Anaphylaxis

What is Anaphylaxis?

Anaphylaxis is a common, severe allergic reaction that can quickly become life-threatening if not treated immediately. It’s like your body going into a state of high alert, affecting multiple systems of your body at the same time. Anaphylaxis can be extremely dangerous and even deadly because it can cause you to have trouble breathing.

In the past, doctors classified anaphylactic reactions into two categories: those caused by certain types of allergies (IgE-mediated responses) and those that weren’t directly related to allergies (anaphylactoid reactions). Nowadays, however, doctors simply refer to these reactions as anaphylaxis, regardless of what exactly causes them.

This makes sense because, regardless of the cause, the effects of anaphylaxis on the body are the same, and the treatments used are identical. So, in medical language, the term “anaphylaxis” is widely accepted to describe this kind of severe allergic reaction.

What Causes Anaphylaxis?

Anaphylaxis can be caused by different triggers, such as certain medicines, foods, or insect bites. Some people can also have a severe reaction to allergy shots meant to help improve allergies. A rising sensitivity to latex is becoming more common, and like all hypersensitivities, it carries the risk of anaphylaxis. Sometimes, the cause of the reaction isn’t known; this is referred to as idiopathic anaphylaxis.

Alpha-gal anaphylaxis is another cause of this condition. It involves a reaction from antibodies in your body to a specific type of sugar found in red meat, called galactose alpha-1,3-galactose.

Risk Factors and Frequency for Anaphylaxis

Anaphylaxis, a severe allergic reaction, is believed to affect between 1% to 3% of people worldwide during their lifetime, and this number appears to be on the rise. Although it can happen to anyone, it’s more commonly seen in younger individuals and those living in developed countries. Sadly, anaphylaxis is often mistakenly identified or not spotted at all. Late or incorrect diagnosis can lead to serious health risks or even death.

Signs and Symptoms of Anaphylaxis

Anaphylaxis is a severe allergic reaction that starts mildly. The main symptoms vary depending on how the person came into contact with the allergen that’s causing the reaction. Skin reactions such as itching and hives are common, but sometimes, breathing troubles occur first especially when the allergen is ingested. Other symptoms to watch out for include feelings of fullness or a lump in the throat, persistent throat clearing, and difficulty breathing. If any of these exist, it’s important to quickly administer a medicine called epinephrine.

Anaphylaxis often develops rapidly, typically within an hour after exposure to the allergen. Importance is stressed on this first hour because about half of the fatalities related to anaphylaxis happen during this period. The quicker the symptoms arise and worsen, the more severe the condition. Most deaths are caused by loss of airway and severe shock. Early detection and proactive treatment significantly lower the risk of bad outcomes.

It’s also important to know that anaphylaxis can recur in a two-phase manner in about 20% of cases. This means that even after successful treatment of the initial symptoms, symptoms can return, usually peaking 8 to 11 hours after the first reaction. Even though this only significantly affects 4 to 5% of people with diagnosed anaphylaxis, a potentially lethal second reaction should not be ignored after treating the first one.

While most of the attention is given to the aforementioned respiratory, skin, and low blood pressure symptoms, end-organ damage from poor blood flow also needs to be considered. This can lead to:

• Abdominal pain and cramps
• Vomiting
• Weak muscle tone
• Fainting
• Incontinence

About 25 to 30% of patients undergoing anaphylaxis exhibit these gastrointestinal symptoms. While loss of control of the airway due to swelling is indeed a primary concern, it’s crucial not to overlook anaphylaxis in patients who haven’t reported upper airway swelling or respiratory issues.

Testing for Anaphylaxis

The process of identifying an allergic reaction called anaphylaxis is more about noting symptoms rather than running any lab tests. Anaphylaxis is a severe, possibly life-threatening situation and it’s crucial that it’s recognized immediately since most cases result in deaths within the first hour of coming into contact with what caused the reaction.

Generally, you might suspect anaphylaxis if there are symptoms in two or more body systems at once, even if there aren’t any breathing difficulties or low blood pressure involved. Doctors rely on clear criteria to make sure they identify anaphylaxis as quickly as possible, since delaying treatment can be very risky.

The criteria they use – starting from when symptoms appear – includes rapid development of skin symptoms (like hives) alongside any of the following:

• Breathlessness, wheezing, strained breathing (stridor), low oxygen in the blood, or problems maintaining the airway open. Persistent coughing and throat clearing could be warning signs.
• Low blood pressure (meaning systolic blood pressure is less than 90 mm Hg or it’s more than 30% lower than normal).
• Signs that organs aren’t functioning properly, such as loss of muscle tone, fainting, or loss of bladder control.

If a person has probably been exposed to something they’re allergic to and they have symptoms in any two of these body systems, it may be anaphylaxis:

• Skin symptoms: rashes, itching, redness, hives, or swelling of face, lips, tongue, or uvula.
• Respiratory symptoms like the ones listed above.
• Low blood pressure like described above.
• Stomach issues: ongoing painful cramping or vomiting.

A diagnosis can also be made if a person is known to have been exposed to something they’re allergic to and they experience low blood pressure.

Remember: these criteria are a guide to help doctors identify anaphylaxis, but they don’t have to meet them exactly in order to treat it.

Angioedema, the swelling of the lower layers of skin or mucosa, can present symptoms similar to anaphylaxis. The main difference is that angioedema doesn’t usually cause hives. If doctors are unsure, they will treat it as anaphylaxis to be safe.

Lab tests usually aren’t useful for diagnosing anaphylaxis. No existing test can accurately confirm or rule out anaphylaxis. Even though blood levels of certain substances like histamine or tryptase can increase during anaphylaxis, those levels can go up and down too quickly or stay elevated for too long to be useful diagnostic tools.

