Clinical effects of combined anti-H1 and anti-H2 treatment in patients presenting with acute allergic syndromes: A randomized controlled trial

Management of anaphylaxis in children

Anaphylaxis is a severe, life-threatening immunoglobulin E (IgE)-mediated hypersensitivity reaction. The key to successful management of anaphylaxis involves rapid diagnosis, assessment, and early initiation of therapy. Epinephrine is the undisputed initial therapy for anaphylaxis, and its administration should never be delayed. In most cases, additional interventions such as oxygen therapy, fluid resuscitation, beta-agonists, antihistamines, and corticosteroids should be strongly considered. Although hospital course must be individualized to meet each patient's needs, a minimum of 4 to 6 hours of observation period after complete symptom resolution may be reasonable to monitor for recurrence of symptoms and biphasic reaction. Before discharge, every patient should receive patient education about anaphylaxis, a prescription for self-injectable epinephrine, and instructions for follow-up care.

Histamine and tryptase levels in patients with acute allergic reactions: An emergency department-based study

BACKGROUND

Emergency department visits for acute allergic reactions are common. Although the diagnosis and classification of these allergic reactions is primarily empiric, it is not always clear whether certain signs and symptoms constitute systemic mediator release syndromes, such as anaphylaxis, and thus may warrant more aggressive therapy or follow-up.

OBJECTIVE

We sought to determine associations between various clinical signs and symptoms with both plasma histamine levels and serum tryptase levels in adult patients presenting to an emergency department with acute allergic syndromes. The clinical correlates of raised beta-tryptase levels were also investigated.

METHODS

Ninety-seven adult emergency department patients were prospectively studied by using a questionnaire, physical examination, and serum-plasma sampling. Plasma histamine and serum total and beta-tryptase levels were determined. Clinical groupings were compared for mediator levels by using simple and multivariate analysis.

RESULTS

Elevated levels of plasma histamine (>10 nmol/L) and serum total tryptase (>15 ng/mL) were observed in 42 and 20 patients, respectively. Detectable beta-tryptase (>/=1 ng/mL) was observed in 23 patients, including 15 of the patients with elevated total tryptase levels. Suspected food allergy incidences and the duration of reaction were similar in patients with increased histamine levels and in patients with increased tryptase levels. Increased total tryptase levels, histamine levels, or both were observed in some patients who did not have airway, cardiovascular, or abdominal signs. Histamine levels correlated better with clinical signs than tryptase levels. Histamine elevations (>10 nmol/L) were observed more frequently in patients characterized by the following clinical signs in univariate analysis: the presence of urticaria, more extensive erythema, abnormal abdominal findings, and wheezing. Total tryptase increases were observed more frequently only in patients with urticaria. Histamine levels correlated with initial heart rates. In multivariate analysis the extent of urticaria was the best single predictor of plasma histamine levels and of either an elevated histamine or tryptase level. Detectable beta-tryptase levels were observed in some patients who had neither elevated total tryptase nor elevated histamine levels. Unlike patients without detectable beta-tryptase levels, patients who had detectable beta-tryptase levels had a significant correlation between total tryptase and histamine levels (P <.05).

CONCLUSIONS

Raised histamine and, less commonly, raised tryptase levels are observed in almost 50% of patients presenting to emergency departments with acute allergic reactions. Some cases associated with systemic mediator release do not have classical features of severe anaphylaxis, such as hypotension or tachycardia. The lack of total tryptase elevations in many patients with elevated plasma histamine levels suggests basophil involvement. The clinical utility of beta-tryptase determinations in the evaluation of acute allergic reactions needs further study.