To investigate the compounding effects of cigarette smoking on other known risk factors for SIDS, namely thermal and oxygen stress, researchers exposed pregnant rat pups to either room air (control) or mainstream cigarette smoke equivalent to that a pack-a-day smoker would experience.
“Our approach sought to quantify the effects of cigarette smoke holistically, rather than using nicotine exposure as a proxy for cigarette smoke. Nicotine is just one of the 4,700 known toxins in cigarette smoke that could have protracted effects on embryonic development and postnatal growth,” said Dr. Shabih Hasan, staff neonatologist and associate professor in the department of pediatrics at the University of Calgary, and the principal investigator of the new study.
In this study, both plasma nicotine levels in the mothers and reduced birth weight in the pups were comparable to those of moderate to heavy smoking human mothers and the infants born to them. A total of 30 control and 39 cigarette smoke-exposed one-week-old rat pups were randomized to undergo either thermoneutral or hyperthermic exposure to an oxygen-depleted environment. Researchers then analyzed the respiratory responses to the challenges.
Overall, just 13 percent of the control animals exhibited gasping, whereas nearly three times that 36 percent of the cigarette smoke exposed animals did. Furthermore, none of the control animals exhibited gasping under hypoxic conditions during thermoneutral experiments, whereas 25 percent of the cigarette smoke exposed animals did. Under hyperthermic conditions, just 29 percent of the control group displayed gasping behavior, compared to nearly half of the cigarette smoke exposed group.
“These observations provide important evidence of how prenatal cigarette smoke exposure, hypoxic episodes and hyperthermia might place infants at higher risk for SIDS and further support efforts to foster prenatal smoking cessation programs”, said Hasan.
MEDICA.de; Source: American Thoracic Society