There is a situation called Kounis Syndrome when a person could have heart problems like a heart attack or heart tissue damage during anaphylaxis.

Treatment Options for Anaphylaxis

If you’re experiencing an allergic reaction, it’s important to seek medical help promptly because there’s a risk it could progress quickly and become a severe allergic reaction, or anaphylaxis.

The first priority for healthcare providers during an allergic reaction is ensuring your airway is open and you can breathe properly. If you have severe swelling around your mouth or throat sounds (“stridor”), or you have a type of deep tissue swelling known as angioedema, your medical team might need to take steps to establish a secure airway for you. This is because swelling can worsen over time, making it harder to establish a clear airway later on.

Once your ability to breathe is secured, the next step is to attempt to remove any cause of the allergic reaction, if it’s known. For example, if a bee sting has caused the reaction, the doctors would try to remove the stinger. In cases where the allergic reaction was caused by something you ingested, they would not normally attempt to rinse out your stomach, as this might not be effective and could delay other treatments.

Epinephrine (also known as adrenaline) is a medication used in allergic reactions. It’s usually injected into the muscle, with the thigh being the preferred site. Epinephrine effectively calms the allergic reaction and improves symptoms. If doctors wait too long before giving epinephrine, the outcome can be worse. Though many patients only need a single dose, some may require additional doses every 5 to 10 minutes until their symptoms improve.

IV fluids and medications like steroids, antihistamines, bronchodilators, and vasopressors can also be used in the management of an allergic reaction. They help increase fluids in the body, decrease the immune response causing the reaction, relieve symptoms, and maintain blood pressure. Patients with pre-existing conditions such as asthma may benefit from inhalers to widen the airways.

Steroids and antihistamines may be given to reduce the duration and/or severity of the allergic reaction. Once your condition is stabilized, you may be switched to oral medication to continue your treatment. For patients at risk of fluid retention, specific steroids might be chosen.

In some cases where conventional treatments aren’t successful, glucagon might be used. Glucagon can work in cases where an allergic reaction is resistant to other treatments. However, it has possible side effects like nausea, vomiting, low blood potassium levels, dizziness, and high blood sugar levels.

Researchers are exploring novel treatments for anaphylaxis. One such agent is Sirtuin 6, which could possibly help manage allergic reactions by interfering with the immune response leading to anaphylaxis.

What else can Anaphylaxis be?

When a doctor is trying to diagnose a patient, they consider various conditions that could be causing the symptoms. These could include:

• Angioedema (swelling area under the skin)
• Anxiety
• Arrhythmias (irregular heartbeat)
• Asthma
• Carcinoid syndrome (a type of cancer)
• Epiglottitis (inflammation of the flap at the base of the tongue)
• Foreign-body airway obstruction (something stuck in the airway)
• Gastroenteritis (inflammation of the stomach and intestines)
• Mastocytosis (a disease involving an excess of mast cells that lead to allergic reactions)
• Myocardial ischemia/infarction (reduced blood flow to the heart)
• Seizure
• Vasovagal episode (sudden drop in heart rate and blood pressure leading to fainting)
• Vocal cord dysfunction (improper functioning of the vocal cords)

What to expect with Anaphylaxis

With quick, effective treatment and close monitoring, the chances of health complications or death due to an allergic reaction can be greatly reduced. Getting medical help immediately, once an allergic reaction is noticed, can make a big difference to the patient’s outcome. In fact, 50% of fatalities related to allergic reactions occur within the first hour of symptoms appearing.

Hospitalization is needed in only 4% or less of acute allergic reactions diagnosed in the emergency room. If a severe allergic reaction or anaphylaxis occurs, it can usually be completely resolved with a drug called epinephrine. After treatment, doctors might suggest patients stay in the emergency room for about 4 hours to monitor the situation. If no further treatments are required, patients can go home with a prescription for an epinephrine autoinjector pen, used to treat severe allergy symptoms rapidly. However, in cases where breathing is affected, treatment isn’t working, or the patients’ condition is unstable, they may need to be admitted to intensive care for close monitoring.

Patients who have had severe allergic reactions before, take beta-blockers, are elderly, live alone, or have difficulty accessing healthcare, should be watched for a longer period.

In addition to the prescription for the epinephrine pen, antihistamines and corticosteroids might also be prescribed for 3 to 5 days to reduce inflammation. If the cause of the allergic reaction is not known, corticosteroids might be prescribed for 1 to 2 weeks. Doctors might also provide recommendations for additional epinephrine pens so that they can be kept in different locations (home, office, car etc.) and can be accessed easily whenever needed. Remember, it’s crucial to always have access to the epinephrine autoinjector around the clock if the allergy symptoms recur.

Patients with severe allergies or anaphylaxis who are on a type of medication known as beta-blockers may experience more severe or long-lasting symptoms; they should talk to their doctors about possibly adjusting their medication. Patients might also consider medical alert bracelets for quick assistance in future situations.

Possible Complications When Diagnosed with Anaphylaxis

The main complications that can happen after an anaphylactic reaction include:

• Wheezing (a whistling sound while breathing)
• Stridor (a high pitched sound resulting from obstructed air flow in the throat)
• Low level of oxygen in the blood (hypoxemia)
• Low blood pressure (hypotension)
• Damage to organs (end-organ dysfunction)
• Death

Preventing Anaphylaxis

Patients should be given multiple devices that can automatically inject epinephrine — a medicine used to treat severe allergic reactions. They should have access to these devices 24 hours a day and should be taught how to use them if their symptoms start to return.

Patients should also understand the importance of wearing medical alert bracelets or similar items. These bracelets can help alert others to their medical conditions in case of an emergency or in situations when the patient can’t communicate this information themselves.