Airway reactivity in infants

A positive response to methacholine and metaproterenol

Research output: Contribution to journalArticle

98 Citations (Scopus)

Abstract

Because the presence of bronchial smooth muscle reactivity in infants remains controversial, airway reactivity was assessed in 10 normal, asymptomatic male infants <15 mo of age by measuring the changes that occurred in the maximal expiratory flows at functional residual capacity (V̇maxFRC) during a methacholine bronchial challenge test. Sleeping infants inhaled doubling concentrations of methacholine by 2 min of tidal breathing, starting with a concentration of 0.075 mg/ml, and the bronchial challenge was stopped when V̇maxFRC decreased by at least 40%. The threshold concentration of methacholine required to produce a decrease in V̇maxFRA by 2 SD's of the control value was 0.43 mg/ml (0.11-0.90). By a methacholine concentration of 1.2 mg/ml, all infants decreased V̇maxFRC by at least 40% (range 404-75%), and the mean dose required to produce a 40% decrease was 0.72 mg/ml. The airway reactivity was not related to base-line flows. During the methacholine challenge, no infant developed wheezing, but the percent oxygen saturation of the group decreased significantly (P < 0.05) from 94 to 92%. Following the methacholine, the infants inhaled the bronchodilator metaproterenol, and 10 min later, V̇maxFRC returned to the base line. This study demonstrates that infants exhibit airway reactivity as evidenced by bronchoconstriction with methacholine and the subsequent bronchodilation with metaproterenol.

Original languageEnglish
Pages (from-to)1155-1159
Number of pages5
JournalJournal of Applied Physiology
Volume62
Issue number3
StatePublished - 1987

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Metaproterenol
Methacholine Chloride
Bronchial Provocation Tests
Functional Residual Capacity
Bronchoconstriction
Bronchodilator Agents
Respiratory Sounds
Smooth Muscle
Respiration
Oxygen

ASJC Scopus subject areas

  • Endocrinology
  • Physiology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

Airway reactivity in infants : A positive response to methacholine and metaproterenol. / Tepper, Robert.

In: Journal of Applied Physiology, Vol. 62, No. 3, 1987, p. 1155-1159.

Research output: Contribution to journalArticle

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abstract = "Because the presence of bronchial smooth muscle reactivity in infants remains controversial, airway reactivity was assessed in 10 normal, asymptomatic male infants <15 mo of age by measuring the changes that occurred in the maximal expiratory flows at functional residual capacity (V̇maxFRC) during a methacholine bronchial challenge test. Sleeping infants inhaled doubling concentrations of methacholine by 2 min of tidal breathing, starting with a concentration of 0.075 mg/ml, and the bronchial challenge was stopped when V̇maxFRC decreased by at least 40{\%}. The threshold concentration of methacholine required to produce a decrease in V̇maxFRA by 2 SD's of the control value was 0.43 mg/ml (0.11-0.90). By a methacholine concentration of 1.2 mg/ml, all infants decreased V̇maxFRC by at least 40{\%} (range 404-75{\%}), and the mean dose required to produce a 40{\%} decrease was 0.72 mg/ml. The airway reactivity was not related to base-line flows. During the methacholine challenge, no infant developed wheezing, but the percent oxygen saturation of the group decreased significantly (P < 0.05) from 94 to 92{\%}. Following the methacholine, the infants inhaled the bronchodilator metaproterenol, and 10 min later, V̇maxFRC returned to the base line. This study demonstrates that infants exhibit airway reactivity as evidenced by bronchoconstriction with methacholine and the subsequent bronchodilation with metaproterenol.",
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