Allergic and Anaphylactic Reactions
Start
The immune system
Pathophysiology: Lets talk terminology
- Immune system: Bodily system that is responsible for fighting off infection and disease
- There are several components of the immune system in the body and they can be found in the blood, bone marrow and lymphatic system
- The immune response starts with the introduction of a pathogen or antigen. A substance that is foreign to the body.
- The main goal of the immune system is to find, fight and destroy these foreign invaders
Pathophysiology: Lets talk terminology cont.
- There are two types of immune systems in the body:
- Cell-mediated immunity: This involves a direct, full frontal attack of the foreign invader. Specialized cells of the body engulf or form granules of the substance to break them down and excrete them from the body. The main lymphocyte that is used in this process is the T lymphocyte.
- Humoral immunity: A complicated chemical attack composed of immunoglobulins (IgA, IgD, IgE, IgG, and IgM). This attack of the pathogen forms anitbodies of the five classes of immunoglobulins from the specialized B lymphocytes. Humoral immunity is specialized to create a memory of certain pathogens or antigens. All immunoglobulins are antibody proteins.
- A third non-specific form of immune response is called inflammation. This is the first immunity system to react to any form of pathogen or injury.
That's great. How does this pertain to Allergic reactions and anaphylaxis?
We are getting there! Let's talk about what an allergy is and why the immune system plays a role.
Allergies
In certain individuals, this exposure can cause a hypersensitivity. An unexpected or exaggerated response to an antigen.
An individual must be intitially exposed to an antigen. This is called sensitization.
This results in an immune response in an individual with repeated exposure inducing a stronger response than the first exposure.
Hypersensitivity and allergen are the same terms.
Types of Hypersensitivity
Delayed
Immediate
It is the result of cellular immunity (cell-mediated) that does not involve antibodies from humoral immunity. Typical delayed hypersensitivity reactions are skin rashes from exposure to poison ivy, medications, or chemicals. These reactions tend to be less severe and dissipate over a period of time.
Exposure to an antigen results in the response of humoral immunity and the release of antibodies. Large quantities of IgE antibodies are released in the presence of the antigen. The most common allergens are medications, foods, animals, insect stings (hymenoptera) stings, fungi, molds, and radiology contrast. These reactions tend to be more severe and do not resolve over time.
Immediate Hypersensitivity
- Allergens can enter the body through various routes
- Hymenoptera stings: Such as bees, wasps or other venomous insects that inject their venom directly into circulation of the body. These account for the vast majority of anaphylactic reactions.
- Penicillin injection: Second most common cause of anaphylactic reaction.
- Oral ingestion
- Inhalation
- Topical (enters through the skin)
How does Immediate Hypersensitivity work?
Pathology
Antigen enters the body, resulting in a large release of IgE (anitbody protein) into circulation.
IgE attaches to basophils and mast cells (granulocytes) that contain within them chemicals to aid in immune reponse. These chemicals include histamine, heparin and other substances.
Through the attachment of IgE to basophils and mast cells, immune chemicals are released into the tissues from granules found within the basophils and mast cells.
Due to the process of degranulation (release of immune defense chemicals) this is what results in an allergic reaction.
Histamine Receptors
Affects smooth muscle and endothelial cells during acute allergic reactions increasing vascular permeability.
H1
Affects the CNS, resulting in a change of secretions of neurotransmitters.
H3
Affects the release of mast cells, eosinophils and T cells that regulate immune responses in the body.
Affects gastric parietal cells causing a secretion of gastric acid, increasing intestinal motility.
H2
H4
What makes Immediate Hypersensitivity so dangerous?
What is anaphylaxis? what are the symptoms? and how do we treat it?
Anaphylaxis
Anaphylaxis is due to an allergen reaching the circulatory system of the body, causing it to be distributed throughout the system.
Allergen Exposure
Allergen reacts with the basophils and mast cells stimulating the over release of histamine from the granulocytes.
Release of Immune Chemicals
The over release of histamine binds with its receptor sites. The massive quantities stimulate their respective body systems causing a distributive effect.
Body Systems
Body Systems deep dive
Respiratory
Skin
Gastrointestinal
+ info
+ info
+ info
Signs and symptoms of allergic reactions VS. anaphylaxis
Allergic Reaction
Anaphylaxis
- Itching
- Localized rash or swelling
- Slow progression of symptoms
- Mild respiratory compromise
- Mild to moderate severity
- No cardiovascular compromise
- Involves one system
- Immediate reaction
- Severe and potentially fatal
- Involves multiple systems
- Airway obstruction
- Bronchospasm
- Diffuse urticaria
- Hypotension (late)
- Tachycardia
- Bradycardia (late)
- Nausea/Vomiting/Diarrhea
- Tachypnea
- Respiratory failure (late)
- Anxiety
- Sense of impending doom
VS
So, how do we treat anaphylaxis?
timeline
Airway
IV access
Medications
Reevaluation
Protect the airway at all cost!
