Chapter 21 - Allergy and Anaphylaxis

Part One; You and your partner are dispatched to Pioneer Park, a local recreational area where residents frequently picnic and enjoy a variety of outdoor festivities, especially during the spring and summer months. The nature of the call is "possible allergic reaction" for a 25-year-old man. You arrive to find a crowd of onlookers who frantically motion to you. As you move through the crowd, you see a man sitting on the ground. He appears to be very anxious and has hives all over his chest and arms. In fragmented sentences, he explains that he was playing Frisbee when something stung him on his back. He also says that it's hard to breathe and he feels very dizzy. You see that his breathing is labored and note the presence of wheezes. 1. How can you discern between a mild or moderate allergic reaction and anaphylaxis? 2. Assuming this person is having a severe, life-threatening allergic reaction, what would you expect his vital signs to indicate? Given his presentation, would you call for other resources?

1. Allergic reactions and anaphylaxis can have some of the same signs and symptoms, such as hives, urticaria, and gastrointestinal symptoms. However, anaphylaxis has additional potentially life-threatening signs and symptoms such as dyspnea, airway swelling, or shock-related findings. 2. He would likely have tachycardia, and may have tachypnea, usually with decreased oxygen saturation, and/or hypotension. Because anaphylaxis can be life threatening, it is important to obtain ALS support for treatment of shock or respiratory compromise that may not respond sufficiently to BLS measures or that re-exacerbate before the patient can be transferred to the hospital.

Part Two; You immediately request ALS assistance as you ready your EpiPen. You expect to see vital signs that indicate an increased vascular container diameter (hypotension) along with the heart's attempts to compensate for that larger container (tachycardia). You also expect to see a subsequent decreased oxygen level secondary to the swelling of the airway and the problems with the circulation. Your partner takes the patient's initial vital signs and reports that the patient's blood pressure is 94/56 mm Hg, pulse is 130 beats/min, respirations are 42 breaths/min, and pulse oximetry reads 90%. You explain to the patient that you need to administer epinephrine to reverse the effects of the insect bite. You tell him that the injection may sting but that he should not pull away. You place your knee along the inside of his leg to prevent his moving, and you administer the EpiPen. Your partner gives the patient high-flow oxygen and removes the stinger by scraping it off with a tongue depressor. You then have him lie down. 3. In some states, EMTs have kits that contain epinephrine and occasionally antihistamines that they can administer by mouth. Is an EpiPen a multidose preparation?

3. EpiPens are single-dose injectors. However, some patients may have an autoinjector (such as TwinJect) that has two doses that may be utilized by the EMT to assist the patient.

Part Three; A few moments after you administer the EpiPen, you notice that the patient is breathing more easily. His blood pressure and pulse oximetry values have risen, and pulse and respiration counts have decreased. The paramedics have now arrived. 4. What treatment would you expect the paramedics to provide?

4. ALS will start an intravenous infusion through which they may give fluid boluses, antihistamines, or steroids. They may also give additional intramuscular epinephrine with a regular syringe. If the airway or respiratory status deteriorates, they may decide to intubate the patient.

Part Four; You assist the paramedics in moving the patient to the ambulance. There you see one paramedic has already prepared to initiate intravenous fluids, administer Benadryl, and administer oxygen. 5. Why is it important to rapidly administer epinephrine to a patient who is in anaphylaxis?

5. If the airway or respiratory system continues to swell, it can lead to respiratory arrest. Likewise, if perfusion continues to be compromised for several minutes, severe shock and even cardiac arrest can occur.

Stridor

A harsh, high-pitched respiratory sound, generally heard during inspiration, that is caused by partial blockage or narrowing of the upper airway; may be audible without a stethoscope.

Wheezing

A high-pitched, whistling breath sound that is most prominent on expiration, and which suggests an obstruction or narrowing of the lower airways; occurs in asthma and bronchiolitis.

Epinephrine

A medication that increases heart rate and blood pressure but also eases breathing problems by decreasing muscle tone of the bronchiole tree; a substance produced by the body (commonly called adrenaline), and a drug produced by pharmaceutical companies that increases pulse rate and blood pressure; the drug of choice for an anaphylactic reaction.

Toxin

A poison or harmful substance.

Wheal

A raised, swollen, well-defined area on the skin resulting from an insect bite or allergic reaction.

