Maternal smoking is a major risk factor for SIDS. The mechanism of action may be a nicotine mediated attenuation of the hypoxic defense as evidenced by impaired arousal and blunted ventilatory response to acute hypoxemia in young lambs exposed to an acute nicotine infusion (Hafström et al, Pediatr Res 39:386A, 1996). The aim of this study was to determine whether prenatal nicotine exposure alters the cardiorespiratory response to hypoxia after birth.
Subjects & Methods: Five pregnant ewes were infused continously with nicotine, 40 mg/d, during the last trimester. Nicotine conc. were 6.7 ± 1.0 ng/ml. Five lambs acted as controls (CTRL). Hypoxic tests (change in minute ventilation (V1), oxygen saturation(SaO2), heartrate (HR) and bloodpressure (BP) to FiO2 0.1 for 5 min) were performed during quiet sleep.
Results: Nicotine treated (NIC) lambs increased their ventilation and heartrate significantly less and decreased their SaO2 significantly more than controls. BP change did not differ. Table
Conclusion: Prenatal nicotine exposure has marked inhibitory effects on the cardiorespiratory response to hypoxemia. The combination of a minimal heart rate increase and a reduced ventilatory response suggests that prenatal nicotine exposure impairs sympathetic activiation during hypoxic stress. (HD 28916)
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Hafström, O., Milerad, J., Poole, S. et al. Prenatal nicotine exposure impairs the cardiorespiratory response to acute hypoxemia in sleeping lambs. • 1798. Pediatr Res 41, 302 (1997). https://doi.org/10.1203/00006450-199704001-01817
Acta Paediatrica (2007)