Apneic oxygenation is an important process when performing a rapid sequence intubation.

A medical student in his fourth year of training recently asked me about apneic oxygenation. I told him that, based on the pulmonary physiology, it didn’t make much sense to me. It was then very ironic that just two days later, I witnessed an apneic oxygenation technique employed on a patient in one of our trauma bays. The emergency medicine physician placed a nasal cannula in the patient’s nose and assisted the patient’s breathing with a bag-valve mask (BVM) even though the BVM was also connected to an oxygen supply. Then, induction agents were given, and the patient was intubated with the nasal cannula still in place.

Watching this process first-hand piqued my interest. Why was I not aware of this new “extra-oxygen” process and what evidence supports apneic oxygenation? I decided to share my findings with you.

The Scientific Process
To understand how apneic oxygenation works, we must first focus on the physiology of respiration. Gases flow down their concentration gradients. The air we breathe has a higher concentration of oxygen than the tissues that metabolize it. This means the oxygen in the air inside our lungs is readily absorbed by the alveoli, flows through our blood stream, diffuses into the body’s tissues and is converted into carbon dioxide.

Because the oxygen is converted into another molecule, it will keep moving forward in this process as long as the lungs contain oxygen, blood is circulating and tissues are consuming it. Apneic oxygenation allows this cycle to continue when the patient isn’t breathing by putting oxygen into the lungs.

In one study, “Apneic Oxygenation in Man,” volunteers were intubated and pharmacologically paralyzed to prevent breathing.(1) With the endotracheal tube filled with pure oxygen and connected to a circular circuit, one volunteer subject maintained a 100% oxygen saturation level for almost an hour without taking a breath. The other volunteers similarly maintained their oxygen saturation levels for extended periods of time.

While oxygenation was occurring, the patients developed an acidosis and their carbon dioxide tension increased three mmHg per minute on average. The lowest pH recorded was 6.72.

In another study, patients were pre-oxygenated before induction and, after the patients became apneic, a catheter was inserted nasally.(2) Patients were divided into two groups: the first had its pharynx insufflated through the catheter, while the second group did not. After the patients desaturated or 10 minutes had elapsed, they were pre-oxygenated manually. Then, the process was repeated while the second group received insufflation and the first did not.

The study showed that without oxygen insufflation, the participants began to desaturate at around seven minutes.(2) However, all the anesthesia providers maintained their patient’s oxygen saturation for 10 minutes with oxygen insufflation.

Note: Although there’s a mechanism to entrain oxygen into the lungs outside of breathing, there’s no mechanism to expel carbon dioxide. The carbon dioxide in the blood stream rapidly eqiulibriates with teh carbon dioxide in the lung. For more discussion on the differences between oxygen and ventilation, see the November JEMS article, “Oxygenation & Ventilation Are Not the Same Thing.”

The goal is to increase the amount of time it takes for the patient to become critically hypoxic (less than 70% oxygen saturation) in case there are problems with intubation.

Why, When & How to Use It
Understanding the benefit of apneic oxygenation, you can see why it’s an important process to use when performing a rapid sequence intubation. Your goal is to increase the amount of time it takes for the patient to become critically hypoxic (less than 70% oxygen saturation) in case there are problems with intubation.(3) In a 2010 study, apneic oxygenation was shown to increase the time until an obese patient started to become hypoxic by about 2.5 minutes.(4)

To perform apneic oxygenation when performing a rapid sequence intubation, the patient should either be placed head up or in reverse Trendelenburg at a 20–30° angle.(3) Insert a nasal cannula and set it for at least five liters of oxygen per minute. If possible, the patient should then be pre-oxygenated by allowing three minutes of tidal volume breathing, or eight vital capacity breaths(.)3 This involves providing 100% oxygen to the patient either while they breathe or while the medical provider assists the patient’s breathing.

Ideally positive end-expiratory pressure (PEEP) or continuous positive airway pressure (CPAP) should be added for optimal pre-oxygenation.(5) There doesn’t seem to be a clinical benefit to pre-oxygenating longer than four minutes.6 Lastly, make sure to keep the nasal cannula properly placed when the clinician removes the mask and performs a laryngoscopy.

How to be Prepared to Perform Apneic Oxygenation
There are just a few downsides to apneic oxygenation, but they don’t outweigh the benefits. First, there needs to be a second oxygen source for the nasal cannula. This is rarely an issue in a room or bay equipped to handle critically ill patients. However, this may be difficult in the prehospital setting. Second, the nasal cannula itself can complicate getting a good seal on the patient’s face.

If you cannot get an adequate seal, you can position the nasal cannula above the mask and quickly place it in the nares once the mask is removed to perform intubation.

Conclusion
The key to apneic oxygenation is that it can significantly increase the amount of time before an apneic patient becomes critically hypoxic. With the correct equipment available, this process is an easy and effective way to provide additional oxygen to patients when they aren’t breathing. Providers experienced in advanced airway placement should strongly consider discussing adding an apneic oxygenation technique to their protocols for scenarios when intubating conditions are less than ideal.

Joshua Sappenfield, MD, is a fellow at the R Adams Cowley Shock Trauma Center, Department of Anesthesiology, University of Maryland Medical Center. He can be reached at jsappenfield@anes.umm.edu.

References

1. Frumin MJ, Epstein RM, Cohen G. Apneic oxygenation in man. Anesthesiology. 1959;20:789–798.

2. Teller LE, Alexander CM, Frumin MJ, et al. Pharyngeal insufflation of oxygen prevents arterial desaturation during apnea. Anesthesiology. 1988;69(6):980–982.

3. Weingart SD, Levitan RM. Preoxygenation and prevention of desaturation during emergency airway management. Ann Emerg Med. 2012;59(3):165–175.

4. Ramachandran SK, Cosnowski A, Shanks A, Turner CR. Apneic oxygenation during prolonged laryngoscopy in obese patients: a randomized, controlled trial of nasal oxygen administration. J Clin Anesth. 2010;22(3):164–168.

