Air movement in the human sleeping environment and sudden infant death

John Andrew Corbyn

Searches for disease or abnormality within the infant have not led to an explanation for many Sudden Infant Death Syndrome or SIDS cases. The following study is concerned with the analysis of SIDS in terms of the microclimate at the face and the inhalation of previously exhaled air. The inhalation of previously exhaled air is known as re-breathing. The physiology of re-breathing and SIDS is discussed. Statistical data concerning SIDS and environmental conditions is reviewed. It was found that exhaled air can accumulate at the face of a sleeping infant with an excess of carbon dioxide and a deficiency of oxygen. Transport of these gases is affected by jet action of the nose, temperature, .humidity, pollution (which affects aerosol formation) and other conditions. A simulator for studying sleeping environments is described. It was found that in certain circumstances the carbon dioxide content of inhaled air can be above the industrial threshold limit of 0.5% with values of over 2% occurring. It is found that physiological mechanisms exist such that a re-breathing; of vitiated air can account for a proportion of SIDS cases. In particular a sleeping infant acclimatized to an atmosphere with excess carbon dioxide may suffer from a reduced lung ventilation rate on subsequent exposure to a normal atmosphere. The associations between SIDS and particular environmental conditions were found to be consistent with re-breathing as a cause of SIDS. It is recommended that sleeping infants have unobstructed passage of exhaled air away from the face. Detailed safety precautions are given. Investigations of SIDS deaths should include physical model studies of the environment in which they occurred. Investigations for evidence of past exposure to continual re-breathing among SIDS victims is necessary.

Air movement in the human sleeping environment and sudden infant death

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