If you clicked on part II, thinking there was a list of links to free things you can purchase to improve airway management outcomes, you will find no such link. A silver bullet solution that will enhance your patient outcomes in airway management and/or reduce the risk of the procedure in the prehospital environment does not exist.
But I can guarantee that 100% of your organizations own everything you need to implement the changes to enable the best possible outcomes (within the proper contexts). In Part I, we talked about organizational culture and leadership’s influence on our mindsets surrounding the execution of airway management and their outcomes. In Part II, we will unpack a handful of FREE processes and procedures you can implement at no cost to the organization. I refer to them as “free” not because this is a free blog but because it will cost your organization exactly $0 to implement most of these interventions into your airway management programs. You are likely already required to stock these items on your units.
Pre-Oxygenation Strategy
Pre-oxygenation is a cornerstone of airway management of all types and in all environments. Those risks include things like anoxic brain injury and cardiac arrest. The goal of pre-oxygenation before induction is to prolong or extend the safe apnea period. This is the period of time that a patient can go without breathing or receiving assisted ventilation before they desaturate to a dangerous level. In the context of prehospital airway management, this is the period between paralysis and the restoration of respiration via positive pressure ventilation after the placement of an airway (be it an ET tube, supraglottic airway, or surgical airway).
The risks of hypoxia are well-known and documented. Weingart and Levitan’s landmark paper on pre-oxygenation strategies states that 6% of the study population experienced a cardiac arrest that was associated with peri-intubation hypoxia.1 A more extensive review of the literature on hypoxia and airway management reveals a desaturation rate that ranges from 19%-70%, with one paper by Jaber suggesting 50% of patients desaturate no matter what we do for them pre-intubation. Weingart also suggests that desaturation can happen in less than 30 seconds if the patient is critically ill.2
Our goals for pre-oxygenation are three-fold:
1.) Decrease the duration of apnea
2.) Prolong the safe apnea time
3.) Increase the odds of first-pass success
Hypoxia is associated with more attempts across all environments and care settings.1,5 This is likely because clinicians are making prudent decisions to abandon their airway attempt when they see a dangerous drop in oxygen saturation levels.1 Continuing an intubation attempt beyond a safe oxygenation level will likely result in a hypoxic cardiac arrest and exponentially increase morbidity and mortality in that patient. In one study, cardiac arrest carried a 32% mortality rate (NEAR) when intubation is attempted when the patient is hypoxic! The NEAR folks found a 210% increase in the odds of cardiac arrest when intubation is attempted in hypoxic patients.
Check out EMS Lighthouse episode 48 for more on NEAR and airway data. (See below)3
Pre-oxygenation is a bit more complicated than the term implies. Why is it not simply supplying the patient with supplemental oxygen or hyperventilating them with a BVM? Because three physiologic elements contribute to our ability to successfully preoxygenate a patient…or not.
What we are trying to accomplish is replacing as much of the functional reserve capacity of the lungs with pure oxygen to the greatest extent possible, and to do that, we need as much lung surface area (alveoli) as possible recruited and filled with OXYGEN…not nitrogen and oxygen. This brings us to the next element of the preoxygenation strategy: de-nitrogenation.
Atmospheric air is comprised of 78% nitrogen and 21% oxygen…plus some other small-time players. Atmospheric air is more commonly referred to as “room air” in our vernacular, but the nitrogen/oxygen content is still the same, and it is still the same in our lungs. This means that in our alveoli, a large portion of the space is occupied by nitrogen, not oxygen, reducing the amount of oxygen content available for movement to hemoglobin. We can influence this by creating a pressure gradient with oxygen. Providing the patient with 100% oxygen for a period of time will help “wash out” or de-nitrogenate the alveoli and allow the alveoli to be occupied with 100% oxygen instead of a mere 21%.
Simple right? 100% oxygen provided over time will increase the O2 content in the alveoli. Not exactly… 100% oxygen supplied over time will increase the O2 content in the alveoli that are being ventilated in healthy and perfused lungs. In some cases, not every alveolar unit participates in gas exchange, and not every unit is being perfused well enough to participate meaningfully. Airspace problems that result from diseases like COPD complicate this as they often suffer from atelectasis and have large areas of lungs that may not be aerated.
Free Resource #1: Elevate Your Approach
Supercharge your preoxygenation strategy by simply positioning your patient correctly. Raise the head of the bed to increase FRC and improve lung mechanics. This is not to be confused with ramping or placing the patient’s ear in alignment with the sternal notch (ear-to-sternal-notch), which would be the next step in elevating your approach.
