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Allergic Reactions and Anaphylaxis

Allergic Reactions and Anaphylaxis

Medical Emergencies

Clinical manifestations of allergic reactions range from mild, delayed reactions developing as long as 48 hours after exposure to the antigen, to immediate and life-threatening reactions developing within seconds.

Of the four basic types of hypersensitivity reactions, two are particularly relevant to the dental practice :

  • Type I Immediate hypersensitivity or Anaphylactic reactions - can be severe and life-threatening.
  • Type IV Delayed hypersensitivity reactions - seen clinically as contact dermatitis among large number of dental personnel.

Type I reactions can be subdivided as Generalised (systemic) anaphylaxis and Localised anaphylaxis (Skin reactions, Respiratory tract reactions, Cardiovascular reactions and Food allergy in the g.i. tract).

Delayed Onset Skin Reactions

  • Takes about 60 minutes or more to appear after antigenic exposure.

  • Clinical Manifestations

    • Localised areas of erythema (rash, flushed skin), urticaria (hives), pruritus (itching) and angioedema.

  • Management

    1. Terminate all dental procedures and stop administration of all drugs presently in use.
    2. Administer anti-histamines (IV or IM) such as Diphenhydramine (50mg for patients weighing more than 30kg and 25mg for children, 15-30kg ) or Chlorpheniramine (10-20mg).
    3. Prescribe oral anti-histamines (Diphenhydramine 50mg or Chlorpheniramine 8 mg) for 2-3 days to be taken 4-6 hourly (q6h).
    4. Do not discharge the patient until the clinical signs and symptoms have resolved and do not allow the patient to leave the dental office alone or operate a motor vehicle.

Rapid Onset Skin Reactions

  • Develops in less than 60 minutes.

  • Clinical Manifestations

    • Erythema (rash, flushed skin), urticaria (hives), pruritus (itching) and angioedema.
    • Conjunctivitis and Rhinitis.

  • Management

    1. Terminate all dental procedures and stop administration of all drugs presently in use.
    2. Monitor and record vital signs (Pulse, blood pressure and respiratory rate) every 5 minutes.
    3. Epinephrine : Recommended when there is involvement of respiratory and cardiovascular systems. Dose : 0.3ml 1:1000 IM or SC (0.3mg for patients more than 30kg body weight, 0.15mg for 15-30kg, 0.075mg for less than 15kg). Epinephrine can be administered every 5-20 minutes as needed, to a maximum of three doses.
    4. Anti-histamines (Diphenhydramine or Chlorpheniramine) : Recommended when there is no cardiovascular and respiratory involvement and / or after resolution of the .cardiovascular or respiratory symptoms (IM, to provide more prolonged clinical activity).
    5. Consult patient's physician.
    6. Observe the patient for 1 hour.
    7. Prescribe oral anti-histamines (Diphenhydramine or Chlorpheniramine) for 2-3 days to be taken 4-6 hourly (q6h).
    8. Shift the patient to a hospital for further observation and additional treatment.

Lower Respiratory Tract Reactions (Bronchospasm)

  • There is constriction of bronchial smooth muscles and airway mucosal inflammation.

  • More common in asthmatics allergic to bisulfates and patients allergic to aspirin.

  • Clinical Manifestations

    • Respiratory distress, wheezing, mild dyspnea and cyanosis.
    • Flushing, perspiration, tachycardia and greatly increased anxiety.
    • Use of accessory muscles of respiration.

  • Management

    1. Terminate all dental procedures and stop administration of all drugs presently in use.
    2. Activation of the emergency medical services and consult patient's physician.
    3. Place the patient in sitting / semi-erect position.
    4. Assessment of circulation, airway and breathing.
    5. Administer epinephrine : IM or SC (0.3ml of 1:1000 for patient weighing more than 30kg, 0.15mg for 15-30kg, 0.075mg for less than 15kg). It can be administered every 5-20 minutes as needed, to a maximum of three doses. Epinephrines does not relieve bronchospasm produced by leukotrienes, other inhalation bronchodilators, such as albuterol, may be used.
    6. Oxygen administration : 5-6L per minute by facemask or nasally.
    7. Administer anti-histamines (Diphenhydramine or Chlorpheniramine) : to minimize the likelihood of recurrence of bronchospasm, by occupying the histamine receptor site.
    8. Observe in office for at least 1 hour.
    9. Prescribe oral anti-histamines (diphenhydramine or chlorpheniramine) for 2-3 days to be taken 4-6 hourly (q6h).
    10. Shift the patient to a hospital for further observation and additional treatment.

Upper Respiratory Tract Reactions (Laryngeal edema)

  • This is a life threatening condition, with swelling of the vocal cords in the larynx.

  • Clinical Manifestations

    • Patient is in respiratory distress and usually unable to speak.
    • Produces high-pitched crowing sounds (stridor : partial obstruction) or no sound (complete obstruction).
    • Little or no movement of air can be heard or felt through the mouth and nose, despite exaggerated chest movements.
    • Cyanosis.
    • Loss of consciousness due to hypoxia or anoxia.

