryland recently pioneered a Difficult Airway Response Team (DART), consisting of anesthesiologists, ED physicians, otolaryngologists, and trauma surgeons, showing effectiveness in early studies at improving emergent airway management outside the operating theatre.9
Failure to oxygenate and ventilate necessitates an emergency surgical cricothyrotomy. Do not delay definitive airway management for backup from a colleague if the patient requires immediate airway management.
Error 4: Failure to select appropriate methods and medications
When determining the appropriate methods and medications required for intubation of a specific patient, it is important to always yield on the side of caution – as a slight mistake can lead to permanent, if not fatal damage.
Technique is of paramount importance when establishing the airway. Trauma can easily occur. When inserting the blade of the laryngoscope, injury to the lips, teeth, tongue, nose, pharynx, and larynx can lead to traumatic complications. The blade should be inserted with the handle pointing towards the patient’s feet, and once the blade tip reaches the vallecular space, the angle changes to 40 degrees from the horizontal position.12,13 Angle and positioning will determine cord exposure, not force. The handle should be lifted upwards towards the intersection of the ceiling and the wall and to the left. Stylets and bougies are narrow tools that can also put a patient at risk for puncture, perforation, laceration, and bleeding.13 Insertion must also be done as a gentle fluid motion, just as when sliding the ET tube on top. Traumatic complications put the patient at risk of bleeding and aspiration. Likewise, multiple attempts at laryngoscopy can cause a sympathomimetic response.
The appropriate tube size should also be decided prior to intubation. Using too large of a tube for the patient’s weight may result in trauma to the vocal cords and other airway structures. Likewise, the appropriate sized blade is of utmost important. A laryngoscopy blade that is too big can cause damage to the airway structures and obscure your view of the vocal cords.
Proper medications must also be selected when the decision is made to rapidly induce a patient in order to gain airway access. It is essential that vital signs be consistently monitored, as the choice of neuromuscular blockade in RSI is dependent upon it. Ketamine and etomidate are preferred in the hemodynamically unstable patient.15 Additionally, the rapid switch of apnea to positive pressure ventilation can have a significant cardiovascular and autonomic response, which can lead to prompt hemodynamic collapse in a patient already at risk.14,15,16 Push-dose pressors such as epinephrine or phenylephrine should be available prior to intubation for the event of peri-intubation hypotension. For instructions on mixing these medications: http://emcrit.org/wp-content/uploads/push-dose-pressors.pdf.
Error 5: Failure of decision-making
Intubation in the ED often entails a chaotic environment, which requires a calm amid the storm in order to maintain sound judgment while making life-and-death decisions. A stepwise approach is needed to ensure no key steps were missed when deciding if a patient needs to be intubated, how the patient should be intubated, if it will be a difficult intubation, and how the difficult airway should be managed.17
If a patient requires emergent airway management, it is important that this decision is made immediately on evaluation. Delaying intubation can increase morbidity and mortality. For instance, a stroke patient can further lose oropharyngeal reflexes causing the tongue to fall backward, causing partial obstruction of the airway. This patient will be unable to clear secretions, elevating the risk of aspiration. Other examples include, a patient with anaphylaxis who has not yet reached the point of becoming stridulous, or a patient with hoarseness following smoke inhalation.17
Upon recognition of the “can’t intubate, can’t ventilate” scenario, the decision to perform a cricothyrotomy must be made immediately, prior to the patient suffering from a hypoxic cardiac arrest. Cricothyrotomy is not a failure of endotracheal airway management; rather, it is a lifesaving procedure due to poor airway anatomy.
Oftentimes the decision will not be clear-cut. In these situations, it is important to look at the clinical picture in its entirety, taking into account the pathologic process, age, risk factors, comorbidities, respiratory status, and available resources. Never second-guess seeking help and always make decisions based on the patient’s best interest.
