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Key Feature 10: In a patient with unexplained recurrent respiratory symptoms, include allergy (ex: sick building syndrome, seasonal allergy) in the differential diagnosis.
Skill: Clinical Reasoning Phase: Hypothesis generation Allergic reactions present in multiple ways. They can cause symptoms in varying combinations that commonly involve the respiratory tract (upper and/or lower), skin and/or mucous membranes, gastrointestinal tract, cardiovascular system, and nervous system. Unless someone is having an episode of anaphylaxis (for which there should be a high index of suspicion), the symptoms and signs that are the manifestations of an allergic reaction have their own differential, and allergy may be only one of the possible etiologies causing the symptoms based on the clinical presentation. Usually these signs and symptoms are not life-threatening, however, so there is time to get to the root cause. In general, in order to diagnose an allergy as contributing to a patient's symptoms/signs, it is important to be aware of all of the possible ways in which an allergy may present, and it should be on the differential when a patient presents with respiratory symptoms and skin rashes/pruritus and/or mucous membrane swelling in particular (as these are the more common ways that allergies manifest). As indicated above, other organ systems can be affected, and with recurrent symptoms the possibility of allergy should be heightened (such as repeated paroxysms of gastrointestinal upset, for which one isolated episode would be much less suggestive of allergy). Besides understanding how allergy may present, it is important to gather a comprehensive history to assess for potential exposure to allergens. This should include a review for possible
If the clinician thinks that an allergy may be causing or contributing to the paroxysmal and recurrent symptoms the patient is experiencing, two options are: 1. To trial empiric therapy and see if this improves the patient's symptoms*, and 2. To refer to an allergy and immunology specialist for a more extensive workup (see the American Academy of Allergy, Asthma & Immunology Consultation and Referral Guidelines for when a referral may be warranted). Empiric therapy (first-line)
*When providing empiric therapy, it is important to consider the natural history of disease processes and the placebo effect, both of which may lead to improvement in symptoms unrelated to the active ingredient in the medication.
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Key Feature 6: Advise patients with any known drug allergy or previous major allergic reaction to get a MedicAlert bracelet. Skill: Clinical Reasoning, Patient Centered Phase: Treatment Key Feature 7b: In a patient presenting with an anaphylactic reaction: Treat immediately and aggressively. Skill: Selectivity, Clinical Reasoning Phase: Treatment Key Feature 7c: In a patient presenting with an anaphylactic reaction: Prevent a delayed hypersensitivity reaction through observation and adequate treatment (ex: with steroids). Skill: Clinical Reasoning Phase: Treatment I must admit, I have never yet seen a physician recommend a patient wear a MedicAlert bracelet for a major allergy or anything else, though I have on a few instances seen patients who wear them. If a patient is at risk of having a serious allergic reaction, this seems like an option I ought to at the very least present as something they can do to help prevent a future severe reaction (ex: medication error in hospital, should a patient be brought in unresponsive) or as an alert to a responding bystander should they be found unresponsive to indicate they could be having an anaphylactic reaction. Let's talk about logistics. A MedicAlert bracelet (or neck chain, etc) signifies the person wearing it has a serious medical condition that in an emergency situation may require due consideration. They are not just for patients at risk of a future episode of anaphylaxis; they can be worn by anyone who has a serious medical condition that may warrant consideration in an emergency response situation. The bracelet typically states the patient's name, the serious medical condition that the patient has (including serious allergies), along with contact information for an emergency hotline number the responder can call to obtain more information (for a monthly subscription fee, or alternatively a number for a primary caregiver or next-of-kin could be engraved). Check out the video here for an overview of the MedicAlert bracelet. The bracelets per the website have a wide price range, and the cheapest ones seem to go for $40 or so. There's the cost of maintaining a subscription for those who do want access to the emergency hotline service (I saw a $5 monthly fee advertised on the website). I imagine there are many patients who are and many patients who are not be interested in getting a MedicAlert bracelet for various reasons (ex: cost, appearance, perceived value). Although I've not had personal experience responding to an unresponsive patient wearing a MedicAlert bracelet, I could imagine it would be helpful in gathering urgent information to help the patient. In any case, it is important to be able to recognize when a patient may be having an episode of anaphylaxis to be able to respond appropriately (see my post on Feb 23 for the signs and symptoms of anaphylaxis). What would I need to do to treat a patient with suspected anaphylaxis? The UpToDate article "Anaphylaxis: Emergency treatment" (2018) provides a useful summary of the overview of the approach to the acute management of anaphylaxis in children and adults. A couple of notes regarding the above summaries:
