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2005 Fiscal Year Final Research Report Summary

Experimental study on a causal relationship between sleeping in a face-down position and sudden death in infants

Research Project

Project/Area Number 16590549
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Legal medicine
Research InstitutionSt.Marianna University School of Medicine

Principal Investigator

MUKAI Toshiji  St.Marianna University of Medicine, Dept.of Legal Medicine, Professor and Charman, 医学部, 教授 (20200230)

Co-Investigator(Kenkyū-buntansha) YODA Takashi  St.Marianna University of Medicine, Dept.of Pediatrics, Lecturer, 医学部, 講師 (50220752)
HAYAKAWA Hideyuki  St.Marianna University of Medicine, Dept.of Legal Medicine, assistant, 医学部, 助手 (10373052)
Project Period (FY) 2004 – 2005
KeywordsSudden Infant Death Syndrome / prone sleeping / animal testing / re-breathing / suffocation
Research Abstract

An animal experiment was conducted to investigate whether covering both nose and mouth by bedding may cause lethal hypoxemia in healthy infants.
[Methods]
A mask of a dead infant was made of polyurethane resin, and a vertical load of 1.5 kg was added. An endotracheal tube was placed in a piglet and linked to the nasal cavity of the mask, through which the piglet breathed. Blood pressure (BP), heart rate (HR), arterial oxygen saturation (O_2sat), respiratory rate (RR), expired air oxygen concentration (exO_2) and expired air carbon dioxide concentration (exCO_2) were monitored continuously, and arterial oxygen concentration (PaO_2) and arterial carbon dioxide concentration (PaCO_2) were monitored as necessary. For bedding, soft and hard Japanese beds (futons) and a mattress dedicated for prone sleeping were used.
[Results]
1.When the mask was placed in a face-down position on the soft futon, the animal immediately started forced inspiration. O_2sat and exO_2 quickly decreased within three minutes, and PaO_2 decreased to 29.8 mmHg three minutes later. When the mask was placed in a face-up position three minutes later, respiratory condition and all test values quickly returned to normal.
2.When the mask was correspondingly placed on the hard futon, PaO_2 gradually decreased to 44.2 mmHg five minutes later, 30.1 mmHg 25 minutes later and 31.0 mmHg 35 minutes later. O_2sat and exO_2 also gradually decreased, and the animal died 50 minutes later.
3.When the mask was correspondingly placed on the mattress dedicated for prone sleeping, PaO_2 decreased to 36 mmHg five minutes later. O_2sat and exO_2 quickly decreased for the first three minutes and thereafter decreased as gradually as BP, HR and RR did, and the animal died 25 minutes later.
[Conclusion]
These findings suggest that infants may quickly die from hypoxemia caused by both nose and mouth being covered by bedding while they sleep in a prone position, especially in a face-down position.

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Published: 2007-12-13  

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