How to Manage the Difficult Airway

It started as a simple lift assist, helping another crew get an obese CHF patient out of his house and into the rig. Soon, however, it became apparent that the responding crew would need more than just extra muscle to manage the patient. His level of consciousness was deteriorating, and his oxygen saturation and capnography readings were worsening despite the CPAP the responding crew applied. Before we could muscle him out of his cramped, dark bedroom, he stopped breathing altogether, and the first-in medic looked at me hopefully and asked, “Get the airway for me?”

This is the way most EMS war stories start: “So there we were, with a 460-pound snowman CHFer who needed a tube, with only me and my trusty laryngoscope standing between him and certain death. And that’s when it happened: A deep voice boomed from above, ‘Need any help, son?’ and shaft of white light bathed the patient’s face…”

No, really, that’s the way it happened. I don’t know where the cop came from, but at the moment I was immensely happy to see him and his xenon flashlight. After I handed him a pair of gloves from my thigh pocket, he probably regretted the offer, but together we managed to get the airway secured.

Strategies

Paramedics have long prided themselves for intubating under conditions that would daunt the most skilled anesthesiologist, but challenging conditions and austere environments are not an acceptable excuse for failure. What matters are results. This article will explore strategies for managing difficult airways in the prehospital environment, focusing on the tools and techniques commonly available to EMS providers.

Airway management is not merely a psychomotor skill to be utilized when the patient can no longer manage their own. Rather, it is a mind-set and a constellation of skills, tools and techniques that we employ not only to manage non-patent airways with various adjuncts, but also to preserve patients’ ability to manage their own airways. The following are strategies we can use to manage difficult airways:

• It’s not about the tube. There is a reason we call it airway management. The goal is not to employ a specific device, but to ensure adequate oxygenation and ventilation. As long as that goal is achieved, it should not matter whether we use an oropharyngeal airway, a King LTS-D, an endotracheal tube or simply lean over and tap our narcotic overdose patient on the shoulder and remind him, “Hey, buddy, take a breath,” whenever we see the capnograph waveform pause for longer than we deem comfortable.

Airway management is not just one thing; it is a continuum of interventions ranging from simple positioning to surgical cricothyrotomy. Generally we need only progress as far along the continuum as is necessary to achieve adequate oxygenation and ventilation.

In the aforementioned narcotic overdose patient, if we can keep our lethargic, somnolent patient breathing adequately during transport by the simple act of engaging him in conversation, shouldn’t we do that, rather than resort to an invasive airway procedure or risk the effects of narcotic withdrawal by using naloxone?

• Positioning makes a difference. Supine positioning can result in a marked reduction in functional residual capacity and some decrease in total lung capacity, particularly among the obese,¹ and a 25-degree head-up position has been demonstrated to be superior to supine positioning in preoxygenation of obese patients.² We should weigh the benefits of supine positioning versus the risk of respiratory decompensation and transport our patients in semi-Fowler’s position whenever possible.

Positioning is equally important when preparing the patient for insertion of an airway adjunct. While the sniffing position is generally considered optimum for aligning the axes of the airway in direct laryngsocopy, there has been little consensus on what the sniffing position actually is. Many providers simply hyperextend the neck in an attempt to better visualize airway structures; in reality this practice may misalign airway structures and make visualization more difficult. Achieving the sniffing position requires not hyperextension, but flexion of the neck—roughly 35 degrees, with 15 degrees of head extension.³

Doing this while keeping the axes of the airway properly aligned for direct visualization requires elevation of the head in all but the smallest of children. Older children and adults will require several layers of padding under the head, and the morbidly obese will require the addition of significantly more padding under the shoulders, a technique known as “ramping.”  

Ideally, the patient’s face should remain parallel with the ceiling, and the external auditory meatus should be horizontally aligned with the sternum. Add padding wherever needed to approximate this position. Even when not performing direct laryngoscopy, this position allows for better airflow and oxygenation than supine positioning.

• Use the right tool for the job. There is a reason why laryngeal mask airways are supplanting endotracheal intubation in hospital operating suites: Supraglottic airways work. If the ED is scant minutes away and your patient’s airway can be effectively secured using a blindly inserted, minimally invasive supraglottic airway, why intubate? For resuscitation purposes and relatively short transport times, supraglottic airways have been demonstrated to be as effective as ETIs, and they’re easier to place.

Keep in mind that for certain patients, particularly those with anatomical impediments to direct laryngoscopy, a supraglottic airway adjunct may not simply be your rescue airway; it may be your preferred airway.

For patients with anterior glottis (thyromental distance less than 3 finger widths), the use of a gum elastic bougie may facilitate passage of the endotracheal tube. Bougies are helpful in many cases and can make the difference between missed airways and successful ones. Some EMS medical directors may even require their routine use.

• Assess your patients. For any patient with significant respiratory distress or neurological compromise, assess with the potential need for airway management in mind. While scoring systems like Mallampati and the LEMON (look externally, evaluate the 3-3-2 rule, Mallampati scoring, obstruction, neck mobility) mnemonic may represent the ideal pre-intubation assessment, their use requires a calm, cooperative patient.

EMS patients, particularly those in need of advanced airway management, are rarely calm and cooperative, and the LEMON mnemonic has significant limitations in prehospital application.⁴ In one study, a ratio of neck circumference to thyromental distance of greater than 5.0 was found to be a more accurate predictor of difficult intubation in the obese,⁵ and may be more readily adaptable to prehospital use than other currently used indices.

