TREATMENT PLAN OF ALLERGIC RESPONSE DURING ANESTHESIA

                                               Allergic responses during anesthesia are not that rare and can be life threatening. Airway maintenance, 100% oxygen administration, intravenous volume expansion, and epinephrine are essential to treat the hypotension and hypoxia that result from vasodilation, increased capillary permeability and broncho spasm. All patients who have experienced an anaphylactic reaction should be admitted to an intensive care unit for 24 hours of monitoring because manifestations may recur after successful treatment.

INITIAL THERAPY:-

1. Stop administration of antigen.
2. MAINTAIN AIRWAY AND ADMINISTER 100% OXYGEN:- Profound ventilation-perfusion abnormalities producing hypoxia can occur with anaphylactic reactions. Always administer 100% oxygen with VENTILATORY SUPPORT as needed. 
3. DISCONTINUE ALL ANESTHETIC DRUGS:- Inhalational anesthetic drugs are not the broncho dilators of choice in treating broncho-spasm after anaphylaxis especially during hypotension. These drugs interfere with the body"s compensatory responses to cardiovascular collapse. Halothane sensitizes the heart to epinephrine.
4. VOLUME EXPANSION:-  Hypovolemia rapidly follows during anaphylactic shock. Initially 2 to 4 liters of lactated ringer"s solution, or colloid or normal saline should be administered, keeping in mind that an additional 25-50 ml/kg may be necessary if hypotension persists.
5. ADMINISTER EPINEPHRINE:- Epinephrine is the drug of choice because :-

                                a) Alfa adrenergic effects vasoconstrict to reverse hypotension.
                                b) Beta-2 receptor stimulation helps in broncho dilation.
                                c) It inhibits mediator release by increasing cAMP in mast cells and basophils
           In hypotensive patients, 5-10 micro gram boluses of epinephrine should be administered I/V to restore BP. Additional volumes and incrementally increased doses of epinephrine should be administered until hypotension is corrected. 0.1 to 1.0 mg of epinephrine should be given in patients with cardiovascular collapse. Patients with laryngeal edema without hypotension should receive S/C epinephrine.
SECONDARY TREATMENT:-

• ANTIHISTAMINES :- 0.5-1 mg/kg of diphenhydramine may be useful in  treating acute anaphylaxis. H1 antagonists available for parenteral administration may have ANTI-DOPAMINERGIC effects and should be given slowly to prevent precipitous hypotension potentially hypovolemic patients.
• CATECHOLAMINES :- Epinephrine infusions may be useful in patients with persistent hypotension or bronchospasm after initial resuscitation. DOSE - 5-10 micro grams /min and titrated to correct hypotension. Nor epinephrine is also given in doses of 5-10 micrograms/min.
• BRONCHODILATORS
• CORTICOSTEROIDS:- They are often administered as adjuncts to therapy when refractory bronchospasm or refractory shock occurs after resuscitation therapy.Recommended dose of hydrocortisone is 0.25-1 g I/V. Alternately 1-2 g of methyl prednisolone 30-35 mg/kg I/V may be useful. Administering corticosteroids after an  anaphylactic reaction may attenuate the late phase reactions reported to occur 12-24 hours after anaphylaxis
• AIRWAY EVALUATION:- Persistent facial edema suggests airway edema. The trachea of these patients should remain intubated until the edema subsides.
• REFRACTORY HYPOTENSION:- Vasopressin may attenuate pathologic induced vasodilation