First Aid Elective Project 

Topic: Anaphylaxis

Name: Alwin Sonny

Introduction and importance

Anaphylactic shock is a very dangerous, medical emergency which needs to be dealt with prompt actions to save someone’s life. So, it is very important to be aware of what anaphylaxis is and how to be able to react to it, to save the persons life. Anaphylaxis often occurs because of an allergic reaction to something and can occur within minutes of contact with the allergen. With more than 150 million EU citizens suffering from chronic allergic disease (1), we see that anaphylaxis and allergies in general are important to be aware of as so many people can be affected by it. Furthermore, allergies are becoming more and more prevalent with statistics saying that by 2025, more than 50% of Europeans will suffer from allergies which again shows this topic is something we should be aware of (1). Also, with so many allergens around the chances of people accidently getting into contact with something they are allergic to is quite high. Most of the time this may not lead into problems as serious as anaphylactic shock but still can be dangerous. Typical allergens we in counter are usually medication of food related as we as from certain materials like rubber(latex). Most of these, we usually encounter in our day to day life. Usually people only know they are allergic to something if they have had an allergic reaction to it in the past. This means it’s even more dangerous and could happen unexpectedly, which is especially with the case with allergies to medication and certain foods. So, we need to be aware to notice if someone is having an allergic reaction and what to do to help make sure the condition does not get worse. 

What is anaphylaxis? –  Allergies

The American academy of Allergy, Asthma and immunology (AAAAI) defines anaphylaxis as “a serious, life threatening allergic reaction” (2). So, to properly understand anaphylaxis we need to investigate allergic reactions and how they occur. AAAAI also define allergic reactions as “the immune system overreacting to a harmless substance known as allergen” (2). Allergens are harmless substances which can trigger the immune system to produce a response. Whilst patients experience allergic reactions in a wide range of symptoms, certain factors affecting the response may be the same.  There are many known allergens which can produce an immune response in people and the most common ones include: pollen, dust, foods, insect stings, medication and latex. Statistics show that there are more than 170 foods which have been reported to cause some sort of allergic reaction. With 8 major types of food allergens which include: milk, egg, peanut, tree nuts, wheat, soy, fish and crustacean shellfish. These cause the most serious food allergy reactions in the US (3). The more common triggers for drug allergies are; Penicillin and related antibiotics, Anticonvulsants, Aspirin, ibuprofen and other nonsteroidal anti-inflammatory drugs (NSAIDs), Chemotherapy drugs. Statistics show that Worldwide, adverse drug reactions may affect up to 10% of the world’s population and affect up to 20% of all hospitalized patient (4).

Basic Pathophysiology of allergies

The immune system has a major role in how allergies come about, but it is also part of the bodies defence system which helps the body to respond to pathogens and other foreign substances which may cause harm so is massively important for our survival. But that’s doesn’t mean the immune system is perfect, allergies occur when the immune system goes over the top and acts to try and protect the body from substances which are of no threat to us(allergen). The immune system comprises of many molecules and cells and involves a variety of cells and proteins in its response. The molecules which play a major role in the immune response are different types of immunoglobins (antibodies), B and T lymphocytes, mast cells and other molecules related to inflammation. When the body is exposed to an antigen, a specific IgE antibody is made that attaches to high-affinity receptors, called Fc epsilon type I, located on mast cells and basophils. When the body gets re exposed to that allergen, cross-linking of cell-bound IgE antibody occurs, resulting in Fc epsilon receptor aggregation and activation. The resultant mast cell degranulation leads to release of inflammatory mediators such as histamine, prostaglandins and tryptase produce the symptoms related to allergies like edema, irritations and inflammation. Therefore, people may not get an allergic reaction to the allergen upon their first interaction but after the body has produced antibodies to produce a response to it. The majority of allergic reactions manifest as skin responses, such as flushing, pruritus, and transient urticaria. In more severe reactions, a larger number of deep dermal mast cells are recruited, resulting in angioedema. (5) (6)

What causes anaphylaxis- 

Anaphylaxis occurs when the immune systems is very hypersensitive to the allergen and produces response which are life threatening unless dealt with promptly. This intense reaction happens when an excessive release of chemicals puts the person into shock. Certain people are more at risk of anaphylaxis. If you have allergies or asthma and have a family history of anaphylaxis, your risk is higher. And, if you’ve experienced anaphylaxis your risk of having another anaphylactic reaction is increased. Foods, medications, insect stings, and allergen immunotherapy injections are the most common provoking factors for anaphylaxis, but any agent capable of producing a sudden degranulation of mast cells or basophils can induce anaphylaxis. In addition, a substantial number of anaphylaxis cases have no recognized cause, called idiopathic anaphylaxis. It used to be though that anaphylaxis was to describe Ig E mediated response whereas, Anaphylactoid was thought to describe non-Ig E mediated response. Now they are both coined under the term anaphylaxis. (7). Anaphylaxis can be further categorised on the basis that firstly the immune reaction is quick, and symptoms get rapidly worse, but once treated, the symptoms go and don’t return (Uniphasic). The other is when the immune response is may be mild or severe to start with, followed by a period when there are no symptoms, and then increasing symptoms with breathing and blood-pressure problems (Biphasic).