Allergen

A substance that causes an allergic reaction.

Anaphylaxis

An extreme, life-threatening, systemic allergic reaction that may include shock and respiratory failure.

Histamines

Chemical substances released by the immune system in allergic reactions that are responsible for many of the symptoms of anaphylaxis, such as vasodilation.

Leukotrienes

Chemical substances that contribute to anaphylaxis; released by the immune system in allergic reactions.

Angioedema

Localized areas of swelling beneath the skin, often around the eyes and lips, but can also involve other body areas as well.

Your partner notes the presence of a medical alert bracelet around the patient's wrist. What should be done and why?

Remove the bracelet. As swelling increases, there is a risk that the jewelry will become constrictive and difficult to remove later. This could result in reduced perfusion to the extremity.

You and your partner are dispatched to 1284 NW 152 Avenue for a child experiencing respiratory distress. On arrival, a frantic woman meets you at the door and begs you to hurry. She informs you that her 12-year-old son was playing in the backyard when he felt a sudden pain on the back of his leg. You find the child on the back porch, in obvious distress, leaning forward in a chair with his elbows on his knees, struggling to catch his breath. Due to severe dyspnea, he is unable to answer your questions. You also notice that his left arm is in a cast. Your partner immediately applies a nonrebreathing mask as you complete the primary assessment. The child's respirations are rapid and shallow, and his pulse is rapid and thready. His skin is pale with patches of raised red spots on his hands, arms, and face. Your partner conducts a systematic rapid physical exam as you obtain vital signs and a SAMPLE history from the mother. When you inquire about allergies, the mother tells you the child had a very mild reaction to a bee sting several months ago. His medical history also includes asthma, anxiety, and a recent fracture of his arm. Your partner informs you that he heard wheezes in all lung fields and observed additional raised red spots on the child's chest.

See all multiple choice questions to determine how to correctly proceed with treating the patient.

Urticaria

Small areas of generalized itching and/or burning that appear as multiple raised areas on the skin; hives.

Besides an allergic reaction, provide an example of another illness or injury you should consider as part of the differential diagnosis.

Some examples include: sepsis (a rash may indicate wide-spread infection), or an anxiety attack (the patient is anxious and breathing rapidly). In an adult patient, pulmonary embolus would also be a possibility, though it is not very likely in a child.

Envenomation

The act of injecting venom.

Immune System

The body system that includes all of the structures and processes designed to mount a defense against foreign substances and disease-causing agents.

Allergic Reaction

The body's exaggerated immune response to an internal or surface agent.

Immune Response

The body's response to a substance perceived by the body as foreign.

Immunology

The study of the body's immune system.

Following the administration of epinephrine, the patient reports that his heart is beating "very fast." How should you respond?

This is a normal side effect of epinephrine. The tachycardia is the result of the drug's stimulation of the body's stress response, and therefore the patient experiences an increased heart rate, increased workload on the heart, and increased demand for oxygen by the heart. Therefore, you should reassure the patient that this effect is normal.

Your partner suggests that, in addition to epinephrine, the two of you should assist the patient in using his albuterol inhaler. How should you respond? Why?

You should agree to the use of albuterol, as the patient has a history of asthma and exhibits wheezing, which is an indication of lower airway obstruction. Because the primary effect of albuterol is bronchodilation, the inclusion of this treatment could be beneficial.

Your partner indicates that he heard wheezes in all lung fields. What did he hear? a. A high-pitched whistling sound caused by bronchoconstriction b. A coarse, low-pitched breath sound heard in patients with chronic mucus in the upper airways c. A high-pitched noise heard primarily on inspiration d. Crackling, moist breath sounds

a. A high-pitched whistling sound caused by bronchoconstriction

What possible chemical is being released into this patient's body during this reaction? a. Histamine b. Antihistamine c. Epinephrine d. Glucose

a. Histamine

Which medication should be administered first for this patient? a. Albuterol b. Epinephrine c. Acetaminophen (Tylenol) d. Diphenhydramine (Benadryl)

b. Epinephrine

What should you do first? a. Administer albuterol. b. Transport to the hospital. c. Administer epinephrine. d. Coach the patient to slow his breathing.

c. Administer epinephrine.

The raised red spots are most likely: a. angioedema. b. acne. c. urticaria. d. a fungal infection.

c. urticaria.