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A Piglet Model of Neonatal Hypoxic-Ischemic Encephalopathy
Published on: May 16, 2015
Prenatal cigarette smoke exposure attenuates recovery from hypoxemic challenge in preterm infants
Jennifer Schneider1, Ian Mitchell, Nalini Singhal
1Department of Pediatrics and Institute of Maternal and Child Health, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada.
Insights
Prenatal cigarette smoke exposure impairs breathing pause recovery and oxygen saturation in preterm infants during hypoxemia. This may increase their risk for sudden infant death syndrome.
Area of Science:
- Neonatal physiology
- Respiratory control
- Environmental influences on infant health
Background:
- Cardiorespiratory control is immature in preterm infants, increasing vulnerability.
- Limited data exist on prenatal cigarette smoke (CS) exposure effects in this population.
- Prenatal CS exposure and hypoxemia can impact cardiorespiratory regulation.
Purpose of the Study:
- To assess the impact of prenatal CS exposure on breathing pauses and oxygen saturation in preterm infants.
- To investigate these effects under both baseline and hypoxemic conditions.
- To determine if prenatal CS exposure alters recovery from breathing pauses and hypoxemia.
Main Methods:
- Studied 22 preterm infants (28-36 weeks gestation), comparing 12 exposed to prenatal CS with 10 controls.
- Recorded cardiorespiratory variables under normoxemic and hypoxemic conditions.
- Analyzed breathing pause duration, recovery, oxygen saturation (SpO2), and heart rate.
Main Results:
- CS-exposed infants showed delayed spontaneous recovery of breathing pauses and lower SpO2 during and after hypoxemia.
- Heart rate increased significantly more in CS-exposed infants during hypoxemia.
- No significant difference in wakefulness episodes during hypoxemia between groups.
Conclusions:
- Prenatal CS exposure significantly affects breathing pause dynamics and oxygenation in preterm infants during hypoxemia.
- These cardiorespiratory alterations may contribute to the increased risk of sudden infant death syndrome (SIDS) in exposed infants.
- Findings highlight the critical need to address prenatal CS exposure to improve preterm infant outcomes.
Rationale:
The effects of prenatal cigarette smoke (CS) exposure and hypoxemia on cardiorespiratory control have been investigated in full-term infants. However, few data are available in preterm infants, who form a particularly vulnerable population, with developmentally immature cardiorespiratory control.
Objectives:
To investigate the effects of prenatal CS exposure on the duration and recovery of breathing pauses and oxygen saturation levels under baseline and hypoxemic conditions in preterm infants.
Methods:
The study was performed on 22 (12 born to smoking and 10 to nonsmoking mothers) spontaneously breathing preterm infants between 28 and 36 weeks' gestation. Cardiorespiratory variables were recorded under baseline normoxemic and hypoxemic conditions.
Measurements And Main Results:
Breathing pauses, pause indices, time to recovery, percent pause recovery, oxygen saturation (Sp(O2)), periods of wakefulness, and cardiorespiratory rates were compared between the two groups. Spontaneous recovery of breathing pauses (P = 0.03) and Sp(O(2)) levels (P = 0.017) were attenuated in CS-exposed infants as compared with the control group during the hypoxemic and posthypoxemic periods, respectively. The episodes of wakefulness during the hypoxemic challenge were similar between the two groups. Furthermore, CS-exposed infants showed a greater increase in heart rate (P < 0.001) during the hypoxemic challenge when compared with control infants.
Conclusions:
We provide evidence of how prenatal CS exposure and hypoxemic episodes affect the duration and recovery of breathing pauses in preterm infants. These observations could help explain why these infants are at a particularly high risk for sudden infant death syndrome.