5. Weingart SD. Preoxygenation, reoxygenation, and delayed sequence intubation in the emergency department. J Emerg Med. 201; 40(6):661–667.

6. Mort TC, Waberski BH, Clive J. Extending the preoxygenation period from 4 to 8 mins in critically ill patients undergoing emergency intubation. Crit Care Med. 2009;37(1):68–71.

Overcoming fear is the first step to slaying the dragon of a difficult airway. The next is choosing your tools to face the monster. Photo Chris Swabb

By Jim Radcliffe, BS, MBA, EMT-P

I hope everyone is having a great year. I know the economy is tight and there’s all this political stuff going on in and out of our industry, but that’s not why we got into this business in the first place. Somewhere in our lives, we were bitten by the EMS bug. Some of us really came down with it and we have spent most of our lives serving other people. Believe it or not, I’ve had the honor and privilege of knowing some paramedics and EMT’s in their 80s still serving and teaching, running circles around their younger counterparts.

However, it doesn’t matter how old or young, new to medicine or experienced you are, we all have to understand the anatomy and physiology (A&P). Few have the luxury of going through programs with excellent science programs that mirror what medical school students must learn, so A&P becomes scary. One particularly scary and disorienting area of A&P is the airway. The A&P of the airway is scary for a couple reasons, I know it was to me and still is today—but for different reasons. I would like us to take a few minutes to take a look at the A&P from a couple perspectives and talk about how we might make it a little less scary for everyone.

Bring on the Nightmares
Do you remember when you were a student or a new paramedic and going into the operating room for an airway rotation? How about that first field intubation you did? It was probably in front of your preceptor or field training officer (FTO). Wow, I know it was a couple decades ago for me, but I still remember that my hands were shaking and I was sweating while trying to verbally walk myself through the steps and reviewing the A&P in my head.

I did all this as I attempted to impress the anesthesiologist behind me, whom I had met only an hour before. Then I remember noticing that he was right behind me, and his chin was almost on my shoulder as he was trying to look down my laryngoscope blade to see what I was seeing. I know it sounds like a Steve Berry cartoon, but it’s true. It took me several years and my turn as a preceptor and instructor to understand that intubation is not just scary for the student but also for the preceptors and FTOs.

Over the past several years I’ve learned a couple things I think could really help us conquer this fear of the airway A&P and help us all to be better providers and paramedics. So the first thing we have to do is what my good friend Charlie used to say, “Take a deep breath and relax and think about what’s for lunch.” To be a good provider, you have to know the A&P upside down and backwards (and I like to say so well that you have nightmares about the epiglottis.)

Monsters, Dragons & Beasts—Oh My!
So let’s start at the top and review some basic A&P that we all must know. Air comes into our patient through the nose and the mouth as they breathe or we breathe for them. The air going in through the nose is warm filtered and humidified as it goes over the turbinates lined with cilia to filter out the dust and things floating in the air to keep it out of our airways. That air then proceeds down through the nasal pharynx, connects with the posterior oral airway and goes down to the larynx.

Remember that the oral and nasal passages are separated by the hard and soft pallet. The air going in through the mouth must pass by the teeth and proceed the first monster of the airway, the tongue. Yes it seems like and looks like a monster the first time you attempt to slay the dragon of an airway and you are staring down a laryngoscope blade at that beast. No wonder it’s the largest and most common airway obstruction. After getting passed the tongue there is this strange character that you meet called the uvala. He is just hanging there off of the soft pallet pointing you south toward the darkness of the airway. When the patient is breathing this is like a wind tunnel but when you are marching through here with a little metal stick with a light on the end of it the air is still, stagnate and full of foul odors. As you begin to round the corner to head down to the larynx the uvula reminds you, “watch out for the epiglottis just around the corner.

Oh yes the epiglottis, not quite as large as the tongue but still a monster that’s slippery and illusive. For years, I would intubate by looking for the vocal cords Then one day, I realized that everyone has an epiglottis and it’s always in the same place. Think about it for a minute; pull up that old A&P picture from the recesses of your brain and look at the side view. Yep that’s it. Follow the center of the tongue, the forough, to the base of the tongue. At the base of every tongue is an epiglottis. The landmark between the tongue and the epiglottis is called the vallecula. The epiglottis comes in many sizes depending on the size of the patient and how many Whoppers they consume daily.

If you’re intubating, then you most likely have laid the patient flat on their back. (I’m not sure who ever thought to do that, because all the stomach content is now running toward the posterior oral airway and we have to lift all of the structures out of the way.) If you can, place the patient in a low Fowler’s position, it will make your life so much easier and help fix that crook in your neck as well.

Weapons of Choice
If your patient is large, you’ll most likely find a large, floppy epiglottis lying in a pool of slime at the bottom of the posterior oral airway, just waiting to jump up and ruin your day. You’ll need one other weapon in your arsenal to slay this monster, which would be your suction, never leave home without it. It seems that this monster is a lot easier to defeat when you take away his hiding places. Also when you put the patient in a low fowler’s position and put about two inches of padding behind the patient’s head you straighten out the airway and take away the corner’s for the epiglottis to hide. Choosing the correct light stick (laryngyscope blade) is important here, depending on the size of this epiglottis you may need a thin, wide or curved stick to defeat the monster. We will save the choice of weapon for another discussion. Once you defeat these two monsters, entering the cave of the airway dragon is pretty easy from there.

Over the past several years, numerous additions to the EMS airway resources have improved prehospital airway management. One simple change has been the introduction of fiberoptic and LED lighting systems on laryngoscope blades, which has made illuminating the airway much easier.