Anaphylaxis pathophysiology

Anaphylaxis, for most of the time, arises from the activation of mast cells and basophils through a mechanism involving crosslinking of IgE and aggregation of the high-affinity receptors for IgE. This mechanism is so sensitive that minute quantities of the allergen can cause a reaction. Upon activation, mast cells and/or basophils quickly release preformed mediators from secretory granules that include histamine, tryptase, carboxypeptidase A, and proteoglycans. Downstream activation of phospholipase A2, followed by cyclooxygenases and lipoxygenases, produces arachidonic acid metabolites, including prostaglandins, leukotrienes, and platelet-activating factor. The inflammatory cytokine, tumour necrosis factor-α, is released as a preformed mediator and as a late-phase mediator with other cytokines and chemokines. These are the chemical mediators are all directly contributing to the allergic response through smooth muscle contraction, bronchoconstriction, vasodilation, increased vascular permeability, and edema. Histamine stimulates vasodilation and increases vascular permeability, heart rate, cardiac contraction, and glandular secretion. Prostaglandin D2 is a bronchoconstrictor, pulmonary and coronary vasoconstrictor, and peripheral vasodilator. Leukotrienes produce bronchoconstriction, increase vascular permeability, and promote airway remodelling. Platelet-activating factor is also a potent bronchoconstrictor and increases vascular permeability. Tumour necrosis factor-α activates neutrophils, recruits other effector cells, and enhances chemokine synthesis. (7) 

Symptoms

The classic presentation of anaphylaxis begins with pruritus, cutaneous flushing, and urticaria. These symptoms are followed by a sense of fullness in the throat, anxiety, a sensation of chest tightness, shortness of breath, and light-headedness. A complaint of a “lump in the throat” and hoarseness heralds life-threatening laryngeal edema in a patient with symptoms of anaphylaxis. These major symptoms may be accompanied by abdominal pain or cramping, nausea, vomiting, diarrhoea, bronchospasm, rhinorrhoea, conjunctivitis, and/or hypotension. As the cascade progresses, respiratory distress, decreased level of consciousness, and circulatory collapse may ensue. In severe cases, loss of consciousness and cardiorespiratory arrest may result. Signs and symptoms begin suddenly, often within 60 minutes of exposure, in most patients. In general, the faster the onset of symptoms, the more severe is the reaction—one half of anaphylactic fatalities occur within the first hour. After the initial signs and symptoms abate, patients are at a small risk for a recurrence of symptoms caused by a second phase of mediator release, peaking 8 to 11 hours after the initial exposure and manifesting symptoms and signs 3 to 4 hours after the initial clinical manifestations have cleared. The late-phase allergic reaction is primarily mediated by the release of newly generated cysteinyl leukotrienes, the former slow-reacting substance of anaphylaxis (8)

Figure 4 shows the signs and symptoms of anaphylaxis according to systems

Treatment for anaphylaxis

In severe anaphylaxis, securing the airway is the major priority. Examine the mouth, pharynx, and neck for signs and symptoms of angioedema: uvula edema or hydrops, audible stridor or respiratory distress. If angioedema is producing respiratory distress, intubate early, because delay may result in complete airway obstruction secondary to progression of angioedema. Provide enough oxygen to maintain oxygen saturation of above 90%.

If the causative agent can be identified, termination of exposure should be tried. In insect stings, remove any remaining stinging remnants because the stinger continues to inject venom even if it is detached from the insect. Pay extra attention when removing ticks and only remove if you know what you are doing. 

Epinephrine which is also known as adrenaline, is a hormone which should be given as soon as possible. It reduces mucosal edema, treats hypotension and stimulates increase in heart rate and myocardial contractility which enables the heart to pump more blood around the body faster and enables more oxygen to be transported to tissues. Furthermore, epinephrine enables bronchodilation to get more oxygen in and limits the release of further inflammatory chemicals. Therefore, epinephrine is the treatment of choice for anaphylaxis. The epinephrine should be injected into the upper outer muscles of the thigh, as it is more effective at achieving peak blood epinephrine levels. People who have had severe allergic reactions or anaphylaxis will usually be prescribed auto-injectors which contain the set dose of epinephrine. The EpiPen injects 0.3 milligram epinephrine for adults per injection. 