  • Management

    1. Terminate all dental procedures and stop administration of all drugs presently in use.
    2. Activate the emergency medical services and consult patient's physician.
    3. Place the patient in upright / semi-erect position, if conscious. If the degree of laryngeal edema is significant, the level of consciousness will be altered and supine position with feet elevated is more appropriate.
    4. Assessment of circulation, airway and breathing. Extend the patient's neck via head tilt-chin lift, or jaw thrust-chin lift, followed by the insertion of a nasopharyngeal or oropharyngeal airway.
    5. Epinephrine : 0.3ml of 1:1000 epinephrine IM or SC for more than 30kg patients (0.15ml for 15-30kg, 0.075ml for less than 15kg patient), repeated every 5-20 minutes as necessary.
    6. Oxygen administration : 5-6L per minute by facemask or nasally.
    7. Monitor vital signs every 5 minutes.
    8. Administer anti-histamines (Diphenhydramine or Chlorpheniramine) and corticosteroid (Hydroscortisone 100mg) IM or IV, after clinical recovery i.e, airway improvement, normal or improved breath sounds, abscence of cyanosis and less exaggerated chest excursions.
    9. Cricothyrotomy : Indicated when total airway obstruction cannot be reopened at all or not in time by epinephrine and other drugs.
    10. Shift the patient to a hospital for further observation and additional treatment.

Generalised anaphylaxis

  • Clinical Manifestations

    • Begins with patient complaining of malaise or feeling of impending doom.
    • Skin manifestation : Flushing, urticaria and pruritus on the face and trunk.
    • Nausea, vomiting, abdominal cramps and urinary incontinence.
    • Dyspnea, wheezing and stridor.
    • Cyanosis of nail beds and mucosa.
    • Cardiovascular Manifestations : Initial tachycardia, followed by hypotension, cardiac dysrhythmias and cardiac arrest.
    • Total airway obstruction and loss of consciousness.

  • Management

    1. Terminate all dental procedures and stop administration of all drugs presently in use.
    2. Activate the emergency medical services and consult patient's physician.
    3. Place the patient in supine position with feet elevated.
    4. Assessment of circulation, airway and breathing. Maintain the airway via head tilt-chin lift, or jaw thrust-chin lift and carry out BLS as needed.
    5. Administer Epinephrine : 0.3ml of 1:1000 epinephrine IM or SC for more than 30kg patients (0.15ml for 15-30kg, 0.075ml for less than 15kg patient), repeated every 5-20 minutes as necessary.
    6. Oxygen administration : 5-6L per minute by facemask or nasally.
    7. Monitor vital signs every 5 minutes.
    8. Administer anti-histamines (Diphenhydramine or Chlorpheniramine) and corticosteroid (Hydroscortisone 100mg) IM or IV, once there is improvement in patient's condition.
    9. Cricothyrotomy : Indicated when total airway obstruction cannot be reopened at all or not in time by epinephrine and other drugs.
    10. Shift the patient to a hospital for further observation and additional treatment.

Points to Note

  • Overdose reactions are much more frequently encountered than allergic drug reactions (85% of adverse drug reactions result from the pharmacologic actions of a drug, while only 15% are immunologic reactions). Hence, it is important to fully evaluate an alleged history of allergy.
  • Urticaria : Wheals (smooth, slightly elevated patches of skin) consisting of slightly elevated areas of epithelial tissue that are erythematous and indurated.
  • Angioedema : Large areas of swollen tissue (measuring several centimetres in diameter), generally with little erythema or induration.
  • Despite the potentially severe cardiovascular disturbances, the usual cause of death in anaphylaxis is laryngeal obstruction by vocal cord edema.
  • Epinephrine inhaler should not be used when the patient has history of significant cardiovascular disease, including hypertension, angina pectoris, heart failure or status postmyocardial infarction.
  • The preferred IM injection site for epinephrine is the vastus lateralis muscle, located on the anterior lateral aspect of the thigh.
  • 1:1000 epinephrine concentrations are not to be used intravenously. 1ml should always be diluted with 9ml of diluent to produce 1:10,000 concentration, which is titrated IV at a rate of 1ml (0.1mg) per minute.
  • The maximum dose for 1:10,000 epinephrine should not exceed 5.0ml.
  • Epinephrine is relatively contraindicated in elderly patients and in cases of coronary artery disease, hypertension and angina pectoris. Also, it must be avoided in patients with life-threatening tachydysrhythmias. In these situations, anti-histamines or corticosteroid (whichever is appropriate) can be considered. However, in the presence of continued deterioration of the patient, epinephrine must be (re)administered.
  • Corticosteroids inhibit edema and capillary dilation by stabilizing basement membranes, hence preventing relapse. They are of little immediate value because of their slow onset of action (apprx 6 hours), even when administered intravenously.

References

  • Medical Emergencies in the Dental Practice (7th Edition), Stanley F. Malamed, Daniel L Orr II, Mosby Elsevier.
  • Contemporary Oral and Maxillofacial Surgery (6th Edition), James R Hupp, Edward Ellis III, Myron R Tucker, Mosby Elsevier.

*This article is an excerpt from the above mentioned books and Medical Sutras does not make any ownership or affiliation claims.