The introduction of video laryngoscope, which enables users to capitalize on a superior glottic view and access provided by the video image, has significantly changed first attempt success rates When you’re dealing with difficult airways in which you can’t get good line-of-sight visualization, video laryngoscopy uses a camera and a video monitor to visualize the airway and the glottis, enabling faster intubation. It has also given us a huge educational advantage. In teaching settings, the video laryngoscope allows the preceptor or instructor to see what the student or new provider is observing. For the classroom or lab setting, video trainers allow the instructor to walk the student through the airway and discuss issues that are encountered. I have found the use of video laryngoscope in cadaver labs has been extremely helpful to the students. Many video laryngoscopes have a “video out” feature that allows you to push the image to a larger screen for a group to be able to see what the intubator—whether the instructor or another student—is observing.

No More Fear
Over the years teaching in cadaver and airway classes, students will ask why they were never told these things in their initial training. I have found that understanding the A&P, the use of landmarks and the introduction of video laryngoscope has helped to take the scariness out of prehospital airway management. Hope this helps your practice.

Be Safe,
Jim Radcliffe, MBA, BS, EMT-P

1. Medications, including epinephrine, diphenhydramine, dopamine and dosed fluid boluses;

2. Supplemental oxygen; and

3. Airway support.

The effects of the treatment often lead to the three following outcomes:

1. Signs and symptoms are sometimes mild enough and recognized early enough, and they often fade when self-treated;
2. Signs and symptoms don’t subsequently recur from this type of exposure; and
3. Treatment is rendered, and improvement of the signs and symptoms is seen; however, symptoms may recur in four to 12 hours. This late phase reaction requires further treatment and close observation, and it can occur in about 10% of the cases. About 20% of anaphylactic reactions are severe enough and persistent enough to require intense EMS treatment and hospitalization. Let’s take a look at a few more cases.

Rick Rod, RN, CEN, NREMT-P, is currently the paramedic field training coordinator and clinical educator for San Diego EMS- Rural/Metro of San Diego and San Diego Fire-Rescue Department

A bee sting is an example of an allergen that can trigger an anaphylactic reaction.
Photo Kathy Keatley Garvey

Learning Objectives:
>> Identify the different types of anaphylaxis.
>> Learn the pathophysiology and the leading causes of anaphylactic reactions.
>> List methods of treatment for anaphylactic incidents.

Key Terms
Allergen: An environmental substance that can produce a hypersensitive allergic reaction in the body but may not be intrinsically harmful.

Anaphylactic reaction: An acute allergic responses triggered by IgE-mediated antigen-stimulated mast cell activation resulting in histamine release.

Anaphylactic shock: A severe and sometimes fatal systemic allergic reaction to a sensitizing substance, such as a drug, vaccine, specific food, serum, insect venom or chemical.

Anaphylaxis: An exaggerated, life-threatening hypersensitivity reaction to a previously encountered antigen.

Basophil: A granulocytic white blood cell that represent 1% or less of the total white blood cell count. The relative number of basophils increases in severe allergic reactions.

Bronchodilation: A widening of the lumen of the bronchi, allowing increased airflow to and from the lungs.

Mast cells: A constituent of connective tissue containing large basophilic granules that contain heparin, serotonin, bradykinin and histamine.

Paramedics responding to a school cafeteria for a respiratory distress call encounter a 7-year-old male patient with a known allergy to peanuts, who lapsed into acute respiratory distress after he had nibbled on a snack bar that contained peanuts.

His chief complaint to the school nurse was tightening in the throat, which quickly progressed to a chief complaint of shortness of breath. He was only able to speak three or four word phrases, and his respiratory rate climbed to 44 by the time the EMS crew arrived on scene.

The young patient soon became unresponsive, apneic and grossly cyanotic. Paramedics introduced bag-valve-mask (BVM) rescue breathing. Because the patient’s allergy history was known, he was also quickly administered epinephrine via the intramuscular (IM) route while peripheral IV access was obtained. Because of his shock state, it was difficult to gain peripheral vein access, so an EZ-IO needle was placed via the intraosseous (IO) route in his left proximal tibia. Diphenhydramine was then given via IO, and BVM assistance was continued.

His initial oxygen saturation measured 33%. After approximately one minute of BVM oxygenation, oxygen saturation improved to 80%. Nebulized albuterol and ipratroprium bromide were then introduced to the BVM circuit and delivered to the patient. Paramedics consulted with a base hospital physician, and an order for epinephrine via IO was given. Shortly after the IO epi was administered, the patient’s oxygen saturation increased to 92%, and transport was initiated.

Anaphylaxis refers to a rapidly developing allergic reaction that can affect a number of the body’s systems at once. Severe anaphylactic reactions can be fatal and happen within minutes. Anaphylactic reactions can happen so suddenly and become severe so rapidly that there have been examples of hospital inpatient deaths.

Many patients can suffer minor allergy symptoms; however, some can react in a more rapid and accelerated manner that can result in severe shock and, often, death. Substances injected into, or ingested by, an individual gain access into the bloodstream and can trigger anaphylaxis. A reaction involving the skin, lungs, nose, throat and gastrointestinal tract can then result.

Severe cases of anaphylaxis can occur within seconds or minutes of exposure and be fatal if untreated or not treated fast enough. Most anaphylactic reactions are less severe and can be ended with prompt medical attention or EMS and ALS interventions.

Pathophysiology
Approximately 1,500 deaths are reported annually from anaphylaxis. Causes for anaphylaxis can be divided into four major subtypes: food, drugs, latex reaction and insect stings. Largely depending on the substance, the chance of anaphylaxis after exposure to a substance has been from less than 1% to up to 10%.

The physiology of anaphylaxis and its leading causes can be divided into two major groups. The first group is commonly related to the production of Immunoglobulin E (IgE). The body produces IgE when it’s exposed to an allergen. The production of IgE causes the body to become sensitized to the allergen. Further exposures to the allergen by a sensitized individual may result in anaphylaxis. The severity of the anaphylactic reaction is difficult to predict. This group is referred to as IgE-mediated anaphylaxis.