Elevating the HOB provides a couple of distinct advantages regarding airway management. First, it places the opening of the airway and esophagus ABOVE the stomach, using gravity to your benefit in decreasing the chances of the airway becoming soiled with emesis and aspiration. The other advantage is that it improves respiratory mechanics and allows for better recruitment of FRC. When a patient is flat, the posterior lung fields are prone to atelectasis and challenging to recruit to participate in ventilation. Moreover, the weight of the anterior chest wall also rests on the lungs, and this position does not always allow for adequate tidal volume breaths to be delivered due to an inhibition of lung expansion. Be careful not to raise the bed and the HOB to the degree that you are trying to manage the airway from the back of the patient’s head. This may feel like the patient is sitting upright in front of you, and you have to reach around and over the top of the head to manipulate the airway. For best results, put the top of the patient’s head at the very top of the bed’s mattress.4
Let’s add elevating the ear to the sternal notch, also known as the “sniffing” position, to this elevation of strategy. This positioning allows for better alignment of the airway anatomy and can greatly improve the ability to get a view of the glottic opening. Think of how you would sniff a flower. You naturally bring your head forward and align your airways to take a deep breath. We are mimicking this same movement with our ramping maneuver. This is best accomplished by using towels, blankets, or pillows to “build a ramp” that elevates the head and brings it forward until the ears break the plane of the anterior chest.5
Better positioning leads to better respiratory mechanics leads to better oxygenation and improvement of functional reserve capacity which leads to an average of 90 seconds longer time to desaturation.1 Buying this time can also increase the chances of first-pass success without adverse events.
We know that hypoxia is an independent predictor of multiple attempts and a host of morbidity and mortality.5 One likely cause is that when the operator sees that the patient is desaturating, it prompts them to abandon the attempt and re-oxygenate the patient before attempting intubation again.5 Perhaps that extra 90 seconds might be just what the doctor ordered to ensure the best chance of first-pass success without adverse events.
Free Resource # 2: Apneic Oxygenation (ApOx)
Apneic oxygenation? How can patients oxygenate themselves if they are not actively breathing/ventilating or receiving positive pressure ventilation? This cannot possibly be evidence-based… right? Wrong. Apneic oxygenation has been observed and well-documented for the better part of the last century. For several years, its application has shown a benefit in this specific context.1,7
ApOx is accomplished by simply placing a nasal cannula on the patient at flush rate (15lpm +) and allowing for the passive flow of oxygen into the airways. But there has to be more to it than that, right?
Dalton’s Law dictates that the gasses in the alveoli will move to equalize with atmospheric air, nature will seek a balance, and nitrogen, oxygen, and carbon dioxide (and a few others) will attempt to achieve that balance. By influencing Henry’s Law, we can create a pressure gradient where we can put enough oxygen into the alveoli so that it freely moves across the alveolar-capillary membrane into the bloodstream. If we keep an oxygen source that constantly delivers high flow, high concentration oxygen, we can keep the patient oxygenated without ventilating them simultaneously. Right?
One significant problem with this can affect the utility of this approach… shunt physiology. If the patient has an air space disease like COPD, the lungs’ overall oxygen capacity is reduced, which may not be as effective of an approach as it could be. If the patient has poor blood flow through the lungs, there will also be reduced efficacy.
The benefit of apneic oxygenation is two-fold: continuing oxygenation throughout the entire procedure (a bonus being without PPV); and increasing the safe apnea time (bonus being without dangerous hypercapnia). While it is not a definitive way to oxygenate a patient, it can temporize things and buy enough time to complete an airway procedure with reduced risk to the patient. In some cases, this can be as little as 3 minutes or as long as 8.1
Close-Out
The next installment will evaluate how some systems and services have implemented clinical bundles to improve airway management outcomes. Sometimes, this happens by just aligning the tools they have on hand with their place in the process and mandating their use every time.
Until next time.
BIBLIOGRAPHY
1. Weingart SD, Levitan RM. Preoxygenation and prevention of desaturation during emergency airway management. Ann Emerg Med. 2012 Mar;59(3):165–75.e1. doi: 10.1016/j.annemergmed.2011.10.002. Epub 2011 Nov 3. PMID: 22050948.
2. Jaber S, Jung B, Corne P, Sebbane M, Muller L, Chanques G, Verzilli D, Jonquet O, Eledjam JJ, Lefrant JY. An intervention to decrease complications related to endotracheal intubation in the intensive care unit: a prospective, multiple-center study. Intensive Care Med. 2010 Feb;36(2):248–55. doi: 10.1007/s00134–009–1717–8. Epub 2009 Nov 17. PMID: 19921148.
3. April MD, Arana A, Reynolds JC, Carlson JN, Davis WT, Schauer SG, Oliver JJ, Summers SM, Long B, Walls RM, Brown CA 3rd; NEAR Investigators. Peri-intubation cardiac arrest in the Emergency Department: A National Emergency Airway Registry (NEAR) study. Resuscitation. 2021 May;162:403–411. doi: 10.1016/j.resuscitation.2021.02.039. Epub 2021 Mar 5. PMID: 33684505.
4. 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 Apr;122(4):1101–7. doi: 10.1213/ANE.0000000000001184. PMID: 26866753.
5. 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. doi: 10.1381/0960892042386869. PMID: 15527629.
6. Sakles, J. C., Chiu, S., Mosier, J., Walker, C., & Stolz, U. (2013). The importance of first pass success when performing orotracheal intubation in the emergency department. Academic Emergency Medicine: Official Journal Of The Society For Academic Emergency Medicine, 20(1), 71–78. doi:10.1111/acem.12055
7. Binks MJ et al. Apneic Oxygenation During Intubation in the Emergency Department and During Retrieval: A Systematic Review and Meta-Analysis. Am J Emerg Med 2017; S0735–6757 (17): 30497. PMID: 28684195
