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)
|Budget Amount *help
¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 2005: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2004: ¥1,800,000 (Direct Cost: ¥1,800,000)
An animal experiment was conducted to investigate whether covering both nose and mouth by bedding may cause lethal hypoxemia in healthy infants.
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.
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.
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.