IgE-mediated anaphylaxis results when basophils and mast cells in tissue and blood become coated with IgE. Basophils and mast cells release substances, known as mediators (largely histamines), which can cause allergic reactions. Subsequent reexposure to allergens can cause an explosive release of these mediators and IgE, resulting in an anaphylactic reaction.

Common IgE-mediated causes include medications, such as penicillin, cephlosporins and anesthetics. Insect stings, including fire ants, wasps, honey bees and hornets, are common causes. Other common causes are foods, such as peanuts, shellfish, eggs, milk and wheat. Vaccines, hormones, latex and animal proteins round out other common causes of IgE-mediated anaphylaxis.

The second group, called non-IgE-mediated anaphylaxis, or anaphylactoid reactions, are similar to IgE-mediated reactions, except they don’t require an IgE-immune reaction.

These types of reactions are thought to result in the commonly unexpected anaphylactic reactions that require 9-1-1 services because of the sudden development of anaphylactic shock. In these cases, no previous sensitivity is required, and the signs and symptoms are no different from IgE-mediated anaphylaxis. It’s difficult to distinguish the difference between the two groups. They are usually most easily differentiated by the attainment of the patient’s history. However, treatment is no different for either group. Common non-IgE-mediated causes of anaphylaxis include non-steroidal anti-inflammatories, narcotics, muscle relaxants and gamma gobulin, X-ray dyes, preservatives, sulfites, and physical exercise.

These reactions occur during intense, prolonged and strenuous exercise and often after eating prior to exertion. In some cases, the cause can be idiopathic. Up to 25% of non-IgE mediated anaphylactic reactions can be idiopathic. Often, IgE-mediated anaphylaxis can be confused with non-IgE-mediated anaphylaxis because the victim most likely was unwittingly sensitized to previous exposures, (i.e., they had previously been bitten or stung by an insect or eaten food with hidden allergens).

Because anaphylaxis affects almost all human systems, reactions of this type are almost always categorized as severe. The severity of the reaction will vary from person to person. The more rapidly the signs and symptoms of anaphylaxis develop, the more likely a severe reaction will result. Subsequent reactions to the same trigger often result in similar reactions; however, this doesn’t necessarily incline the person to a non-IgE-mediated reaction.

Signs & Symptoms
An underlying history of asthma or any type of allergic disease, such as eczema, rhinitis or multiple environmental allergies, doesn’t increase the risk of IgE-medicated anaphylaxis, but it does increase the risk of non-IgE-mediated anaphylaxis and can be more difficult to treat. The risks of anaphylaxis may decrease over time, but a person who’s known to be at risk should always be prepared for the worst. Many patients usually have refillable prescriptions from their doctors for such products as EpiPen Auto-Injectors and usually have oral diphenhydramine nearby.

The symptoms of anaphylaxis can occur within seconds of exposure or can take an hour or more. The earliest symptoms are often related to changes in the skin, including hives and itching—especially in the groin and armpits. Flushing of the skin, often with a patchy appearance, coupled with a complaint of warmth is common. These symptoms are often accompanied by a feeling of impending doom, rapid and often irregular pulses, and increased anxiety. Continued symptoms include swelling of the throat and tongue, resulting in hoarseness, as well as difficulty breathing and swallowing. Sneezing, wheezing and runny nose all increase difficulty breathing. Vomiting, diarrhea and abdominal cramping may also develop.

In more severe cases—about 25% of all anaphylactic reactions—the mediators flood the bloodstream and cause gross capillary vasodilatation and a subsequent drop in blood pressure, lightheadedness and loss of consciousness, resulting in anaphylactic shock. The speed and severity of the reaction indicate the treatment needed to mitigate the anaphylaxis. The effects of the treatment often lead to the three following outcomes:

>> Signs and symptoms are sometimes mild enough and recognized early enough, and they often fade when self-treated;
>> Signs and symptoms don’t subsequently recur from this type of exposure; and
>> Treatment is rendered, and improvement of the signs and symptoms is seen; however, symptoms may recur in four to 12 hours. This late phase reaction requires further treatment and close observation, and it can occur in about 10% of the cases. About 20% of anaphylactic reactions are severe enough and persistent enough to require intense EMS treatment and hospitalization. Let’s take a look at a few more cases.

Case Presentation No. 2
While visiting a remotely located zoological garden, a 23-year-old man was stung by an insect, presumed to be some type of bee or wasp. Although the insect wasn’t seen, the man found the stinger and removed it quickly after being stung. The man rapidly developed hives, experienced difficulty breathing and complained of his throat feeling tight and swollen. Nearby zookeepers summoned onsite first-aid personnel, who administered oxygen and called 9-1-1.

On arrival, paramedics find the patient supine on a park bench being cared for by park first-aid personnel. They tell the crew that the patient has had no previous history of allergic reactions, and no knowledge of having been stung by a bee before. The patient is observed by the crew to be flushed (red faced) and lethargic. Audible and auscultated wheezing is heard.

The patient’s initial blood pressure taken by the first-aid crew was 100/60. Paramedics recheck the blood pressure and find it to now be 80/40. His pulses are thready with a rate of 130 bpm corresponding with an ECG rhythm of sinus tachycardia, and his oxygen saturation is measured at 70%.

The paramedic crew quickly administers 0.3 mg of epinephrine 1:1,000 IM while they prepare for IV access. The patient becomes unresponsive, and his blood pressure is no longer obtainable. The ECG rhythm remains sinus tachycardia at a rate of 150 bpm. No pulses can be now felt. IO vascular access is quickly obtained, and the paramedic’s base hospital physician quickly orders epinephrine 1:10,000 (0.1 mg) via IO. Chest compressions and BVM ventilations are initiated.

The patient is placed on a spine board, and advanced airway equipment is readied. After two minutes of chest compressions and ventilations, pulses can now be felt at the carotid artery. An ECG shows a sinus tachycardia with a heart rate of 130 bpm and blood pressure of 100/64. The patient remains unresponsive; however, respiratory effort is spontaneous and wheezing is clearing, with oxygen saturation at 88%. While the crew prepares for transport, the patient regains consciousness but remains disoriented.