A more helpful assessment tool may be Cormack-Lehane grading of laryngoscopic views. If the initial laryngoscopic view does not show the vocal cords, a difficult airway is identified. Using the BURP technique (backward, upward, rightward pressure on the thyroid cartilage with the operator’s right hand while looking with the laryngoscope in the left hand), many difficult airways can be managed with a bougie. The BURP technique can improve a view one degree in most cases, sometimes allowing the bougie to be used effectively. The BURP technique works best when the operator who is intubating uses it to help bring the glottic opening into view. This is sometimes called bimanual tracheal manipulation in the literature. After finding the right place, the operator can ask an assistant to replace his thumb and first finger with theirs and maintain the view he has found.

• It’s a team sport. Success at securing a difficult airway does not lie solely with the person holding the laryngoscope. Preplanning, even during a crash intubation, is vital. Making proper use of your partner and additional personnel may make the difference between success and failure. After the operator has achieved a view of the cords using the BURP technique, an assistant can help the operator by placing their hands in the same position and maintaining the view. This technique, plus lip retraction at the right corner of the mouth, can greatly improve a direct laryngoscopic view, usually by at least one Cormack and Lehane grade.^6,7 You only have to see this work once to become a believer. BURP plus bougie can work wonders with a difficult airway.

• Take your time. Seriously, it’s not a race. There is no one standing over your shoulder with a stopwatch, and there are no points awarded for finishing fast.

Forget about the “30-second rule” for an intubation attempt. This is a fallacy without any scientific basis. It has been repeated ad infinitum in EMS texts and is still adhered to by the National Registry of EMTs without any medical evidence to support it. An otherwise healthy adult patient preoxygenated to 98% saturation takes 6–8 minutes to desaturate after the onset of apnea. For children, the obese or those with significant chronic respiratory pathology, you can cut that window in half. Still, you have a window measured in minutes, not seconds.8

The only time limitation you realistically need to consider is the brief window during a compressor switch in cardiopulmonary resuscitation. If you can’t pass a tube without interrupting chest compressions, perhaps the wiser course of action would be to insert a supraglottic airway or defer intubation as a post-ROSC stabilization maneuver, if needed.

There is a saying that applies here: Slow is smooth, and smooth is fast. By slowing down and taking a methodical approach to preparation of equipment and communicating with your team members, not only do you reduce the likelihood of mistakes, but you give yourself and your team the opportunity to calm and center yourselves for what can be a stressful, lifesaving procedure.

One technique also has the potential to greatly broaden that window for successful intubation: Adding a nasal cannula at 15 LPM to your other preoxygenation techniques has been shown to maintain an oxygen saturation of 98% or better in apneic patients for as long as an hour.^8,9

Yes, you read that correctly: a nasal cannula at 15 LPM. The principle here is one of simple physics: By filling the nasopharynx and oropharynx with oxygen, you create an oxygen reservoir, and oxygen will migrate down its concentration gradient into the lungs and into the blood, thus improving the saturation level.

Conclusion

Few situations challenge the skills of prehospital providers like managing difficult airways. While the advent of supraglottic airways and CPAP and the de-emphasis of endotracheal intubation in ACLS guidelines have resulted in ever-dwindling opportunities to practice endotracheal intubation, proficiency at airway management remains a vital element in the prehospital provider skill set. While new airway adjuncts and tools like video laryngoscopy offer intriguing possibilities, they are still no substitute for thorough assessment, preplanning and communication with team members.

Do those things well, and they may make an impossible intubation merely difficult, and a difficult intubation relatively easy. Mental preparation and rehearsal are the keys. Think about your plans for managing difficult airways, practice scenarios with your team members, and when the time comes to perform, you will be ready.

References

1. Salome CM, King GG, Berend N. Physiology of obesity and effects on lung function. J Appl Physiol, 2010 Jan; 108(1): 206–11.

2. Dixon BJ, Dixon JB, Carden JR, et al. Preoxygenation is more effective in the 25 degrees head-up position than in the supine position in severely obese patients: a randomized controlled study. Anesthesiology, 2005 Jun; 102(6): 1,110–15, discussion 5A.

3. El-Orbany M, Woehlk H, Salem MR. Head and neck position for direct laryngoscopy. Anesth Analg, 2011 Jul; 113(1): 103–9.

4. Dowdy B. EMS World. When Life Gives You Lemons, www.emsworld.com/article/10319023/when-life-gives-you-lemons.

5. Kim WH, Ahn HJ, Lee CJ, et al. Neck circumference to thyromental distance ratio: a new predictor of difficult intubation in obese patients. Br J Anaesth, 2011 May; 106(5): 743–8.

6. Takahata O, Kubota M, Mamiya K, et al. The efficacy of the “BURP” maneuver during a difficult laryngoscopy. Anesth Analg, 1997 Feb; 84(2): 419–21.

7. Benumof JL, Cooper SD. Quantitative improvement in laryngoscopic view by optimal external laryngeal manipulation. J Clin Anesth, 1996 Mar; 8(2): 136–40.

8. Weingart SD, Levitan RM. Preoxygenation and prevention of desaturation during emergency airway management. Ann Emerg Med, 2012 Mar; 59(3): 165–75.e1.

9. Levitan R. NO DESAT! (Nasal Oxygen During Efforts Securing a Tube). Emergency Physicians Monthly, www.epmonthly.com/archives/features/no-desat-/.

Steven “Kelly” Grayson, NREMT-P, CCEMT-P, is a critical care paramedic for Acadian Ambulance in Louisiana. He has spent the past 14 years as a field paramedic, critical care transport paramedic, field supervisor and educator. He is the author of the book En Route: A Paramedic’s Stories of Life, Death, and Everything In Between and the popular blog A Day in the Life of an Ambulance Driver.

William E. “Gene” Gandy, JD, LP, NREMT-P, has been a paramedic and EMS educator for over 30 years. He has implemented a two-year associate’s degree paramedic program for a community college, served as both a volunteer and paid paramedic, and practiced in both rural and urban settings. He lives in Tucson, AZ.