Allergies and Anesthesia Flashcards
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What is an allergy?
Reproducible adverse reaction to an extrinsic substance mediated by the immune system
What are the 4 types of allergic reactions?
Type 1: immediate
Type 2: cytotoxic
Type 3: immune complex
Type 4: delayed
What are some examples of type 1 reaction?
- Atopy
- Urticaria (hives)
- Angioedema (swelling)
- Anaphylaxis
What type of reactions occur because of hemolytic reactions or HIT ?
Type 2 (cytotoxic)
What are some examples of type 3 reaction?
Serum sickness
– reaction to an injection of foreign proteins
What are some examples of type 4 reaction?
Contact dermatitis
– skin reaction because of direct contact with a substance
What is anaphylaxis?
An exaggerated response to a foreign substance that is mediated by an antigen-antibody reaction
What is the onset of an anaphylactic reaction?
Minutes
What is it about an anaphylactic reaction that makes it unique?
It requires a previous exposure to antigen to have a reaction
What is the one most common feature of an anaphylactic reaction that makes it deadly?
Circulatory collapse
What is the incidence and mortality rates for an anaphylactic reaction?
1:5000
Mortality 6%
What is the mechanism of an allergic reaction?
- Antigen causes stimulation of IgE antibodies
- Antibodies fix to mass cells and basophils
- 2nd exposure of antigen results in antibody binding onto mass cells/basophils
- Binding stimulates degranulation and release of chemical mediators
What are the most common chemical mediators released from mass cells/basophils?
- -Histamine
- -Leukotriene
- Prostaglandins
What does histamine release cause?
- Increased capillary permeability
- Peripheral vasodilation
- Bronchoconstriction
What does leukotriene release cause?
- Bronchoconstriction
- Increased capillary permeability
- Negative iontropy
What does prostaglandins release cause?
- Bronchoconstriction
- - Vasodilation
What resembles anaphylaxis but is not mediated by the immune system and does not involve IgE antibodies?
Anaphylactoid reactions
With anaphylactoid reactions, what is the most often cause?
Pharmacologic
– Drug has direct action on mast cells/basophils to release large amounts of histamine
Can an anaphylactoid reaction occur on 1st exposure?
YES
T OR F
Anaphylactoid reactions clinically are indistinguishable from anaphylactic reactions and are equally life-threatening?
TRUE
What are some predisposing factors for anaphylactoid reactions?
- Pregnancy
- Youth (peds)
- History of atopy
Under anesthesia, what are some clinical signs your patient is having some sort of reaction?
- Circulatory collapse
- Pulmonary insults
- Cutaneous signs
What are some indications of circulatory collapse?
- Profound Vasodilation secondary to decreased SVR
- Profound hypotension that difficult to fix
- Tachycardia
- Pulmonary vasoconstriction / HTN
- End result, cardiac arrest
What are some of the pulmonary insults that can present?
- Wheezing (heard throughout chest)
- Severe bronchospasm
- Increased PIP
- Laryngeal edema and/or stridor
- Pulmonary edema
- Acute respiratory failure / hypoxia
What are some of the signs you can see on the skin?
- Uticaria (hives)
- Flushing
- Periorbital edema
- Perioral edema
What are the basics once a reaction has been identified?
- Reactions vary in severity and clinical manifestations
- IMMEDIATE recognition and treatment is a must
- AVOID worst case scenario: DEATH
What are treatment options/plan of care once a reaction has been identified?
- Stop administration of antigen
- 100% O2 and PPV
- Discontinue volatile agents
- Intravascular volume expansion
- Epinephrine
- If needed, external cardiac massage (chest compressions)
When giving intravascular volume expanders, is it better to give colloids or crystalloids?
– Colloids
because of increased capillary permeability colloids stay in vascular longer
What is the dose for giving intravascular volume expanders?
20 mg/kg boluses
Total: 1-4 L
What dose of epi do you administer?
1:10,000
@ 0.1 mL/kg IV
== repeat dose every 3-5 min doubling the 2nd dose
How does epi help in treating anaphylactic shock?
- B2 agonist effect relaxes bronchial smooth muscle
- - A agonist effect vasoconstricts blood vessels
Once patient has stabilized, what are some secondary treatment options?
- Drug and dose
- What it treats/does/is in parentheses
- Diphenhydramine 0.25-1 mg/kg (Antihistamine)
- Hydrocortisone 8 mg/kg (Corticosteroid)
- Albuterol ( Inhaled bronchodilator)
- Aminophylline (Bronchospasm)
- Bicarb (as needed for acidosis)
- Inotrope infusion as needed for BP
What are some immediate post-op management goals after a reaction?
- Admit to ICU
- Clotting screen and blood gases
- Airway evaluation before extubation
What are the different types of skin test available for reactions?
- Intradermal
- RAST (radioallergosorbent test)
- ELISA (enzyme linked immunosorbent assay)
What is difference in RAST and ELISA?
- RAST tests patient serum against specific IgE antibodies
- - ELISA measures antigen specific antibodies
What are some common offenders of causing reactions in the OR?
- Muscle relaxants (most common)
- Induction drugs
- LA
- Opioids
- Antibiotics
- Latex
- Halothane and others
What are 2 most common muscle relaxants to cause reactions?
- Succ
- - Atracurium
T OR F
There is a cross reactivity between sux and ND muscle relaxants?
TRUE
What is the unique thing with reactions and induction drugs?
Anaphylaxis may occur even after previous uneventful drug exposure
Do the barbiturates cause reactions?
Very rare, but when they do occur very life threatening
Are patients truly allergic to propofol?
Not likely, most likely due to other allergies (egg, soy, etc)
What is true with LA(local anesthetics) and reactions?
True allergic reactions rare
Most reactions are just adverse effects
Are esters or amides more likely to cause the reaction?
Esters because they are metabolized by PABA
What is the main opioid reaction we are concerned with?
Morphine
causes direct histamine release along with arterial and venous dilation
What is the only class of drug that brings about true anaphylaxis reactions?
Antibiotics
What is the cross sensitivity of PCN and cephalosporins (ancef)?
1-2%
but still err on side of caution
Vancomycin produces which type of reaction?
- Produces both
- - However anaphylactoid most common and causes redman’s syndrome
What is the only anaphylactic reaction that has delayed onset?
Latex
What is the time frame before you will begin to see symptoms?
30-40 min after exposure
What are the high-risk patient populations that may have cross sensitivity to latex?
- Spina bifida
- - Healthcare workers
Halothane has a direct correlation to what adverse outcome?
Hepatitis
What are some allergic symptoms brought on by halothane?
–Eosinophilia
–Rash
–Fever
(Prior exposure to halothane increases these risks)
What are other things that can cause a reaction?
- Blood products (around 3%)
- IV Contrast
- Protamine
- High risk patient population (allergy to seafood, diabetic)
T OR F
True anaphylaxis is rare when given anesthetic agents
TRUE
T OR F
Anaphylactoid reactions occur much more commonly?
TRUE
What is the key to preventing death when your patient has a reaction?
- Have a high index of suspicion
- Prompt recognition
- Aggressive treatment