Treatment
Treatment for anaphylactic reactions includes oxygenation, airway support, and medications, such as nebulized albuterol or ipratroprium. Additional medications, including epinephrine, diphenhydramine, dopamine and dosed fluid boluses, may also be required. CPR is often necessary. Maintenance of a patient’s oxygenation levels and airway support are of primary concern. Maintaining oxygen levels is often the key to successful resuscitation efforts, although it may present one of the largest challenges.

All patients suffering from anaphylaxis should be placed on supplemental oxygen as soon as possible, and maintenance of oxygen saturation should be monitored. Development of severe wheezing, increased bronchial secretions, and swollen or inflamed respiratory anatomy, increases the need for supplemental oxygenation. Management of the airway with advanced airway devices may initially present a challenge. Basic management may be required until the actions of delivered medications have a chance to reduce the airway obstacles.

The focus of the resuscitative efforts for anaphylactic reactions should be largely directed at mitigating the anaphylactic process. It’s important to provide inline nebulized medications, including albuterol and ipratroprium, via a device that will ensure proper delivery, such as handheld oxygen-powered nebulizer devices, nebulizer mask configurations or devices placed within the BVM circuit.

Careful consideration should be given to the use of fluid boluses or aggressive fluid infusions to treat the hypotensive effects of anaphylaxis. The presence of clear lungs may be an indication to use fluid to help increase volume and preload to aid in the resuscitation of hypotension and also dilute the histamine boluses within the bloodstream. Normal saline solution is ordinarily preferred; however, it’s important to be wary of fluid shifts because they may have medical implications. Selecting an alternative fluid may be more helpful. Epinephrine, a sympathomimetic with both alpha and beta effects, has actions that include bronchodilation (beta-2) and vasoconstriction (alpha). Actions on the heart include increased heart rate (beta-1, chronotropic), contractility (inotropic), atrial-ventricular conduction and automaticity (dromotropic).

Onset of actions usually occurs when administered via IV or when IM is one to two minutes with duration of action of five to 10 minutes. IM route action occurs in about five to 10 minutes, with a duration of action of one to four hours. Dosages for IM routes are usually 0.3 mg of a 1:1,000 concentration and 0.1mg of 1:10,000 concentration for IV or IM routes. These dosages are common for anaphylactic reactions.

Many people with a known history of allergic or anaphylactic reactions carry an EpiPen Auto-Injector. Most EpiPens deliver a 0.3 mg dosage of epinephrine via the IM route when the device is pressed against the injection site. Devices often carried by children deliver an IM dosage of 0.15 mg of epinephrine. First responders should consider the dosage administered and an estimation of the time when it was injected when assessing patients with anaphylactic reactions.

Another primary prehospital medication that’s helpful with resuscitation of anaphylactic reactions is diphenhydramine hydrachloride. A common brand name, Benadryl, is a potent antihistamine. The action of diphenhydramine results when it binds to histamine receptor sites, blocking the effects of histamines.

Notable onset of action is 15–30 minutes and can last from six to 12 hours. Preferable routes during an anaphylactic emergency include IM, IV and IO. It should be noted that the subcutaneous route has been abandoned in the prehospital setting for the delivery of injectable medications for anaphylactic reactions where capillary stability in the dermis during an anaphylactic reaction is often compromised and uptake of medications is delayed. Corticosteroidal and steroidal medications are also used in the prehospital setting; however, these medications aren’t considered resuscitative. Onset of action for these medications is considered outside the resuscitative window; however, it’s believed to reduce the chances of recurrence or late phase reactions.

Use of these medications for anaphylactic reactions is typically considered during a post resuscitative, planned therapeutic regimen to aid in recovery and prevention of anaphylactic reactions. Corticosteroid, often referred to as the “sooner the better” therapy deployed in the prehospital setting, has seen positive outcomes for patients who have suffered an anaphylactic reaction. However, it’s not clearly known whether the administration of the drug in the prehospital setting is more beneficial than delivery of the drug after emergency department (ED) admission.

Albuterol (Proventil and Ventolin) is a potent sympathomimetic bronchodilator (beta-2 specific). Albuterol works by relaxing bronchial smooth muscles by stimulating beta-2 adrenergic receptors, producing bronchodilation, relieving bronchospasm and decreasing airway resistance. Onset of action occurs in about five minutes, peaks in about an hour and lasts up to five hours. Initial dosage (usually in combination with ipratroprium) is 6 mL (0.083%) via nebulizer.

Ipratroprium bromide (Atrovent) is an anticholinergic bronchodilator. It works as an antagonist on the actions of acetylcholine. It prevents the interaction of acetylcholine with muscarinic receptors in bronchial smooth muscle, causing bronchodilation. The effects also cause drying of respiratory tract secretions with an onset of action within 15–30 minutes, peaking in one to two hours and lasting about four to five hours. Adult dosage (usually in combination with albuterol) is 2.5 mL (0.02%) via nebulizer. Dopamine hydrocholoride (Intropin) is a sympathomimetic vasopressor with both alpha and beta properties. In low and medium dosages, it selectively dilates blood vessels supplying the brain, kidneys, heart and gastrointestinal tract. At medium to high doses, it can increase cardiac output by improving contractility and stroke volume, with a resulting increase in blood pressure.

At high dosages it causes vasoconstriction and an increase in heart rate. Onset of action occurs in less than five minutes and duration is approximately 10 minutes after drug administration has stopped. First responders should quickly assess patients suffering from anaphylactic reactions and institute appropriate interventions as the needs are identified. Information about the history of the situation is extremely helpful in these situations, so seek out anyone who witnessed the event or who was able to discuss the problem with the patient before the patient became incapacitated.