Anaphylaxis is unpredictable. It can be a sudden threat to life or it can settle without much ado. It can be prolonged or brief, and it can present in a biphasic pattern, in which it manifests as a delayed hypersensitivity reaction. It used to be common practice to give corticosteroids when treating anaphylaxis as a way of preventing this unpredictable biphasic pattern that occurs in some patients. But new evidence, as described by the UpToDate article, "Anaphylaxis: Emergency treatment" (2018), reveals there is no utility in doing this. The article states, "The onset of action of glucocorticoids takes several hours. Therefore, these medications do not relieve the initial symptoms and signs of anaphylaxis. The rationale for giving them is to theoretically prevent the biphasic or protracted reactions that occur in some cases of anaphylaxis. However, a systematic review of the literature failed to retrieve any randomized, controlled trials in anaphylaxis that confirmed the effectiveness of glucocorticoids. In addition, a study of emergency department patients with allergic reactions or anaphylaxis failed to find a decrease in return emergency department visits or biphasic reactions among patients treated with glucocorticoids." With a lack of effective agents to prevent a delayed hypersensitivity reaction, it is important to be sure that after patients appear stable after a period of observation, that they are discharged with 2 epinephrine auto injectors, a personalised written anaphylaxis emergency action plan, and an understanding that they are at risk for a delayed hypersensitivity reaction which can happen up to 3 days after the initial reaction. It must be clearly communicated that if this delayed reaction were to occur, that they should return for emergency medical care and not hesitate to use their EpiPen if they have repeat signs/symptoms in keeping with anaphylaxis, as described on the emergency action plan. And last but not least, regardless of whether or not a delayed reaction occurred or not, all patients should have followup with their family doctor +/- referral to an allergy and immunology specialist. The American Academy of Allergy, Asthma & Immunology provides a great summary of when a referral to see such a specialist is indicated with respect to anaphylaxis. Key Feature 3: In a patient reporting allergy (ex: to food, to medications, environmental), ensure that the patient has the appropriate medication to control symptoms (ex: antihistamines, bronchodilators, steroids, an EpiPen).
Skill: Clinical Reasoning Phase: Treatment Key Feature 4: Prescribe an EpiPen to every patient who has a history of, or is at risk for, anaphylaxis. Skill: Clinical Reasoning Phase: Treatment Key Feature 5: Educate appropriate patients with allergy (ex: to food, medications, insect stings) and their families about the symptoms of anaphylaxis and the self-administration of the EpiPen, and advise them to return for immediate reassessment and treatment if those symptoms develop or if the EpiPen has been used. Key Feature 8: In patients with anaphylaxis of unclear etiology refer to an allergist for clarification of the cause. Skill: Clinical Reasoning Phase: Referral Key Feature 9a: In the particular case of a child with an anaphylactic reaction to food: Prescribe an EpiPen for the house, car, school, and daycare. Skill: Clinical Reasoning Phase: Treatment Key Feature 9b: In the particular case of a child with an anaphylactic reaction to food: Advise the family to educate the child, teachers, and caretakers about signs and symptoms of anaphylaxis, and about when and how to use the EpiPen. Skill: Clinical Reasoning Phase: Treatment When a patient reports a history of an allergy, making sure they have medications to manage these symptoms is important for the primary care practitioner. This can be both life-saving or simply decrease symptoms from an allergic reaction and sometimes make a big difference on quality of life. Three general categories of allergens are medications, food, and environmental triggers. If a patient has ever had a history of anaphylaxis, to a known or unknown trigger, the first thing to make sure is that they have a sufficient number of EpiPens (at least 2) and the they know when and how to use them, as this can be life-saving should they experience a future episode of anaphylaxis. Other elements of managing allergic reactions may include:
This is how I would write scripts for the first-line medications (in an otherwise well person):
*What does "as directed" mean? It means that the EpiPen (epinephrine autoinjector) ought to be injected into the outer thigh ASAP in the setting of suspected anaphylaxis (see my last blog post for a description of how this may present). The common expression to remember how to use the EpiPen goes, "Blue to the sky, orange to the thigh." Upon injection, a click should be heard, and the injector should be held in the thigh for 10 seconds. After this the patient must go directly to the ED. If the patient is every unsure if they are having an episode of anaphylaxis, the advice is to err on the side of caution. All patients with a history of anaphylaxis should have a personalised anaphylaxis emergency action plan. This should be shared with any caretakers (ex: teachers, coaches, etc.), and the patient should always have at least EpiPen with them at all times (The World Health Organization recommends having one autoinjector for every 10-20 min of travel time to reach medical care.) If it is not feasible for patients to carry their autoinjectors (which is ideal), then there is also the option of having multiple autoinjectors in various locations (ex: at home, in the car, at school, etc.). The CFPC Key Features for Allergy suggest that it is particularly important to have EpiPens in all locations where patients are and to have all caretakers understand the indications and how to administer the Epipen autoinjection. My understanding of this is that the risk of exposure to a food trigger can be greater than other exposures as food contamination is common and can occur anywhere a person eats/ This would be unlike one's risk of exposure to a medication that causes anaphylaxis, or an environmental allergen, where exposure is probably more predictable. Priority Topic: Allergy
