Parental Smoking and Airway Reactivity in Healthy Infants.
Am J Respir Crit Care Med. 2004 Oct 22 Tepper RS, Williams-Nkomo T, Martinez T, Kisling J, Coates C, Daggy J. Department of Pediatrics, Indiana University Medical Center, Indianapolis, IN, USA.
Parental tobacco smoking is associated with lower airway function and an increased incidence of wheezy respiratory illnesses in infants. We evaluated in 76 healthy infants whether exposure to parental tobacco smoking was associated with airway hyper-reactivity, which could contribute to lower airway function and the increased wheezy illnesses. Airway function was measured using the raised volume rapid thoracic compression technique and airway reactivity was assessed by methacholine challenge (0.015 - 10 mg/ml), which was stopped for >30% decrease in FEF75 or the final dose with < 30% decrease. Parental tobacco smoking was associated with lower baseline airway function (FEF50: 600 vs. 676 ml/s, p < 0.04 and FEF25-75: 531 vs. 597 ml/s, p < 0.05). Infants exposed to tobacco smoking were about half as likely to develop >30% decline in FEF75 at any given MCh dose (hazard ratio = 0.4, p = 0.001). In addition, a history of asthma in an extended family member increased the likelihood that an infant would develop >/=30% decline in FEF75 (hazard ratio=1.7, p=0.04). We conclude that exposure to parental smoking is associated with lower airway function, but not increased airway reactivity; however, family history of asthma is associated with heightened airway reactivity.