Often, as in the first case presentation, the patient has a known allergy and felt the risk of exposure was less than they actually experienced. In this case, the wrapper from the snack food was retained, and first responders were able to quickly identify the allergen. Treatment focused on the mitigation of the anaphylactic reaction with emergency interventions for the symptoms that required them.

Timing is important, especially when there are delays from the time of exposure to the time 9-1-1 is summoned and first responders encounter the patient with anaphylaxis. Many people, not knowing they have been exposed or being exposed with no previous history of problems, dismiss the initial signs and symptoms. Unfortunately, the signs and symptoms progress so rapidly that help may be out of reach for a period of time, which could be detrimental to their chances of survival.

Case Presentation No. 3
A 53-year-old female with previous exposures to bee stings with no reactions was meeting friends for a horseback ride. She stopped to clear a small tree that had fallen across her path. As she moved toward the obstruction, she was stung by a wasp near her left temple. She quickly brushed the wasp away and cleared the tree from the trail.

While she was returning to her horse, she remarked to her friends that she felt dizzy. She dismissed the feeling, took three more steps toward her horse and collapsed. Her friends realized she lapsed into an unconscious state and was not breathing well, so they placed her in a supine position in the bed of a pickup truck and called 9-1-1 to request an EMS unit meet them at the nearest rendezvous location. The responding EMS crew was BLS and there were no nearby first responder services. Because of the remote location, 20 minutes elapsed from the time of the exposure to the arrival of the BLS ambulance.

On arrival, the EMS crew finds the female without a pulse and not breathing. CPR is initiated and an immediate transport to the nearest hospital, approximately 30 minutes away, is initiated. An ALS ambulance is dispatched to intercept the BLS ambulance near the halfway point to the destination hospital. Cardiac arrest algorithms are followed for asystole by the ALS crew during transport. The patient was delivered to the hospital approximately 50 minutes after the sting, where a return of spontaneous circulation was achieved.

The patient in this case had an expired prescription for an EpiPen Auto-Injector. The patient’s friends had no knowledge of the patient’s previous exposures or risk factors. The situation was further compounded by the lack of available ALS services and the remote location. People with known exposures or allergies are usually counseled for preparedness, uses of medications and availability of special kits to carry with them. They’re also usually counseled about best practices to avoid exposures, including sharing information with others to help decrease the risks
of exposures.

Patient No. 1 was admitted to the hospital for observation and completely recovered. He was discharged home 24 hours later with his parents and with appropriate education and direction including carrying use of an Epi Pen. Patient No. 2 was admitted to the hospital for observation and recovery of anoxic brain syndrome. He was released after three days of care without any significant or noticeable effects and direction to have an Epi Pen available at all times. Patient No. 3 was admitted to the Medical Intensive Care Unit and subsequently succumbed after absence of brain function was discovered and life support terminated by her family. The family has since made Epi Pen products available in and around their ranch and vehicles.

Conclusion
EMS should educate the public that it’s always better to contact them when an exposure is identified rather than allow the signs and symptoms to progress untreated. Everyone should take precautions should the unexpected anaphylactic reaction occur.

Rick Rod, RN, CEN, NREMT-P, is currently the Paramedic Field Training Coordinator and Clinical Educator for City of San Diego EMS – Rural/Metro of San Diego and San Diego Fire-Rescue Department

References
1. Tintinalli J, ed. Tintinalli’s Emergency Medicine: A comprehensive study guide 4th edition. McGraw-Hill: New York, (209–211), 2011.
2. Neumar R, Otto C, Link M, et al. Part 8: Adult advanced cardiovascular life support: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2010;11(122):S729–S767.
3. San Diego County Paramedic Association: Protocol and Medication Guide. 2011–2012 ed. SDCPA: La Mesa, Calif.

Do they make a “Suctioning for Dummies” book?

As the saying goes, ignorance is bliss.

Step 1: Know your equipment.

Step 2: Assemble the equipment correctly.

Step 3: Don’t look in the mouth.

Step 4: Use the steel stylet that comes with the Glidecope.

Step 5: Don’t Get too close to the Cords.

Read “See Cords Around Corners” for more from Dr. Snyder.

The adult Glidescope blades come in two sizes, a 3 and a 4. The 4 is what I use for nearly all adults and is listed as 90 pounds and up. Image Courtesy Graham Snyder, MD

I placed the 4 Mac into the mouth, but it was not good. The man’s jaw and mouth were barely large enough to place the blade between the teeth, yet his tongue seemed gargantuan. The thickness of his torso plus the very real fear of worsening a possible c-spine injury resulted in a view of only a pink wall of tissue.

“Want me to get the scope?” queried the respiratory therapist.

“This is not a candidate; there’s too much blood,” I responded, envisioning the futility of attempting to snake a tiny flexible fiberoptic wire through the patient’s nose or into his mouth–the tissue compressed flat in his supine position and the tiniest droplet of blood or saliva leading to complete loss of view.

“Not the flexible fiberscope, the video laryngoscope,” The respiratory therapist clarified as he placed the plastic blade in my hand and turned the video screen in my direction.

I had picked up the Glidescope a number of times at conferences when walking by promotional booths. On a dry plastic mannequin head, it seemed to work spectacularly. The view of the cords was superior to all but the easiest of direct laryngoscopy, and the force needed to obtain that view was a fraction of that needed normally.

But would it work in a high-pressure, high-stakes clinical setting?

The patient was difficult to bag so I had about 60 seconds before I would need a rescue device or proceed to cricothyroidotomy.

I gently inserted the blade sliding down the center of the tongue and in seconds was greeted with a textbook view of not only the larynx, but the arytenoids and the aryepiglottic folds as well! There was four times the amount of information I needed to place an ET tube normally. I grabbed the endotracheal tube, which the RT had preloaded on the strange glidescope stylet, not knowing that my challenge had just begun.