Give some fluid!
Reversal and prevention
Patient Monitoring
National v Local Guidlines
VS
+ info
+ info
Citations
- Whyte, A. F., Soar, J., Dodd, A., Hughes, A., Sargant, N., & Turner, P. J. (2022, July). Emergency treatment of anaphylaxis: Concise clinical guidance. Clinical medicine (London, England). https://pmc.ncbi.nlm.nih.gov/articles/PMC9345203/
- SCRETAC: SECRETAC: Southern Colorado RETAC Guidelines: Colorado Regional Plans: Southeastern Colorado Business Information. Southern and Southeastern Colorado RETAC. (2023, May 9). https://southerncoloradoretac.org/scretac-documents/
- McLendon, K. (2023, January 26). Anaphylaxis. StatPearls [Internet]. https://www.ncbi.nlm.nih.gov/books/NBK482124/
THANKS!
Cristian Danyow
NIH Anaphylaxis
https://pmc.ncbi.nlm.nih.gov/articles/PMC9345203/
Airway Management
- Administer oxygen in hypoxic patients
- Ventilatory assistance in hypoventilation and apnea
- Basic airway maneuvers such as head tilt chin lift and jaw thrust
- Consider basic airway adjuncts
- Be prepared for endotracheal intubation
- Be prepared for surgical and or needle cricothyrotomy
SCRETAC Guidlines
Intravenous Access
- Establish early IV access
- Be prepared for IO access
- Early isotonic crystalloid solution bolus or continous infusion in cases of hypotension
- Place secondary line
- Allows ease of emergency medication administration
Histamine
An immunological chemical mediator of an allergic reaction that works on specific histamine receptors. The effects on the body include bronchoconstriction, intestinal motility, vasodilation and vascular permeability. All of these effects are what contribute to the potency of histamine. Vascular permeability increases fluid leakage into interstitial spaces, causing angioneurotic edema or angioedema, which typically involves the head, neck, face, and upper airway.
Body Systems affected:
- Cardivascular: vasodilation, increased heart rate, decreased in blood pressure
- Respiratory: Bronchospasm caused by SRS-A (slow-reacting substance of anaphylaxis), wheezing, stridor, laryngeal edema, laryngospasm, bronchoconstriction
- Gastrointestinal: Nausea, vomiting, diarrhea, abdominal cramping
- Skin: Flushing, itching, urticaria, edema, cyanosis
- Nervous System: Dizziness, headache, convulsions, tearing
Anaphylaxis:
Signs and symptoms of anaphylaxis begin within seconds of exposure to the allergen. In some rare cases, symptoms can be delayed and have affects that occur over an hour later post-exposure.
Respiratory
The respiratory system is affected in multiple ways by the over-release of histamine. SRS-A (slow-reacting substance of anaphylaxis) is released from basophils and mast cells potentiates the affects of histamine. SRS-A causes bronchospasm, constricting the bronchioles like you would find in an asthma attack. The vascular permeability of the capillaries increases laryngeal edema. This, in turn, can cause wheezing in the lungs and upper airway, progressing toward stridor and ultimately complete occlusion of the airway.
Skin
The skin is a common organ that is involved in both allergic reactions and anaphylaxis. In severe reactions, flushed red rashes appear across the body. Due to the histamine in the system, capillary permeability allows extravasation into the third spaces, causing urticaria (hives). The vasodilation of the cardiovascular system sends blood to the surface of the skin, causing the skin to appear flushed and hot. Diaphoresis and cyanosis can develop in later stages as the other systems of the body start to fail if the patient is left untreated.
Gastrointestinal
As histamine ravages the body, creating reaction on reaction, the gastrointestinal system becoming affected can be an ominous sign. H2 receptors stimulate gastric acid secretion, increasing the motility in the system. Abdominal cramping and overactive bowel signs start to develop as the H2 receptors are stimulated. In severe or later stages of anaphylaxis, nausea, vomiting, and diarrhea start to develop. The body is trying to eliminate the allergen at all costs, thus involving the gastrointestinal system.
