What is the treatment for local anesthetic allergic reactions?
Mast cell degranulation liberates histamine, leukotrienes, prostaglandins, platelet-activating factor, and kinins that produce adverse systemic effects. Table 55.2 summarizes the clinical manifestations of allergic reactions and notes specific therapy for potentially lethal reactions. Management of allergic reactions requires immediate identification of the offending agent and cessation of its administration. Cutaneous manifestations such as itching, burning, urticaria, or flushing can be treated with diphenhydramine, 0.5–1.0 mg/kg intravenously. Respiratory signs, including coughing and wheezing, are indications for supplemental oxygen and bronchodilators. The inhaled β-2-selective agents, such as albuterol, are the preferred bronchodilators. Severe cases may require epinephrine or isoproterenol. Laryngeal edema, pulmonary edema, and other signs of respiratory distress require endotracheal intubation and positive pressure ventilation. Mild hypotension is treated with intravenous fluids. Profound hypotension requires therapy with fluids and epinephrine. Epinephrine 0.5–1.0 mg is administered for cardiovascular collapse. Hydrocortisone or methylprednisolone helps prevent future reactions but probably does little for the acute situation. When endotracheal intubation is performed for airway edema, extubation should be preceded by a deflation test. To perform this test, deflate the endotracheal tube’s cuff, administer positive-pressure ventilation, and listen for gas escaping between the tube and the airway. The absence of gas escaping from the outside the endotracheal tube suggests persistent airway edema.