Expired nitric oxide and airway reactivity in infants at risk for asthma.
BACKGROUND
Family histories of atopy, as well as histories of atopic dermatitis and food allergy, are important risk factors for an infant to have asthma. Although atopic sensitization appears to contribute to the development of asthma, it is unclear when the airways become involved with the atopic process and whether airway function relates to the atopic characteristics of the infant.


OBJECTIVE
We sought to evaluate whether atopic infants without prior episodes of wheezing have increased expired nitric oxide (eNO) levels and heightened airway reactivity.


METHODS
Infants with eczema were recruited, and atopic status was defined by specific IgE levels to foods or aeroallergens and total IgE levels. eNO, forced expiratory flow at 75% exhaled volume (FEF(75)), and airway reactivity to inhaled methacholine were measured in sedated infants. Airway reactivity was quantified by using the provocative concentration to decrease FEF(75) by 30%.


RESULTS
Median age for the 114 infants evaluated was 10.7 months (range, 2.6-19.1 months). Infants sensitized to egg or milk compared with infants sensitized to neither egg nor milk had lower flows (FEF(75): 336 vs 285 mL/s, P < .003) and lower lnPC(30) (mg/mL) provocative concentrations to decrease FEF(75) by 30% (-0.6 vs -1.2, P < .02) but no difference in eNO levels. Infants with total serum IgE levels of greater than 20 IU/mL had higher eNO levels compared with infants with IgE levels of 20 IU/mL or less (14.6 vs 11.2 ppb, P < .023) but no difference in forced flows or airway reactivity.


CONCLUSIONS
Our findings suggest that atopic characteristics of the infant might be important determinants of the airway physiology of forced expiratory flows, airway reactivity, and eNO.
Tepper
Robert S
RS
Department of Pediatrics, Indiana University Medical Center, James Whitcomb Riley Hospital for Children, Wells Center for Pediatric Research, Indianapolis, Ind. Electronic address: rtepper@iupui.edu.
Llapur
Conrado J
CJ
Department of Pediatrics, Hospital del Niño Jesús, Cátedra de Metodología de la Investigación, Facultad de Medicina, Universidad Nacional de Tucumán, Tucumán, Argentina.
Jones
Marcus H
MH
Department of Pediatrics, Pontifícia Universidade Católica do Rio Grande do Sul, Porte Alegre, Brazil.
Tiller
Christina
C
Department of Pediatrics, Indiana University Medical Center, James Whitcomb Riley Hospital for Children, Wells Center for Pediatric Research, Indianapolis, Ind.
Coates
Cathy
C
Department of Pediatrics, Indiana University Medical Center, James Whitcomb Riley Hospital for Children, Wells Center for Pediatric Research, Indianapolis, Ind.
Kimmel
Risa
R
Department of Pediatrics, Indiana University Medical Center, James Whitcomb Riley Hospital for Children, Wells Center for Pediatric Research, Indianapolis, Ind.
Kisling
Jeffrey
J
Department of Pediatrics, Indiana University Medical Center, James Whitcomb Riley Hospital for Children, Wells Center for Pediatric Research, Indianapolis, Ind.
Katz
Barry
B
Department of Biostatistics, Indiana University Medical Center, Indianapolis, Ind.
Ding
Yan
Y
Department of Biostatistics, Indiana University Medical Center, Indianapolis, Ind.
Swigonski
Nancy
N
Department of Pediatrics, Indiana University Medical Center, James Whitcomb Riley Hospital for Children, Wells Center for Pediatric Research, Indianapolis, Ind.