Epinepherine: Used in the treatment of anaphylaxis. It is a sympathetic agonist, increasing the heart rate, contractile force, peripheral vasoconstriction, and reversal of bronchospasm. Dosages:: Adult- 0.3-0.5mg IM (1:1000) Peds- 0.01mg/kg IM (1:1000)Adult- 0.05-0.1mg IV (1:10000) slow push Peds- 0.01mg/kg IV (1:10000)Antihistamines: Second line agents block the effects of histamine at the specific receptor. They reduce the amount of histamine that is able to bind to the receptors. Antihistamines are nonselective and block both H1 and H2 receptors. They do not reduce the amount of histamine in the system. Diphenhydramine: Nonselective antihistamine Dosages: Adult- 25-50mg PO, IV, IM Peds- 2mg/kg PO, IV, IMCorticosteroids: Although not useful in the moment of the emergency setting of anaphylaxis, they provide useful affects by surpressing inflammatory responses associated with anaphylaxis. They are used for the prevention of the reaction worsening. Methylprednisolone: Adult 80-250mg IVDexamethasone: Adult 4-24mg IV Peds: 2mg/kg IVHydrocortisone: 40-250mg IV Peds: 0.6 mg/kg IVBeta Agonists: Also used in the treatment in asthma and COPD, selective Beta Agonists help in the treatment of bronchospasm in anaphylaxis by stimulating Beta-2 receptors, responsible for bronchodilation. Albuterol: 2.5mg/3mL Nebulized Peds: 0.2-0.5mg nebulizedVasopressors: Extended severe allergic reactions may need to be treated with vasopressors to manage acute hypotension, used with fluid resuscitation. Common medications are dopamine, norepinephrine, phenylephrine, and epinephrine.
- Monitoring the effectiveness of medications given
- Monitor patient alertness
- Monitor Airway
- Monitor for deterioration
- Pulse oximetry
- Capnography
- Blood pressure
- 4-lead ECG
- Consider 12-lead ECG
- This patient is in Distributive Shock! Treat them like it!
Allergic and Anaphylactic Reactions
Cristian Danyow
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Transcript
Allergic and Anaphylactic Reactions
Start
The immune system
Pathophysiology: Lets talk terminology
Pathophysiology: Lets talk terminology cont.
That's great. How does this pertain to Allergic reactions and anaphylaxis?
We are getting there! Let's talk about what an allergy is and why the immune system plays a role.
Allergies
In certain individuals, this exposure can cause a hypersensitivity. An unexpected or exaggerated response to an antigen.
An individual must be intitially exposed to an antigen. This is called sensitization.
This results in an immune response in an individual with repeated exposure inducing a stronger response than the first exposure.
Hypersensitivity and allergen are the same terms.
Types of Hypersensitivity
Delayed
Immediate
It is the result of cellular immunity (cell-mediated) that does not involve antibodies from humoral immunity. Typical delayed hypersensitivity reactions are skin rashes from exposure to poison ivy, medications, or chemicals. These reactions tend to be less severe and dissipate over a period of time.
Exposure to an antigen results in the response of humoral immunity and the release of antibodies. Large quantities of IgE antibodies are released in the presence of the antigen. The most common allergens are medications, foods, animals, insect stings (hymenoptera) stings, fungi, molds, and radiology contrast. These reactions tend to be more severe and do not resolve over time.
Immediate Hypersensitivity
How does Immediate Hypersensitivity work?
Pathology
Antigen enters the body, resulting in a large release of IgE (anitbody protein) into circulation.
IgE attaches to basophils and mast cells (granulocytes) that contain within them chemicals to aid in immune reponse. These chemicals include histamine, heparin and other substances.
Through the attachment of IgE to basophils and mast cells, immune chemicals are released into the tissues from granules found within the basophils and mast cells.
Due to the process of degranulation (release of immune defense chemicals) this is what results in an allergic reaction.
Histamine Receptors
Affects smooth muscle and endothelial cells during acute allergic reactions increasing vascular permeability.
H1
Affects the CNS, resulting in a change of secretions of neurotransmitters.
H3
Affects the release of mast cells, eosinophils and T cells that regulate immune responses in the body.
Affects gastric parietal cells causing a secretion of gastric acid, increasing intestinal motility.
H2
H4
What makes Immediate Hypersensitivity so dangerous?
What is anaphylaxis? what are the symptoms? and how do we treat it?
Anaphylaxis
Anaphylaxis is due to an allergen reaching the circulatory system of the body, causing it to be distributed throughout the system.
Allergen Exposure
Allergen reacts with the basophils and mast cells stimulating the over release of histamine from the granulocytes.