For the past 11 years, I’ve been giving lectures on management of the difficult airway to the right students at the wrong time in their career. Learning direct laryngoscopy and effective placement of an endotracheal tube is a challenge in itself. When you add the extreme stress and anxiety of a horrifically unstable patient, it’s a wonder we can pull it off at all. However, with the combination of good lectures, operating room and/or simulation time, we all learn the art. Once you become proficient, in truth, it’s not that hard…except when it is.

The majority of difficult airways occur because of an inability to visualize the vocal cords. Usually, this is not a surprise. The causes are innumerable and sometimes additive. Even before beginning the procedure, when a patient has a small mouth, a large tongue, and a short jaw, you should anticipate a difficult airway and make plans for managing it.

There are plenty of other options, including lighted stylets, retrograde intubation and LMAs. The most important thing is that you be well practiced in the technique so that when the time comes, when the stakes are the highest, you are relaxed, confident and proficient.

This is just as true when using video laryngoscopy, and is often ignored because at first glance it seems both very similar in the technique we are all confident in (direct laryngoscopy) and is easier than direct laryngoscopy. This is true, BUT if you do not make the appropriate modifications to your technique, you will at best struggle and at worst have a failed airway.

Video laryngoscopes allow for spectacular visualization of the larynx often in cases where direct laryngoscopy would be extremely difficulty or impossible. This is best demonstrated by a patient with a small mouth and big tongue, which unfortunately is the case with all infants.

The magic of the Glidescope is you do not have to physically look in the mouth (only at the video screen), so intubation can still be accomplished on these tiny airways as demonstrated below in this 16-month infant simulator. See the video and photograph below.

Intubation can still be accomplished on tiny airways, as demonstrated in this 16-month infant simulator. Photo Courtesy Graham Snyder, MD

Click here for video.

Step 1: Know your Equipment.
There are a variety of different video laryngoscopes, each of which have its own unique performance characteristics. At our institution, we use the Glidescope Ranger. But no matter what you use, you must learn the unique geometry of the blades and significantly different techniques for intubation before the time of crisis. This can be accomplished with a stable patient and bedside supervision with an experienced practitioner—and ideally complemented by both supervised and independent practice using human patient simulators or airway task trainers.

Step 2: Assemble the Equipment Correctly.
There are really only three pieces of equipment. The wand (light source and fiberoptic camera), the plastic blade cover and the video screen. The wand plugs into the video screen intuitively and then the blade cover slides onto the wand with a definitive click. The wand must go in straight into the plastic sheath. If the wand is placed into the blade cover rotating 90 degrees, the screen will be 90 degrees off but in addition there will be extremely distracting glare. Make sure that the writing on the blade cover aligns with the writing on the wand. If you don’t, when you look in the mouth you will not be able to tell whether the blurry spots on the video screen are from saliva obscuring the view or from the plastic refracting.

Step 3: Don’t Look in the Mouth.
The Glidescope looks very similar to a Macintosh laryngoscope, leading people to mistakenly attempt to use it as one but everything is different. For one, the basic maneuver is more of a gentle straight up lift than the diagonal forward movement used in direct laryngoscopy. Also, much more importantly, getting the camera to find the cords has nothing to do with the maneuver needed to directly visualize the cords. Keep your eyes on the camera once you are inside the mouth and guide the video screen toward the cords.

Step 4: Use the Steel Stylet that Comes with the Glidecope.
You will be advancing the tube around and over the tongue and must maintain the curve of the original stylet or else the tube will not be able to find the larynx. If you use a normal stylet, it will get straightened out by the time you get to the larynx and will repeatedly, (and extraordinarily frustratingly) pass into the esophagus. You will no longer have the angle needed to pass into the cords.

Correct Technique

Incorrect Technique

Step 5: Don’t Get too Close to the Cords.
The temptation when using the Glidescope (because you obtain such a gorgeous video of the cords) is to press the camera close to the larynx. If the larynx fills the entire video screen, then the tip of your blade is millimeters away from the larynx. However, wherever the camera is, the tube will come in just below that point so if you’re abutting the cords already, when you pass the tube it will pass just below the cords (into the esophagus). If, however, you back away a little from the cords, then, because of the angle of the stylet, once the tube passes in front of the blade it will angle up and smoothly in between the cords.

Incorrect Technique

Correct Technique

Step 6: Back the Stylet out while Advancing the Tube.
The stylet is quite rigid steel and has nearly a 90-degree curve in it. This works perfectly for making the turn around the tongue and effortlessly going through the cords. However, since the trachea does not have a curve in it, as soon as the tip of the tube is placed between the cords, the stylet must be backed out to allow it to pass. Conveniently, there is a little flip top on the end of the stylet perfectly positioned for your thumb to kick it back and the tube to slide into the trachea. This is not optional. It is physically impossible to pass the tube with the stylet in place, so once the tip is between the cords, you or your assistant must remove the stylet.

Remove the stylet to secue the airway. Photo Courtesy Graham Snyder, MD

Conclusion
In my difficult case, once I took the respiratory therapist’s suggestion, I found the trauma patient’s vocal cords in seconds and with a sigh of relief advanced the tip of the orotracheal tube between the cords. I was puzzled briefly by the resistance I felt when I attempted to advance the tube, when the paramedic who brought the patient in (who was also watching the screen) reminded me, “You have to remove the stylet or it won’t advance.” He leaned forward, and like lighting a Zippo, he flicked the stylet lever (see image at left) backwards and the tube effortlessly advanced securing the airway.

When properly used, the video laryngoscope can transform extremely difficult intubations into nearly effortless lifesaving maneuvers and can be used in easy intubations as a safe and controlled way to teach the art and the science of orotracheal intubation.

Video laryngoscopy uses a camera and a video monitor to visualize the airway and the glottis, enabling faster intubation. Photo James Radcliffe

The ancient Egyptians figured this out when they built the Great Pyramids thousands of years ago. They used tools to work smarter, not harder.

