anaphylaxis in anesthesia

Clinical manifestations and management of anaphylactic reaction in anaesthesia practice?

Defination of anaphylaxis : It is  an “immediate systemic reaction caused by rapid, IgE-mediated immune release of potent mediators from tissue mast cells and basophils.”

anaphylactoid reactions, which “mimic signs and symptoms of anaphylaxis, but are caused by the non-IgE-mediated release of potent mediators from mast cells and basophils.”

What Is the Pathophysiology  and clinical features of anaphylactic reaction?

Antigen binding to IgE antibodies causes anaphylaxis,Prior exposure to the antigen or a substance of similar structure is needed to produce sensitization, 

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On reexposure, the antigen binds to bridge two immunospecific IgE antibodies on the surfaces of mast cells and basophils to release a complex series of inflammatory molecules that can be sufficient to produce acute cardiopulmonary dysfunction

Clinical Menifestions of anaphylactic reaction:

The released mediators produce a symptom complex of 

• bronchospasm and upper airway edema in the respiratory system, 
• vasodilation and increased capillary permeability in the cardiovascular system, and 
• urticaria in the cutaneous system.

Signs and Symptoms of Anaphylaxis

CUTANEOUS: Itching, flushing, urticaria , angioedema (perioral), and sweating

OPHTHALMIC: Itching, tearing, periorbital edema

NOSE AND MOUTH: Sneezing, runny nose, nasal congestion

RESPIRATORY TRACT: Difficulty in breathing, sensation of choking, wheezing, increased airway secretions, swelling of the upper throat, hoarseness; patients may have wheezing, increased airway pressures during positive pressure ventilation

CARDIOVASCULAR SYSTEM: Palpitations, arrhythmias (supraventricular, ventricular, and asystole), hypotension, and cardiac arrest; patients may also display vasodilatory shock (low systemic vascular resistance) and pulmonary vasoconstriction

GASTROINTESTINAL SYSTEM: Nausea, vomiting, abdominal cramps, bloating, and diarrhea

NERVOUS SYSTEM: Dizziness, weakness, fainting, a sense of impending doom, and seizures

Management of anaphylaxis

1) STOP ANTIGEN ADMINISTRATION: This may prevent further inflammatory cell recruitment. If the culprit antigen is not known, terminating the administration may not be possible.

2)MAINTAIN AIRWAY AND ADMINISTER 100% OXYGEN: Hypoxemia is one of the most severe problems associated with anaphylaxis and hence 100% oxygen supplementation of the airway and ventilatory support is needed and monitored with pulse oximetry and end-tidal carbon dioxide monitoring. Additionally, arterial blood gas analysis can be very helpful during resuscitation.

3)DISCONTINUE ALL ANESTHETIC DRUGS: Patients develop shock and cardiopulmonary dysfunction following anaphylactic reactions and as the  Anesthetic drugs interfere with the body's compensatory response to cardiovascular collapse they are discontinued.

4)START INTRAVASCULAR VOLUME EXPANSION:Volume expansion, as well as vasopressor support, is to attenuate acute hypotension. Initially, 25 to 50 mL per kg of lactated Ringer's solution, colloid, or normal saline is administered and monitored to give Additional volume if hypotension persists.

GIVE EPINEPHRINE: Epinephrine is the mainstay agent when resuscitating patients during anaphylactic shock. α-adrenergic effects vasoconstrict venous capacitance beds and arterial resistance vessels to reverse hypotension; β2 receptor stimulation produces bronchodilation and recommendations are to use epinephrine 0.1 mg IV slowly over 5 minutes. (Epinephrine may be diluted.) An epinephrine infusion at rates of 1 to 4 µg per minute may prevent the need to repeat the dose but critical monitoring is essential.

Secondary treatment

• Corticosteroids
• Catecholamines 
• Antihistamine 
• Additional monitoring
• Documentation