Hypotension is generally the result of distributive shock and responds to fluid resuscitation. Administer an isotonic crystalloid solution bolus of 1 to 2 L (10 to 20 mL/kg in children) concurrently with epinephrine

The second-line anaphylaxis treatments include corticosteroids, antihistamines, inhaled bronchodilators, vasopressors, and glucagon. These drugs are used to treat anaphylaxis refractory to the first-line treatments or associated with complications, and to prevent recurrences

First aid for anaphylaxis

If you notice that someone near you have developed symptoms which may indicate to anaphylaxis, then act promptly and follow these steps in dealing with the situation: 

1. Immediately call your local medical emergency number to get medical help. Tell them you think someone is having a severe allergic reaction and give any information you have on what may have triggered it. 
2.  Look at their airway for any obstruction and check if they are breathing enough.
3. Ask the person if he or she is carrying an epinephrine autoinjector. If yes, then ask if they need help injecting it. If so help inject the epinephrine into the thigh. If there is no improvement from the condition, then give them another epinephrine injection after 5 or 10 minutes.
4.  Have the person lie still on his or her back. Raise their leg if necessary to help provide more blood flow to the top end. If the person has trouble breathing allow them to sit up.
5. Loosen tight clothing and cover the person with a blanket. Don’t give the person anything to drink.
6. If there’s vomiting or bleeding from the mouth, turn the person on his or her side to prevent choking.
7. If there is no sign of breathing, coughing or movement begin to start continuous chest compressions around 100 to 120 every minute. Do this until the paramedics arrive (9) (10)

Conclusion

To summarise, anaphylaxis is a severe condition which can lead to death if it is not treated swiftly. Anaphylaxis is caused by an over reaction of the immune system to a harmless substance (allergen). Furthermore, arises from the activation of mast cells and basophils through a mechanism involving crosslinking of IgE and aggregation of the high-affinity receptors for IgE, which leads to the release of certain chemicals which regulate the bodies inflammatory response. This brings about a wide range of symptoms, the more common ones include: Pharyngeal or laryngeal edema, Shortness of breath and/or wheezing, Hypotension, angioedema and Skin Flushing. With regards to treatment for anaphylaxis, Epinephrine (Adrenaline) is the best medication to relieve some of the symptoms and reduce some of the inflammatory chemicals in the blood. If you are someone who has had major allergic reactions in the past, then it is advisable to carry an Epinephrine autoinjector around with you. If you see someone going into anaphylaxis, then make sure you immediately call for a medical emergency. Also make sure the patient is laying down and that their airways are not obstructed. Try to remove contact from allergen. If they are carrying an Epinephrine autoinjector with them, then assist them in taking an injection on their thighs. Based on the facts, anaphylaxis is a major medical emergency, therefore a swift response should be made in getting medical treatment in time to reduce their symptoms and recover.

Bibliography

1. Muraro, Prof. Antonella. Tackling the Allergy Crisis in Europe. The European Academy of allergy and clinical immunology (EAACI). [Online] march 2016. [Cited: 04 27, 2019.] https://www.eaaci.org/images/media/EAACI_Manifesto_brochure_Interactive.pdf. 1.

2. Anaphylaxis. American Academy of Allergy, asthma, and immunology. [Online] American Academy of Allergy, asthma, and immunology, 2019. [Cited: 04 27, 2019.] https://www.aaaai.org/conditions-and-treatments/allergies/anaphylaxis. 2.

3. Food allergies – facts and statistics. food allergies.org. [Online] food allergies.org. [Cited: april 26, 2019.] https://www.foodallergy.org/life-with-food-allergies/food-allergy-101/facts-and-statistics.

4. Allergy statistics . American Academy of Allergy Asthma and Immunology. [Online] American Academy of Allergy Asthma and Immunology, 2012. [Cited: 04 27, 2019.] https://www.aaaai.org/about-aaaai/newsroom/allergy-statistics.

5. Elliott Middleton, JR,MD, Charles E. Reed, MD, John W. Yunginger, MD. Allergy principles and practice volume 1 fith edition. St Louis, Missouri : Mosby, 1998. 0-8151-0072-8.

6. osco, Dominique L., et al. Allergy and Anaphylaxis.” Principles and Practice of Hospital Medicine. New York : McGraw-Hill Education, 2017.

7. Tintinalli, et al. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. New York : McGraw-Hill, 2016.

8. What is anaphylaxis signs and symptoms. anaphylaxis.org. [Online] Anaphylaxis campaign, 2019. [Cited: 04 30, 2019.] https://www.anaphylaxis.org.uk/hcp/what-is-anaphylaxis/fact-sheets/.

9. First aid Anphlaxis. mayoclinic. [Online] mayoclinic, 02 06, 2018. [Cited: 04 29, 2019.] https://www.mayoclinic.org/first-aid/first-aid-anaphylaxis/basics/art-20056608.

10. allergic reactions. St Johns Ambulance. [Online] 2015. [Cited: 04 29, 2019.] http://www.sja.org.uk/sja/first-aid-advice/illnesses-and-conditions/allergic-reactions.aspx.

Image reference

Figure 1 – https://medlineplus.gov/ency/article/000812.htm

Figure 2 – https://www.researchgate.net/figure/Humoral-and-cellular-mechanisms-of-allergic-inflammation-Modified-and-adapted-from-Abdel_fig1_290201803

Figure 3 – https://www.researchgate.net/figure/Pathogenesis-of-anaphylaxis-mechanisms-and-triggers-cells-mediators-and-organ-systems_fig3_317183490

Figure 4 – file:///C:/Users/sonny/Downloads/TABLE%2014-3_Clinical%20Manifestations%20of%20Anaphylaxis.pdf 

Figure 5 – https://www.allergylifestyle.com/shop/allergy-shop/epipen-jext-trainer-pens/epipen-trainer/