Intubation is the same way; for years I’ve been watching students and experienced providers in labs and in the field do the same exact thing as the guy moving the furniture. The more frustrated they get, the more brute force they apply and the worse the situation gets. It isn’t until they slow down and begin to work smarter that they begin to have success. There are numerous ways that prehospital providers can gain mechanical advantage and optimize our laryngeal view. We have to understand which tools to use for this each patient during each intubation attempt. Choosing the right blade or techniques is important, as is understanding that some patients or situations dictate other options, such as blind-insertion airways or video laryngoscopy. Video laryngoscopy uses a camera and a video monitor to visualize the airway and the glottis, enabling faster intubation when you’re dealing with difficult airways in which you can’t get good line-of-sight visualization.

People have been placing metal sticks in mouths for centuries to examine the oral pharynx, and inventors have been keeping pace by creating a bigger and better device at every turn. But let’s stop and consider what we are really trying to accomplish with direct laryngoscopy.

Four Steps for Direct Laryngoscopy
Step one is to move any obstacles, such as vomit, food or teeth, out of the field of view with good suction. Trying to visualize an airway through all that stuff is like trying to drive 60 mph in a torrential rain storm without windshield wipers. You’re not going to be able to drive in the rain without wipers, and you’re not going to successfully intubate without suction. The suction unit is our best friend when it comes to airway management for EMS (but it seems to be the one piece of equipment that is left in the truck, missing a hose or uncharged, so it often isn’t there when the need arises).Once we clear the airway, then we’re ready to take a look at the airway.

Step two is to get that first look before anything else gets in the airway. The scissor technique allows us to open the mouth of the supine patient so we can get a great look at the posterior oral pharynx. This is where we begin to identify our landmarks and possible obstructions. Looking straight into the mouth, the first thing we see is the tongue. The size of the tongue plays a part in determining which blade we will use for intubation. If we’re able to see past the tongue, we’ll see the uvula lying in the posterior oral pharynx. As we begin looking into the mouth, we consider the proportion of the structures to the overall space. This helps determine the level of difficulty—or as a good friend always says, “how fun” it will be manage the airway. Once we have a good assessment, we’ll have some idea what tools we might want to use.

Step three is to choose the right tool for the job. Prior even to opening the airway, the experienced provider has already assessed the patient externally to determine the level of difficulty to anticipate and the equipment to use. Several scoring systems out there assess the level of difficulty of an airway. The most common is the Mallampati score, which ranges from 1 to 4 with 1 being the best view and 4 being the worst. Richard Levitan, MD, came up with a great tool that we will refer to as the “Four Ds” for oral tracheal intubation. The Four Ds include distortion, disproportion, dentitions and dysmobility. A good way for a provider to assess the Four Ds is using the 3-3-2 technique, which includes 3 fingers breath between the incisors, 3 fingers from the hyoid bone to the chin and 2 fingers from the floor of the mouth to the top of the thyroid cartilage. The rule of thumb is the fewer the fingers, the straighter the blade. Imagine trying to get a big fat stick in an opening that’s barely wide enough to get the tongue through. Choosing the correct laryngoscope blade will help ensure that our efforts aren’t impeded by the tool.

Step four is selecting an intubation technique. The direct laryngoscope is a lever with a light at the end of it. Unlike a video laryngoscope, which enables users to capitalize on a superior glottic view and access provided by the video image, direct laryngoscopy doesn’t allow us to look around corners. Therefore, we must have a good understanding of the anatomy to correctly place and use it. The first obstacle that we must move with our lever is the tongue. We simply follow the center of the tongue with tip of the blade and gently lift as we advance, and the blade will naturally come to the vallecula at the base of the tongue. Simply pulling the tongue forward and down will displace the tongue and expose the laryngeal structures; veterinarians have been doing that for years to secure airways in large animals. Remember the laws of physics—every action has an equal and opposite reaction. This means that whatever you do with the handle of the blade will move the other end of the blade. Remember you can’t look around corners so trying to play seesaw or rocking back toward the teeth is only going to impede your view.

EMS Airway Expert Charlie Eisele shows the airway structures on a cross section of a plasticized cadaver head. Photo James Radcliffe

Relax & Recall Your Anatomy Lessons
Remember to work smarter, not harder. When I teach together with my flight medic friend of mine (the one who grades intubation difficulty in levels of fun), he always says, “Relax. Your most important decision in your shift is what’s for lunch. This will pass.”

So relax and take a deep breath. If you’re one of those folks who needs to take a death grip on the handle and your arm shakes when you intubate, try a pediatric handle and hold it with two fingers and your thumb toward the base of the blade. Great. Now imagine those ancient Egyptians again moving large stones with a lever. They didn’t move it by rocking back; they lifted up and forward. so place the laryngoscope blade at the base of the tongue and lift up and out to move it out of the field of view to visualize the laryngeal structures.

I tried every trick and gadget I could find for years, but they never seemed to work and all I did was get frustrated. I was told if you drop the head of the patient off the end of the stretcher or prop up the shoulders, it would make a better view—wrong. It wasn’t until I started to study the anatomy and consider what I was trying to accomplish that I realized that all I was doing was moving all the structures into my field of view, requiring me to move them even farther to get that good look at the larynx. However, if the patient’s condition will allow, then raise the head to bring the ears even with the chest, thus aligning the axes to allow for a better view.

Success Is As Easy As…
Finding your success is as easy as following this simple rule: Don’t block your view. Keep the blade at an angle to maximize the field of view by sweeping the tongue to the left and slightly turning the handle toward the left. Make sure when inserting the tube to keep the tube to the right side of the mouth, and watch the tip advance through the glottic opening. One technique for advancing the tube is the hook method, simply sliding the tube into the oral cavity from the right corner of the mouth.

If you understand the anatomy and the mechanics of direct laryngoscopy, your success rate will greatly improve. Remember that intubation is a finesse skill, not brute force, so relax and work smarter, not harder.

Be Safe,
Jim Radcliffe, MBA, BS, EMT-P