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Updated: Aug 2, 2026

A Swine Model of Neonatal Asphyxia
Published on: October 11, 2011
Dampened ventilatory response to added dead space in newborns of smoking mothers
R Y Bhat1, S Broughton, B Khetriwal
1Division of Asthma, Allergy and Lung Biology, Guy's, King's and St Thomas' School of Medicine, King's College London, UK.
Background:
Term newborns can compensate fully for an imposed dead space (tube breathing) by increasing their minute ventilation.
Objective:
To test the hypothesis that infants of smoking mothers would have an impaired response to tube breathing.
Design:
Prospective study.
Setting:
Perinatal service.
Patients:
Fourteen infants of smoking and 24 infants of non-smoking mothers (median postnatal age 37 (11-85) hours and 26 (10-120) hours respectively) were studied.
Interventions:
Breath by breath minute volume was measured at baseline and when a dead space of 4.4 ml/kg was incorporated into the breathing circuit.
Main Outcome Measures:
The maximum minute ventilation during tube breathing was determined and the time constant of the response calculated.
Results:
The time constant of the infants of smoking mothers was longer than that of the infants of non-smoking mothers (median (range) 37.3 (22.2-70.2) v 26.2 (13.8-51.0) seconds, p = 0.016). Regression analysis showed that maternal smoking status was related to the time constant independently of birth weight, gestational or postnatal age, or sex (p = 0.018).
Conclusions:
Intrauterine exposure to smoking is associated with a dampened response to tube breathing.
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