Release of Immune Chemicals
The over release of histamine binds with its receptor sites. The massive quantities stimulate their respective body systems causing a distributive effect.
Body Systems
Body Systems deep dive
Respiratory
Skin
Gastrointestinal
+ info
+ info
+ info
Signs and symptoms of allergic reactions VS. anaphylaxis
Allergic Reaction
Anaphylaxis
VS
So, how do we treat anaphylaxis?
timeline
Airway
IV access
Medications
Reevaluation
Protect the airway at all cost!
Give some fluid!
Reversal and prevention
Patient Monitoring
National v Local Guidlines
VS
+ info
+ info
Citations
THANKS!
Cristian Danyow
NIH Anaphylaxis
https://pmc.ncbi.nlm.nih.gov/articles/PMC9345203/
Airway Management
SCRETAC Guidlines
Intravenous Access
Histamine
An immunological chemical mediator of an allergic reaction that works on specific histamine receptors. The effects on the body include bronchoconstriction, intestinal motility, vasodilation and vascular permeability. All of these effects are what contribute to the potency of histamine. Vascular permeability increases fluid leakage into interstitial spaces, causing angioneurotic edema or angioedema, which typically involves the head, neck, face, and upper airway.
Body Systems affected:
Anaphylaxis:
Signs and symptoms of anaphylaxis begin within seconds of exposure to the allergen. In some rare cases, symptoms can be delayed and have affects that occur over an hour later post-exposure.
Respiratory
The respiratory system is affected in multiple ways by the over-release of histamine. SRS-A (slow-reacting substance of anaphylaxis) is released from basophils and mast cells potentiates the affects of histamine. SRS-A causes bronchospasm, constricting the bronchioles like you would find in an asthma attack. The vascular permeability of the capillaries increases laryngeal edema. This, in turn, can cause wheezing in the lungs and upper airway, progressing toward stridor and ultimately complete occlusion of the airway.
Skin
The skin is a common organ that is involved in both allergic reactions and anaphylaxis. In severe reactions, flushed red rashes appear across the body. Due to the histamine in the system, capillary permeability allows extravasation into the third spaces, causing urticaria (hives). The vasodilation of the cardiovascular system sends blood to the surface of the skin, causing the skin to appear flushed and hot. Diaphoresis and cyanosis can develop in later stages as the other systems of the body start to fail if the patient is left untreated.
Gastrointestinal
As histamine ravages the body, creating reaction on reaction, the gastrointestinal system becoming affected can be an ominous sign. H2 receptors stimulate gastric acid secretion, increasing the motility in the system. Abdominal cramping and overactive bowel signs start to develop as the H2 receptors are stimulated. In severe or later stages of anaphylaxis, nausea, vomiting, and diarrhea start to develop. The body is trying to eliminate the allergen at all costs, thus involving the gastrointestinal system.
Epinepherine: Used in the treatment of anaphylaxis. It is a sympathetic agonist, increasing the heart rate, contractile force, peripheral vasoconstriction, and reversal of bronchospasm. Dosages:: Adult- 0.3-0.5mg IM (1:1000) Peds- 0.01mg/kg IM (1:1000)Adult- 0.05-0.1mg IV (1:10000) slow push Peds- 0.01mg/kg IV (1:10000)Antihistamines: Second line agents block the effects of histamine at the specific receptor. They reduce the amount of histamine that is able to bind to the receptors. Antihistamines are nonselective and block both H1 and H2 receptors. They do not reduce the amount of histamine in the system. Diphenhydramine: Nonselective antihistamine Dosages: Adult- 25-50mg PO, IV, IM Peds- 2mg/kg PO, IV, IMCorticosteroids: Although not useful in the moment of the emergency setting of anaphylaxis, they provide useful affects by surpressing inflammatory responses associated with anaphylaxis. They are used for the prevention of the reaction worsening. Methylprednisolone: Adult 80-250mg IVDexamethasone: Adult 4-24mg IV Peds: 2mg/kg IVHydrocortisone: 40-250mg IV Peds: 0.6 mg/kg IVBeta Agonists: Also used in the treatment in asthma and COPD, selective Beta Agonists help in the treatment of bronchospasm in anaphylaxis by stimulating Beta-2 receptors, responsible for bronchodilation. Albuterol: 2.5mg/3mL Nebulized Peds: 0.2-0.5mg nebulizedVasopressors: Extended severe allergic reactions may need to be treated with vasopressors to manage acute hypotension, used with fluid resuscitation. Common medications are dopamine, norepinephrine, phenylephrine, and epinephrine.