Anaphylaxis

Question 1

The classic presentation of anaphylaxis begins with

Answer 1

pruritus, cutaneous flushing, and urticaria

Question 2

A complaint of _____ and _____ heralds life-threatening laryngeal edema

Answer 2

“lump in the throat” and hoarseness

Question 3

In most patients, signs and symptoms usually begin within

Answer 3

60 minutes of exposure

Question 4

one half of anaphylactic fatalities occur witin

Answer 4

the first hour

Question 5

recurrence / second phase of a biphasic reaction occur when

Answer 5

3 to 4 hours after the initial clnical manifestations have cleared, peaking 8 to 11 hours after the initial exposure

Question 6

How to diagnose anaphylaxis

Answer 6

Diagnosis is clinical, and consider anaphylaxis when involvement of any two or more body systems is observed, Twith or without hypotension or respiratory compromise

Question 7

he most common anaphylaxis imitator

Answer 7

vasovagal reaction
characterized by hypotension, palllor, bradycardia, diaphoresis, and weakness, sometimes accompanied by loss of consciousness

Question 8

Remarks on triaging allergic reacionts

Answer 8

Triage of all acute allergic reactions should be at the highest level of urgency because of the possibility of sudden deterioration.

Question 9

1st-line therapy in anaphylaxis

Answer 9

1. Airway protection
2. Oxygenation
3. Decontamination
4. Epinephrine
5. IV crystalloids

Question 10

2nd-line therapy in anaphylaxis

Answer 10

1. Corticosteroids
2. Antihistamines
3. Bronchodilators
4. Vasopressors
5. Glucagon

Question 11

In severe anaphylaxis, this is the first priority

Answer 11

securing the airway
Examine the mouth, pharynx, and neck for signs and symptoms of angioedema:
- uvula edema or hydrops
- audible stridor
- respiratory distress
- hypoxia

Question 12

Provide supplemental oxygen to maintain arterial oxygen sautration ______

Answer 12

> 90%

Question 13

Mechanism of epinephrine

Answer 13

a1: reduces mucosal edema and treats hypotension
B1: increases heart rate and myocardial contractility
B2: bronchodilation and limits further mediator release

Question 14

Remarks on epinephrine use

Answer 14

Observational studies indicate that epinephrine is underused, often dosed suboptimally, and uderprescribed upon discharge

Most reasons proposed to withhold epinpehrine are flawed, and the therapeutic benefits of epinephrine exceed the risk when given in appropriate routes and doses, even in elderly patients

Question 15

When and how to administer epinephrine IM?

Answer 15

In patients without signs of cardiovascular compromise or collapse

0.3 - 0.5 mg (0.3 - 0.5 mL of 1:1000 dilution) IM every 5-10 mins to anterior thigh
(pedia: 0.01 mg/kg)

Question 16

When and how to administer epinephrine IV?

Answer 16

In patients who are refractory to treatment despite repeated doses of epinephrine IM or has signs of cardiovascular compromise or collapase.

IV bolus of 100 mcg (0.1 mg) over 5-10 minutes

IV infusion of 1 mcg/min titrating to effect

Question 17

Precaution for epinephrine

Answer 17

In those taking beta blockers, blood pressure should be checked because epinephrine use may result in severe hypertension secondary to unopposed a-adrenergic stimulation.

Age is NOT a barrier to epinephrine IM injections in patients with anaphylaxis.

For the initial IV bolus, it should be stressed that ot is very diliute, is given over 5-10 minutes, and should be stopped immediately if dysrhythmia or chest pain occur

Question 18

a bolus of ____ of isotonic crystalloid solution should be administered concurrently with epinephrine

Answer 18

1 to 2 liters
(10 to 20 mL/kg in children)

Question 19

Corticosteroids are given for what and how?

Answer 19

to prevent protracted and biphasic reactions

Hydrocortisone 250-500 mg IV
(5-10 mg/kg in children)

Methylprednisolone 80-125 mg IV
(2 mg/kg in children)

Question 20

these corticosteroids are preferred for the elderly

Answer 20

Methylprednisolone (0.5) and dexamethasone (0)
lowest mineralocorticoid effect, producing less fluid retention.

These can be used also in patients in whom fluid retention would be problematic.

Hydrocortisone has 1.0 relative mineralocorticoid potency.

Question 21

Remarks on antihistamines

Answer 21

H1 antihistamine (diphenhydramine): most patients
H2 antihistamine (ranitidine or cimetidine): severe cases, especially with circulatory shock

Question 22

Precautions for cimetidine

Answer 22

Cimetidine should not be used for patients who are
- elderly (side effects)
- have multiple comorbidities (interference with metabolism of many drugs)
- have renal or hepatic impairment
- or whose anaphylaxis is complicated by B-blocker use (cimetidine prolongs metabolism of B-blockers, and may prolong the anaphylactic state)

Question 23

Agents used for allergic bronchospasm

Answer 23

Given if wheezing is present:
-Salbutamol
- inhaled anticholnergics
- IV magnesium sulfate 2g over 20 minutes

Question 24

1st line vasopressor in anaphylaxis

Answer 24

IV Epinephrine infusion

Question 25

Concurrent use of B-blockers is a risk factor for _____

Answer 25

severe prolonged anaphylaxis (as B2 supposedly inhibits further mediator release) For patients taking B-blockers with hypotension refractory to fluids and epinephrine, give **glucagon 1 mg IV every 5 minutes** until hypotension resolves, followed by **5-15 mcg/min IV infusion**

Question 26

Remarks on admitting anaphylaxis cases

Answer 26

With appropriate initial treatment, admission to hospital is **rare**, only required in about 1% to 4% of acute allergic reactions treated in the ED All unstable patients with anaphylaxis **refractory** to treatment or in whom **airway** interventions were required should. be admitted to the **ICU**

Question 27

Anaphylaxis can be observed in the ED for how long?

Answer 27

6 hours. Patients who remain symptom free have low risk of biphasic reaction.

Question 28

Consider prolonged observation for which patients?

Answer 28

lives ***A***lone using ***B***eta blockers significant ***C***omorbidities *(including but not limited to* ***asthma***) reside long ***D***istance from medical care ***E***lderly ***F***ast history of severy reaction

Question 29

What to prescribe to anaphylaxis patients upon discharge

Answer 29

Epinephrine autoinjector, at least 2 Diphenhydramine 25-50 mg PO every 6-8h for 3-5 days Prednisone 40-60 mg PO daily for 3-5 days *(or 20-30 BID for 3-5 days)*