References / Further Reading:
- Hasegawa K., Kazuaki S., et al. (2012). Association between Repeated Intubation Attempts and Adverse Events in Emergency Departments: An Analysis of a Multicenter Prospective Observational Study. Annals of Emergency Medicine: An International Journal. 60-6 (749-754). http://www.annemergmed.com/article/S0196-0644(12)00371-X/abstract
- Nickson, C. (2014). Airway Assessment. Life in the Fast Lane. Web. http://lifeinthefastlane.com/ccc/airway-assessment/
- Nickson, C. (2014). Difficult Airway Algorithms. Life in the Fast Lane. Web. http://lifeinthefastlane.com/ccc/difficult-airway-algorithms/
- Levitan, R. (2014) Tips and Tricks for Performing Cricothyrotomy. ACEP Now: The Official Voice of Emergency Medicine. http://www.acepnow.com/article/tips-tricks-performing-cricothyrotomy/
- Stone, M. Chan, W. (2014). Focused Ultrasound for Airway Management. Philips Tutorial. Web. https://www.acep.org/uploadedFiles/ACEP/Clinical_and_Practice_Management/innovatED/Innovation/Philips%20Healthcare%20-%20Airway_Tutorial_FNL_short.pdf
- Levitan, R. (2015). Avoiding Common Laryngoscopy Errors. Emergency Physicians Monthly. Web. http://epmonthly.com/article/avoiding-common-laryngoscopy-errors/
- Levitan, R. Mechem, C. Ochroch, A. Shofer, S. Hollander, J. (2003). Head-Elevated Laryngoscopy Position: Improving Laryngeal Exposure during Laryngoscopy by Increasing Head Elevation. Annals of Emergency Medicine. 41:3 (322-330). https://www.med.unc.edu/emergmed/files/Patient%20positioning%20in%20intubation.pdf
- Nickson, C. (2015). Critical Care Compendium: Direct Laryngoscopy. Life in the Fast Lane. Web. http://lifeinthefastlane.com/ccc/direct-laryngoscopy/
- Mark, L. Merzer, K. Cover, R. Pandian, V. Bhatti, N. et.al. (2015). Difficult Airway Response Team: A Novel Quality Improvement Program for Managing Hospital Wide Airway Emergencies. Anesthesia Analgesia. 121(1): 127-39. http://www.ncbi.nlm.nih.gov/pubmed/26086513
- Kundra, P. Mishra, S. Ramesh, A. (2011). Ultrasound of the Airway. Indian Journal of Anaesthesia. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3237144/
- Carley, S. Gwinnutt, C. Butler, J. Sammy, I. Driscoll, P. (2002). Rapid Sequence Induction in the Emergency Department: A Strategy for Failure. Emergency Medicine Journal.19: 109-113. http://emj.bmj.com/content/19/2/109.full
- Divatia, J. Bhowmick, K. (2005). Complications of Endotracheal Intubation and Other Airway Management Procedures. Indian Journal of Anaesthesia. 49 (4): 308-318. http://medind.nic.in/iad/t05/i4/iadt05i4p308.pdf
- Lafferty, K. Byrd, R. (2014). Rapid Sequence Intubation: Overview. Medscape. Web. http://emedicine.medscape.com/article/80222-overview
- Scherzer, D. Leder, M. Tobias, T. (2012). Pro-Con Debate: Etomidate or Ketamine for Rapid Sequence Intubation in Pediatric Patients. The Journal of Pediatric Pharmacology and Therapeutics. 17(2): 142-149. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3470433/
- Meena, A. Suvarna, A. Kaul, S. (2002). Critical Care Management of Acute Stroke. Neurology India. 50(1): 37-49. ISSN: 0028-3886. http://www.bioline.org.br/request?ni02161
- Brown, C. Walls, R. Grayzel, J. (2008). The Decision to Intubate. UpToDate. Web. http://cursoenarm.net/UPTODATE/contents/mobipreview.htm?