Airway Responsiveness-Associated Features in Infants with Recurrent Respiratory Symptoms

¹ Dept of Allergology, Helsinki University Central Hospital, Helsinki, Finland

^* To whom correspondence should be addressed. E-mail: pekka.malmberg{at}hus.fi.

	Abstract

Increased airway responsiveness (AR) is one of the main pathophysiological manifestations of asthma. We aimed to define the clinical features associated with increased AR in infants with recurrent lower respiratory tract symptoms. AR was evaluated by performing a novel dosimetric methacholine challenge test.

Increased AR to methacholine, defined as a methacholine dose of 0.90 mg producing a 40% fall (PD₄₀) in the maximal flow at functional residual capacity (V'_{max, FRC}), was associated with atopy (OR 4.1; 95% CI 1.3–13.3), a history of physician-confirmed wheezing with respiratory syncytial virus (32.9; 2.5–428.8) or by a non-specified aetiology (4.9; 1.1–22.5), functional residual capacity (FRC) z-score of 2 (36.8; 2.9–472.6), and V'_{max, FRC} z-score (0.5; 0.2–0.9) at baseline, when compared with infants with only mild or no responsiveness to methacholine (PD₄₀V'_{max, FRC} >0.90 mg).

In conclusion, in recurrently symptomatic infants, increased AR is associated with reduced baseline lung function, an atopic trait of the child, a history of physician-confirmed wheeze, and a viral aetiology of wheeze. Future intervention studies are needed to confirm the role of AR in respiratory morbidity during infancy.

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				A. Kotaniemi-Syrjanen, A. Pelkonen, K. Malmstrom, P. Malmberg, and M. Makela Infants with recurrent lower respiratory tract symptoms - who benefits of extensive investigations? Eur. Respir. Rev., April 1, 2008; 17(107): 24 - 25. [Abstract] [Full Text] [PDF]