Anaphylactic Allergic Reactions
An anaphylactic reaction is due primarily to the release of histamine from IgE sensitized mast cells. Histamine produces inflammation and vascular effects such as:
Capillary dilation and increased capillary permeability resulting in blushing and edema formation.
Decreased venous return, blood pressure and cardiac output.
Stimulation of secretions
Increased secretions by the mucous, lacrimal, salivary, pancreatic, gastric and intestinal glands.
The above-described effects can lead to asphyxia from upper respiratory tract obstruction.
It is possible for the patient to develop an anaphylactoid reaction which mimics a true IgE mediated anaphylaxis reaction. An anaphylactoid reaction is an idiosyncratic reaction that occurs when the patient is first exposed to a drug or other agent. Although it is not immunologically mediated, the emergency management is the same as a true anaphylactic reaction.
There are several primary allergic agents used in dentistry:
Antibiotics (penicillins, cephalosporins, tetracyclines, sulfonamides): Parenterally administered penicillin can cause an anaphylactic reaction. The incidence of allergy from Penicillins ranges from 0.7 to 10% and around 2.5 million persons have been estimated to have allergy to Penicillins in the United States.11 Orally administered usually causes a delayed reaction. Patients may not realize they have been previously exposed to a sensitizing dose because the exposure could have been environmental, i.e., penicillin mold in the air, meat, and milk.
Analgesics (aspirin, opioid, NSAIDS): Symptoms can range from mild urticaria to anaphylaxis. Bronchospasm is the most common reaction. For patients with a known allergy to the above analgesics, acetaminophen should be prescribed.
Local anesthetics (esters, procaine, benzocaine, tetracaine): Injectable and topical ester local anesthetics have been primarily implicated in allergic reactions. Reported allergic reactions in amides are probably due to reactions to preservatives such as parabens and sodium metabisulfate.
Other agents: Acrylic resins (denture repairs) and latex (gloves, rubber dams) primarily cause contact dermatitis.
An anaphylactic episode is exhibited by the following reactions:
Urticaria - itching, hives (elevated patches of skin)
Erythema – rash
Angioedema - localized swelling
Bronchospasm - respiratory distress, wheezing
Angioedema to the larynx leading to airway obstruction
Circulatory collapse due to vasodilation presented by light headedness, weakness, syncope and ischemic chest pain
Dysrhythmias - as above plus palpitations
The progression of symptoms is:
Eyes, nose, GI
Should a patient experience an anaphylactic episode, the following steps should be taken:
Assess the problem: Recognize and acknowledge itching, hives, edema, flushed skin.
Activate the office emergency system: Call for help and have oxygen and the emergency drug kit brought to the site of the emergency.
Position the patient:The patient should be positioned comfortably.
Assess circulation, airway and breathing: Monitor the patient’s pulse and blood pressure. Provide BLS as needed. Assess the patient’s airway patency, breathing and adjust the head and jaw position accordingly. If the patient’s condition continues to worsen, contact EMS.
Provide definitive care: Administer epinephrine. Epinephrine counteracts most of the effects of histamine. It produces bronchodilation, raises blood and the heart rate via its α and ß effects and counters skin rash, urticaria and angioedema by an unknown mechanism.
While available in 1 ml ampules of 1:1000 (0.30 mg/dose) for adults and 1:2000 (0.15 mg/dose) for children that is drawn into and administered via a syringe (Figure 10). A more efficient manner of administration during an emergency is with an EpiPen.
Figure 10. Epinephrine injection
EpiPen (0.3 mg epinephrine) and EpiPen Jr (0.15 mg epinephrine) are preloaded epinephrine autoinjectors. They are extremely easy to use and are routinely available with prescription to the public for everyday allergic reactions (insect bites, food allergies).
Directions for use of EpiPen:
Pull off the blue safety release cap.
Swing and firmly push the orange tip against the outer thigh so it “clicks.” HOLD the EpiPen on the thigh for approximately 10 seconds to deliver the drug. Do not inject intravenously as this can cause ventricular tachycardia or into the buttock as this may reduce drug efficacy.
Epinephrine is administered every 15 minutes until recovery or help arrives.