Key Feature 1: In all patients, always inquire about any allergy and clearly document it in the chart. Re-evaluate this periodically. Skill: Clinical Reasoning Phase: History, Follow-up Key Feature 2: Clarify the manifestations of a reaction in order to try to diagnose a true allergic reaction (ex: do not misdiagnose viral rashes as antibiotic allergy, or medication intolerance as true allergy). Skill: Clinical Reasoning Phase: History, Diagnosis Key Feature 7a: In a patient presenting with an anaphylactic reaction: Recognize the symptoms and signs. Skill: Selectivity, Clinical Reasoning Phase: Diagnosis Priority Topic: Antibiotics Key Feature 3: In a patient with a purported antibiotic allergy, rule out other causes (ex: intolerance to side effects, non-allergic rash) before accepting the diagnosis. Skill: Clinical Reasoning Phase: Hypothesis generation, History Inquiring and documenting about any patient allergies is critical and a basic tenet of the "First do no harm" ethic of care. In all patients who are receiving care from any person or institution, this must be documented in their medical record. Whenever I am encountering a patient for the first time, I always evaluate for any allergies before I order medications for them, even when a history of allergy, or lack thereof is documented in their chart; errors in communication and documentation happen. When I am a practicing family physician with my own patient panel, reassessing allergies will be something I plan to do to keep my records as up to date as possible, while also encouraging patients to report any possible allergic reactions to me as they occur. This just seems like good medicine to me. You'll notice I said possible allergic reactions at the end of that last paragraph. As it turns out, a lot of the time, when patients definitively state that they have an allergy, they may in fact not. So it is important to document not just the reported allergy, but the type of reaction that occurred. Some background information that may be useful to know when a patient reports a possible drug allergy, per the UpToDate article, "An approach to the patient with drug allergy" (2018): "'Drug hypersensitivity' is a general term that includes both allergic and pseudoallergic drug reactions, which are a subset of idiosyncratic drug reactions (...) A drug allergy is an adverse drug reaction that is caused by an immunologic reaction elicited by a drug (...) A pseudoallergic drug reaction is a reaction that is similar or identical in presentation to an immunologic reaction, but is NOT mediated by the immune system. The term 'nonimmune-mediated hypersensitivity' is also used." There are various classification schemes that breakdown the various types of allergic and pseudoallergic reactions, and this is all interesting, but what is most important to know is not in fact whether a reaction was an allergic vs a pseudoallergic reaction, but rather if it was a possible type I allergic reaction vs any of the others. The reason for this is because, while all hypersensitivity reactions may be unpleasant, "Type I reactions carry the risk of immediate life-threatening anaphylaxis if the drug is readministered. These reactions most commonly appear within minutes after exposure, but may begin after one hour following oral administration, especially if the drug is taken with food, which further slows absorption." The UpToDate article, "Drug allergy: Classification and clinical features" (2018) outlines when a type I hypersensitivity reaction may be suspected: "The most common signs and symptoms are urticarial rash; pruritus; flushing; angioedema of the face, extremities, or laryngeal tissues (leading to throat tightness with stridor, or rarely asphyxiation); wheezing; gastrointestinal symptoms; and/or hypotension." To simplify this, consider anaphylaxis if there is any combination of the following findings: breathing compromise, skin reaction, low blood pressure, and gastrointestinal upset. It is more likely if the symptoms are severe with a rapid onset and if more than one of the above systems is involved. The general takeaway here is that, in order to not do harm, we need to document possible allergic reactions (and what the reaction was) so that we can take these into consideration when choosing to prescribe new medications. Although avoiding the prescribing of any medication that has given the patient any sort of reaction is preferred, the severity of a past reaction may warrant extra precaution when considering trial of a new medication. Per UpToDate (2018), "A prior history of allergic reactions to one or more drugs increases the risk of developing additional drug allergies." As well, if a serious reaction has occurred to a certain drug, then this way warrant precaution when administering other drugs of the same class, which can be consequential when certain drugs are the best options for treating particular diseases. When in doubt, avoid harm and consider referral to an allergy specialist for a more definitive workup, including allergy testing if available for the suspect drug. One thing I have commonly seen in clinic is the patient who describes having had a rash in response to an antibiotic. Unless this is urticarial and occurring relatively quickly (within an hour or so) after exposure to the medication, this is likely either a type IV hypersensitivity reaction to the medication or the rash was from something unrelated. A common culprit in this situation is the post-viral exanthem, which is a rash that can occur secondary to a viral infection and that is common in pediatric patients. This is particularly common as patients may be suspected of having a bacterial infection while there is an underlying viral illness present (perhaps there was never a bacterial infection at all and the virus was entirely responsible for the symptoms, or there was a viral infection with a bacterial superinfection) and then develop a rash as part of the viral syndrome. But because they were prescribed an antibiotic, it may be unclear as to whether the rash was a type IV hypersensitivity reaction to the antibiotic or a viral exanthem. In this situation, assuming the reaction was mild, the patient could be rechallenged at a later date with the same medication, or they could be referred to an allergy specialist for further testing. This is particularly relevant when it comes to antibiotics. The great majority of patients who report a penicillin allergy do not in fact have one, and avoiding the prescribing of more narrow rather than broader spectrum antibiotics is not an insignificant contributor to the problem of antibiotic resistance (see my previous blog post on this topic). |
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